ABCMdb

ABCB1 p.Asn21Asp

Predicted by SNAP2:	A: N (72%), C: D (63%), D: N (61%), E: N (87%), F: N (66%), G: N (78%), H: N (78%), I: N (72%), K: N (87%), L: N (72%), M: N (82%), P: D (63%), Q: N (87%), R: N (82%), S: N (78%), T: N (87%), V: N (72%), W: N (57%), Y: N (57%),
Predicted by PROVEAN:	A: N, C: N, D: N, E: N, F: N, G: N, H: N, I: N, K: N, L: N, M: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: N, Y: N,

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[hide] Mechanisms of resistance to anticancer drugs: the ... Pharmacogenomics. 2005 Mar;6(2):115-38. Lepper ER, Nooter K, Verweij J, Acharya MR, Figg WD, Sparreboom A
Mechanisms of resistance to anticancer drugs: the role of the polymorphic ABC transporters ABCB1 and ABCG2.
Pharmacogenomics. 2005 Mar;6(2):115-38., [PMID:15882131]

Abstract [show]
ATP-binding cassette (ABC) genes play a role in the resistance of malignant cells to anticancer agents. The ABC gene products, including ABCB1 (P-glycoprotein) and ABCG2 (breast cancer-resistance protein [BCRP], mitoxantrone-resistance protein [MXR], or ABC transporter in placenta [ABCP]), are also known to influence oral absorption and disposition of a wide variety of drugs. As a result, the expression levels of these proteins in humans have important consequences for an individual's susceptibility to certain drug-induced side effects, interactions, and treatment efficacy. Naturally occurring variants in ABC transporter genes have been identified that might affect the function and expression of the protein. This review focuses on recent advances in the pharmacogenetics of the ABC transporters ABCB1 and ABCG2, and discusses potential implications of genetic variants for the chemotherapeutic treatment of cancer.

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90 A detailed analysis of the potential functional consequences of different ABCB1 variants has not yet been performed, except for the five most common non-synonymous coding SNPs (i.e., Asn21Asp, Phe103Leu, Ser400Asn, Ala893Ser/Thr, and Ala998Thr) as assessed by a vaccinia virus-based transient expression system [74]. Login to comment
106 Nonetheless, the association of the C3435T polymorphism with Table 2. Summary of common genetic variants in the ABCB1 gene cDNA position* Region‡ Wild-type allele Variant allele Amino acid Change§ -274 Intron -1 G A -223 Intron -1 C T -146 Intron -1 T C -60 Intron -1 A T -41 Intron -1 A G Non-coding -241 Exon 1 G A Non-coding -145 Exon 1 C G Non-coding -129 Exon 1 T C Non-coding -43 Exon 1 A G Non-coding +140 Intron 1 C A +237 Intron 1 G A -4 Exon 2 C T Non-coding -1 Exon 2 G A Non-coding 61 Exon 2 A G 21 Asn to Asp -8 Intron 3 C G 266 Exon 4 T C 89 Met to Thr 307 Exon 5 T C 103 Phe to Leu -25 Intron 4 G T +139 Intron 6 C T +145 Intron 6 C T 548 Exon 7 A G 183 Asn to Ser 729 Exon 8 A G 243 Syn 781 Exon 8 A G 261 Ile to Val -44 Intron 9 A G -41 Intron 10 T G 1199 Exon 11 G A 400 Ser to Asn -4 Intron 11 G A 1236¶ Exon 12 C T 412 Syn 1308 Exon 12 A G 436 Syn +17 Intron 12 G A +44 Intron 12 C T 1474 Exon 13 C T 492 Arg to Cys +24 Intron 13 C T 1617 Exon 14 C T 539 Syn +38 Intron 14 A G +38 Intron 15 G A 1985 Exon 16 T G 662 Leu to Arg 2005 Exon 16 C T 669 Arg to Cys -27 Intron 17 A G +8 Intron 20 C G *cDNA numbers are relative to the ATG site and based on the cDNA sequence from GenBank accession number M14758 with an A as the reference at position 43. Login to comment

[hide] Genetic polymorphisms of ATP-binding cassette tran... Expert Opin Pharmacother. 2005 Nov;6(14):2455-73. Sakurai A, Tamura A, Onishi Y, Ishikawa T
Genetic polymorphisms of ATP-binding cassette transporters ABCB1 and ABCG2: therapeutic implications.
Expert Opin Pharmacother. 2005 Nov;6(14):2455-73., [PMID:16259577]

Abstract [show]
Pharmacogenomics, the study of the influence of genetic factors on drug action, is increasingly important for predicting pharmacokinetics profiles and/or adverse reactions to drugs. Drug transporters, as well as drug metabolism play pivotal roles in determining the pharmacokinetic profiles of drugs and their overall pharmacological effects. There is an increasing number of reports addressing genetic polymorphisms of drug transporters. However, information regarding the functional impact of genetic polymorphisms in drug transporter genes is still limited. Detailed functional analysis in vitro may provide clear insight into the biochemical and therapeutic significance of genetic polymorphisms. This review addresses functional aspects of the genetic polymorphisms of human ATP-binding cassette transporters, ABCB1 and ABCG2, which are critically involved in the pharmacokinetics of drugs.

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94 Kimchi-Sarfaty et al. [73] assessed the five most common coding SNPs (i.e., N21D, F103L, S400N, A893S and A999T) by using a vaccinia virus-based transient expression system. Login to comment
106 Position Allele Amino acid Allele frequency in Caucasian populations Allele frequency in Japanese populatins Allele frequency in African populations n % n % n % 61 A G 21 Asn 21 Asp 799 89.7 10.3 193 100 0 100 97.5 2.5 266 T C 89 Met 89 Thr 100 99.5 0.5 145 100 0 100 100 0 307 T C 103 Phe 103 Leu 546 99.9 0.1 48 100 0 ND ND ND 325 G A 108 Glu 108 Lys ND ND ND 37 95.9 4.1 ND ND ND 781 A G 261 Ile 261 Val 100 100 0 145 100 0 100 98.5 1.5 1199 G A 400 Ser 400 Asn 696 95.0 5.0 193 100 0 100 99 1 1985 T G 662 Leu 662 Arg 100 99.5 0.5 145 100 0 100 100 0 2005 C T 669 Arg 669 Cys 100 100 0 145 100 0 100 99 1 2485 A G 829 Ile 829 Val 185 99.2 0.8 ND ND ND ND ND ND 2547 A G 849 Ile 849 Met 100 99.5 0.5 145 100 0 100 100 0 2677 G T A 893 Ala 893 Ser 893 Thr 611 55.1 42.1 2.8 241 40.0 41.1 18.9 100 90 10 0.5 2956 A G 986 Met 986 Val ND ND ND 100 99.5 0.5 ND ND ND 3151 C G 1051 Pro 1051 Ala 100 100 0 145 100 0 100 99.5 0.5 3320 A C 1107 Gln 1107 Pro 461 99.8 0.2 ND ND ND ND ND ND 3322 T C 1108 Trp 1108 Arg 100 100 0 145 100 0 100 99.5 0.5 3421 T A 1141 Ser 1141 Thr 100 100 0 145 100 0 100 88.9 11.1 3751 G A 1251 Val 1251 Ile 100 100 0 145 99 1 100 100 0 3767 C A 1256 Thr 1256 Lys 100 99.5 0.5 145 100 0 100 100 0 Data from [31-38, 203]. Login to comment
129 N21D M89T N44S H2N F103L E108K N183S G185V I261V S400N R492C A599T L662R R669C V801M A893S/T I829V I849M M986V A999T G1063A P1051A Q1107P W1108R I1145M S1141T V1251I T1256K COOH ATP-binding site ATP-binding site EXTRACELLULAR INTRACELLULAR A80E Figure 2. Login to comment

[hide] Role of pharmacogenetics of ATP-binding cassette t... Pharmacol Ther. 2006 Nov;112(2):457-73. Cascorbi I
Role of pharmacogenetics of ATP-binding cassette transporters in the pharmacokinetics of drugs.
Pharmacol Ther. 2006 Nov;112(2):457-73., [PMID:16766035]

Abstract [show]
Interindividual differences of drug response are an important cause of treatment failures and adverse drug reactions. The identification of polymorphisms explaining distinct phenotypes of drug metabolizing enzymes contributed in part to the understanding of individual variations of drug plasma levels. However, bioavailability also depends on a major extent from the expression and activity of drug transport across biomembranes. In particular efflux transporters of the ATP-binding cassette (ABC) family such as ABCB1 (P-glycoprotein, P-gp), the ABCC (multidrug resistance-related protein, MRP) family and ABCG2 (breast cancer resistance protein, BCRP) have been identified as major determinants of chemoresistance in tumor cells. They are expressed in the apical membranes of many barrier tissue such as the intestine, liver, blood-brain barrier, kidney, placenta, testis and in lymphocytes, thus contributing to plasma, liquor, but also intracellular drug disposition. Since expression and function exhibit a broad variability, it was hypothesized that hereditary variances in the genes of membrane transporters could explain at least in part interindividual differences of pharmacokinetics and clinical outcome of a variety of drugs. This review focuses on the functional significance of single nucleotide polymorphisms (SNP) of ABCB1, ABCC1, ABCC2, and ABCG2 in in vitro systems, in vivo tissues and drug disposition, as well as on the clinical outcome of major indications.

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761 0.09d c. 61 A>G N21D 0.11d IVS 5-35 G>C intronic 0.006c IVS 5-25 G>T intronic 0.16c IVS 6+139 C>T intronic 0.37d c. 548 A>G N183S 0.01e c. 1199 G>A S400N 0.05d c. 1236 C>T synonymous 0.41d IVS 12+44 C>T intronic 0.05d c. 1474 C>T R492C 0.01e IVS 17-76 T>A intronic 0.46d IVS 17+137 A>G intronic 0.006c c. 2650 C>T synonymous 0.03e c. 2677 G>T/A A893S/T 0.42d /0.02d c. 2956 A>G M986V 0.005b c. 3320 A>C Q1107P 0.002d c. 3396 C>T synonymous 0.03c c. 3421 T>A S1141T 0.00c c. 3435 C>T synonymous 0.54e c. 4030 G >C synonymous 0.005b c. 4036 A>G synonymous 0.30b a Taniguchi et al. (2003). Login to comment

[hide] Clinical pharmacogenetics and potential applicatio... Curr Drug Metab. 2008 Oct;9(8):738-84. Zhou SF, Di YM, Chan E, Du YM, Chow VD, Xue CC, Lai X, Wang JC, Li CG, Tian M, Duan W
Clinical pharmacogenetics and potential application in personalized medicine.
Curr Drug Metab. 2008 Oct;9(8):738-84., [PMID:18855611]

Abstract [show]
The current 'fixed-dosage strategy' approach to medicine, means there is much inter-individual variation in drug response. Pharmacogenetics is the study of how inter-individual variations in the DNA sequence of specific genes affect drug responses. This article will highlight current pharmacogenetic knowledge on important drug metabolizing enzymes, drug transporters and drug targets to understand interindividual variability in drug clearance and responses in clinical practice and potential use in personalized medicine. Polymorphisms in the cytochrome P450 (CYP) family may have had the most impact on the fate of pharmaceutical drugs. CYP2D6, CYP2C19 and CYP2C9 gene polymorphisms and gene duplications account for the most frequent variations in phase I metabolism of drugs since nearly 80% of drugs in use today are metabolised by these enzymes. Approximately 5% of Europeans and 1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant drug metabolising enzyme that demonstrates genetic variants. Studies into CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and CYP2C9*3 alleles. Extensive polymorphism also occurs in a majority of Phase II drug metabolizing enzymes. One of the most important polymorphisms is thiopurine S-methyl transferases (TPMT) that catalyzes the S-methylation of thiopurine drugs. With respect to drug transport polymorphism, the most extensively studied drug transporter is P-glycoprotein (P-gp/MDR1), but the current data on the clinical impact is limited. Polymorphisms in drug transporters may change drug's distribution, excretion and response. Recent advances in molecular research have revealed many of the genes that encode drug targets demonstrate genetic polymorphism. These variations, in many cases, have altered the targets sensitivity to the specific drug molecule and thus have a profound effect on drug efficacy and toxicity. For example, the beta (2)-adrenoreceptor, which is encoded by the ADRB2 gene, illustrates a clinically significant genetic variation in drug targets. The variable number tandem repeat polymorphisms in serotonin transporter (SERT/SLC6A4) gene are associated with response to antidepressants. The distribution of the common variant alleles of genes that encode drug metabolizing enzymes, drug transporters and drug targets has been found to vary among different populations. The promise of pharmacogenetics lies in its potential to identify the right drug at the right dose for the right individual. Drugs with a narrow therapeutic index are thought to benefit more from pharmacogenetic studies. For example, warfarin serves as a good practical example of how pharmacogenetics can be utilized prior to commencement of therapy in order to achieve maximum efficacy and minimum toxicity. As such, pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and licensed drugs.

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487 Exon 2 contains a polymorphism that changes Asn21 to Asp, and the mutation at exon 5 changes Phe103 to Leu. Login to comment
532 Nucleotide change rs number Amino acid change 49T>C rs28381804 F17L 61A>G rs61615398; rs9282564 N21D 131A>G rs1202183 N44S 178A>C rs41315618 I60L 239C>A rs9282565 A80E 266T>C Rs35810889 M89T 431T>C rs61607171 I144T 502G>A rs61122623 V168I 548A>G rs60419673 N183S 554G>T rs1128501 G185V 781A>G rs36008564 I261V 1199G>A rs2229109 S400N 1696G>A rs28381902 E566K 1777C>T rs28381914 R593C 1778G>A rs56107566 R593H 1795G>A rs2235036 A599T 1837G>T rs57001392 D613Y 1985T>G rs61762047 L662R 2005C>T rs35023033 R669C 2207A>T rs41316450 I736K 2398G>A rs41305517 D800N 2401G>A rs2235039 V801M 2485A>G rs2032581 I829V 2506A>G rs28381967 I836V 2547A>G rs36105130 I849M 2677T>A/G rs2032582 S893A/T 2975G>A rs56849127 S992N 3151C>G rs28401798 P1051A 3188G>C rs2707944 G1063A 3262G>A rs57521326 D1088N 3295A>G rs41309225 K1099E 3320A>C rs55852620 Q1107P 3322T>C rs35730308 W1108R 3410G>T rs41309228 S1137I 3421T>A rs2229107 S1141T 3502A>G rs59241388 K1168E 3669A>T rs41309231 E1223D 3751G>A rs28364274 V1251I 3767C>A r35721439 T1256K Data are from NCBI dbSNP (access date: 2 August 2008). Login to comment

[hide] Intracellular trafficking of MDR transporters and ... Curr Top Med Chem. 2009;9(2):197-208. Porcelli L, Lemos C, Peters GJ, Paradiso A, Azzariti A
Intracellular trafficking of MDR transporters and relevance of SNPs.
Curr Top Med Chem. 2009;9(2):197-208., [PMID:19200005]

Abstract [show]
Multi-drug resistance (MDR) frequently contributes to the failure of chemotherapeutic treatments in cancer patients. Mechanisms underlying the development of MDR have been extensively studied and are considered multifactorial. Among them, the ATP-Binding Cassette (ABC) family of proteins plays a pivotal role. Processes of cellular distribution and subcellular localization of MDR-ABC proteins are not yet well explored and to enlighten these topics could be crucial to understand cellular drug uptake and retention. In this review, we analysed literature data concerning i) intracellular trafficking of MDR-ABC proteins (BCRP, P-gp and MRP1) and ii) mechanisms altering their cellular localization and trafficking. Moreover, we describe single nucleotide polymorphisms (SNP) that have been reported for some multidrug resistance (MDR) transporters, such as BCRP and P-gp, emphasizing their ability to affect the expression, function and localization of the transporters, with implications on drug resistance phenotypes.

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229 [113], who showed that HeLa cells transfected with either the wild-type or the ABCB1 polymorphisms A61G (N21D), T307C (F103L), G1199A (S400N), G2677T (A893S) and G2995A (A998T) expressed the transporter at the cell surface. Login to comment
230 Additionally, cells transfected with double mutants (N21D-S400N, N21D-A893S, and S400N-A893S) revealed similar ABCB1 cell surface expression [113]. Login to comment

[hide] Pharmacogenetics of ATP-binding cassette transport... Methods Mol Biol. 2010;596:95-121. Cascorbi I, Haenisch S
Pharmacogenetics of ATP-binding cassette transporters and clinical implications.
Methods Mol Biol. 2010;596:95-121., [PMID:19949922]

Abstract [show]
Drug resistance is a severe limitation of chemotherapy of various malignancies. In particular efflux transporters of the ATP-binding cassette family such as ABCB1 (P-glycoprotein), the ABCC (multidrug resistance-associated protein) family, and ABCG2 (breast cancer resistance protein) have been identified as major determinants of chemoresistance in tumor cells. Bioavailability depends not only on the activity of drug metabolizing enzymes but also to a major extent on the activity of drug transport across biomembranes. They are expressed in the apical membranes of many barrier tissues such as the intestine, liver, blood-brain barrier, kidney, placenta, testis, and in lymphocytes, thus contributing to plasma, liquor, but also intracellular drug disposition. Since expression and function exhibit a broad variability, it was hypothesized that hereditary variances in the genes of membrane transporters could explain at least in part interindividual differences of pharmacokinetics of a variety of anticancer drugs and many others contributing to the clinical outcome of certain leukemias and further malignancies.

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52 Functional Significance of ABCB1 SNPs Table6.3 Frequency of ABCB1 genetic variants in Caucasians, position on DNA, putative effect, and frequencies (134) Position Amino acid or effect Frequency of the variant allele 5'-Flanking -2903 T>C 0.02a 5'-Flanking -2410 T>C 0.10a 5'-Flanking -2352 G>A 0.28a 5'-Flanking -1910 T>C 0.10a 5'-Flanking -1717 T>C 0.02a 5'-Flanking -1325 A>G 0.02a 5'-Flanking -934 A>G 0.10a 5'-Flanking -692 T>C 0.10a 5'-Flanking -41 A>G 0.09b IVS 1a -145 C>G 0.02b IVS 1b -129 T>C 0.06b IVS 1b 12 T>C 0.06c IVS 2 -1 G>A 0.09d c. 61 A>G N21D 0.11d IVS 5 -35 G>C Intronic 0.006c IVS 5 -25 G>T Intronic 0.16c IVS 6 +139 C>T Intronic 0.37d c. 548 A>G N183S 0.01e c. 1199 G>A S400N 0.05d c. 1236 C>T Synonymous 0.41d IVS 12 +44 C>T Intronic 0.05d c. 1474 C>T R492C 0.01e IVS 17 -76 T>A Intronic 0.46d IVS 17 +137 A>G Intronic 0.006c c. 2650 C>T Synonymous 0.03e c. 2677 G>T/A A893S/T 0.42d /0.02d c. 2956 A>G M986V 0.005b c. 3320 A>C Q1107P 0.002d c. 3396 C>T Synonymous 0.03c c. 3421 T>A S1141T 0.00c c. 3435 C>T Synonymous 0.54d c. 4030 Synonymous 0.005b c. 4036 Synonymous 0.30b References: a [42], b [26], c [25], d [28], e [23] with lower activity or expression in Caucasians. Login to comment

[hide] ABC drug transporters: hereditary polymorphisms an... Pharmacogenomics. 2001 Feb;2(1):51-64. Kerb R, Hoffmeyer S, Brinkmann U
ABC drug transporters: hereditary polymorphisms and pharmacological impact in MDR1, MRP1 and MRP2.
Pharmacogenomics. 2001 Feb;2(1):51-64., [PMID:11258197]

Abstract [show]
Transport by ATP-dependent efflux pumps, such as P-glycoprotein (PGP) and multi-drug resistance related proteins (MRPs), influences bioavailability and disposition of drugs. These efflux pumps serve as defence mechanisms and determine bioavailability and CNS concentrations of many drugs. However, despite the fact that substantial data have been accumulated on the structure, function and pharmacological role of ABC transporters and even though modification of PGP function is an important mechanism of drug interactions and adverse effects in humans, there is a striking lack of data on variability of the underlying genes. This review focuses on the human drug transporter proteins PGP (MDR1) and the multi-drug resistance proteins MRP1 and MRP2. An overview is provided of pharmacologically relevant genetic, structural and functional data as well as on hereditary polymorphisms, their phenotypical consequences and pharmacological implications.

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97 SNP Region N Frequency of SNPs (%) Effect Heterozygous Homozygous Observed Estimated T-12C E1 85 11.8 0 0.4 Non-coding G-1A E2 188 11.2 0 0.4 TL initiation A61G E2 188 17.6 0.5 0.81 Asn21Asp G-25T I4 85 26 3.5 2.3 G-35C I4 85 1.2 0 0.01 # T307C E5 85 1.2 0 0.01 Phe103Leu C+139T I5 85 48.2 16.5 16.8 C+145T I5 85 2.4 0 0.01 G1199A E11 85 12.9 0 0.4 Ser400Asn C1236T E12 188 48.9 13.3 14.4 Gly412Gly # C+44T I12 188 11.7 0 0.4 T-76A I16 85 45.9 22.4 20.3 A+137G I17 85 1.2 0 0.01 G2677T E21 83b 43.4 42.2 38.4 Ala893Ser G2995A E24 36b 11.1 38.4 Ala999Thr C3435T E26 537 47.7 26.4 24.1 Ile1145Ile C3396T E26 188 0.53 0 0.01 Wobble § MDR1 sequences gb:AC002457 and AC005068 are defined as 'wild type`. Login to comment
106 A61G leads to the replacement of Asn by Asp at position 21 resulting in a net charge change (basic to acidic) close to the N-terminus of PGP. Login to comment

[hide] Influence of ABCB1, ABCC1, ABCC2, and ABCG2 haplot... Pharmacogenet Genomics. 2005 Sep;15(9):599-608. Colombo S, Soranzo N, Rotger M, Sprenger R, Bleiber G, Furrer H, Buclin T, Goldstein D, Decosterd L, Telenti A
Influence of ABCB1, ABCC1, ABCC2, and ABCG2 haplotypes on the cellular exposure of nelfinavir in vivo.
Pharmacogenet Genomics. 2005 Sep;15(9):599-608., [PMID:16041239]

Abstract [show]
OBJECTIVES: The human immunodeficiency virus protease inhibitor nelfinavir is substrate of polyspecific drug transporters encoded by ABCB1 (P-glycoprotein), ABCC1 (MRP1) and ABCC2 (MRP2), and an inhibitor of BCRP, encoded by ABCG2. Genetic polymorphism in these genes may be associated with changes in transport function. METHODS: A comprehensive evaluation of single nucleotide polymorphisms (39 SNPs in ABCB1, 7 in ABCC1, 27 in ABCC2, and 16 in ABCG2), and inferred haplotypes was done to assess possible associations of genetic variants with cellular exposure of nelfinavir in vivo. Analysis used peripheral mononuclear cells from individuals receiving nelfinavir (n=28). Key results were re-examined in a larger sample size (n=129) contributing data on plasma drug levels. RESULTS AND CONCLUSIONS: There was no significant association between cellular nelfinavir area under the curve (AUC) and SNPs or haplotypes at ABCC1, ABCC2, ABCG2. There was an association with cellular exposure for two loci in strong linkage disequilibrium: ABCB1 3435C>T; AUCTT>AUCCT>AUCCC (ratio 2.1, 1.4, 1, Ptrend=0.01), and intron 26 +80T>C; AUCCC> AUCCT > AUCTT (ratio 2.4, 1.3, 1, Ptrend=0.006). Haplotypic analysis using tagging SNPs did not improve the single SNP association values.

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101 or Ref sequence; locus Frequencies Fold-increase of nelfinavir AUCintracell Significance AA Aa aa Aa2 AA Aa aa Aa2 chi-squared P-value ABCB1 IVS 1 - 80delG rs3214119 27 1 1 1.0 0.03 0.85 c.61A > G (N21D) rs9282564 26 2 1 2.5 3.85 0.05 TAG1 rs3789243 7 17 3 1 0.8 0.6 1.23 0.54 c.1199G > A (S400N) rs2229109 24 2 1 0.9 0.62 0.43 TAG5 rs1128503 4 18 5 1 0.8 1.3 3.33 0.19 TAG6 rs2235046 6 18 3 1 0.6 0.7 4.43 0.11 c.2677G > T (A893S) rs2032582 4 17 5 1 1 1.0 1.7 1.2 6.42 0.09 IVS 21 + 49T > C rs2032583 19 8 1 0.6 3.45 0.06 TAG8, 3435C > T rs1045642 4 18 6 1 1.4 2.1 6.35 0.04 IVS 26 + 59T > G rs2235047 24 2 1 1.0 0.02 0.89 IVS 26 + 80T > C rs2235048 3 17 6 1 1.3 2.4 7.09 0.03 TAG11 rs1186746 16 10 1 1 1.1 0.3 2.46 0.29 TAG12 rs1186745 17 9 1 1 0.7 1.0 0.33 0.85 ABCC1 c.816G > A NM_004996; c.1012G > A 27 1 1 1.5 1.05 0.30 c.825T > C rs246221 13 11 3 1 1.5 0.7 3.99 0.14 c.1062T > C rs35587 13 11 3 1 1.5 0.7 3.02 0.22 IVS 9 + 8A > G rs35588 13 11 3 1 1.5 0.7 3.02 0.22 IVS 10 + 64C > T NC_000016; g.98791C > T 23 3 1 0.4 1.97 0.16 ABCC2 g. Login to comment
69 - 4 C > T exon 2 (50 UTR) Epidauros md-v-177 c.61A > G exon 2 p.N21D Hoffmeyer et al., 2000 md-v-017 rs9282564 IVS 2 + 23 T > C intron 2 Epidauros md-v-057 Tag 1 intron 3 Soranzo et al., 2004 rs3789243 IVS 11 - 40 T > G intron 10 Epidauros md-v-078 rs2235029 c.1137 C > G exon 11 p.P373A Epidauros md-v-079 c.1149 C > T exon 11 synonymous (p.H383H) Epidauros md-v-080 c.1199G > A exon 11 p.S400N Hoffmeyer et al., 2000 md-v-025 rs2229109 IVS11 + 48 T > A intron 11 Epidauros md-v-081 Tag 5 exon 12 Soranzo et al., 2004 rs1128503 Tag 6 intron 16 Soranzo et al., 2004 rs2235046 IVS 21 - 78 G > A intron 20 Epidauros md-v-228 IVS 21 - 43 A > T intron 20 Epidauros md-v-160 c.2547A > G exon 21 p.I849M Kroetz et al., 2003 md-v-222 c. Login to comment
94 We detected an association with phenotype for three loci: ABCB1_61A > G (N21D) (w2 = 3.85, 1 d.f., P = 0.05), median cellular AUCAG > AUCAA (ratio 2.5, 1), ABCB1_3435C > T (w2 = 6.34, 2 d.f., Kruskal-Wallis P = 0.04, Spearman rank test Ptrend = 0.01); median cellular AUCTT > AUCCT > AUCCC (ratio 2.1, 1.4, 1), and ABCB1_ IVS26 + 80T > C (w2 = 7.09, 2 d.f., P = 0.03, Ptrend = 0.006); median cellular AUCCC >AUCCT >AUCTT (ratio 2.4, 1.3, 1). Login to comment
114 Since the only change differentiating haplotype 16 from 20 is at 61A > G (N21D), this may also suggest an effect, separate from the main effect observed at 3435C > T, for 61A > G (N21D). Login to comment
115 We pursued further the apparent association between the ABCB1_61A > G (N21D), ABCB1 3435C > T and IVS26 + 80T > C variant and drug AUC phenotype by testing this association also in a larger number of individuals (n = 129) receiving nelfinavir, and for which plasma AUC phenotypes were available. Login to comment
138 A second variant, ABCB1_61A > G, resulting in a N21D substitution reported to modify the kinetic parameters of P-glycoprotein in vitro [13], was associated with increased cellular nelfinavir exposure in the present study. Login to comment

[hide] Impact of CYP2C8*3 on paclitaxel clearance: a popu... Pharmacogenomics J. 2011 Apr;11(2):113-20. Epub 2010 Apr 6. Bergmann TK, Brasch-Andersen C, Green H, Mirza M, Pedersen RS, Nielsen F, Skougaard K, Wihl J, Keldsen N, Damkier P, Friberg LE, Peterson C, Vach W, Karlsson MO, Brosen K
Impact of CYP2C8*3 on paclitaxel clearance: a population pharmacokinetic and pharmacogenomic study in 93 patients with ovarian cancer.
Pharmacogenomics J. 2011 Apr;11(2):113-20. Epub 2010 Apr 6., [PMID:20368717]

Abstract [show]
The primary purpose of this study was to evaluate the effect of CYP2C8*3 and three genetic ABCB1 variants on the elimination of paclitaxel. We studied 93 Caucasian women with ovarian cancer treated with paclitaxel and carboplatin. Using sparse sampling and nonlinear mixed effects modeling, the individual clearance of unbound paclitaxel was estimated from total plasma paclitaxel and Cremophor EL. The geometric mean of clearance was 385 l h(1) (range 176-726 l h(1)). Carriers of CYP2C8*3 had 11% lower clearance than non-carriers, P=0.03. This has not been shown before in similar studies; the explanation is probably the advantage of using both unbound paclitaxel clearance and a population of patients of same gender. No significant association was found for the ABCB1 variants C1236T, G2677T/A and C3435T. Secondarily, other candidate single-nucleotide polymorphisms were explored with possible associations found for CYP2C8*4 (P=0.04) and ABCC1 g.7356253C>G (P=0.04).

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135 This effect on clearance of a 'non-fixed` variable provides a competing and dynamic biological explanation for clearance that certainly should be Table 4 Clearance of unbound paclitaxel as function of observed genotypes Gene/allelea Effectb Reference homozygote Heterozygote Variant homozygote P-valuee SNP IDf Nc CLd (10th-90th) Nc CLd (10th-90th) Nc CLd (10th-90th) Candidate SNPs for confirmative analysis CYP2C8 1196A4G(*3) K399R 74 395 (297-490) 19 350 (238-458) 0.03* (0.04) rs10509681 ABCB1 1236C4T G412G 29 391 (270-569) 45 393 (299-490) 19 359 (291-437) 0.25 (0.25) rs1128503 2677G4T/Ag A893S/T 26 387 (270-490) 42(GT) 396 (299-490) 20(TT) 356 (294-437) 0.20 (0.26) rs2032582 3435C4T I1145I 11 403 (326-548) 44 387 (282-490) 38 378 (297-468) 0.83 (0.43) rs1045642 Candidate SNPs for exploratory analysis CYP2C8 792C4G(*4) I264M 86 391 (297-490) 7 321 (270-374) 0.04* (0.03) rs1058930 15577956G4T (*1B) - 49 395 (298-552) 43 373 (291-478) 1 461 0.75 (0.36) rs7909236 15578055A4C (*1C) - 69 382 (291-478) 24 393 (300-552) 0.48 (0.62) rs17110453 ABCB1 À1A4G - 1 458 29 396 (270-592) 63 379 (297-477) 0.56 (0.3) rs2214102 61A4G N21D 63 384 (282-490) 29 386 (298-478) 1 437 0.52 (0.77) rs9282564 1199G4A S400N 83 385 (291-490) 10 386 (322-461) 0.74 (0.99) rs2229109 CYP3A4 24616372T4C (*1B) - 85 383 (296-490) 7 397 (270-641) 0.67 (0.72) rs2740574 CYP3A5 219-237G4A Frameshift 84 388 (297-490) 9 360 (176-726) 0.30 (0.36) rs776746 SLCO1B3 699G4A M233I 1 326 19 377 (299-481) 73 388 (291-490) 0.99 (0.46) rs7311358 767G4C G256A 67 386 (298-481) 26 383 (291-490) 0.63 (0.89) rs60140950 CYP1B1 1294C4G (*3) V432L 30 389 (270-530) 36 401 (298-490) 27 361 (300-470) 0.77 (0.24) rs1056836 ABCC1 7356253C4G - 65 394 (297-548) 27 368 (291-470) 1 332 0.04* (0.15) rs504348 ABCC2 1249G4A V417I 67 381 (291-490) 24 396 (297-552) 2 415 (368-468) 0.21 (0.39) rs2273697 3563T4A V1188E 87 386 (296-490) 5 370 (176-569) 0.7 (0.7) rs17222723 4544G4A C1515Y 75 389 (296-490) 3 355 (176-569) 0.72 (0.52) rs8187710 ABCG2 421C4A Q141K 61 374 (291-478) 32 408 (315-548) 0.4 (0.09) rs2231142 34G4A V12M 87 385 (291-490) 4 395 (296-726) 0.68 (0.83) rs2231137 ABCC10 2759T4C I920T 46 386 (297-478) 43 386 (291-548) 4 373 (326-467) 0.88 (0.89) rs2125739 Abbreviations: CL, clearance of unbound paclitaxel; SNP, single-nucleotide polymorphism. Login to comment

[hide] Frequency of single nucleotide polymorphisms in th... Clin Pharmacol Ther. 2001 Mar;69(3):169-74. Cascorbi I, Gerloff T, Johne A, Meisel C, Hoffmeyer S, Schwab M, Schaeffeler E, Eichelbaum M, Brinkmann U, Roots I
Frequency of single nucleotide polymorphisms in the P-glycoprotein drug transporter MDR1 gene in white subjects.
Clin Pharmacol Ther. 2001 Mar;69(3):169-74., [PMID:11240981]

Abstract [show]
BACKGROUND: P-glycoprotein, the gene product of MDR1, confers multidrug resistance against antineoplastic agents but also plays an important role in the bioavailability of common drugs in medical treatment. Various polymorphisms in the MDR1 gene were recently identified. A silent mutation in exon 26 (C3435T) was correlated with intestinal P-glycoprotein expression and oral bioavailability of digoxin. OBJECTIVE: We wanted to establish easy-to-use and cost-effective genotyping assays for the major known MDR1 single nucleotide polymorphisms and study the allelic frequency distribution of the single nucleotide polymorphisms in a large sample of volunteers. METHODS: In this study, the distribution of the major MDR1 alleles was determined in 461 white volunteers with the use of polymerase chain reaction and restriction fragment length polymorphism. RESULTS: Five amino acid exchanges were found with allelic frequencies of 11.2% for Asn21Asp and 5.5% for Ser400Asn. Strikingly, in exon 21 three variants were discovered at the same locus: 2677G (56.4%), 2677T (41.6%), and 2677A (1.9%), coding for 893Ala, Ser, or Thr. A novel missense Gln1107Pro mutation was found in two cases (0.2%). The highest frequencies were observed for intronic and silent polymorphisms; C3435T occurred in 53.9% of the subjects heterozygously, and 28.6% of individuals were homozygous carriers of 3435T/T with functionally restrained P-glycoprotein. CONCLUSION: This study provides the first analysis of MDR1 variant genotype distribution in a large sample of white subjects. It gives a basis for large-scale clinical investigations on the functional role of MDR1 allelic variants for bioavailability of a substantial number of drugs.

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5 Results: Five amino acid exchanges were found with allelic frequencies of 11.2% for Asn21Asp and 5.5% for Ser400Asn. Login to comment
53 A61G in exon 2,14 which resulted in an Asn21Asp exchange, occurred with an allele frequency of 11.2%; therefore only 4 individuals were homozygous carriers. Login to comment

[hide] Naturally occurring mutations and functional polym... J Med Genet. 2002 May;39(5):340-6. Potocnik U, Ravnik-Glavac M, Golouh R, Glavac D
Naturally occurring mutations and functional polymorphisms in multidrug resistance 1 gene: correlation with microsatellite instability and lymphoid infiltration in colorectal cancers.
J Med Genet. 2002 May;39(5):340-6., [PMID:12011154]

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264 To the best of our knowledge, this Table 2 Correlation between MDR1 polymorphisms and increased lymphoid infiltration in tumours Exon Genotype (polymorphism) Amino acid change No (%) of tumours with specific genotype (polymorphism)/No of tumours analysed No (%) of tumours with specific genotype (polymorphism) and lymphoid infiltration p* Promoter †Promoter +8 T/T 313/327 (96%) 152/313 (49%) Promoter Promoter +8 T/C Non-coding 14/327 (4%) 9/14 (64%) 0.036 Intron 1b IVS1-81 (G)4 311/327 (95%) 149/311 (48%) Intron 1b IVS1-81 (G)4/(G)3 Non-coding 16/327 (5%) 12/16 (75%) 0.010 Intron 1b ‡IVS-1 G/G 271/317 (85%) 127/271 (47%) Intron 1b IVS-1 G/A 45/317 (14%) 27/45(60%) NS Intron 1b IVS-1 A/A Non-coding 1/317 (<1%) 1/1 (100%) NS 2 ‡61 A/A 266/321 (83%) 125/266 (47%) 2 61 A/G Asn21Asp 51/321 (16%) 29/51 (57%) NS 2 61 G/G 4/321 (1%) 2/4 (50%) NS Intron 4 ‡IVS4-25 G/G 44/63 (70%) 19/44 (43%) Intron 4 IVS4-25 G/T Non-coding 15/63 (24%) 7/15 (47%) NS Intron 4 IVS4-25 T/T 4/63 (6%) 2/4 (50%) NS 11 1199 G/G 307/327 (94%) 152/307 (50%) 11 1199 G/A Ser400Asn 20/327 (6%) 11/20 (55%) NS 12 ‡1236 C/C 81/327 (25%) 39/81 (48%) 12 1236 C/T No change 163/327 (50%) 80/163 (49%) NS 12 1236 T/T 83/327 (25%) 42/83 (51%) NS Intron 16 IVS16+158 G/G 82/87 (94%) 41/82 (50%) Intron 16 IVS16+158 G/A Non-coding 5/87 (6%) 3/5 (60%) NS 21 §2677 G/G 14/41 (34%) 7/14 (50%) 21 2677 G/T Ala893Ser 17/41 (41%) 7/17 (41%) NS 21 2677 T/T 10/41 (24%) 4 /10 (40%) NS 26 ‡3435 C/C 44/159 (28%) 18/44 (41%) 26 3435 C/T No change 85/159 (53%) 46/85 (54%) NS 26 3435 T/T 30/159 (19%) 15/30 (50%) NS NS=not significant. Login to comment

[hide] Functional characterization of coding polymorphism... Mol Pharmacol. 2002 Jul;62(1):1-6. Kimchi-Sarfaty C, Gribar JJ, Gottesman MM
Functional characterization of coding polymorphisms in the human MDR1 gene using a vaccinia virus expression system.
Mol Pharmacol. 2002 Jul;62(1):1-6., [PMID:12065748]

Abstract [show]
The human MDR1-encoded transporter is a 170-kDa plasma membrane glycoprotein [P-glycoprotein (P-gp)] capable of binding and energy-dependent extrusion of structurally diverse organic compounds and drugs. P-gp seems to play a significant role in uptake, distribution, and excretion of many different drugs. To determine whether common polymorphic forms of P-gp are likely to alter function of P-gp, we characterized five known MDR1 coding polymorphisms (N21D, F103L, S400N, A893S, and A998T) using a vaccinia virus-based transient expression system. Cell surface expression of wild-type P-gp was time-dependent over a time course of 5.5 to 34.5 h; highest expression was obtained by 22 to 26.5 h after infection/transfection, indicating that a semiquantitative assay for P-gp expression levels was possible. HeLa cells stained with the P-gp specific monoclonal antibodies MRK-16 and Western blots probed with C219 revealed similar cell surface expression for the polymorphisms and for wild-type protein. Time-dependent P-gp pump function maximal at 22 h after infection/transfection was demonstrated for the following MDR1 fluorescence substrates: 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoic acid, succinimidyl ester (bodipy-FL)-verapamil, bodipy-FL-vinblastine, calcein-AM, bodipy-FL-prazosin, bisantrene, and bodipy-FL-forskolin, but not for daunorubicin. Transport studies of all tested substrates indicated that the substrate specificity of the pump was not substantially affected by any of the tested polymorphisms. Cell surface expression and function of double mutants including the more common polymorphisms (N21D-S400N, N21D-A893S, and S400N-A893S) showed no differences from wild-type. These results demonstrate that the common MDR1 coding polymorphisms result in P-gps with a cell surface distribution and function similar to wild-type P-gp.

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2 To determine whether common polymorphic forms of P-gp are likely to alter function of P-gp, we characterized five known MDR1 coding polymorphisms (N21D, F103L, S400N, A893S, and A998T) using a vaccinia virus-based transient expression system. Login to comment
7 Cell surface expression and function of double mutants including the more common polymorphisms (N21D-S400N, N21D-A893S, and S400N-A893S) showed no differences from wild-type. Login to comment
20 In this study, we examined the five most common P-gp coding polymorphisms previously reported in the literature (N21D, F103L, S400N, A893S, and A998T). Login to comment
30 Using the technique described by Kunkel et al. (1987), five different mutated sites were introduced into the MDR1 gene with the following primers: for the N21D (A3G) polymorphism, 5Ј TTT TTC ACT TTT ATC GTT CAG TTT AA 3Ј; for the F103L (C3T) polymorphism, 5Ј CAG ATT CAT GAA GAG CCC TGT ATC A 3Ј; for the S400N (G3T) polymorphism, 5Ј TCG AGA TGG GTA ATT GAA GTG AAC AT 3Ј; for the A893S (G3T) polymorphism, 5Ј AGC GAT CTT CCC AGA ACC TTC TAG TT 3Ј; and for the A998T (G3A) polymorphism, 5Ј TAT TTT GGC TTT GGT ATA GTC AGG AGC 3Ј. Login to comment
31 Double mutant MDR1s were generated using the NdeI and XhoI restriction enzymes on single mutant templates (N21D-S400N, N21D-A893S, and S400N-A893S). Login to comment
48 We have chosen HeLa cells for these studies because of their low level of endogenous P-gp expression, their ability to express high TABLE 1 Common MDR1 polymorphisms that change amino acids Location Polymorphic Variant Heterozygous Frequency Reference Exon Nucleotide % 2 61 N21D 17.6 Hoffmeyer et al. (2000) 11.2 Cascorbi et al. (2001) 5.7 Decleves et al. (2000) 5 307 F103L 1.2 Hoffmeyer et al. (2000) 10 1107 G369P 0.2 Cascorbi et al. (2001) 11 1199 S400N 12.9 Hoffmeyer et al. (2000) 5.5 Cascorbi et al. (2001) A893S 43.0 Mickley et al. (1998) A893T 41.6 Cascorbi et al. (2001) 21 2677 A893S 62.0a , 13.0b Kim et al. (2001) A893G 56.4 Cascorbi et al. (2001) 24 2995 A998T 11.0 Mickley et al. (1998) a European Americans. b African Americans. levels of wild-type and mutant P-gp after vaccinia infection/ transfection, and their relative ease of transfection (Hrycyna et al., 1998; Ramachandra et al., 1998; Gribar et al., 2000). Login to comment
63 HeLa cells were infected/transfected with the pTM1-MDR1 vector harboring the MDR1 polymorphisms N21D, F103L, S400N, A893S, and A998T (described in Table 1). Login to comment
70 All cells infected/ transfected with double mutants (N21D-S400N, N21D-A893S, and S400N-A893S) revealed results similar to those of the single mutants (data not shown). Login to comment
71 Discussion In this study a transient vaccinia expression system was used to determine the effect of five known coding human MDR1 polymorphisms on P-gp function: N21D, F103L, S400N, A893S, and A998T. Login to comment
113 Infected/transfected HeLa cells with wild-type pTM1-MDR1 (--), pTM1-MDR1-N21D (- -⅐- -⅐), pTM1-MDR1-F103L (⅐⅐⅐⅐), pTM1-MDR1-S400N (-⅐-⅐-), pTM1-MDR1-A998T (- - - -), and pTM1-MDR1-A893S (⅐⅐⅐-⅐⅐⅐) were incubated and analyzed by FACS as described under Materials and Methods, with MRK-16 or control IGg2a␬ monoclonal antibodies (-⅐-⅐-⅐) 13.5 h after infection/transfection. Login to comment
117 Cells were transfected with pTM1 (control), pTM1-MDR1, (wild-type P-gp), pTM1-MDR1- N21D, pTM1-MDR1-F103L, pTM1-MDR1-S400N, pTM1-MDR1-A893S, and pTM1-MDR1-A998T. Login to comment
119 with A, 0.5 ␮M Calcein-AM: wild-type (--), N21D (- -⅐- -⅐), and S400N (-⅐-⅐-), in the presence of an inhibitor, 5 ␮M cyclosporin A (- - -); B, 0.5 ␮M bodipy-FL-forskolin: wild-type (--), N21D (- -⅐- -⅐), F103L (⅐⅐⅐⅐), and S400N (-⅐-⅐-), in the presence of an inhibitor, 5 ␮M cyclosporin A (- - -); C, 0.5 ␮M bodipy-FL-verapamil: wild-type (--), N21D (- -⅐- -⅐), F103L (⅐⅐⅐⅐), and S400N (-⅐- ⅐-), in the presence of an inhibitor, 5 ␮M cyclosporin A (- - -); D, 0.1 ␮M bodipy-FL-paclitaxel: wild-type (--), A893S (- -⅐- -⅐), in the presence of an inhibitor, 5 ␮M cyclosporin A for the wild-type (- -), and for A893S (- - -). Login to comment

[hide] Distinct haplotype profiles and strong linkage dis... Pharmacogenetics. 2002 Aug;12(6):437-50. Tang K, Ngoi SM, Gwee PC, Chua JM, Lee EJ, Chong SS, Lee CG
Distinct haplotype profiles and strong linkage disequilibrium at the MDR1 multidrug transporter gene locus in three ethnic Asian populations.
Pharmacogenetics. 2002 Aug;12(6):437-50., [PMID:12172212]

Abstract [show]
The MDR1 multidrug transporter plays a key role in determining drug bioavailability, and differences in drug response exist amongst different ethnic groups. Numerous studies have identified an association between the MDR1 single nucleotide polymorphism (SNP) exon 26 3435C>T and differences in MDR1 function. We performed a haplotype analysis of the MDR1 gene in three major ethnic groups (Chinese, Malays and Indians) by examining 10 intragenic SNPs. Four were polymorphic in all three ethnic groups: one occurring in the non-coding region and three occurring in coding exons. All three coding SNPs (exon 12 1236C>T, exon 21 2677G>T/A and exon 26 3435C>T) were present in high frequency in each ethnic group, and the derived haplotype profiles exhibited distinct differences between the groups. Fewer haplotypes were observed in the Malays (n = 6) compared to the Chinese (n = 10) and Indians (n = 9). Three major haplotypes (> 10% frequency) were observed in the Malays and Chinese; of these, two were observed in the Indians. Strong linkage disequilibrium (LD) was detected between the three SNPs in all three ethnic groups. The strongest LD was present in the Chinese, followed by Indians and Malays, with the corresponding LD blocks estimated to be approximately 80 kb, 60 kb and 40 kb, respectively. These data strongly support the hypothesis that strong LD between the neutral SNP exon 26 3435C>T and a nearby unobserved causal SNP underlies the observed associations between the neutral SNP and MDR1 functional differences. Furthermore, strong LD between exon 26 3435T and different unobserved causal SNPs in different study populations may provide a plausible explanation for conflicting reports associating the same exon 26 3435T allele with different MDR1 functional changes.

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101 The previously reported exon 2 61A.G polymorphism, which changes the codon from Asn to Asp at amino acid position 21 in the MDR1 protein, has a minor G allele frequency of 11.2% in German Caucasians [11]. Login to comment

[hide] C3435T polymorphism in the MDR1 gene affects the e... Pharmacogenetics. 2002 Aug;12(6):451-7. Goto M, Masuda S, Saito H, Uemoto S, Kiuchi T, Tanaka K, Inui K
C3435T polymorphism in the MDR1 gene affects the enterocyte expression level of CYP3A4 rather than Pgp in recipients of living-donor liver transplantation.
Pharmacogenetics. 2002 Aug;12(6):451-7., [PMID:12172213]

Abstract [show]
The bioavailability of structurally unrelated drugs is limited by active secretion via the multidrug resistance gene (MDR1) product P-glycoprotein (Pgp) from enterocyte into lumen as well as intestinal metabolism by cytochrome P450 IIIA4 (CYP3A4). In the present study, we analyzed whether genetic polymorphism of the MDR1 had some influence on the intestinal expression levels of Pgp and CYP3A4 and the tacrolimus concentration/dose ratio over the first postoperative days in recipients of living-donor liver transplantation (LDLT). Genotyping assays were performed for the major 10 polymorphisms in the MDR1 gene by the polymerase chain reaction-restriction enzyme length polymorphism method. The allele frequencies of variations at five positions were almost comparable with those in the former studies in Caucasians and Japanese, but there was no variation at the other five positions. Although no polymorphism correlated with the intestinal expression of MDR1 mRNA or the tacrolimus concentration/dose ratio in the LDLT recipients, the C3435T polymorphism significantly affected the intestinal expression level of CYP3A4 mRNA as follows; 3435C/C>3435C/T (P < 0.05 vs. 3435C/C)>3435T/T (P < 0.01 vs. 3435C/C). Therefore, the identified polymorphisms including C3435T in the MDR1 gene were indicated to have no influence on the intestinal expression level of Pgp or the tacrolimus concentration/dose ratio in the recipients of LDLT. On the other hand, the C3435T polymorphism of MDR1 was suggested to correlate with the enterocyte expression of CYP3A4 rather than Pgp linking unknown genetic variation in CYP3A4 gene.

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42 In the present study, the variants in exon 2 G-1A, A61G (Asn21 Asp) in exon 2, T307C (Phe103 Leu) in exon 5, G1199A (Ser400 Asn) in exon 11 and C+44T in intron 12 were not observed. Login to comment

[hide] Does the A118G polymorphism at the mu-opioid recep... Anesthesiology. 2002 Oct;97(4):814-9. Lotsch J, Zimmermann M, Darimont J, Marx C, Dudziak R, Skarke C, Geisslinger G
Does the A118G polymorphism at the mu-opioid receptor gene protect against morphine-6-glucuronide toxicity?
Anesthesiology. 2002 Oct;97(4):814-9., [PMID:12357145]

Abstract [show]
BACKGROUND: Some, but not all, patients with renal dysfunction suffer from side effects after morphine administration because of accumulation of the active metabolite morphine-6-glucuronide (M6G). The current study aims to identify genetic causes that put patients at risk for, or protect them from, opioid side effects related to high plasma M6G. Candidate genetic causes are the single nucleotide polymorphism (SNP) A118G of the mu-opioid-receptor gene (OPRM1), which has recently been identified to result in decreased potency of M6G, and mutations in the MDR1-gene coding P-glycoprotein, of which morphine and M6G might be a substrate. METHODS: Two men, aged 87 and 65 yr, with renal failure (creatinine clearance of 6 and 9 ml/min) received 30 mg/day oral morphine for pain treatment. Both patients had sufficient analgesia from morphine. However, while one patient tolerated morphine well despite high plasma M6G of 1735 nM, in the patient with M6G plasma concentrations of 941 nM it caused severe sleepiness and drowsiness. Patients were genotyped for known SNPs of the OPRM1 and MDR1 genes. RESULTS: The patient who tolerated morphine well despite high plasma M6G was a homozygous carrier of the mutated G118 allele of the mu-opioid-receptor gene, which has been previously related to decreased M6G potency. In contrast, the patient who suffered from side effects was "wild-type" for this mutation. No other differences were found between the OPRM1 and MDR1 genes. CONCLUSIONS: The authors hypothesize that the A118G single nucleotide polymorphism of the mu-opioid-receptor is among the protective factors against M6G-related opioid toxicity. The observation encourages the search for pharmacogenetic reasons that cause interindividual variability of the clinical effects of morphine.

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106 33 T/T T/T MDR1 2 A61G Asn21Asp 11.2 20.6 9 A/G A/G Forward: 5Ј-AGG AGC AAA GAA GAA GAA CTT TTT TAA ACT GAT C-3Ј 9.3 17.6 8 Reverse: 5Ј-GAT TCC AAA GGC TAG CTT GC-3Ј 5 T307C Phe103Leu 0.6 1.2 9 T/T T/T Forward: 5Ј-GTG GTT GCA CAC AGT CAG CA-3Ј Reverse: 5Ј-GGA GGA TGT CTA ATT ACC TGG TCA-3Ј 11 G1199A Ser400Asn 5.5 11.1 9 G/G G/G Forward: 5Ј-CAG CTA TTC GAA GAG TGG GC-3Ј 6.5 12.9 8 Reverse: 5Ј-CCG TGA GAA AAA AAC TTC AAG G-3Ј 21 G2677T Ala893Ser 41.6 49.2 9 T/T T/T Forward: 5Ј-TGC AGG CTA TAG GTT CCA GG-3Ј 63.9 43.4 8 Reverse: 5Ј-GTT TGA CTC ACC TTC CCA G-3Ј 21 G2677A Ala893Thr 0.9 2 9 NA NA Forward: 5Ј-TGC AGG CTA TAG GTT CCA GG-3Ј Reverse: 5Ј-TTT AGT TTG ACT CAC CTT CCC G-3Ј 26 A3320C Gln1107Pro 0.2 0.4 9 A/A A/A 26 C3396T Ala1132Ala 0.3 0.5 8 C/C C/C Forward: 5Ј-ATC TGT GAA CTC TTG TTT TCA GC-3Ј 26 C3435T Ile1145Ile 50.3 47.7 8 T/T T/T Reverse: 5Ј-TCG ATG AAG GCA TGT ATG TTG-3Ј 53.9 50.5 9 - - MRP2 10 G1249A Val417Ile 12.5 20.8 34 G/G G/G Forward: 5Ј-GGG TCC TAA TTT CAA TCC TTA-3Ј Reverse: 5Ј-TAT TCT TCT GGG TGA CTT TTT-3Ј 18 C2302T Arg768Trp 1 2.1 34 C/C C/C Forward: 5Ј-GGA GTA GTG CTT AAT ATG AAT-3Ј 18 C2366T Ser789Phe 1 2.1 34 C/C C/C Reverse: 5Ј-CCC ACC CCA CCT TTA TAT CTT-3Ј 28 C3972T Ile132Ile 21.9 35.4 34 C/T C/T Forward: 5Ј-TGC TAC CCT TCT CCT GTT CTA-3Ј Reverse: 5Ј-ATC CAG GCC TTC CTT CAC TCC-3Ј 31 G4348A Ala1450Thr 1 2.1 34 G/G G/G Forward: 5Ј-AGG AGC TAA CAC ATG GTT GCT-3Ј Reverse: 5Ј-GGG TTA AGC CAT CCG TGT CAA-3Ј † Sequence is not translated. Login to comment

[hide] Genetic polymorphisms of the human MDR1 drug trans... Annu Rev Pharmacol Toxicol. 2003;43:285-307. Epub 2002 Jan 10. Schwab M, Eichelbaum M, Fromm MF
Genetic polymorphisms of the human MDR1 drug transporter.
Annu Rev Pharmacol Toxicol. 2003;43:285-307. Epub 2002 Jan 10., [PMID:12359865]

Abstract [show]
P-glycoprotein is an ATP-dependent efflux pump that contributes to the protection of the body from environmental toxins. It transports a huge variety of structurally diverse compounds. P-glycoprotein is involved in limiting absorption of xenobiotics from the gut lumen, in protection of sensitive tissues (brain, fetus, testis), and in biliary and urinary excretion of its substrates. P-glycoprotein can be inhibited or induced by xenobiotics, thereby contributing to variable drug disposition and drug interactions. Recently, several SNPs have been identified in the MDR1 gene, some of which can affect P-glycoprotein expression and function. Potential implications of MDR1 polymorphisms for drug disposition, drug effects, and disease risk are discussed.

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50 Of the 15 identified SNPs, three polymorphisms resulted in protein alterations, one in exon 2 (Asn21Asp), in exon 5 (Phe103Leu), and in exon 11 (Ser400Asn). Login to comment
52 The SNPs at positions A61G (Asn21Asp), C1236T, and C3435T had been reported previously (23, 26). Login to comment
60 In a Northern Italian population, the extent of linkage disequilibrium TABLE 2 Summary of MDR1 genetic variants in different ethnic groups Location Position Allele Effect Reference promotor 5 flanking/-41a A (28) G exon 1a exon 1a/-145 C (28) G exon 1b exon 1b/-129 T (25, 33) C intron 1 exon 2/-4 C (29) T intron 1 exon 2/-1 G initiation of translation (25, 27, 29) A exon 2 exon 2/61 A Asn21Asp (25-27, 29) G intron 4 exon 5/-35 G (25) C intron 4 exon 5/-25 G (25) T exon 5 exon 5/307 T Phe103Leu (25) C intron 6 exon 6/+139 C (25, 27) T intron 6 exon 6/+145 C (25) T exon 7 exon 7/548 A Asn183Ser (29) G exon 11 exon 11/1199 G Ser400Asn (25, 27, 29) A exon 12 exon 12/1236 C wobble (23, 25, 27, 29) T (Gly412Gly) intron 12 exon 12/+44 C (25, 27) T exon 13 exon 13/1474 C Arg492Cys (29) T intron 16 exon 17/-76 T (25, 27) A intron 17 exon 17/137 A (25) G exon 21 exon 21/2650 C wobble (29) T (Leu884Leu) (Continued ) TABLE 2 (Continued) Location Position Allele Effect Reference exon 21 exon 21/2677 G (22, 23, 27, 29) T Ala893Ser A Ala893Thr exon 24 exon 24/2956 A Met986Val (33) G exon 24 exon 24/2995 G Ala999Thr (22) A exon 26 exon 26/3320 A Gln1107Pro (27) C exon 26 exon 26/3396 C wobble (25) T exon 26 exon 26/3421 T Ser1141Thr (29, 30) A exon 26 exon 26/3435 C wobble (23, 25, 29) T (Ile1145Ile) exon 28 exon 28/4030 G (33) C exon 28 exon 28/4036 A (23, 33) G The positions of the polymorphisms correspond to positions of MDR1 cDNA with the first base of the ATG start codon set to 1 (GenBank accession # M14758). Login to comment
68 The A61G mutation (Asn21Asp) results in a net charge change (basic to acidic) close to the N-terminus of P-glycoprotein, which appears to be of minor functional importance if recombinant mutational analyses of P-glycoprotein are considered (6). Login to comment
86 However, a recent publication characterized the functional consequences of five coding SNPs (Asn21Asp, Phe103Leu, Ser400Asn, Ala893Ser, Ala999Thr) using a vaccinia virus-based transient expression system (40a). Login to comment
312 A new polymorphism (N21D) in the exon 2 of the human MDR1 gene encoding the P-glycoprotein. Login to comment

[hide] MDR1 genotype-related pharmacokinetics and pharmac... Biol Pharm Bull. 2002 Nov;25(11):1391-400. Sakaeda T, Nakamura T, Okumura K
MDR1 genotype-related pharmacokinetics and pharmacodynamics.
Biol Pharm Bull. 2002 Nov;25(11):1391-400., [PMID:12419946]

Abstract [show]
The multidrug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily of membrane transporters. MDR1 acts as an energy-dependent efflux pump that exports its substrates out of cells. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multidrug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and detected 15 single nucleotide polymorphisms (SNPs). They also indicated that a polymorphism in exon 26 at position 3435 (C3435T), a silent mutation, affected the expression level of MDR1 protein in duodenum, and thereby the intestinal absorption of digoxin. To date, the genotype frequencies of C3435T have been investigated extensively using a larger population and interethnic difference has been elucidated, and a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on MDR1 genotype-related MDR1 expression and pharmacokinetics have also been performed around the world; however, results were not always consistent with Hoffmeyer's report. In this review, published reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping. In addition, recent investigations have raised the possibility that MDR1 and related transporters play a fundamental role in regulating apoptosis and immunology, and in fact, there are reports of MDR1-related susceptibility to inflammatory bowel disease, HIV infection and renal cell carcinoma. Herein, these issues are also summarized, and the current status of the knowledge in the area of pharmacogenomics of other transporters is briefly introduced.

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52 Kim et al. defined 15 alleles based on the frequencies of 11 polymorphisms of C-4T (noncoding), G-1A (noncoding), A61G (Asn21Asp), A548G (Asn183Ser), G1199A (Ser400Asn), C1236T (silent), C1474T (Arg492Cys), C2650T (silent), G2677T (Ala893Ser), T3421A (Ser1141Thr) and C3435T (silent).54) Six of 11 accompanied an amino acid change, and the others were conservative mutations. Login to comment
56 In 2001, Hitzl et al. also indicated that healthy Caucasian subjects with T/T3435 had a more decreased efflux of rhodamine from CD56ϩ NK cells and a lower MDR1 mRNA expression in leukocytes than those with C/C3435 .65) In renal tissues, the C3435T polymorphism is reported to be associated with reduced MDR1 expression.31) However, Tanabe et al. suggested that C3435T had no effect on the placental MDR1 expression based on 89 subjects and Western blotting.53) We determined MDR1 mRNA levels in biopsy specimens of the duodenum obtained from 13 healthy Japanese subjects by real time quantitative RT-PCR and found that MDR1 mRNA expression was higher in T/T3435 than C/C3435 or C/T3435 (Fig. 1).66) The discrepancies between the reports might be ex- November 2002 1393 Table 2. Summary of Genetic Polymorphisms in MDR1 Position Location Effect A1a/-41G Intron Noncoding C-145G Exon 1a Noncoding T-129C (T12C) Exon 1b Noncoding C-4T Exon 2 Noncoding G-1A Exon 2 Noncoding A61G Exon 2 Asn21Asp G5/-25T Intron G5/-35C Intron T307C Exon 5 Phe103Leu C6/ϩ139T Intron A548G Exon 7 Asn183Ser G1199A Exon 11 Ser400Asn C1236T Exon 12 Silent C12/ϩ44T Intron C1474T Exon 13 Arg492Cys T17/-76A Intron A17/ϩ137G Intron C2650T Exon 21 Silent G2677(A,T) Exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G Exon 24 Met986Val G2995A Exon 24 Ala999Thr A3320C Exon 26 Gln1107Pro C3396T Exon 26 Silent T3421A Exon 26 Ser1141Thr C3435T Exon 26 Silent G4030C Exon 28 Silent A4036G Exon 28 Silent This list was based on the literature (refs. 49-54). Login to comment
61 Kim et al. indicated that cells transduced with a variant MDR1 containing Ser893 showed a reduced intracellular accumulation of [3 H]-digoxin compared with cells with the wild-type Ala893 , suggesting enhanced efflux by the polymorphism of Ala893Ser (G2677T).54) On the other hand, very recently, Kimchi-Sarfaty et al. indicated that the cell surface expression and function of double mutants including the more common polymorphisms (A61G (Asn21Asp) and G1199A (Ser400Asn), A61G (Asn21Asp) and G2677T (Ala893Ser), G1199A (Ser400Asn) and G2677T (Ala893Ser)) showed no differences from the wild-type.67) MDR1 Genotype-Related Pharmacokinetics The aim of the clinical study by Greiner et al.64) was to elucidate the role of intestinal MDR1 expression in the interaction of digoxin with rifampin, and plasma concentration-time profiles were monitored after oral and intravenous administration of digoxin at 1 mg before and after oral administration of rifampin once daily for 16 d. Using the digoxin plasma concentration data after MDR1 induction by rifampin, Hoffmeyer et al.50) suggested that intestinal absorption of digoxin was greater in the subjects with the T-allele at position 3435. Login to comment

[hide] The effects of the human MDR1 genotype on the expr... Clin Pharmacol Ther. 2002 Nov;72(5):572-83. Siegmund W, Ludwig K, Giessmann T, Dazert P, Schroeder E, Sperker B, Warzok R, Kroemer HK, Cascorbi I
The effects of the human MDR1 genotype on the expression of duodenal P-glycoprotein and disposition of the probe drug talinolol.
Clin Pharmacol Ther. 2002 Nov;72(5):572-83., [PMID:12426521]

Abstract [show]
BACKGROUND AND OBJECTIVES: A single-nucleotide polymorphism (SNP) of the human multidrug-resistance gene in wobble position of exon 26 reportedly predicts expression and function of P-glycoprotein in human enterocytes and lymphocytes. Several other allelic variants of MDR1 have been identified, some of which lead to amino acid exchange with as yet unknown functional relevance. METHODS: In healthy white volunteers, we investigated the influence of the hereditary variants C3435T in exon 26 and G2677T/A (Ala893Ser/Thr) in exon 21 and the influence of 7 frequent or putative functional SNPs on duodenal MDR1 messenger ribonucleic acid (n = 32) and immunoreactive P-glycoprotein (n = 37) expression. Moreover, the disposition of the probe drug talinolol was evaluated in 55 subjects after oral administration (100 mg) and in 23 subjects after intravenous administration(30 mg). RESULTS: Duodenal MDR1 messenger ribonucleic acid and P-glycoprotein, as assessed by real-time polymerase chain reaction (TaqMan) and immunostaining, were not influenced by any MDR1 polymorphism studied. Talinolol disposition was not affected by the exon 26 mutation C3435T. In carriers of the TT/TA variants of G2677T/A, the area under the serum concentration-time curve values of oral talinolol were slightly but significantly elevated compared with those in carriers of at least 1 wild-type allele (P <.05, Kruskal-Wallis test; P =.014, Mann-Whitney U test). However, multiple comparisons with combinations of putative functional SNPs did not confirm a significant influence of the MDR1 genotype on talinolol disposition. CONCLUSIONS: We did not identify any influence of MDR1 genotypes on duodenal expression of P-glycoprotein and disposition of talinolol in humans.

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32 The following 10 most frequent or putatively functional SNPs of the MDR1 gene were identified, as recently described19 : intron 1 (exon 2 -1) G/A, exon 2 A61G (amino acid exchange Asn21Asp), intron 6 (exon 6 ϩ139) C/T, exon 11 G1199A (Ser400Asn), exon 12 C1236T, intron 12 (exon 12 ϩ44) C/T, intron 16 (exon 17 -76) T/A, exon 21 G2677T (Ala893Ser), G2677A (Ala893Thr), and exon 26 C3435T. Login to comment
112 Other authors, however, did not observe any significant correlation between the MDR1 genotype and fexofenadine disposition35 ; furthermore, a study in human placenta trophoblasts obtained from 100 Japanese women revealed less placental P-glycoprotein (Western blotting) in individuals having the G2677A/T allele.20 The nonanonymous variants A61G (Asn21Asp) in exon 2 and G1199A (Ser400Asn) in exon 11 were also expected to have a functional impact on human P-glycoprotein. Login to comment
113 The Asn21Asp exchange is located close to the N-terminus and the Ser400Asn variant just preceding the first adenosine triphosphate-binding domain.22 However, both mutations in our study did not influence P-glycoprotein expression and talinolol disposition. Login to comment

[hide] Pharmacogenetics of MDR1 and its impact on the pha... Pharmacogenomics. 2003 Jul;4(4):397-410. Sakaeda T, Nakamura T, Okumura K
Pharmacogenetics of MDR1 and its impact on the pharmacokinetics and pharmacodynamics of drugs.
Pharmacogenomics. 2003 Jul;4(4):397-410., [PMID:12831320]

Abstract [show]
The multi-drug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette (ABC) superfamily of membrane transporters. MDR1 was originally isolated from resistant tumor cells as part of the mechanism of multi-drug resistance, but over the last decade, it has been elucidated that human MDR1 is also expressed throughout the body to confer intrinsic resistance to the tissues by exporting unnecessary or toxic exogeneous substances or metabolites. A number of various types of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics and pharmacodynamics. In 2000, Hoffmeyer et al. performed a systemic screening for MDR1 polymorphisms and indicated that a single nucleotide polymorphism (SNP), C3435T in exon 26, which caused no amino acid change, was associated with the duodenal expression of MDR1 and thereby the plasma concentrations of digoxin after oral administration. Interethnic differences in genotype frequencies of C3435T have been clarified, and, at present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical studies on the effects of C3435T on MDR1 expression and function in the tissues, and also on the pharmacokinetics and pharmacodynamics have been performed around the world; however, there are still discrepancies in the results, suggesting that the haplotype analysis of the gene should be included instead of SNP detection, and the design of clinical trials must be carefully planned to avoid misinterpretations. A polymorphism of C3435T is also reported to be a risk factor for a certain class of diseases such as the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this might also be explained by the effects on MDR1 expression and function. In this review, the latest reports are summarized for the future individualization of pharmacotherapy based on MDR1 genotyping.

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75 Position Location Effect A1a/-41G Intron Non-coding C-145G Exon 1a Non-coding T-129C (T12C) Exon 1b Non-coding C-4T Exon 2 Non-coding G-1A Exon 2 Non-coding A61G Exon 2 Asn21Asp G5/-25T Intron G5/-35C Intron T307C Exon 5 Phe103Leu C6/+139T Intron A548G Exon 7 Asn183Ser G1199A Exon 11 Ser400Asn C1236T Exon 12 Silent C12/+44T Intron C1474T Exon 13 Arg492Cys T17/-76A Intron A17/+137G Intron C2650T Exon 21 Silent G2677(A,T) Exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G Exon 24 Met986Val G2995A Exon 24 Ala999Thr A3320C Exon 26 Gln1107Pro C3396T Exon 26 Silent T3421A Exon 26 Ser1141Thr C3435T Exon 26 Silent G4030C Exon 28 Silent A4036G Exon 28 Silent See references [34-39]. Login to comment

[hide] Sequence diversity and haplotype structure in the ... Pharmacogenetics. 2003 Aug;13(8):481-94. Kroetz DL, Pauli-Magnus C, Hodges LM, Huang CC, Kawamoto M, Johns SJ, Stryke D, Ferrin TE, DeYoung J, Taylor T, Carlson EJ, Herskowitz I, Giacomini KM, Clark AG
Sequence diversity and haplotype structure in the human ABCB1 (MDR1, multidrug resistance transporter) gene.
Pharmacogenetics. 2003 Aug;13(8):481-94., [PMID:12893986]

Abstract [show]
OBJECTIVES: There is increasing evidence that polymorphism of the ABCB1 (MDR1) gene contributes to interindividual variability in bioavailability and tissue distribution of P-glycoprotein substrates. The aim of the present study was to (1) identify and describe novel variants in the ABCB1 gene, (2) understand the extent of variation in ABCB1 at the population level, (3) analyze how variation in ABCB1 is structured in haplotypes, and (4) functionally characterize the effect of the most common amino acid change in P-glycoprotein. METHODS AND RESULTS: Forty-eight variant sites, including 30 novel variants and 13 coding for amino acid changes, were identified in a collection of 247 ethnically diverse DNA samples. These variants comprised 64 statistically inferred haplotypes, 33 of which accounted for 92% of chromosomes analyzed. The two most common haplotypes, ABCB1*1 and ABCB1*13, differed at six sites (three intronic, two synonymous, and one non-synonymous) and were present in 36% of all chromosomes. Significant population substructure was detected at both the nucleotide and haplotype level. Linkage disequilibrium was significant across the entire ABCB1 gene, especially between the variant sites found in ABCB1*13, and recombination was inferred. The Ala893Ser change found in the common ABCB1*13 haplotype did not affect P-glycoprotein function. CONCLUSION: This study represents a comprehensive analysis of ABCB1 nucleotide diversity and haplotype structure in different populations and illustrates the importance of haplotype considerations in characterizing the functional consequences of ABCB1 polymorphisms.

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141 Unauthorized reproduction of this article is prohibited. Table 1 Genetic variation in ABCB1 Allele frequencyd Variant cDNA NT DNA/AA AA Total CA AA AS ME PA No.a positionb changec position change (n ¼ 494) (n ¼ 200) (n ¼ 200) (n ¼ 60) (n ¼ 20) (n ¼ 14) 1.1Ã (À274) G to A Intron À1 0.006 0 0.016 0 0 0 1.2Ã (À223) C to T Intron À1 0.002 0.005 0 0 0 0 1.3Ã (À146) T to C Intron À1 0.002 0 0.005 0 0 0 1.4Ã (À60) A to T Intron À1 0.004 0 0.010 0 0 0 1.5 (À41) A to G Intron À1 0.002 0 0 0.017 0 0 1.6Ã À241 G to A Non-coding 0.002 0 0 0.017 0 0 1.7 À145 C to G Non-coding 0.002 0 0 0.017 0 0 1.8 À129 T to C Non-coding 0.060 0.051 0.071 0.036 0.100 0.071 1.9 À43 A to G Non-coding 0.012 0 0.020 0.036 0 0 1.10Ã (+140) C to A Intron 1 0.013 0.005 0.021 0 0 0.071 1.11Ã (+237) G to A Intron 1 0.004 0 0.010 0 0 0 2.1 À4 C to T Non-coding 0.004 0 0.010 0 0 0 2.2 À1 G to A Non-coding 0.036 0.080 0.005 0 0.050 0 2.3 61 A to G 21 Asn to Asp 0.045 0.080 0.025 0.017 0 0 4.1Ã (À8) C to G Intron 3 0.002 0.005 0 0 0 0 4.2Ã 266 T to C 89 Met to Thr 0.002 0.005 0 0 0 0 5.1 (À25) G to T Intron 4 0.210 0.158 0.300 0.067 0.200 0.286 8.1 729 A to G 243 Syn 0.002 0.005 0 0 0 0 8.2Ã 781 A to G 261 Ile to Val 0.006 0 0.015 0 0 0 10.1Ã (À44) A to G Intron 9 0.400 0.450 0.255 0.685 0.450 0.571 11.1Ã (À41) T to G Intron 10 0.002 0 0 0.017 0 0 11.2 1199 G to A 400 Ser to Asn 0.014 0.025 0.010 0 0 0 12.1Ã (À4) G to A Intron 11 0.002 0 0.005 0 0 0 12.2 1236 C to T 412 Syn 0.385 0.459 0.209 0.685 0.450 0.571 12.3Ã 1308 A to G 436 Syn 0.002 0 0.005 0 0 0 12.4Ã (+17) G to A Intron 12 0.008 0 0.020 0 0 0 12.5 (+44) C to T Intron 12 0.088 0.046 0.168 0 0 0 13.1 (+24) C to T Intron 13 0.530 0.521 0.542 0.540 0.450 0.571 14.1 1617 C to T 539 Syn 0.002 0.005 0 0 0 0 14.2 (+38) A to G Intron 14 0.540 0.505 0.540 0.683 0.450 0.500 15.1 (+38) G to A Intron 15 0.004 0.005 0.005 0 0 0 16.1Ã 1985 T to G 662 Leu to Arg 0.002 0.005 0 0 0 0 16.2Ã 2005 C to T 669 Arg to Cys 0.004 0 0.010 0 0 0 18.1Ã (À27) A to G Intron 17 0.008 0.010 0.005 0 0.050 0 20.1Ã (+8) C to G Intron 20 0.002 0 0.005 0 0 0 20.2 (+24) G to A Intron 20 0.126 0.121 0.150 0.067 0.200 0 20.3Ã (+40) C to T Intron 20 0.014 0 0.035 0 0 0 21.1Ã 2547 A to G 849 Ile to Met 0.002 0.005 0 0 0 0 21.2 2650 C to T 884 Syn 0.004 0.005 0.005 0 0 0 21.3a 2677 G to T 893 Ala to Ser 0.308 0.464 0.100 0.450 0.400 0.357 21.3b 2677 G to A 893 Ala to Thr 0.035 0.036 0.005 0.067 0 0.357 22.1 (+31) G to A Intron 22 0.002 0 0.005 0 0 0 25.1Ã 3151 C to G 1051 Pro to Ala 0.002 0 0.005 0 0 0 26.1Ã 3322 T to C 1108 Trp to Arg 0.002 0 0.005 0 0 0 26.2 3421 T to A 1141 Ser toThr 0.047 0 0.111 0 0.050 0 26.3 3435 C to T 1145 Syn 0.392 0.561 0.202 0.400 0.500 0.500 28.1 3751 G to A 1251 Val to Ile 0.002 0 0 0 0.050 0 28.2 3767 C to A 1256 Thr to Lys 0.002 0.005 0 0 0 0 28.3 (+21) T to C Intron 28 0.031 0 0.077 0 0 0 a Variants are numbered sequentially by exon. Login to comment
156 Only two haplotypes (ABCB1Ã14 and ABCB1Ã14A) contain two non-synonymous changes (Asn21Asp and Ala893Ser). Login to comment
164 M89T I849M V1251I T1256K S1141TW1108R P1052AR669C A893S/T L662R Cytoplasm S400N I261V N21D Extracellular Fig. 1. Login to comment
301 Other non-synonymous variants (Asn21Asp, Phe103Leu, Ser400Asn, and Ala998Thr) have also been shown not to affect P-glycoprotein function [43]. Login to comment

[hide] P-glycoprotein: from genomics to mechanism. Oncogene. 2003 Oct 20;22(47):7468-85. Ambudkar SV, Kimchi-Sarfaty C, Sauna ZE, Gottesman MM
P-glycoprotein: from genomics to mechanism.
Oncogene. 2003 Oct 20;22(47):7468-85., 2003-10-20 [PMID:14576852]

Abstract [show]
Resistance to chemically different natural product anti-cancer drugs (multidrug resistance, or MDR) results from decreased drug accumulation, resulting from expression of one or more ATP-dependent efflux pumps. The first of these to be identified was P-glycoprotein (P-gp), the product of the human MDR1 gene, localized to chromosome 7q21. P-gp is a member of the large ATP-binding cassette (ABC) family of proteins. Although its crystallographic 3-D structure is yet to be determined, sequence analysis and comparison to other ABC family members suggest a structure consisting of two transmembrane (TM) domains, each with six TM segments, and two nucleotide-binding domains. In the epithelial cells of the gastrointestinal tract, liver, and kidney, and capillaries of the brain, testes, and ovaries, P-gp acts as a barrier to the uptake of xenobiotics, and promotes their excretion in the bile and urine. Polymorphisms in the MDR1 gene may affect the pharmacokinetics of many commonly used drugs, including anticancer drugs. Substrate recognition of many different drugs occurs within the TM domains in multiple-overlapping binding sites. We have proposed a model for how ATP energizes transfer of substrates from these binding sites on P-gp to the outside of the cell, which accounts for the apparent stoichiometry of two ATPs hydrolysed per molecule of drug transported. Understanding of the biology, genetics, and biochemistry of P-gp promises to improve the treatment of cancer and explain the pharmacokinetics of many commonly used drugs.

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85 Kioka et al. (1989) showed a slight increase in resistance to doxorubicin, but no effect on colchicine or vinblastine Table 2 Common MDR1 exonic polymorphisms Exon number Polymorphic nucleotide variant Change in amino acid References 1 À145 - Ito et al. (2001) 1 À129 - Hoffmeyer et al. (2000); Tanabe et al. (2001) 2 61 N21D Cascorbi et al. (2001); Decleves et al. (2000); Hoffmeyer et al. (2000); Kim et al. (2001) 5 307 F103L Hoffmeyer et al. (2000) 7 548 N183S Kim et al. (2001) 10 1107 G369P Hoffmeyer et al. (2000) 11 1199 S400N Cascorbi et al. (2001); Hoffmeyer et al. (2000); Kim et al. (2001) 12 1236 Wobble Cascorbi et al. (2001); Hoffmeyer et al. (2000); Kim et al. (2001); Kioka et al. (1989) 13 1474 R492C Kim et al. (2001) 21 2650 Wobble Kim et al. (2001) 21 2677 893A, S, or T Cascorbi et al. (2001); Kim et al. (2001); Kioka et al. (1989); Mickley et al. (1998) 24 2956 M986V Tanabe et al. (2001) 24 2995 A999T Mickley et al. (1998) 26 3320 Q1107P Cascorbi et al. (2001) 26 3396 Wobble Hoffmeyer et al. (2000) 26 3421 S1141T Kim et al. (2001) 26a 3435 Wobble Hoffmeyer et al. (2000); Kim et al. (2001); Kioka et al. (1989) 28 4030 - Tanabe et al. (2001) 28 4036 - Kioka et al. (1989); Tanabe et al. (2001) a The only polymorphism that correlates with changes in drug delivery and disposition P-glycoprotein SV Ambudkar et al resistance in the SNP located on exon 21, position 2677, Ser893 (Kioka et al., 1989). Login to comment
110 HeLa cells were infected/transfected with empty vector (pTM1), wild-type pTM1-MDR1, pTM1-MDR1-S400N, pTM1-MDR1-N21D, pTM1-MDR1-F103L, pTM1-MDR1-A998T, and pTM1-MDR1-A893S, and were analysed by FACS as described previously (Kimchi-Sarfaty et al., 2002) Table 3 Selected substrates and modulators of P-glycoprotein Substrates Modulators Vinca alkaloids Calcium channel blockers Vinblastine Verapamil Vincristine Dihydropyridines Anthracyclines Antiarrhythmics Daunorubicin Quinine Doxorubicin Antihypertensives Antibiotics Reserpine Dactinomycin Antibiotics Actinomycin D Cephalosporins Other cytotoxic agents Immunosuppressants Mitomycin Cyclosporin A Taxol Steroid hormones Colchicine Progesterone Puromycin HIV protease inhibitors Digoxin Saquinavir Alcoholism treatment drug Disulfiram Phytochemical Curcumin Moreover, most of these studies correlated the manifestation of this polymorphism with a change in drug delivery or disposition. Login to comment

[hide] No effect of MDR1 C3435T variant on loperamide dis... Clin Pharmacol Ther. 2003 Nov;74(5):487-98. Pauli-Magnus C, Feiner J, Brett C, Lin E, Kroetz DL
No effect of MDR1 C3435T variant on loperamide disposition and central nervous system effects.
Clin Pharmacol Ther. 2003 Nov;74(5):487-98., [PMID:14586389]

Abstract [show]
BACKGROUND: The MDR1 gene encodes the efflux transporter P-glycoprotein, which is highly expressed in the small intestine and in the blood-brain barrier. A major function of P-glycoprotein is to limit the absorption and central nervous system exposure of numerous xenobiotics. A genetic polymorphism in the MDR1 gene (C3435T) has been associated with changes in the intestinal expression level and function of P-glycoprotein. The aim of this study was to investigate the effect of this polymorphism on disposition and brain entry of the P-glycoprotein substrate loperamide. METHODS: Healthy white volunteers were genotyped for the MDR1 C3435T polymorphism, and a 16-mg oral dose of loperamide was administered to 8 subjects with the 3435TT genotype and 8 subjects with the 3435CC genotype. Plasma levels of loperamide were determined by liquid chromatography-tandem mass spectrometry. Loperamide-induced respiratory depression was detected as the ventilatory response to carbon dioxide and was used as a measure of central nervous system side effects. RESULTS: We found no significant difference in loperamide pharmacokinetics between individuals homozygous for the C and the T alleles in position 3435 of MDR1, as follows: peak plasma drug concentration, 3164 +/- 1053 pg/mL and 3021 +/- 984 pg/mL; area under the concentration-time curve from 0 to 8 hours, 14414 +/- 4756 pg. h/mL and 14923 +/- 6466 pg. h/mL; and time to peak plasma drug concentration, 3.9 +/- 1.4 hours and 3.9 +/- 2.6 hours for the MDR1 3435CC and 3435TT genotypes, respectively (P >.05, for all parameters). Hypercapnic ventilatory response changed only minimally after ingestion of loperamide (the coefficient of variation during the 0- to 8-hour period was 21% +/- 14% for the sample population), and there was no MDR1 3435 genotype-related effect on respiratory response. Carriers of the 2 major MDR1 haplotypes, MDR1*1 and MDR1*13, did not differ in their response to loperamide. CONCLUSION: There was no association between the MDR1 C3435T variation and plasma levels or central nervous system effects of the P-glycoprotein substrate loperamide in a white study population. The MDR1 haplotype structure was quite variable and supports the use of haplotypes instead of single nucleotide polymorphisms in determining clinical consequences of genetic variation.

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118 One individual was homozygous for MDR1*14, which contains the G2677T variation, leading to the Ser893 coding change plus an additional A61G variant resulting in an Asn21Asp change in P-glycoprotein. Login to comment
168 In the MDR1 3435CC group, 2 individuals had haplotypes encoding P-glycoprotein variants (Ala893Thr and Asn21Asp), and all subjects in the MDR1 3435TT group were at least heterozygous for a haplotype encoding for the P-glycoprotein Ala893Ser variant. Login to comment

[hide] Haplotype analysis of ABCB1/MDR1 blocks in a Japan... Pharmacogenetics. 2003 Dec;13(12):741-57. Sai K, Kaniwa N, Itoda M, Saito Y, Hasegawa R, Komamura K, Ueno K, Kamakura S, Kitakaze M, Shirao K, Minami H, Ohtsu A, Yoshida T, Saijo N, Kitamura Y, Kamatani N, Ozawa S, Sawada J
Haplotype analysis of ABCB1/MDR1 blocks in a Japanese population reveals genotype-dependent renal clearance of irinotecan.
Pharmacogenetics. 2003 Dec;13(12):741-57., [PMID:14646693]

Abstract [show]
We performed comprehensive haplotyping of ABCB1/MDR1 gene blocks using 49 genetic polymorphisms, including seven novel ones, obtained from 145 Japanese subjects. The ABCB1/MDR1 gene was divided into four blocks (Blocks -1, 1, 2, and 3) based on linkage disequilibrium analysis of polymorphisms. Using an expectation-maximization based program, 1, 2, 8, and 3 haplotype groups (3, 12, 32, and 18 haplotypes) were identified in Blocks -1, 1, 2, and 3, respectively. Within Block 2, haplotype groups *1, *2, *4, *6, and *8 reported by Kim and colleagues (Clin Pharmacol Ther 2001; 70:189-199) were found, and additional three groups (*9 to *11) were newly defined. We analyzed the association of haplotypes with the renal clearance of irinotecan and its metabolites in 49 Japanese cancer patients given irinotecan intravenously. There was a significant association of the *2 haplotype in Block 2, which includes 1236C>T, 2677G>T and 3435C>T, with a reduced renal clearance of those compounds. Moreover, tendencies of reduced and increased renal clearance were also observed with *1f in Block 2 and *1b in Block 3, respectively. These findings suggest that the P-glycoprotein encoded by ABCB1/MDR1 in the proximal tubules plays a substantial role in renal exclusion of drugs and, moreover, that block-haplotyping is valuable for pharmacogenetic studies.

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103 746Pharmacogenetics2003,Vol13No12 Copyright(c)LippincottWilliams&Wilkins.Unauthorizedreproductionofthisarticleisprohibited. Table 3 Classification of major ABCB1 haplotypes Site Exon 2 Exon 5 Exon 7 Exon 11 Exon 12 Exon 13 Exon 21 Exon 21 Exon 21 Exon 26 Exon 26 Exon 27 Exon 28 PositionÃ Exon 1 Exon 1 61A.G 325G.A 548A.G 1199G.A 1236C.T 1474C.T 2650C.T 2677G.T 2677G.A 3421T.A 3435C.T 3587T.G 3751G.A Effect on protein À4C.T À1G.A N21D E109K N183S S400N G412G R492C L884L A893S A893T S1141T I1145I I1196S V1251I Classification by Kim et al. [12] Ã1 - - - - - - - - - - - Ã1A - - - - A - - - - - - Ã1B T - - - - - - - - - - Ã1C - - - - - - - - - A - Ã1D - - - G - - - - - - - Ã2 - - - - - T - - T - T Ã2A - - G - - T - - T - T Ã2B - - - - - T - T T - T Ã2C - - - - - T T - T - T Ã3 - - - - - - - - T - T Ã4 - - - - - T - - - - T Ã5 - A - - - - - - - - T Ã6 - - - - - - - - - - T Ã7 - - - - - - - - T - - Ã8 - - - - - T - - - - - Classification of haplotype group detected in this paperÃÃ Block 1 Ã1 - - - - Ã2 - - G - Block 2 Ã1 - - - - - - - - - Ã2 - - T - - T - - T Ã4 - - T - - - - - T Ã6 - - - - - - - - T Ã8 - - T - - - - - - Ã9 - - - - - - - - - Ã10 - - - - - - A - - Ã11 - - T - - - A - - Block 3 Ã1 - - Ã2 - A Ã3 G - ÃAdenine of the initiation codon ATG in exon 2 was numbered +1. Login to comment

[hide] Polymorphisms in human MDR1 (P-glycoprotein): rece... Clin Pharmacol Ther. 2004 Jan;75(1):13-33. Marzolini C, Paus E, Buclin T, Kim RB
Polymorphisms in human MDR1 (P-glycoprotein): recent advances and clinical relevance.
Clin Pharmacol Ther. 2004 Jan;75(1):13-33., [PMID:14749689]

Abstract [show]
Drug transporters are increasingly recognized to be important to drug disposition and response. P-glycoprotein, the encoded product of the human MDR1 (ABCB1) gene, is of particular clinical relevance in that this transporter has broad substrate specificity, including a variety of structurally divergent drugs in clinical use today. Moreover, expression of this efflux transporter in certain tissue compartments such as the gastrointestinal tract and brain capillary endothelial cells limits oral absorption and central nervous system entry of many drugs. Recently, a number of single-nucleotide polymorphisms (SNPs) in MDR1 have been identified. An increasing number of studies have also implicated certain commonly occurring SNPs in MDR1 in problems including altered drug levels and host susceptibility to diseases such as Parkinson's disease, inflammatory bowel disease, refractory seizures, and CD4 cell recovery during human immunodeficiency virus therapy. However, in many such cases, the reported effects of MDR1 SNPs have been inconsistent and, in some cases, conflicting. In this review SNPs in MDR1 in relation to population frequencies, drug levels, and phenotypes are outlined. In addition, issues relating to MDR1 haplotypes, environmental factors, and study design, as potential confounding factors of the observed MDR1 polymorphism effect in vivo, are also discussed.

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75 Summary of genetic polymorphisms in MDR1 Location Position Mutation Effect Mutant allele frequency (%) Hoffmeyer et al89 : C Cascorbi et al90 : C Siegmund et al91 : C Promotor 5' flanking/-41 A/G Noncoding Exon 1a Exon 1a/-145 C/G Noncoding Exon 1b Exon 1b/-129 T/C Noncoding 5.9 Intron 1 Exon 2/-4 C/T Noncoding Intron 1 Exon 2/-1 G/A Initial translation 5.6 9 3.7 Exon 2 Exon 2/61 A/G Asn21Asp 9.3 11.2 8.9 Intron 4 Exon 5/-35 G/C 0.6 Intron 4 Exon 5/-25 G/T 16.5 Exon 5 Exon 5/307 T/C Phe103Leu 0.6 0 Intron 6 Exon 6/ϩ139 C/T 40.6 37.2 35.8 Intron 6 Exon 6/ϩ145 C/T 1.2 Exon 7 Exon 7/548 A/G Asn183Ser Exon 11 Exon 11/1199 G/A Ser400Asn 6.5 5.5 2.9 Exon 12 Exon 12/1236 C/T Silent 37.8 41 34.3 Intron 12 Exon 12/ϩ44 C/T 5.9 4.9 7.5 Exon 13 Exon 13/1474 C/T Arg492Cys Intron 16 Exon 17/-76 T/A 45.3 46.2 49.3 Intron 17 Exon 17/ϩ137 A/G 0.6 Exon 21 Exon 21/2650 C/T Silent Exon 21 Exon 21/2677 G/T Ala893Ser 41.6 40.3 G/A Ala893Thr 1.9 3.7 Exon 24 Exon 24/2956 A/G Met986Val Exon 24 Exon 24/2995 G/A Ala999Thr Exon 26 Exon 26/3320 A/C Gln1107Pro 0.2 Exon 26 Exon 26/3396 C/T Silent 0.3 Exon 26 Exon 26/3421 T/A Ser1141Thr Exon 26 Exon 26/3435 C/T Silent 48.1 53.9 50.7 Exon 28 Exon 28/4030 G/C Exon 28 Exon 28/4036 A/G The positions of the polymorphisms were established with the first base of the ATG start codon set to 1. Login to comment

[hide] Functional implications of genetic polymorphisms i... Pharm Res. 2004 Jun;21(6):904-13. Pauli-Magnus C, Kroetz DL
Functional implications of genetic polymorphisms in the multidrug resistance gene MDR1 (ABCB1).
Pharm Res. 2004 Jun;21(6):904-13., [PMID:15212152]

Abstract [show]
The multidrug resistance (MDR1) gene product P-glycoprotein is a membrane protein that functions as an ATP-dependent efflux pump, transporting exogenous and endogenous substrates from the inside of cells to the outside. Physiological expression of P-glycoprotein in tissues with excretory or protective function is a major determinant of drug disposition and provides a cellular defense mechanism against potentially harmful compounds. Therefore, P-glycoprotein has significant impact on therapeutic efficacy and toxicity as it plays a key role in absorption of oral medications from the intestinal tract, excretion into bile and urine, and distribution into protected tissues such as the brain and testes. There is increasing interest in the possible role of genetic variation in MDR1 in drug therapy. Numerous genetic polymorphisms in MDR1 have been described, some of which have been shown to determine P-glycoprotein expression levels and substrate transport. Furthermore, some of these polymorphisms have an impact on pharmacokinetic and pharmacodynamic profiles of drug substrates and directly influence outcome and prognosis of certain diseases. This review will focus on the impact of genetic variation in MDR1 on expression and function of P-glycoprotein and the implications of this variation for drug therapy and disease risk.

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28 6, June 2004 ((c) 2004) 9040724-8741/04/0600-0904/0 (c) 2004 Plenum Publishing Corporation Table I. MDR1 Coding Variants cDNA positiona NT change DNA/AA position AA change Allele frequencyb Total (n ‫ס‬ 494) CA (n ‫ס‬ 200) AA (n ‫ס‬ 200) AS (n ‫ס‬ 60) ME (n ‫ס‬ 20) PA (n ‫ס‬ 14) 61 A to G 21 Asn to Asp 0.045 0.080 0.025 0.017 0 0 266 T to C 89 Met to Thr 0.002 0.005 0 0 0 0 729 A to G 243 Syn 0.002 0.005 0 0 0 0 781 A to G 261 Ile to Val 0.006 0 0.015 0 0 0 1199 G to A 400 Ser to Asn 0.014 0.025 0.010 0 0 0 1236 C to T 412 Syn 0.385 0.459 0.209 0.685 0.450 0.571 1308 A to G 436 Syn 0.002 0 0.005 0 0 0 1617 C to T 539 Syn 0.002 0.005 0 0 0 0 1985 T to G 662 Leu to Arg 0.002 0.005 0 0 0 0 2005 C to T 669 Arg to Cys 0.004 0 0.010 0 0 0 2547 A to G 849 Ile to Met 0.002 0.005 0 0 0 0 2650 C to T 884 Syn 0.004 0.005 0.005 0 0 0 2677 G to T 893 Ala to Ser 0.308 0.464 0.100 0.450 0.400 0.357 2677 G to A 893 Ala to Thr 0.035 0.036 0.005 0.067 0 0.357 3151 C to G 1051 Pro to Ala 0.002 0 0.005 0 0 0 3322 T to C 1108 Trp to Arg 0.002 0 0.005 0 0 0 3421 T to A 1141 Ser to Thr 0.047 0 0.111 0 0.050 0 3435 C to T 1145 Syn 0.392 0.561 0.202 0.400 0.500 0.500 3751 G to A 1251 Val to Ile 0.002 0 0 0 0.050 0 3767 C to A 1256 Thr to Lys 0.002 0.005 0 0 0 0 a cDNA numbers are relative to the ATG site and based on the cDNA sequence from GenBank accession number M14758. Login to comment
94 A vaccinia virus expression system was used to examine the Asn21Asp, Phe103Leu, Ser400Ala, Ala893Ser, and Ala893Thr P-glycoprotein variants. Login to comment
118 Functional Impact in vitro of MDR1 Variants Amino acid change Functional effect of the variant allele Reference Val185Ser Increased colchicine resistance [30] ⌬Phe335 Decreased resistance to vinca alkaloids; no resistance to dactinomycin [31] Lys536Gln, Gly534Asp, Lys536Arg, Ser532Arg, ⌬Tyr490 Defective RNA processing [33] Ala893Ser Acquired overexpression of one allele in drug-resistant cells [20] Ala893Ser Decreased digoxin efflux [19] Asn21Asp, Phe103Leu, Ser400Ala, Ala893Ser, Ala893Thr No effect on P-glycoprotein cell surface expression and substrate specificity [69] Ala893Ser No difference in calcein-AM transport [27] Ala893Ser/Thr No difference in transport of verapamil, digoxin, viblastine and cyclosporine A [35] 3435 polymorphisms were analyzed separately, with AUC values being highest for individuals carrying the reference alleles. Login to comment

[hide] Pharmacogenomics of drug transporters: a new appro... Biol Pharm Bull. 2004 Jul;27(7):939-48. Ishikawa T, Onishi Y, Hirano H, Oosumi K, Nagakura M, Tarui S
Pharmacogenomics of drug transporters: a new approach to functional analysis of the genetic polymorphisms of ABCB1 (P-glycoprotein/MDR1).
Biol Pharm Bull. 2004 Jul;27(7):939-48., [PMID:15256718]

Abstract [show]
In the 21st century, emerging genomic technologies (i.e., bioinformatics, functional genomics, and pharmacogenomics) are shifting the paradigm of drug discovery research and improving the strategy of medical care for patients. In order to realize the personalized medicine, it is critically important to understand molecular mechanisms underlying inter-individual differences in the drug response, namely, pharmacological effect vs. side effect. Evidence is now accumulating to strongly suggest that drug transporters are one of the determinant factors governing the pharmacokinetic profile of drugs. Effort has been made to identify genetic variation in drug transporter genes. In particular, genetic variations of the human ABCB1 (P-glycoprotein/MDR1) gene have been most extensively studied. Hitherto more than fifty single nucleotide polymorphisms (SNPs) and insertion/deletion polymorphisms in the ABCB1 gene have been reported. However, at the present time, information is still limited with respect to the actual effect of those genetic polymorphisms on the function of ABCB1. In this context, we have undertaken functional analyses of ABCB1 polymorphisms. To quantify the impact of genetic polymorphisms on the substrate specificity of ABCB1, we have developed a high-speed screening system and a new structure-activity relationship (SAR) analysis method. This review addresses functional aspects of the genetic polymorphism of ABCB1 and provides the standard method to evaluate the effect of polymorphisms on the function.

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79 For this purpose, the cDNA of ABCB1 was cloned from the human liver cDNA library, and several variant forms (i.e., N21D, N44S, F103L, G185V, S400N, A893S, A893T, M986V) were prepared by site-directed mutagenesis (see Fig. 4A for primers). Login to comment
94 The variant forms (i.e., N21D, N44S, F103L, G185V, S400N, A893S, A893T, M986V) exhibited the verapamil-enhanced ATPase activity, as did the wild type of ABCB1. Login to comment
97 The variant G185V (acquired mutation) was found to have the highest Vmax value, which was followed by N21D (Table 1). Login to comment
118 Kinetic Parameters of the Wild Type and SNP Variants of ABCB1 Variant Km Vmax (mM) (nmol/min/mg protein) Wild type 2.190Ϯ0.150 13.14Ϯ1.95 N21D 0.502Ϯ0.126 45.26Ϯ11.33 N44S 0.580Ϯ0.148 31.03Ϯ4.65 F103L 1.100Ϯ0.078 36.34Ϯ8.33 G185V 0.831Ϯ0.102 56.76Ϯ6.76 S400N 0.327Ϯ0.025 13.74Ϯ2.08 A893S 0.441Ϯ0.042 17.24Ϯ6.72 A893T 0.904Ϯ0.244 10.77Ϯ1.35 M986V 0.419Ϯ0.062 22.69Ϯ6.84 The wild type and variants of ABCB1 were then expressed it in Sf9 cells using the pFASTBAC1 vector and recombinant baculoviruses. Login to comment

[hide] Pharmacogenetics of drug transporters and its impa... Curr Top Med Chem. 2004;4(13):1385-98. Sakaeda T, Nakamura T, Okumura K
Pharmacogenetics of drug transporters and its impact on the pharmacotherapy.
Curr Top Med Chem. 2004;4(13):1385-98., [PMID:15379652]

Abstract [show]
Most drug responses are determined by the interplay of several gene products that influence pharmacokinetics and pharmacodynamics, i.e., drug metabolizing enzymes, drug transporters, and drug targets. With the sequencing of the human genome, it has been estimated that approximately 500-1200 genes code for drug transporters. Concerning the effects of genetic polymorphisms on pharmacotherapy, the best characterized drug transporter is the multidrug resistant transporter P-glycoprotein/MDR1, the gene product of MDR1. Little such information is available on other drug transporters. MDR1 is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily, and is expressed mainly in intestines, liver, kidneys and brain. A number of various types of structurally unrelated drugs are substrates for MDR1, and their intestinal absorption, hepatobiliary secretion, renal secretion and brain transport are regulated by MDR1. The first investigation on the effects of MDR1 genotypes on pharmacotherapy was reported in 2000: a silent single nucleotide polymorphism (SNP), C3435T in exon 26, was found to be associated with the duodenal expression of MDR1, and thereby the plasma concentration of digoxin after oral administration. At present, a total of 28 SNPs have been found at 27 positions on the MDR1 gene. Clinical investigations on the association of MDR1 genotypes with the expression and function of MDR1 in tissues, and with pharmacokinetics and pharmacodynamics have mainly focused on C3435T; however, there are still discrepancies in the results, suggesting that the haplotype of the gene should be analyzed instead of a SNP. C3435T is also reported to be a risk factor for a certain class of diseases including the inflammatory bowel diseases, Parkinson's disease and renal epithelial tumor, and this also might be explained by the effects on MDR1 expression and function. In this review, the latest reports on the effects of genetic polymorphisms of MDR1 on pharmacotherapy are summarized, and the pharmacogenetics of other transporters is briefly introduced.

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127 Position Location Effect A1a/-41G intron noncoding C-145G exon 1a noncoding T-129C (T12C) exon 1b noncoding C-4T exon 2 noncoding G-1A exon 2 noncoding A61G G5/-25T G5/-35C exon 2 intron intron Asn21Asp T307C C6/+139T exon 5 intron Phe103Leu A548G exon 7 Asn183Ser G1199A exon 11 Ser400Asn C1236T C12/+44T exon 12 intron silent C1474T T17/-76A A17/+137G exon 13 intron intron Arg492Cys C2650T exon 21 silent G2677(A,T) exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G exon 24 Met986Val G2995A exon 24 Ala999Thr A3320C exon 26 Gln1107Pro C3396T exon 26 silent T3421A exon 26 Ser1141Thr C3435T exon 26 silent G4030C exon 28 silent A4036G exon 28 silent The list was based on the reports [67,68,71-74]. Login to comment

[hide] Functional evaluation of ABCB1 (P-glycoprotein) po... Drug Metab Pharmacokinet. 2004 Feb;19(1):1-14. Ishikawa T, Hirano H, Onishi Y, Sakurai A, Tarui S
Functional evaluation of ABCB1 (P-glycoprotein) polymorphisms: high-speed screening and structure-activity relationship analyses.
Drug Metab Pharmacokinet. 2004 Feb;19(1):1-14., [PMID:15499164]

Abstract [show]
Evidence is accumulating to strongly suggest that drug transporters are one of the determinant factors governing the pharmacokinetic profile of drugs. Effort has been made to identify genetic variation in drug transporter genes. In particular, genetic variations of the human ABCB1 (MDR1) gene have been most extensively studied. Hitherto more than fifty single nucleotide polymorphisms (SNPs) and insertion/deletion polymorphisms in the ABCB1 gene have been reported. However, at the present time, information is still limited with respect to the actual effect of those genetic polymorphisms on the function of ABCB1. In this context, we have undertaken functional analyses of ABCB1 polymorphisms. To quantify the impact of genetic polymorphisms on the substrate specificity of ABCB1, we have developed a high-speed screening system and a new structure-activity relationship (SAR) analysis method. This review addresses functional aspects of the genetic polymorphism of ABCB1 and provides the standard method to evaluate the effect of polymorphisms on the function.

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78 For this purpose, the cDNA of ABCB1 was cloned from the human liver cDNA library, and several variant forms (i.e., N21D, N44S, F103L, G185V, S400N, A893S, A893T, M986V) were prepared by site-directed mutagenesis (see Fig. 2A for primers). Login to comment
86 The variant forms (i.e., N21D, N44S, F103L, G185V, S400N, A893S, A893T, M986V) exhibited the verapamil-enhanced ATPase activity, as did the wild type of ABCB1. Login to comment
89 The variant G185V (acquired mutation) was found to have the highest Vmax value, which was followed by N21D (Table 2). Login to comment
105 Kinetic parameters of the wild type and SNP variants of ABCB1 Variant Km Vmax (mM) (nmolWminWmg protein) Wild type 2.190±0.150 13.14±1.95 N21D 0.502±0.126 45.26±11.33 N44S 0.580±0.148 31.03±4.65 F103L 1.100±0.078 36.34±8.33 G185V 0.831±0.102 56.76±6.76 S400N 0.327±0.025 13.74±2.08 A893S 0.441±0.042 17.24±6.72 A893T 0.904±0.244 10.77±1.35 M986V 0.419±0.062 22.69±6.84 The wild type and variants of ABCB1 were then expressed it in Sf9 cells using the pFASTBAC1 vector and recombinant baculoviruses. Login to comment

[hide] Ethnic differences in genetic polymorphisms of CYP... Drug Metab Pharmacokinet. 2004 Apr;19(2):83-95. Ozawa S, Soyama A, Saeki M, Fukushima-Uesaka H, Itoda M, Koyano S, Sai K, Ohno Y, Saito Y, Sawada J
Ethnic differences in genetic polymorphisms of CYP2D6, CYP2C19, CYP3As and MDR1/ABCB1.
Drug Metab Pharmacokinet. 2004 Apr;19(2):83-95., [PMID:15499174]

Abstract [show]
Metabolic capacities for debrisoquin, sparteine, mephenytoin, nifedipine, and midazolam, which are substrates of polymorphic CYP2D6, CYP2C19, and CYP3A, have been reported to exhibit, in many cases, remarkable interindividual and ethnic differences. These ethnic differences are partly associated with genetic differences. In the case of the drug transporter ABCB1/MDR1, interindividual differences in its transporter activities toward various clinical drugs are also attributed to several ABCB1/MDR1 genetic polymorphisms. In this review, the existence and frequency of various low-activity alleles of drug metabolizing enzymes as well as populational drug metabolic capacities are compared among several different races or ethnicities. Distribution of nonsynonymous ABCB1/MDR1 SNPs and haplotype frequency in various races are summarized, with the association of nonsynonymous SNPs with large functional alterations as a rare event.

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85 Ethnic dierences in nonsynonymous SNPs of ABCB1W MDR1 cDNA positiona Position and amino acid change C AA AS J 61AÀG N21D 0.080 0.025 0.017 0 266TÀC M89T 0.005 0 0 0 781AÀG I261V 0 0.015 0 0 1199GÀA S400N 0.025 0.010 0 0 1985TÀG L662R 0.005 0 0 0 2005CÀT R669C 0 0.010 0 0 2547AÀG I849M 0.005 0 0 0 2677GÀT A893S 0.464 0.100 0.450 0.403 2677GÀA A893T 0.036 0.005 0.067 0.200 3151CÀG P1051A 0 0.005 0 0 3322TÀC W1108R 0 0.005 0 0 3421TÀA S1141T 0 0.111 0 0 3751GÀA V1251I 0 0 0 0.010 3767CÀA T1256K 0.005 0 0 0 C, 100 Caucasians; AA, 100 African-Americans; AS, 30 Asians; J, 145 Japanese (our study 116) ). Login to comment

[hide] Polymorphism of MDR1 gene in healthy japanese subj... Drug Metab Pharmacokinet. 2002;17(5):479-81. Honda T, Dan Y, Koyabu N, Ieiri I, Otsubo K, Higuchi S, Ohtani H, Sawada Y
Polymorphism of MDR1 gene in healthy japanese subjects: a novel SNP with an amino acid substitution (Glu108Lys).
Drug Metab Pharmacokinet. 2002;17(5):479-81., [PMID:15618700]

Abstract [show]
We discovered a novel single nucleotide polymorphism (SNP) at position 325 (G325A) in exon 5 of the multidrug-resistance 1 (MDR1) gene in a study of 37 healthy Japanese subjects. Details are as follows. SNP, 020614Honda001; GENE NAME, human P-glycoprotein (MDR1); ACCESSION NUMBER, M29427; LENGTH, 25 bases; 5'-ATGAATCTGGAGG/AAAGACATGACCA-3'. This SNP is expected to cause an amino acid substitution (Glu108Lys). In this study, one homozygote and one heterozygote for G325A were identified.

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13 To date, the following SNPs in the MDR1 gene leading to amino acid substitutions have been identiˆed: A61G (Asn21Asp) in exon 2, T307C (Phe103Leu) in exon 5, G1199A (Ser400Asn) in exon 11, G2677T (Ala893Ser) in exon 21, G2677A (Ala893Thr) in exon 21 and A2956G (Met986Val) in exon 24. Login to comment

[hide] Twelve novel single nucleotide polymorphisms in AB... Drug Metab Pharmacokinet. 2002;17(6):566-71. Itoda M, Saito Y, Komamura K, Ueno K, Kamakura S, Ozawa S, Sawada J
Twelve novel single nucleotide polymorphisms in ABCB1/MDR1 among Japanese patients with ventricular tachycardia who were administered amiodarone.
Drug Metab Pharmacokinet. 2002;17(6):566-71., [PMID:15618713]

Abstract [show]
Twelve novel single nucleotide polymorphisms (SNPs) were found in the gene encoding the ATP-binding cassette transporter, P-glycoprotein, from 60 Japanese individuals who were administered the anti-antiarrythmic drug, amiodarone. The detected SNPs were as follows: 1) SNP, MPJ6_AB1017 (IVS6-109); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 2) SNP, MPJ6_AB1018 (IVS7+14); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 3) SNP, MPJ6_AB1021 (IVS9-44); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 4) SNP, MPJ6_AB1052 (IVS12+17); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 5) SNP, MPJ6_AB1029 (IVS15-69); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 6) SNP, MPJ6_AB1040 (IVS24+16); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 7) SNP, MPJ6_AB1053 (IVS27-189); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 8) SNP, MPJ6_AB1054 (IVS27-172); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 9) SNP, MPJ6_AB1048 (IVS27-167); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 10) SNP, MPJ6_AB1055 (IVS27-152); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 11) SNP, MPJ6_AB1049 (IVS27-119); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168; 12) SNP, MPJ6_AB1051 (at nucleotide 3751 (exon 28) from the A of the translation initiation codon); GENE NAME, ABCB1; ACCESSION NUMBER, NT_017168. Among these SNPs, only MPJ6_AB1051 resulted in an amino acid alteration, V1251I.

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18 Much eort has been taken to uncover polymorphisms in the ABCB1WMDR1 gene since a synonymous SNP, which correlated with diminished MDR1 expression levels in the human duodenum, was reported by Homeyer et al.7) To date, information on 19 single nucleotide polymorphisms (SNPs) including 7 nonsynonymous ones (N21D, F103L, S400N, A893S, A893T, A999T and Q1107P) for ABCB1WMDR1 have been reported in Caucasians.8,9) ABCB1WMDR1 gene SNPs including intronic10) and 2 nonsynonymous SNPs (E108K, M986V)11,12) were also reported in Japanese population. Login to comment
78 Moreover, the reported nonsynonymous polymorphisms, N21D, F103L, S400N, A893S and A999T have been shown not to substantially aect the activity of P-glycoprotein14) . Login to comment

[hide] Single nucleotide polymorphisms of ABCB1 (MDR1) ge... Eur J Clin Pharmacol. 2005 Apr;61(2):97-102. Epub 2005 Feb 4. Allabi AC, Horsmans Y, Issaoui B, Gala JL
Single nucleotide polymorphisms of ABCB1 (MDR1) gene and distinct haplotype profile in a West Black African population.
Eur J Clin Pharmacol. 2005 Apr;61(2):97-102. Epub 2005 Feb 4., [PMID:15692830]

Abstract [show]
OBJECTIVE: The ABCB1 (MDR1) multidrug transporter plays a key role in determining drug bioavailability. Differences in drug response exist among different ethnic groups. However, until now, no haplotype data are available in a Black African population. METHODS: Exons 2, 7, 10, 11, 12, 14, 17, 21, 26, and the surrounding intronic regions were sequenced using genomic DNA from 111 Beninese subjects to examine 19 intragenic single nucleotide polymorphisms (SNPs). Linkage disequilibrium analysis and haplotypes were generated using the expectation-maximization algorithm. RESULTS: We identified 12 SNPs, 3 of which were novel: IVS9-57delA, IVS9-8T>A, 1662G>C (exon 14). The most common SNP was IVS14+38A>G. At the MRD1 locus, 53 haplotypes were inferred from the SNP data sets. The 4 SNPs, IVS6+139C>T, IVS9-44A>G, 1236C>T, and 3435C>T, showed strong linkage disequilibrium with each other, confirming the block concept. Moreover, our findings suggest that ABCB1 exonic SNPs are less frequently observed in our population than in African-Americans. CONCLUSION: Our data are compatible with a close evolutionary relationship in Black Africans from Benin.

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66 AA amino acid, n number of chromosomes examined, ND not detected Variant no.a cDNA positionb NT changec DNA/AA position AA change Allele frequencyd (n=222) 2.1 À4 C to T Non-coding 0.0045 2.2 À1 G to A Non-coding 0 2.3 61 A to G 21 Asn to Asp 0 6.1 139 C to T Intron 6 0.17 9.0* À57 del A Intron 9 0.009 10.1 À44 A to G Intron 9 0.18 10.0* À8 T to A Intron 9 0.0045 11.1 À41 T to G Intron 10 0 11.2 1199 G to A 400 Ser to Asn 0 12.2 1236 C to T 412 Syn 0.15 14.1 1617 C to T 539 Syn 0 14.0* 1662 G to C 554 Syn 0.009 14.2 38 A to G Intron 14 0.49 17.1 À76 T to A Intron 16 0.347 21.2 2650 C to T 884 Syn 0 21.3a 2677 G to T 893 Ala to Ser 0.009 21.3b 2677 G to A 893 Ala to Thr 0 26.2 3421 T to A 1141 Ser to Thr 0.054 26.3 3435 C to T 1145 Syn 0.14 a Variants are numbered sequentially by exon. Login to comment

[hide] Effect of the MDR1 C3435T variant and P-glycoprote... J Clin Pharmacol. 2005 Apr;45(4):411-21. Putnam WS, Woo JM, Huang Y, Benet LZ
Effect of the MDR1 C3435T variant and P-glycoprotein induction on dicloxacillin pharmacokinetics.
J Clin Pharmacol. 2005 Apr;45(4):411-21., [PMID:15778422]

Abstract [show]
This study investigated 2 hypotheses about genotype-phenotype relationships for the efflux transporter, P-glycoprotein: (1) the presence of a synonymous C3435T variant in exon 26 of the MDR1 gene correlates to higher plasma concentrations of a P-glycoprotein substrate, dicloxacillin, and (2) the effects of genotypic differences decrease under conditions of P-glycoprotein induction by rifampin. Eighteen healthy volunteers received two 1-g doses of dicloxacillin, one on the 1st study day and the other on the 11th day of rifampin dosing (600 mg daily). Dicloxacillin and its 5-hydroxymethyl metabolite were analyzed using liquid chromatography/tandem mass spectrometry. Mean dicloxacillin C(max) measurements were 30.5 +/- 13.5, 33.3 +/- 4.7, and 31.1 +/- 12.8 mug/mL in individuals with the CC, CT, and TT genotype at position 3435 in exon 26 of the MDR1 gene. Following rifampin dosing, the mean dicloxacillin C(max) across genotypes decreased from 31.4 +/- 10.8 to 22.9 +/- 7.0 microg/mL (P < .05), whereas the mean oral clearance increased from 235 +/- 82 to 297 +/- 71 mL/min (P < .001), and the mean absorption time increased from 0.71 +/- 0.55 to 1.34 +/- 0.77 h (P < .05). Rifampin treatment increased the formation clearance, C(max), and AUC of the 5-hydroxymethyl metabolite by 135%, 119%, and 59%, respectively. The C3435T variant had no effect on dicloxacillin pharmacokinetics. The data suggested that rifampin induced intestinal P-glycoprotein and increased dicloxacillin metabolism.

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121 These results are consistent with the linkage reported between the 6 variant sites in the MDR1*13 haplotype.17 Three of the subjects in the 3435TT group also had a MDR1 variant leading to an Asn21Asp change in P-glycoprotein. Login to comment

[hide] Complex haplotypic effects of the ABCB1 gene on ep... Pharmacogenomics. 2005 Jun;6(4):411-7. Hung CC, Tai JJ, Lin CJ, Lee MJ, Liou HH
Complex haplotypic effects of the ABCB1 gene on epilepsy treatment response.
Pharmacogenomics. 2005 Jun;6(4):411-7., [PMID:16004559]

Abstract [show]
OBJECTIVES: The aim of this study was to investigate the association of the complex haplotype system of the adenosine triphosphate-binding cassette B1 (ABCB1) gene with the epilepsy treatment response. METHODS AND RESULTS: Ten polymorphisms were genotyped in 108 drug-resistant epileptic patients, 223 seizure-free patients and 287 normal controls. Highly significant linkage disequilibrium was shown among exon 12 C1236T, exon 21 G2677T and exon 26 C3435T. Haplotypic analysis demonstrated that patients with the CGC, TGC, and TTT haplotypes were more likely to be drug resistant. Further analysis of haplotype combinations demonstrated that drug-resistant patients tended to have the CGC/CGC, CGC/TGC, CGC/TTT, and TGC/TTT haplotype combinations over the seizure-free patients and controls (all p-values < 0.0001). In contrast, patients with the TTC/TTC, TTC/CGT, TTC/TGT, CGT/CGT and TGT/CGT haplotype combinations were more likely to be seizure-free (all p-values<0.0001 except CGT/CGT [p=0.0063]). CONCLUSION: Our results showed that the three loci, C1236T, G2677T and C3435T, jointly influenced the treatment response for epileptic patients. They should be regarded together as a complex polymorphic drug-response system. These findings suggest that examination of the haplotypes of the three loci could be useful in predicting drug resistance in epilepsy.

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40 The following 10 SNPs of the ABCB1 gene were identified by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) [15]: intron 1 (exon 2 -1) G/A, exon 2 A61G (amino acid exchange Asn21Asp), intron 6 (exon 6 +139) C/T, exon 11 G1199A (Ser400Asn), exon 12 C1236T, intron 12 (exon 12 +44) C/T, intron 16 (exon 17 -76) T/A, exon 21 G2677T (Ala893Ser), G2677A (Ala893Thr), and exon 26 C3435T. Login to comment

[hide] Single nucleotide polymorphisms in human P-glycopr... Expert Opin Drug Deliv. 2006 Jan;3(1):23-35. Dey S
Single nucleotide polymorphisms in human P-glycoprotein: its impact on drug delivery and disposition.
Expert Opin Drug Deliv. 2006 Jan;3(1):23-35., [PMID:16370938]

Abstract [show]
Drug efflux pumps belong to a large family of ATP-binding cassette transporter proteins. These pumps bind their substrate and export it through the membrane using energy derived from ATP hydrolysis. P-glycoprotein, the main efflux pump in this family, is expressed not only in tumour cells but also in normal tissues with excretory function (liver, kidney and the intestine). It has a broad specificity of substrates and plays an important role in drug delivery and disposition. Recently, genetic screening of P-glycoprotein has yielded multiple single nucleotide polymorphisms, which seem to alter transporter function and expression. This review discusses the various polymorphisms of this gene and its impact on drug disposition and diseases.

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123 Location Position Mutation Effect Promoter 5`/-41 A→G Noncoding Exon 1a Exon 1a/-145 C→G Noncoding Exon 1b Exon 1b/-129 T→C Noncoding Intron 1 Exon 2/-4 C→T Noncoding Intron 1 Exon 2/-1 G→A Initiation of translation Exon 2 Exon 2/61 A→G Asn21Asp Intron 4 Exon 5/-35 G→C Intron 4 Exon 5/-25 G→T Exon 5 Exon 5/307 T→C Phe103Leu Intron 6 Exon 6/+139 C→T Intron 6 Exon 6/+145 C→T Exon 7 Exon 7/548 A→G Asn183Ser Exon 11 Exon 11/1119 G→A Ser400Asn Exon 12 Exon 12/1236 C→T Silent base change Intron 12 Exon 12/+44 C→T Exon 13 Exon 13/1474 C→T Arg492Cys Intron 16 Exon 17/-76 T→A Intron 17 Exon 17/+137 A→G Exon 21 Exon 21/2650 C→T Silent base change Exon 21 Exon 21/2677 G→T G→A Ala893Ser Ala893Thr Exon 24 Exon 24/2956 A→G Met986Val Exon 24 Exon 24/2995 G→A Ala999Thr Exon 26 Exon 26/3320 A→C Gln1107Pro Exon 26 Exon 26/3396 C→T Silent base change Exon 26 Exon 26/3421 T→A Ser1141Thr Exon 26 Exon 26/3435 C→T Silent base change Exon 28 Exon 28/4030 G→C Exon 28 Exon 28/4036 A→G The positions of the polymorphism are from the first base of the ATG start codon set to 1. Login to comment

[hide] MDR1 gene: susceptibility in Spanish Crohn's disea... Inflamm Bowel Dis. 2006 Jan;12(1):33-7. Urcelay E, Mendoza JL, Martin MC, Mas A, Martinez A, Taxonera C, Fernandez-Arquero M, Diaz-Rubio M, de la Concha EG
MDR1 gene: susceptibility in Spanish Crohn's disease and ulcerative colitis patients.
Inflamm Bowel Dis. 2006 Jan;12(1):33-7., [PMID:16374256]

Abstract [show]
BACKGROUND: The multidrug resistance MDR1 gene codes for a membrane transporter associated with inflammatory bowel disease. The polymorphism Ala893Ser/Thr (G2677T/A) previously showed significant association with Crohn's disease (CD) and the Ile1145Ile (C3435T) with ulcerative colitis (UC). We studied the association of both polymorphisms in an independent population to reveal the impact of the MDR1 gene on predisposition to inflammatory bowel disease. METHODS: Case-control study with 321 CD and 330 UC white Spanish patients recruited from the same center, and 352 healthy ethnically matched controls. RESULTS: A significant association of MDR1 C3435T with CD was observed (CC vs (CT + TT): P = 0.007; OR [95% CI] = 1.58 [1.12-2.23]). A CD susceptibility haplotype 2677T/C3435 was identified. No difference between UC patients as a whole and controls could be detected. CONCLUSIONS: New evidence supports the role of the MDR1 gene on CD susceptibility. Therefore, considering our results and those from others, the MDR1 gene behaves as a common risk factor for both CD and UC. We discovered that the C3435 allele conferring susceptibility to CD is different from the described 3435T UC risk allele.

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24 However, the C3435T variant together with another missense mutation, Asn21Asp, did not show association with any IBD in the latter study. Login to comment

[hide] MDR1 genotype-related pharmacokinetics: fact or fi... Drug Metab Pharmacokinet. 2005 Dec;20(6):391-414. Sakaeda T
MDR1 genotype-related pharmacokinetics: fact or fiction?
Drug Metab Pharmacokinet. 2005 Dec;20(6):391-414., [PMID:16415525]

Abstract [show]
Multidrug resistant transporter MDR1/P-glycoprotein, the gene product of MDR1, is a glycosylated membrane protein of 170 kDa, belonging to the ATP-binding cassette superfamily of membrane transporters. A number of various types of structurally unrelated drugs are substrates for MDR1, and MDR1 and other transporters are recognized as an important class of proteins for regulating pharmacokinetics. The first investigation of the effects of MDR1 genotypes on pharmacotherapy was reported in 2000; a silent single nucleotide polymorphism (SNP), C3435T in exon 26, was found to be associated with the duodenal expression of MDR1, and thereby the plasma concentration of digoxin after oral administration. In the last 5 years, clinical studies have been conducted around the world on the association of MDR1 genotype with MDR1 expression and function in tissues, and with the pharmacokinetics and pharmacodynamics of drugs; however, there are still discrepancies in the results on C3435T. In 1995, a novel concept to predict in vivo oral pharmacokinetic performance from data on in vivo permeability and in vitro solubility has been proposed, and this Biopharmaceutical Classification System strongly suggested that the effects of intestinal MDR1 on the intestinal absorption of substrates is minimal in the case of commercially available oral drugs, and therefore MDR1 genotypes are little associated with the pharmacokinetics after oral administration. This review summarizes the latest reports for the future individualization of pharmacotherapy based on MDR1 genotyping, and attempts to explain discrepancies.

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29 Representative genetic polymorphisms in MDR1 Position Location EŠect A1aW-41G intron noncoding C-145G exon 1a noncoding T-129C (T12C) exon 1b noncoding C-4T exon 2 noncoding G-1A exon 2 noncoding A61G exon 2 Asn21Asp G5W-25T intron G5W-35C intron T307C exon 5 Phe103Leu C6W＋139T intron C6W＋145T intron A548G exon 7 Asn183Ser G1199A exon 11 Ser400Asn C1236T exon 12 silent C12W＋44T intron C1474T exon 13 Arg492Cys T17W-76A intron A17W＋137G intron C2650T exon 21 silent G2677A,T exon 21 Ala893Thr (G2677A) Ala893Ser (G2677T) A2956G exon 24 Met986Val G2995A exon 24 Ala999Thr A3320C exon 26 Gln1107Pro C3396T exon 26 silent T3421A exon 26 Ser1141Thr C3435T exon 26 silent G4030C exon 28 silent A4036G exon 28 silent See references 27, 32-36. Login to comment

[hide] Pharmacogenetics of HIV therapy. Pharmacogenet Genomics. 2006 Oct;16(10):693-703. Owen A, Pirmohamed M, Khoo SH, Back DJ
Pharmacogenetics of HIV therapy.
Pharmacogenet Genomics. 2006 Oct;16(10):693-703., [PMID:17001288]

Abstract [show]
Drug treatment in HIV disease is characterized by variable responses, in terms of both efficacy and toxicity. Both genetic and environmental factors are important determinants of this variability, although the relative contributions are unclear and likely to vary with different drugs. Many of the antiretrovirals are metabolized by polymorphically expressed enzymes (cytochrome P450, CYP450; glucuronyl transferase, GT) and/or transported by drug transporters (ABC and SLC families). Initial studies of antiretroviral efficacy have therefore focused on these genes. For example, it has recently been shown that a CYP2B6 genetic variant predicts higher plasma efavirenz exposure and possibly increased central nervous system toxicity. A large number of studies on ABCB1 genetics with antiretrovirals have also been undertaken; however, as in other therapeutic areas, the data have been contradictory, and currently, no firm conclusions can be reached on the effect of ABCB1 variability as a determinant of efficacy. Indeed, this highlights the need for validation of initial association studies in pharmacogenetic research. By contrast, the clearest association between genetic variants and response relates to the hypersensitivity reaction that occurs with abacavir. The identification that the major histocompatibility complex haplotype 57.1 acts as a strong genetic predisposing factor can be regarded as a prime example of how fundamental research can be translated into a pharmacogenetic test. Nevirapine hypersensitivity has also been related to an HLA gene (HLA-DRB1*0101) but the predictive value does not appear to be sufficient to implement in clinical practice. Much more work needs to be done to define the genetic factors determining response to antiretroviral agents. These studies need to be sufficiently powered and utilize a modern genotyping strategy. Most importantly, the phenotype needs to be carefully characterized. We also need to disseminate this information: a pivotal resource for this can be found at www.HIV-pharmacogenomics.org.

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171 Pharmacogenetics of HIV therapy Owen et al. 699 Table 1 Polymorphisms that have been studied within the context of metabolism, transport and toxicity (but not progression and response) along with the reference ID (where available), the genotypic consequence and the observed phenotype for antiretroviral drugs Gene SNP (haplotype) Reference SNP Genotypic consequence Phenotypic consequence Confirmation CYP3A4 A - 392G (CYP3A4*1B) rs2740574 Promoter; altered expression No effect on nelfinavir or efavirenz Yes for nelfinavir; controversial for efavirenz T878C (CYP3A4*18) rs4986909 L293P; altered activity No effect on efavirenz No CYP3A5 A6986G (CYP3A5*3) rs776746 Splice defect No effect on nelfinavir, saquinavir or efavirenz AUC but altered urinary metabolic ratio of saquinavir Yes for efavirenz G14690A (CYP3A5*6) rs10264272 Splice defect No effect on nelfinavir or efavirenz Yes CYP2C19 G681A (CYP2C19*2) rs4244285 Truncated protein Higher nelfinavir AUC and trend toward decreased virological failure; no effect on efavirenz Yes for efavirenz; controversial for nelfinavir CYP2D6 A2549del (CYP2D6*3) NT21914757 Frameshift Trend to higher plasma levels of nelfinavir and efavirenz No G1846A (CYP2D6*4) rs3892097 Splice defect Trend to higher plasma levels of nelfinavir and efavirenz No T1707del (CYP2D6*6) rs5030655 Frameshift Higher plasma nelfinavir concentrations No CYP2B6 G516 T (CYP2B6*6, *7, *9, *13, *19 and *20) rs3745274 Q172H Higher plasma and intracellular efavirenz AUCs and increased neurotoxicity Yes, numerous studies C1459T (CYP2B6*5 and *7) rs3211371 R487C No effect on nelfinavir or efavirenz No ABCB1 IVS1 - 80delG rs3214119 N/A No influence on cellular nelfinavir No A61G rs9282564 N21D No influence on cellular nelfinavir No TAG1 rs3789243 N/A No influence on cellular nelfinavir No G1199A rs2229109 S400N No influence on cellular nelfinavir No TAG5 rs1128503 N/A No influence on cellular nelfinavir No TAG6 rs2235046 N/A No influence on cellular nelfinavir No IVS21 + T49C rs2032583 N/A No influence on cellular nelfinavir No C3435T rs1045642 Synonymous Some evidence of an influence on plasma and intracellular nelfinavir; decreased efavirenz plasma concentrations; currently under debate; increase in HDL cholesterol with efavirenz Controversial G2677T rs2032582 Ala893Ser No effect on efavirenz, ritonavir, nelfinavir, indinavir or viral decay and CD4 count Yes IVS26 + T59G rs2235047 N/A No influence on cellular nelfinavir No IVS26 + T80C rs2235048 N/A Increased intracellular nelfinavir concentrations No TAG11 rs1186746 N/A No influence on cellular nelfinavir No TAG12 rs1186745 N/A No influence on cellular nelfinavir No ABCC1 G816A P272P No influence on cellular nelfinavir No T825C rs246221 V275V No influence on cellular nelfinavir No T1062C rs35587 Synonymous No influence on cellular nelfinavir No IVS9 + A8G rs35588 N/A No influence on cellular nelfinavir No IVS10 + C64T N/A No influence on cellular nelfinavir No ABCC2 C - 24T rs717620 N/A No influence on cellular nelfinavir No G1249A rs2273697 V417I No influence on cellular nelfinavir No C1436G Synonymous No influence on cellular nelfinavir No IVS16 - G47A N/A No influence on cellular nelfinavir No T3563A rs8187694 V1188E No influence on cellular nelfinavir No C4488T rs8187707 Synonymous No influence on cellular nelfinavir No IVS31 + G12A rs8187708 N/A No influence on cellular nelfinavir No IVS31 + C74T N/A No influence on cellular nelfinavir No G4544A rs8187710 C1515Y No influence on cellular nelfinavir No G + 259T N/A No influence on cellular nelfinavir No ABCG2 - 19571_ - 19568delT- CAC rs4148162 Deletion No influence on cellular nelfinavir No A-19541G N/A No influence on cellular nelfinavir No G34A rs2231137 V12M No influence on cellular nelfinavir No IVS2 + 35G rs4148152 N/A No influence on cellular nelfinavir No C421A rs2231142 Q141K No influence on cellular nelfinavir No APOCIII C-482T Pending Promoter Hyperlipidaemia in presence of ritonavir Yes T-455C Pending Promoter Hyperlipidaemia in presence of ritonavir Yes C3238G rs5128 30 UTR variant Hyperlipidaemia in presence of ritonavir Yes APOE 2060T/2198T (APOEe2) rs429358 R112C/R158C Hyperlipidaemia in presence of ritonavir Yes 2060T/2198C (APOEe3) rs7412 R112C/R158R Hyperlipidaemia in presence of ritonavir Yes TNFa G - 238A rs361525 Promoter Rapid development of lipoatrophy Controversial SPINK-1 C112T rs17107315 N34S Associated with risk of pancreatitis Yes, in general population CFTR G1717 - 1A Splice defect Associated with risk of pancreatitis Yes, in general population IVS8 5T Splice defect Associated with risk of pancreatitis Yes, in general population HLA-B HLA-B*57.1 N/A Abacavir hypersensitivity Yes, but not in all populations HLA-DR HLA-DRB1*0101 N/A Nevirapine hypersensitivity No HSPA1L C2437T rs2227956 M493T Abacavir hypersensitivity No UGT1A1 A(TA)7TAA, - 43_ - 42in- sTA (UGT1A1*28) rs8175347 Promoter; insertion at TATA box Gilberts syndrome, hyperbilirubinaemia in presence of atazanavir and indinavir but not saquinavir Yes MT-CO1 C7028T Synonymous Haplogroup T associated with greater incidence of peripheral neuropathy No 700 Pharmacogenetics and Genomics 2006, Vol 16 No The NNRTI nevirapine can also cause a hypersensitivity syndrome characterized by a rash with systemic symptoms; occasionally liver injury may be part of the clinical picture, or alternatively, may actually be the only manifestation. 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[hide] ABCB1 and cytochrome P450 genotypes and phenotypes... Clin Pharmacol Ther. 2006 Dec;80(6):668-81. Crettol S, Deglon JJ, Besson J, Croquette-Krokar M, Hammig R, Gothuey I, Monnat M, Eap CB
ABCB1 and cytochrome P450 genotypes and phenotypes: influence on methadone plasma levels and response to treatment.
Clin Pharmacol Ther. 2006 Dec;80(6):668-81., [PMID:17178267]

Abstract [show]
BACKGROUND AND OBJECTIVE: The in vivo implication of various cytochrome P450 (CYP) isoforms and of P-glycoprotein on methadone kinetics is unclear. We aimed to thoroughly examine the genetic factors influencing methadone kinetics and response to treatment. METHODS: Genotyping for CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4, CYP3A5, ABCB1, and UGT2B7 polymorphisms was performed in 245 patients undergoing methadone maintenance treatment. To assess CYP3A activity, the patients were phenotyped with midazolam. RESULTS: The patients with lower CYP3A activity presented higher steady-state trough (R,S)-methadone plasma levels (4.3, 3.0, and 2.3 ng/mL x mg for low, medium, and high activity, respectively; P = .0002). As previously reported, CYP2B6*6/*6 carriers had significantly higher trough (S)-methadone plasma levels (P = .0001) and a trend toward higher (R)-methadone plasma levels (P = .07). CYP2D6 ultrarapid metabolizers presented lower trough (R,S)-methadone plasma levels compared with the extensive or intermediate metabolizers (2.4 and 3.3 ng/mL x mg, respectively; P = .04), whereas CYP2D6 poor metabolizer status showed no influence. ABCB1 3435TT carriers presented lower trough (R,S)-methadone plasma levels (2.7 and 3.4 ng/mL . mg for 3435TT and 3435CC carriers, respectively; P = .01). The CYP1A2, CYP2C9, CYP2C19, CYP3A5, and UGT2B7 genotypes did not influence methadone plasma levels. Only CYP2B6 displayed a stereoselectivity in its activity. CONCLUSION: In vivo, CYP3A4 and CYP2B6 are the major CYP isoforms involved in methadone metabolism, with CYP2D6 contributing to a minor extent. ABCB1 genetic polymorphisms also contribute slightly to the interindividual variability of methadone kinetics. The genetic polymorphisms of these 4 proteins had no influence on the response to treatment and only a small influence on the dose requirement of methadone.

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24 P-gp is expressed in various human tissues, including the intestine, liver, kidneys, testes, lymphocytes, and blood-brain barrier.21 P-gp actively transports xenobiotics from the intracellular to the extracellular domain, resulting in a protective role against their potentially toxic accumulation, by enhancement of their elimination and limitation of their distribution in the body.22 The important role of P-gp in the limitation of access of xenobiotics to the brain has been demonstrated in vivo by studies on P-gp-deficient mice.23 The synonymous 3435CϾT single-nucleotide polymorphism (SNP) of the ABCB1 gene has been associated with lower P-gp expression.24 Since this first report by Hoffmeyer et al,24 contradictory results have been published on the impact of various ABCB1 SNPs (mostly 3435CϾT and 2677GϾT) on P-gp expression and function and on the kinetics of different P-gp substrates.21,25 Interestingly, it has recently been shown that the 3435TT genotype, in linkage disequilibrium with the 2677TT genotype, is associated with reduced P-gp expression resulting from a decrease in messenger ribonucleic acid stability.26 Another interesting SNP, ABCB1 61AϾG (N21D), is a nonsynonymous polymorphism. Login to comment

[hide] Function-altering SNPs in the human multidrug tran... PLoS Genet. 2007 Mar 9;3(3):e39. Jeong H, Herskowitz I, Kroetz DL, Rine J
Function-altering SNPs in the human multidrug transporter gene ABCB1 identified using a Saccharomyces-based assay.
PLoS Genet. 2007 Mar 9;3(3):e39., 2007-03-09 [PMID:17352537]

Abstract [show]
The human ABCB1 (MDR1)-encoded multidrug transporter P-glycoprotein (P-gp) plays a major role in disposition and efficacy of a broad range of drugs including anticancer agents. ABCB1 polymorphisms could therefore determine interindividual variability in resistance to these drugs. To test this hypothesis we developed a Saccharomyces-based assay for evaluating the functional significance of ABCB1 polymorphisms. The P-gp reference and nine variants carrying amino-acid-altering single nucleotide polymorphisms (SNPs) were tested on medium containing daunorubicin, doxorubicin, valinomycin, or actinomycin D, revealing SNPs that increased (M89T, L662R, R669C, and S1141T) or decreased (W1108R) drug resistance. The R669C allele's highly elevated resistance was compromised when in combination with W1108R. Protein level or subcellular location of each variant did not account for the observed phenotypes. The relative resistance profile of the variants differed with drug substrates. This study established a robust new methodology for identification of function-altering polymorphisms in human multidrug transporter genes, identified polymorphisms affecting P-gp function, and provided a step toward genotype-determined dosing of chemotherapeutics.

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207 Third, only a few coding SNPs have been functionally tested, such as A893S and N21D, which our analysis predicted would have a weak functional impact [26]. Login to comment

[hide] Effect of an antiretroviral regimen containing rit... Clin Pharmacol Ther. 2008 Jul;84(1):75-82. Epub 2008 Jan 9. Wyen C, Fuhr U, Frank D, Aarnoutse RE, Klaassen T, Lazar A, Seeringer A, Doroshyenko O, Kirchheiner JC, Abdulrazik F, Schmeisser N, Lehmann C, Hein W, Schomig E, Burger DM, Fatkenheuer G, Jetter A
Effect of an antiretroviral regimen containing ritonavir boosted lopinavir on intestinal and hepatic CYP3A, CYP2D6 and P-glycoprotein in HIV-infected patients.
Clin Pharmacol Ther. 2008 Jul;84(1):75-82. Epub 2008 Jan 9., [PMID:18183034]

Abstract [show]
This study aimed to quantify the inhibition of cytochrome P450 (CYP3A), CYP2D6, and P-glycoprotein in human immunodeficiency virus (HIV)-infected patients receiving an antiretroviral therapy (ART) containing ritonavir boosted lopinavir, and to identify factors influencing ritonavir and lopinavir pharmacokinetics. We measured activities of CYP3A, CYP2D6, and P-glycoprotein in 28 patients before and during ART using a cocktail phenotyping approach. Activities, demographics, and genetic polymorphisms in CYP3A, CYP2D6, and P-glycoprotein were tested as covariates. Oral midazolam clearance (overall CYP3A activity) decreased to 0.19-fold (90% confidence interval (CI), 0.15-0.23), hepatic midazolam clearance and intestinal midazolam availability changed to 0.24-fold (0.20-0.29) and 1.12-fold (1.00-1.26), respectively. In CYP2D6 extensive metabolizers, the plasma ratio AUC(dextromethorphan)/AUC(dextrorphan) increased to 2.92-fold (2.31-3.69). Digoxin area under the curve (AUC)(0-12) (P-glycoprotein activity) increased to 1.81-fold (1.56-2.09). Covariates had no major influence on lopinavir and ritonavir pharmacokinetics. In conclusion, CYP3A, CYP2D6, and P-glycoprotein are profoundly inhibited in patients receiving ritonavir boosted lopinavir. The covariates investigated are not useful for a priori dose selection.

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127 Genotyping for the CYP3A5*3 allele was done as described using a melting curve analysis technique.45,46 Genotyping for P-glycoprotein was done by direct sequencing of the MDR1 exons 2, 12, 21, and 26, including the single nucleotide polymorphisms C-4T, G-1A, A61G (Asn21Asp), C1236T (synonymous), G2677T (Ala893Ser), G2677A (Ala893Thr), and C3435T (synonymous). Login to comment

[hide] Substrate-dependent effects of human ABCB1 coding ... J Pharmacol Exp Ther. 2008 May;325(2):435-42. Epub 2008 Feb 20. Gow JM, Hodges LM, Chinn LW, Kroetz DL
Substrate-dependent effects of human ABCB1 coding polymorphisms.
J Pharmacol Exp Ther. 2008 May;325(2):435-42. Epub 2008 Feb 20., [PMID:18287207]

Abstract [show]
One of the many obstacles to effective drug treatment is the efflux transporter P-glycoprotein (P-gp), which can restrict the plasma and intracellular concentrations of numerous xenobiotics. Variable drug response to P-gp substrates suggests that genetic differences in ABCB1 may affect P-gp transport. The current study examined how ABCB1 variants alter the P-gp-mediated transport of probe substrates in vitro. Nonsynonymous ABCB1 variants and haplotypes with an allele frequency >/=2% were transiently expressed in HEK293T cells, and the transport of calcein acetoxymethyl ester and 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY-FL)-paclitaxel was measured in the absence or presence of the P-gp inhibitor cyclosporin A. The A893S, A893T, and V1251I variants and the N21D/1236C>T/A893S/3435C>T haplotype altered intracellular accumulation compared with reference P-gp in a substrate-dependent manner. It is interesting that certain variants showed altered sensitivity to cyclosporin A inhibition that was also substrate-specific. These functional data demonstrate that nonsynonymous polymorphisms in ABCB1 may selectively alter P-gp transport and drug-drug interactions in a substrate- and inhibitor-dependent manner.

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4 The A893S, A893T, and V1251I variants and the N21D/ 1236CϾT/A893S/3435CϾT haplotype altered intracellular accumulation compared with reference P-gp in a substrate-dependent manner. Login to comment
55 The following variants were created from the reference ABCB1 plasmid in pCIneo: 61AϾG (N21D), 1199GϾA (S400T), 1596TϾG [a nonfunctional nucleotide-binding domain (NBD) mutant], 2005CϾT (R669C), 2677GϾA (A893T), 3421TϾA (S1141T), and 3751GϾA (V1251I). Login to comment
103 There are six polymorphic residues that meet these criteria: N21D, S400T, R669C, A893S/T, S1141T, and V1251I. Login to comment
104 Residue 893 is interesting because it is triallelic and occurs naturally in haplotypes, with the two common synonymous SNPs, 1236CϾT and 3435CϾT as well as N21D (Kroetz et al., 2003). Login to comment
111 Intra-and interexperimental replicates (n ϭ 3) for reference, NBD, and variant P-gp samples have TABLE 2 Allele frequencies, evolutionary conservation, and Grantham values for selected ABCB1 nonsynonymous polymorphisms and haplotypes Variant or Haplotype Allele Frequenciesa Amino Acid Conservationc Grantham Valued Nucleotide Change Amino Acid Change AA (n ϭ 200) CA (n ϭ 200) Reference Variant % 61AϾG N21D 2.5 8 23 1199GϾA S400T 1 2.5 d, ha, mk ms, r 46 2005CϾT R669C 1 0 d, ha, mk, r, s 180 2677GϾT A893S 10 46.4 ha, ms, r d, mk, s 99 2677GϾA A893T 0.5 3.6 ha, ms, r 58 3421TϾA S1141T 11.1 0 d, ha, mk, ms, r, s 58 3751GϾA V1251I 0b 0 d, ha, mk, ms, r s 29 1236CϾT/2677GϾT/3435CϾT A893S 6 34 N.A. N.A. N.A. 61AϾG/1236CϾT/2677GϾT/3435CϾT N21D/A893S 2.5 8 N.A. N.A. N.A. N.A., not applicable. Login to comment
135 The representative histogram of APC fluorescence for empty vector (gray, dotted), NBD mutant (gray), reference (black), and variant-transfected cells (N21D, yellow; S400N, cyan; R669C, purple; A893S, green; A893T, orange; S1141T, pink; V1251I, blue; 1236CϾT/A893S/3435CϾT, brown; and N21D/1236CϾT/A893S/3435CϾT, red) shows P-gp expression based on the intensity of APC fluorescence, as indicated on the x-axis. Login to comment
141 The effects of cyclosporin A on calcein-AM accumulation are displayed in a representative histogram for P-gp reference (black, shaded), N21D (yellow), R669C (purple), and A893S (green). Login to comment
151 It is interesting that the N21D, R669C, and A893S variants are more sensitive to cyclosporin A (136 Ϯ 28, 139 Ϯ 43, and 130 Ϯ 22%, respectively; p Ͻ 0.05) compared to reference (Fig. 2c). Login to comment
156 The N21D, S400N, R669C, and A893T variants and the 1236CϾT/A893S/3435CϾT haplotype were within 5% of the reference (Fig. 3c). Login to comment
157 In contrast, the A893S and V1251I P-gp variants and the N21D/1236CϾT/A893S/ 3435CϾT haplotype showed intracellular paclitaxel levels that were 114 Ϯ 13, 118 Ϯ 12, and 124 Ϯ 13% of reference, respectively (p Ͻ 0.01), indicating decreased P-gp function. Login to comment
160 The haplotype containing N21D/1236CϾT/A893S/3435CϾT was 53 Ϯ 8% less sensitive to cyclosporin A inhibition than reference (p Ͻ 0.01). Login to comment
163 Six of 13 previously described nonsynonymous variants were chosen for study based on an allele frequency Ͼ2%: N21D, S400N, A893S, A893T, S1141T, and V1251I. Login to comment
170 The data collected in the absence of cyclosporin A for empty vector (gray, dotted), P-gp reference (black), NBD mutant (gray), A893S (green), V1251I (blue), and haplotype N21D/1236CϾT/A893S/3534CϾT (red) are shown in a representative fluorescence histogram (a). Login to comment
171 The effects of cyclosporin A on BODIPY-FL-paclitaxel accumulation are displayed in a representative histogram in b for P-gp reference (black, shaded), A893S (green), A893T (orange), S1141T (pink), V1251I (blue), and haplotype N21D/1236CϾT/A893S/3534CϾT (red). Login to comment
177 These haplotypes contained A893S, 1236CϾT, and 3435CϾT either with or without N21D. Login to comment
193 Previous work consistent with the current findings has shown that N21D, S400N, and A893S do not change calcein-AM transport (Kimchi-Sarfaty et al., 2002; Kroetz et al., 2003). Login to comment
206 In one study, the N21D, F103L, S400N, A893S, and A998T SNPs and three double mutants (N21N/S400N, N21D/A893S, and S400N/ A893S) were investigated using a vaccinia virus expression system with BODIPY-FL-paclitaxel, and no differences in function were noted among the variant and reference P-gps (Kimchi-Sarfaty et al., 2002). Login to comment
207 Our results are similar for N21D and S400N, but we found that A893S and N21D/A893S have decreased transport of BODIPY-FL-paclitaxel (Table 3). Login to comment
214 There was increased function for A893S and S1141T depending on the substrate, TABLE 3 Substrateand inhibitor-dependent effects of P-gp variants on transport function Variant or Haplotype Calcein-AM BODIPY-FL-Paclitaxel -CsAa ϩCsAb -CsA ϩCsA N21D 1 S400T R669C 1 A893S 1 2 2 A893T 1 2 S1141T 2 V1251I 1 2 2 1236CϾT/A893S/3435CϾT N21D/1236CϾT/A893S/3435CϾT 2 2 a Arrows indicate statistically significant changes in P-gp function relative to reference in the absence of cyclosporin A (-CsA). Login to comment
224 The N21D, R669C, and A893S P-gp variants show increased inhibition of calcein-AM transport by cyclosporin A. Login to comment
225 In contrast, the A893S, A893T, and S1141T variants and the N21D/1236CϾT/A893S/3435CϾT haplotype are less sensitive to cyclosporin A inhibition of BODIPY-FL-paclitaxel transport. Login to comment
229 Intracellular accumulation of calcein-AM and/or BODIPY-FL-paclitaxel was altered by A893S, A893T, V1251I, and N21D/1236CϾT/A893S/3435CϾT. Login to comment

[hide] Single nucleotide polymorphisms in the multidrug r... Pharmacogenet Genomics. 2008 Mar;18(3):263-73. Vaclavikova R, Nordgard SH, Alnaes GI, Hubackova M, Kubala E, Kodet R, Mrhalova M, Novotny J, Gut I, Kristensen VN, Soucek P
Single nucleotide polymorphisms in the multidrug resistance gene 1 (ABCB1): effects on its expression and clinicopathological characteristics in breast cancer patients.
Pharmacogenet Genomics. 2008 Mar;18(3):263-73., [PMID:18300948]

Abstract [show]
OBJECTIVES: Resistance of tumor cells to multiple cytostatic agents is one of the major impediments of successful cancer chemotherapy. A large part of resistance of tumors to chemotherapy is caused by the ABC transporter P-glycoprotein encoded by the ABCB1 gene. The main aim of this study was to assess the prognostic value of ABCB1 genotype and phenotype in breast cancer. METHODS: Six ABCB1 single nucleotide polymorphisms (SNPs) were determined in 90 Czech breast cancer patients by a novel method that allows simultaneous assessment of multiple polymorphisms on a single electronic microarray. Expression levels of ABCB1 were quantified in tumor and nontumor samples of breast cancer patients by real-time PCR. T-test, analysis of variance and Fisher's exact test were used to analyze the effect of ABCB1 polymorphisms on ABCB1 expression levels and for the analysis of associations between ABCB1 expression, genotype and clinical and pathological characteristics. RESULTS: ABCB1 was expressed in 98.9% of the tumor and in 97.5% of the nontumor samples. ABCB1 was downregulated in 79.5% of tumors compared with the nontumor samples. No significant correlation was observed between ABCB1 mRNA expression levels and clinical and pathological characteristics. High frequencies of the variant alleles in ABCB1 exon 12 (1236C>T, 38.3%) and exon 26 (3435C>T, 54.0%) were observed. Individuals with variant alleles in exons 12 and 26 had significantly lower ABCB1 expression levels in their tumors. SNPs in exons 12 and 26 also correlated with estrogen receptor status of patients. CONCLUSION: ABCB1 SNPs may affect function of P-glycoprotein by influencing the expression level and modify breast cancer prognosis.

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79 Six SNPs in ABCB1 [( - 1)G > A, rs2214102; 61A > G, Asn21Asp, rs9282564; 1199G> A, Ser400Asn, rs2229109; 1236C> T, Gly412Gly, rs1128503; ( + 44)C > T, rs2032588 and 3435C > T, Ile1145Ile, rs1045642] were detected on the NanoChip Molecular Biology Workstation (Nanogen Inc.). Login to comment
154 Age, menopausal status, staging, tumor size, nodal status and histological type and grade of tumor did not significantly associate either with frequencies of Table 3 Distribution of ABCB1 genotypes and allele frequencies in breast cancer patients ABCB1 genotypea Nb Allele frequency ( - 1)G > A, rs2214102 G/G 77 (88.5) G (93.1) G/A 8 (9.2) A (6.9) A/A 2 (2.3) Total 87 61A > G, Asn21Asp, rs9282564 Asn/Asn 75 (84.3) Asn (91.6) Asn/Asp 13 (14.6) Asp (8.4) Asp/Asp 1 (1.1) Total 89 1199G > A, Ser400Asn, rs2229109 Ser/Ser 86 (95.6 Ser (97.8) Ser/Asn 4 (4.4) Asn (2.2) Asn/Asn 0 (0) Total 90 1236C > T, Gly412Gly, rs1128503 C/C 32 (35.6) C (61.7) C/T 47 (52.2) T (38.3) T/T 11 (12.2) Total 90 12( + 44)C > T, rs2032588 C/C 79 (89.8) C (93.8) C/T 7 (8.0) T (6.2) T/T 2 (2.2) Total 88 3435C > T, Ile1145Ile, rs1045642 C/C 17 (19.5) C (46.0) T/C 46 (52.9) T (54.0) T/T 24 (27.6) Total 87 a Protein positions are displayed for nonsynonymous single nucleotide polymorphisms (SNPs) in exons. Login to comment

[hide] Influence of ABCB1 genetic polymorphisms on cyclos... Pharmacogenet Genomics. 2008 Apr;18(4):307-15. Crettol S, Venetz JP, Fontana M, Aubert JD, Ansermot N, Fathi M, Pascual M, Eap CB
Influence of ABCB1 genetic polymorphisms on cyclosporine intracellular concentration in transplant recipients.
Pharmacogenet Genomics. 2008 Apr;18(4):307-15., [PMID:18334915]

Abstract [show]
OBJECTIVE: The expression on lymphocytes of P-glycoprotein, an efflux transporter encoded by the ABCB1 gene, might influence cyclosporine intracellular concentration. METHODS: ABCB1 genotypes, cyclosporine intracellular and blood concentrations were determined in 64 stable renal, liver or lung transplant recipients. RESULTS: Cyclosporine intracellular concentration correlated moderately with blood concentration (r=0.30, P<0.00005). The ABCB1 1199A carriers presented a 1.8-fold decreased cyclosporine intracellular concentration (P=0.04), whereas the 3435T carriers presented a 1.7-fold increase (P=0.02) as well as a 1.2-fold increased blood concentration (P=0.04). In contrast, ABCB1 61A>G, 1236C>T and 2677G>T polymorphisms did not influence cyclosporine intracellular and blood concentrations. CONCLUSION: This is the first report demonstrating that ABCB1 polymorphisms influence cyclosporine intracellular concentration. Interestingly, its influence on intracellular concentration is significantly higher than on blood concentration (P<0.002). This may therefore modulate cyclosporine immunosuppressive activity.

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135 In this study, ABCB1 61A > G (N21D), 1236C > Tand 2677G > T (A893S) SNPs did not influence cyclosporine intracellular and blood concentrations. Login to comment

[hide] Association of four DNA polymorphisms with acute r... Transpl Int. 2008 Sep;21(9):879-91. Epub 2008 Apr 25. Grinyo J, Vanrenterghem Y, Nashan B, Vincenti F, Ekberg H, Lindpaintner K, Rashford M, Nasmyth-Miller C, Voulgari A, Spleiss O, Truman M, Essioux L
Association of four DNA polymorphisms with acute rejection after kidney transplantation.
Transpl Int. 2008 Sep;21(9):879-91. Epub 2008 Apr 25., [PMID:18444945]

Abstract [show]
Renal transplant outcomes exhibit large inter-individual variability, possibly on account of genetic variation in immune-response mediators and genes influencing the pharmacodynamics/pharmacokinetics of immunosuppressants. We examined 21 polymorphisms from 10 genes in 237 de novo renal transplant recipients participating in an open-label, multicenter study [Cyclosporine Avoidance Eliminates Serious Adverse Renal-toxicity (CAESAR)] investigating renal function and biopsy-proven acute rejection (BPAR) with different cyclosporine A regimens and mycophenolate mofetil. Genes were selected for their immune response and pharmacodynamic/pharmacokinetic relevance and were tested for association with BPAR. Four polymorphisms were significantly associated with BPAR. The ABCB1 2677T allele tripled the odds of developing BPAR (OR: 3.16, 95% CI [1.50-6.67]; P=0.003), as did the presence of at least one IMPDH2 3757C allele (OR: 3.39, 95% CI [1.42-8.09]; P=0.006). BPAR was almost fivefold more likely in patients homozygous for IL-10 -592A (OR: 4.71, 95% CI [1.52-14.55]; P=0.007) and twice as likely in patients with at least one A allele of TNF-alpha G-308A (OR: 2.18, 95% CI [1.08-4.41]; P=0.029). There were no statistically significant interactions between polymorphisms, or the different treatment regimens. Variation in genes of immune response and pharmacodynamic/pharmacokinetic relevance may be important in understanding acute rejection after renal transplant.

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74 A417G (exon 28)a,b (0.87) rs3842 (0.86)g A61Gc (N21D) (0.91) rs9282564 (0.91)e C1236Ta (0.6) rs1128503 (0.61)e G2677T/Ac (0.58) rs2032582 (0.46)e Multi-drug resistance associated protein 2/adenosine triphosphate-binding cassette, subfamily c, member 2 (MRP2/ABCC2) T3972Cc Exon 28 (0.64) rs3740066 (0.66)e MRP2 is involved in the biliary excretion of mycophenolic acid glucuronide. Login to comment
121 Gene position and genotypes BPAR at 12 months No. patients BPAR incidence (%) Odds ratio P-value* CYP3A4 A-392G GG or AG 20 25.0 0.960 0.942 AAà 195 28.7 - CYP3A5 A6986G AA or AG 37 24.3 0.790 0.587 GGà 186 28.5 - ABCB1 A61G (N21D) GG or AG 37 32.4 1.46 0.362 AAà 180 26.7 - C3435T TT 53 37.7 4.19 0.0099 CT 117 29.9 2.6 CCà 56 16.1 - A417G GG or AG 53 18.9 0.519 0.099 AAà 167 29.9 - C1236T TT 41 43.9 3.9 0.009 CT 103 27.2 1.64 CC 87 20.7 - G2677T/A TT 39 43.6 4.93 0.003 GT 103 29.1 2.37 GA or TA 10 10 0.446 GG 73 17.8 - MRP2 G5`reg 6170A GG 40 27.5 1.26 0.853 AG 104 28.8 1.18 AAà 76 26.3 - T3600A AA or AT 30 16.7 0.363 0.053 TTà 189 29.1 - T3972C TT 31 25.8 1.38 0.63 CT 96 30.2 1.37 CCà 94 24.5 - IMPDH1 G1320A AA 15 33.3 1.0 0.571 AG 67 23.9 0.687 GGà 134 29.1 - IMPDH2 T3757C CC or CT 28 46.4 3.39 0.006 TTà 193 24.9 - Table 3. continued Gene position and genotypes BPAR at 12 months No. patients BPAR incidence (%) Odds ratio P-value* IL-2 T-330G GG 24 25 0.892 0.919 GT 94 28.7 1.06 TTà 105 27.6 - G114T TT 18 44.4 3.1 0.107 GT 97 26.8 0.885 GGà 109 25.7 - IL-10 C-592A AA 18 55.6 4.55 0.024 AC 72 25 0.897 CCà 127 25.2 - A-1082G GG 46 28.3 0.940 0.550 AG 105 23.8 0.688 AAà 69 33.3 - C-819T TT 13 53.8 4.23 0.104 CT 68 26.5 1.06 CC 119 24.4 - C851T CT or TT 6 16.7 0.460 0.465 CC 190 26.8 - TGF-b1 C869T (P10L) CC 37 29.7 1.40 0.214 CT 103 33 1.86 TTà 84 21.4 - C915G (R25P) CC or CG 37 32.4 1.2 0.662 GGà 187 27.8 - TNF-a G308A GA or AA 52 38.5 2.18 0.030 GG 170 24.7 - *P-value for the association test derived from the logistic regression using recipient age, gender, treatment group and donor type as covariates (see Materials and methods). Login to comment

[hide] Structure, function and regulation of P-glycoprote... Xenobiotica. 2008 Jul;38(7-8):802-32. Zhou SF
Structure, function and regulation of P-glycoprotein and its clinical relevance in drug disposition.
Xenobiotica. 2008 Jul;38(7-8):802-32., [PMID:18668431]

Abstract [show]
1. P-glycoprotein (P-gp/MDR1), one of the most clinically important transmembrane transporters in humans, is encoded by the ABCB1/MDR1 gene. Recent insights into the structural features of P-gp/MDR1 enable a re-evaluation of the biochemical evidence on the binding and transport of drugs by P-gp/MDR1. 2. P-gp/MDR1 is found in various human tissues in addition to being expressed in tumours cells. It is located on the apical surface of intestinal epithelial cells, bile canaliculi, renal tubular cells, and placenta and the luminal surface of capillary endothelial cells in the brain and testes. 3. P-gp/MDR1 confers a multi-drug resistance (MDR) phenotype to cancer cells that have developed resistance to chemotherapy drugs. P-gp/MDR1 activity is also of great clinical importance in non-cancer-related drug therapy due to its wide-ranging effects on the absorption and excretion of a variety of drugs. 4. P-gp/MDR1 excretes xenobiotics such as cytotoxic compounds into the gastrointestinal tract, bile and urine. It also participates in the function of the blood-brain barrier. 5. One of the most interesting characteristics of P-gp/MDR1 is that its many substrates vary greatly in their structure and functionality, ranging from small molecules such as organic cations, carbohydrates, amino acids and some antibiotics to macromolecules such as polysaccharides and proteins. 6. Quite a number of single nucleotide polymorphisms have been found for the MDR1 gene. These single nucleotide polymorphisms are associated with altered oral bioavailability of P-gp/MDR1 substrates, drug resistance, and a susceptibility to some human diseases. 7. Altered P-gp/MDR1 activity due to induction and/or inhibition can cause drug-drug interactions with altered drug pharmacokinetics and response. 8. Further studies are warranted to explore the physiological function and pharmacological role of P-gp/MDR1.

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296 Exon 2 contains a polymorphism that changes Asn-21 to Asp, and the mutation at exon 5 changes Phe-103 to Leu. Login to comment

[hide] Genetic analysis of MDR1 and inflammatory bowel di... Inflamm Bowel Dis. 2009 Dec;15(12):1784-93. doi: 10.1002/ibd.21019. Epub 2009 Aug 14. Huebner C, Browning BL, Petermann I, Han DY, Philpott M, Barclay M, Gearry R, McCulloch A, Demmers P, Ferguson LR
Genetic analysis of MDR1 and inflammatory bowel disease reveals protective effect of heterozygous variants for ulcerative colitis.
Inflamm Bowel Dis. 2009 Dec;15(12):1784-93. doi: 10.1002/ibd.21019. Epub 2009 Aug 14., [PMID:19685447]

Abstract [show]
BACKGROUND: Single nucleotide polymorphisms (SNPs) in the multidrug transporter MDR1 have been associated with inflammatory bowel disease (IBD) in different studies. However, the data are highly controversial. Recently, 6 haplotype tagging SNPs (tSNPs), representing the haplotype variations of the MDR1 gene, were identified. The aims of this study were to genotype these variants and correlate them to disease phenotype in New Zealand IBD patients. MATERIALS AND METHODS: A total of 784 IBD patients and 200 healthy subjects were genotyped for 5 tSNPs and the triallelic MDR1 variant G2677T/A using the Sequenom MassArray platform. Furthermore, the effects of these variants were examined in correlation with phenotypic clinical features. RESULTS: Heterozygous carriers for the variants C1236T, rs2235046 (an SNP in intron 16), and G2677T/A showed a lower risk of developing ulcerative colitis (C1236T: odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.42-0.93, P = 0.03; G2677T/A: OR = 0.59, CI = 0.39-0.89, P = 0.02; and rs2235046: OR = 0.59, 95% CI = 0.38-0.91, P = 0.009) as compared with homozygotes. None of the analyzed markers were associated with Crohn's disease on a genotypic level. Subgroup analysis revealed an association for 2 variants with IBD when stratified for age of onset (C1236T SNP and rs3789243). The MDR1 variant C3435T was associated with disease behavior in CD (OR = 1.45, 95% CI = 1.01-2.08, P = 0.04), whereas the SNP rs3789243 was found to be associated with pancolitis in UC patients (OR = 1.35, CI = 1.00-1.82, P = 0.05). CONCLUSIONS: The results of our study support the role of MDR1 as a candidate gene for ulcerative colitis. Furthermore, our results suggest the possibility of a heterozygous advantage for certain MDR1 variants for this disease.

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53 Published MDR1 Genotype Studies Study Participants Population Analyzed SNPs Results Brant et al 2003 IBD_NJ¼211 Jewish and non-Jewish American c.2677G>T/A Association between G2677 allele and IBDHC_NJ¼392 c.3435C>T IBD_J¼114 p.Asn21Asp HC_J¼219 Schwab et al 2003 IBD¼275 German c.3435C>T Association between T3435 allele and UCUC¼149 CD¼126 No genotype-phenotype association HC¼998 Croucher et al 2003 IBD¼949 German c.3435C>T No genotype association CD¼629 UC¼320 HC¼531 IBD¼251 British CD¼164 UC¼87 HC¼164 Glas et al 2004 IBD¼258 German c.3435C>T Association between T3435 allele and UC when using control group 2CD¼135 UC¼123 No genotype association when using control group 1 or pooled controlsHC1¼145 HC2¼145 Gazouli et al 2004 IBD¼205 Greece c.3435C>T No genotype association CD¼120 UC¼85 HC¼100 Potocnik et al 2004 CD¼163 Slovenian c.2677G>T/A T2677 allele associated with UC UC¼144 c.3435C>T T1236 allele associated with UC IBD¼307 c.1236C>T (rs1128503) Intron 13 SNP C allele associated with UCHC¼355 C>T (50 upstream promoter) Intron 16 SNP associated with UC 129T>C (Promotor) 50 upstream promoter SNP associated with refractory CD Intron 1b_-81 del G Intron 41 SNP associated with refractory CD Intron 41_Ex04þ3854 G>T (rs1202172) T1236 allele associated with refractory CD Intron 42_Ex05-1100A>G Intron 13 SNP associated with refractory CD and proctitis Intron 13_Ex13þ81C>T (rs2235035) Intron 16 SNP associated with refractory CD Intron16_Ex17-76T>A (intronic) rs1922242 3 risk haplotypes identified for UC (1236T/2677T/3435T and Intron13C/Intron16A/2677T and 1236T/Intron13C/Intron16A/ 2677T/3435T) One protective haplotype identified for UC Intron13T/Intron16T/2677G) Risk Haplotype 1236T/2677T/3435T associated with refractory CD Intron13T/Intron16T/2677G haplotype protective in proctitis TABLE 1. Login to comment

[hide] Polymorphisms in cytochromes P450 2C8 and 3A5 are ... Pharmacogenomics J. 2011 Apr;11(2):121-9. Epub 2010 Mar 9. Leskela S, Jara C, Leandro-Garcia LJ, Martinez A, Garcia-Donas J, Hernando S, Hurtado A, Vicario JC, Montero-Conde C, Landa I, Lopez-Jimenez E, Cascon A, Milne RL, Robledo M, Rodriguez-Antona C
Polymorphisms in cytochromes P450 2C8 and 3A5 are associated with paclitaxel neurotoxicity.
Pharmacogenomics J. 2011 Apr;11(2):121-9. Epub 2010 Mar 9., [PMID:20212519]

Abstract [show]
Neurotoxicity is one of the most relevant dose-limiting toxicities of the anticancer drug paclitaxel. It exhibits substantial interindividual variability of unknown molecular basis, and represents one of the major challenges for the improvement of paclitaxel therapy. The extensive variability in paclitaxel clearance and metabolism lead us to investigate the association between polymorphisms in paclitaxel elimination pathway and neurotoxicity. We selected 13 relevant polymorphisms in genes encoding paclitaxel metabolizing enzymes (CYP2C8, CYP3A4 and CYP3A5) and transporters (organic anion transporting polypeptide (OATP) 1B1, OATP1B3 and P-glycoprotein) and genotyped them in 118 Spanish cancer patients treated with paclitaxel. After adjusting for age and treatment schedule, CYP2C8 Haplotype C and CYP3A5*3 were associated with protection (hazard ratio (HR) (per allele)=0.55; 95% confidence interval (CI)=0.34-0.89; P=0.014 and HR (per allele)=0.51; 95%CI=0.30-0.86; and P=0.012, respectively) and CYP2C8*3 with increased risk (HR (per allele)=1.72; 95%CI=1.05-2.82; and P=0.032). In each case, the allele causing increased paclitaxel metabolism was associated with increased neurotoxicity, suggesting an important role for metabolism and hydroxylated paclitaxel metabolites. We estimated the HR per paclitaxel-metabolism increasing allele carried across the three polymorphisms to be HR=1.64 (95% CI=1.26-2.14; P=0.0003). The results for P-glycoprotein were inconclusive, and no associations were observed for the other genes studied. The incorporation of this genetic data in treatment selection could help to reduce neurotoxicity events, thereby individualizing paclitaxel pharmacotherapy. These results warrant validation in independent series.

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65 However, its effect on enzyme activity remains unclear.26 On the other hand, CYP3A5 is very polymorphic, and its activity in Caucasians is determined by CYP3A5*3 allele through alternative splicing.37 For the uptake transporters OATP 1B3 and OATP 1B1 we selected missense polymorphisms with reported functional consequences.17 Finally, for ABCB1 we selected the three most studied variants (1236C4T, 2677G4T and 3435C4T)27 associated with altered transport and a missense (N21D) polymorphism described in public databases but not previously studied. Login to comment

[hide] Domperidone treatment for gastroparesis: demograph... Dig Dis Sci. 2011 Jan;56(1):115-24. Epub 2010 Nov 10. Parkman HP, Jacobs MR, Mishra A, Hurdle JA, Sachdeva P, Gaughan JP, Krynetskiy E
Domperidone treatment for gastroparesis: demographic and pharmacogenetic characterization of clinical efficacy and side-effects.
Dig Dis Sci. 2011 Jan;56(1):115-24. Epub 2010 Nov 10., [PMID:21063774]

Abstract [show]
BACKGROUND: Domperidone is a useful alternative to metoclopramide for treatment of gastroparesis due to better tolerability. Effectiveness and side-effects from domperidone may be influenced by patient-related factors including polymorphisms in genes encoding drug-metabolizing enzymes, drug transporters, and domperidone targets. AIMS: The aim of this study was to determine if demographic and pharmacogenetic parameters of patients receiving domperidone are associated with response to treatment or side-effects. METHODS: Patients treated with domperidone for gastroparesis provided saliva samples from which DNA was extracted. Fourteen single-nucleotide polymorphisms (SNPs) in seven candidate genes (ABCB1, CYP2D6, DRD2, KCNE1, KCNE2, KCNH2, KCNQ1) were used for genotyping. SNP microarrays were used to assess single-nucleotide polymorphisms in the ADRA1A, ADRA1B, and ADRA1D loci. RESULTS: Forty-eight patients treated with domperidone participated in the study. DNA was successfully obtained from each patient. Age was associated with effectiveness of domperidone (p=0.0088). Genetic polymorphism in KCNH2 was associated with effectiveness of domperidone (p=0.041). The efficacious dose was associated with polymorphism in ABCB1 gene (p=0.0277). The side-effects of domperidone were significantly associated with the SNPs in the promoter region of ADRA1D gene. CONCLUSIONS: Genetic characteristics associated with response to domperidone therapy included polymorphisms in the drug transporter gene ABCB1, the potassium channel KCNH2 gene, and alpha1D--adrenoceptor ADRA1D gene. Age was associated with a beneficial response to domperidone. If verified in a larger population, this information might be used to help determine which patients with gastroparesis might respond to domperidone and avoid treatment in those who might develop side-effects.

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89 Between-group comparisons were carried out using analysis of Table 1 SNPs evaluated in this study, corresponding genes, and functional consequences of polymorphisms SNP marker Gene/allele Description Effect of genetic polymorphism rs1045642 ABCB1/3435T[C Transporter Ile1145Ile Decreased function rs2032582 ABCB1/2677T[G/A Transporter Ala893Ser Decreased function rs2229109 ABCB1/1199G[A Transporter Asn400Ser Decreased function rs9282564 ABCB1/61A[G Transporter Asn21Asp Decreased function rs3892097 CYP2D6*4/1846G[A Metabolism SNP in intron Loss of function rs5030655 CYP2D6*6/544del Metabolism Frame shift Loss of function rs35742686 CYP2D6*3/865del Metabolism Frame shift Loss of function rs6275 DRD2/1174C[T Dopamine receptor His313His Phenotype-associated allele rs6277 DRD2/1192T[C Dopamine receptor Pro319Pro Phenotype-associated allele rs727957 KCNE1 G/T Potassium voltage-gated channel, Isk-related member 1 SNP in intron Phenotype-associated allele rs16991652 KCNE2/165C[G Potassium voltage-gated channel, Isk-related member 2 Gln9Glu Phenotype-associated allele rs1805123 KCNH2/2703A[C Potassium voltage-gated channel H (eag-related) member 2 K897T Phenotype-associated allele rs3815459 KCNH2 A/G Potassium voltage-gated channel H (eag-related) member 2 SNP in intron Phenotype-associated allele rs757092 KCNQ1 A/G Potassium voltage-gated channel, KQT-like member 1 SNP in intron Phenotype-associated allele rs6107461 ADRA1D C/T Adrenergic receptor a1D SNP upstream of the gene rs6084673 ADRA1D G/A Adrenergic receptor a1D SNP upstream of the gene rs6052462 ADRA1D A/G Adrenergic receptor a1D SNP upstream of the gene rs4813680 ADRA1D C/A Adrenergic receptor a1D SNP upstream of the gene variance (ANOVA) for continuous data and Fisher`s exact test for categorical data. Login to comment
163 This non-synonymous SNP results in amino acid change Asn21Asp in the intracellular domain of P-gp transporter protein, and was demonstrated to modulate inhibition of calcein-AM transport by cyclosporine A [32]. Login to comment

[hide] P-glycoprotein: tissue distribution, substrates, a... Handb Exp Pharmacol. 2011;(201):261-83. Cascorbi I
P-glycoprotein: tissue distribution, substrates, and functional consequences of genetic variations.
Handb Exp Pharmacol. 2011;(201):261-83., [PMID:21103972]

Abstract [show]
P-glycoprotein (ABCB1, MDR1) belongs to the ABC transporter family transporting a wide range of drugs and xenobiotics from intra- to extracellular at many biological interfaces such as the intestine, liver, blood-brain barrier, and kidney. The ABCB1 gene is highly polymorphic. Starting with the observation of lower duodenal protein expression and elevated digoxin bioavailability in relation to the 3435C>T single nucleotide polymorphism, hundreds of pharmacokinetic and outcome studies have been performed, mostly genotyping 1236C>T, 2677G>T/A, and 3435C>T. Though some studies pointed out that intracellular concentrations of anticancer drugs, for example, within lymphocytes, might be affected by ABCB1 variants resulting in differential outcome, current knowledge of the functional significance genetic variants of ABC membrane transporters does not allow selection of a particular SNP to predict an individual's pharmacokinetics.

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13 Absence of the gene, as being the case in double-knockout mice, is conformable N21D S400N A893S/T Q1107P 3435C>T1236T>C N183S R492C S1141T NBD1 NBD2 Intracellular (e.g. lymphocyte) Extracellular M986V Fig. 1 Two-dimensional structure of ABCB1 with locations of amino acid replacements and two frequent synonymous SNPs, NBD ¼ nucleotide binding domain [adapted from Cascorbi and Haenisch (2010)] Inducer intra cellular ABCB1 Transkription Translation ABCB1 (P-gp) luminal Fig. 2 Induction of ABCB1 via the nuclear PXR/RXR receptor leading to accelerated extrusion of P-glycoprotein substrates with life. Login to comment
81 Table 2 Frequency of ABCB1 genetic variants in Caucasians, position on DNA, putative effect, and frequencies [according to Cascorbi (2006) and Cascorbi and Haenisch (2010)] Position Amino acid or effect Frequency of the variant allele Association to expression, kinetics or drug response 50 -flanking À2903 T>C 0.02a 50 -flanking À2410 T>C 0.10a Decreased mRNAa 50 -flanking À2352 G>A 0.28a 50 -flanking À1910 T>C 0.10a 50 -flanking À1717 T>C 0.02a 50 -flanking À1325 A>G 0.02a 50 -flanking À934 A>G 0.10a 50 -flanking À692 T>C 0.10a Decreased mRNAa 50 -flanking À41 A>G 0.09b IVS 1a À145 C>G 0.02b IVS 1b À129 T>C 0.06b IVS 1b 12 T>C 0.06c IVS 2 À1 G>A 0.09d c. 61 A>G N21D 0.11d IVS 5 À35 G>C Intronic 0.006c IVS 5 À25 G>T Intronic 0.16c IVS 6 þ139 C>T Intronic 0.37d c. 548 A>G N183S 0.01e c. 571 G>A G191R 0.07f Reduced chemotherapy resistancef c. 1199 G>A S400N 0.05d c. 1199 C>T S400I 0.02g Elevated activityg c. 1236 C>T Synonymous 0.41d Increased imatinib disposition and therapy responseh IVS 12 þ44 C>T Intronic 0.05d c. 1474 C>T R492C 0.01e IVS 17 À76 T>A Intronic 0.46d IVS 17 þ137 A>G Intronic 0.006c c. 2650 C>T Synonymous 0.03e c. 2677 G>T/A A893S/T 0.42d /0.02d In vitro increased vmax,i increased imatinib response in CMLh c. 2956 A>G M986V 0.005b c. 3320 A>C Q1107P 0.002d c. 3396 C>T Synonymous 0.03c c. 3421 T>A S1141T 0.00c c. 3435 C>T Synonymous 0.54d Decreased mRNA and protein expression,e, k decreased in vitro transport,l no effect on expression and bioavailability of talinolol,m no effect on in vitro transport,n, o decreased digoxin (continued) 4.2.1 Digoxin The heart glycoside digoxin is widely accepted as typical P-glycoprotein substrate. Login to comment

[hide] Modification of menopausal hormone therapy-associa... Endocr Relat Cancer. 2011 Jun 8;18(3):371-84. Print 2011. Rudolph A, Sainz J, Hein R, Hoffmeister M, Frank B, Forsti A, Brenner H, Hemminki K, Chang-Claude J
Modification of menopausal hormone therapy-associated colorectal cancer risk by polymorphisms in sex steroid signaling, metabolism and transport related genes.
Endocr Relat Cancer. 2011 Jun 8;18(3):371-84. Print 2011., [PMID:21490239]

Abstract [show]
The mechanisms underlying the association of menopausal hormone therapy (MHT) with reduced colorectal cancer (CRC) risk are unknown and the identification of genetic modifiers may yield further insight. We explored the effect modification of MHT-associated CRC risk in postmenopausal women by 47 polymorphisms with known or putative functional relevance in 16 candidate genes related to hormone metabolism (COMT, CYP1A1, CYP1A2, CYP1B1, CYP2C9, CYP2C19, CYP3A4, CYP17A1, GSTP, and HSD17B1), transport (ABCB1), and signaling (ESR1, ESR2, SHBG, PGR, and NR1I2). A total of 685 CRC patients and 684 healthy controls from a German population-based case-control study (DACHS) were genotyped. Multiplicative statistical interaction between polymorphisms and ever MHT use as well as duration of use was assessed using multivariate logistic regression. CRC risk associated with ever MHT use as well as with duration was significantly modified by rs1202168 in the transporter gene ABCB1 (P interaction=0.04). The MHT-associated risk reduction was not significant in homozygous non-carriers (odds ratio (OR) ever use=0.84, 95% confidence interval (CI) 0.53-1.34; OR per 5 year duration=0.94, 95% CI 0.83-1.08), while homozygous carriers of the minor T allele had a 57% lower risk with ever use of MHT (95% CI 0.21-0.88) and a 22% lower risk per 5 years of MHT use (95% CI 0.62-0.97). Significant effect modification was also observed for the ESR1_rs910416 polymorphism (P interaction=0.03 for ever use and 0.07 for duration of use), whereby the decreased risk was attenuated in homozygous carriers of the minor C allele (OR ever use=0.87, 95% CI 0.48-1.60, OR per 5 year duration=0.99, 95% CI 0.83-1.18). Results of this exploratory study provide first evidence that polymorphisms in genes related to estrogen transport and signaling may modify MHT-associated CRC risk but warrant replication in an independent population.

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119 Table 2 Genotype frequencies and colorectal cancer risk estimates of polymorphisms in genes related to sex steroid signaling, transport, and metabolism in the female postmenopausal DACHS study population Gene Variant Genotype Effect estimate dbSNP rs# Amino acid substitution and functional consequence MAF Genotype N Co/N Ca OR (95% CI)a P trend ABCB1 rs1045642 I1145I, T allele associated with lower protein expression (Hoffmeyer et al. 2000) 49% T/T 183/190 1.00 T/C 329/336 1.04 (0.77-1.40) C/C 167/156 0.98 (0.69-1.39) 0.914 ABCB1 rs2229109 S400N, functional consequences unknown 6% G/G 596/614 1.00 G/A 86/64 0.69 (0.47-1.03) A/A 1/1 1.00 (0.03-33.9) 0.078 ABCB1 rs1202168 Intronic, functional consequences unknown, in high LD interval (Soranzo et al. 2004) 40% C/C 249/218 1.00 C/T 312/337 1.08 (0.82-1.42) T/T 119/127 1.02 (0.71-1.46) 0.829 ABCB1 rs9282564 N21D, results in a net charge change of the protein (Brinkmann and Eichelbaum 2001) 10% A/A 545/544 1.00 A/G 117/124 1.05 (0.76-1.45) G/G 12/9 0.73 (0.23-2.27) 0.997 ABCB1 rs2214102 50 -UTR, located at a translation initiation site (Hoffmeyer et al. 2000) 7% G/G 593/580 1.00 G/A 81/97 1.33 (0.91-1.92) A/A 6/6 0.96 (0.26-3.51) 0.208 SHBG rs6259 D356N, A allele is associated with reduced clearance of SHBG (Cousin et al. 1998) 11% G/G 525/549 1.00 G/A 141/115 0.69 (0.50-0.95) A/A 6/10 1.13 (0.36-3.60) 0.061 ESR2 rs1255998 30 -UTR, functional consequences unknown, G allele associated with endometrial cancer risk (Ashton et al. 2009) 12% C/C 519/547 1.00 C/G 138/114 0.76 (0.55-1.04) G/G 14/5 0.33 (0.11-1.01) 0.015 ESR2 rs928554 30 -UTR, G allele might create new acceptor splice site (MARIE-GENICA-Consortium 2010a) 40% A/A 246/222 1.00 A/G 316/317 1.19 (0.90-1.56) G/G 111/133 1.48 (1.03-2.13) 0.032 ESR2 rs4986938 30 -UTR, potentially affects pre-mRNA splicing (Zheng et al. 2003) 38% G/G 260/264 1.00 G/A 310/306 0.97 (0.74-1.27) A/A 99/106 1.02 (0.70-1.48) 0.997 ESR2 rs1271572 50 -UTR, might modulate binding of transcription factors (MARIE-GENICA-Consortium 2010a) 42% G/G 231/208 1.00 G/T 329/330 1.29 (0.97-1.70) T/T 120/138 1.40 (0.98-2.00) 0.046 ESR1 rs851984 50 -UTR, functional consequences unknown, T allele associated with breast cancer risk (MARIE-GENICA-Consortium 2010a) 41% C/C 221/231 1.00 C/T 341/314 0.95 (0.72-1.25) T/T 103/122 1.07 (0.74-1.55) 0.833 ESR1 rs2881766 50 -UTR, functional consequences unknown, G allele associated with breast cancer risk (MARIE-GENICA-Consortium 2010a) 18% T/T 461/453 1.00 T/G 190/195 1.02 (0.77-1.35) G/G 25/22 0.95 (0.48-1.87) 0.989 ESR1 rs2071454 50 -UTR, functional consequences unknown 11% T/T 536/551 1.00 T/G 132/120 0.81 (0.59-1.12) G/G 5/8 1.75 (0.51-6.03) 0.467 ESR1 rs2077647 S10S, potentially affects mRNA structure (Tanaka et al. 2003) 47% A/A 183/187 1.00 A/G 347/349 0.97 (0.73-1.30) G/G 140/135 0.93 (0.65-1.33) 0.697 ESR1 rs827421 Intronic, functional consequences unknown 48% T/T 172/178 1.00 T/C 350/355 1.02 (0.76-1.37) C/C 151/143 0.91 (0.64-1.30) 0.620 ESR1 rs2234693 Intronic, C allele introduces a binding site for transcription factor B-myb, leading to altered transcription (Herrington et al. 2002) 46% T/T 188/209 1.00 T/C 348/341 0.93 (0.70-1.24) C/C 136/120 0.87 (0.61-1.24) 0.429 ESR1 rs9340799 Intronic, functional consequences unknown, may lead to altered transcription or splicing (Schuit et al. 2004) 36% A/A 274/287 1.00 A/G 319/317 1.01 (0.78-1.32) G/G 83/72 0.94 (0.63-1.42) 0.864 ESR1 rs3798577 30 -UTR, functional consequences unknown 45% T/T 203/189 1.00 T/C 328/330 1.14 (0.86-1.52) C/C 139/154 1.27 (0.89-1.80) 0.181 Table 2 continued Gene Variant Genotype Effect estimate dbSNP rs# Amino acid substitution and functional consequence MAF Genotype N Co/N Ca OR (95% CI)a P trend ESR1 rs910416 30 near gene, functional consequences unknown, modified estrogen monotherapy- associated breast cancer risk (MARIE-GENICA-Consortium 2010a) 48% T/T 178/188 1.00 T/C 338/314 0.81 (0.61-1.10) C/C 148/159 0.92 (0.65-1.31) 0.599 PGR rs1042838 V660L, SNP possibly affects receptor dimerization, nuclear localization, ligand binding, cofactor interaction (Agoulnik et al. 2004) 15% C/C 495/478 1.00 C/A 154/181 1.32 (0.99-1.76) A/A 24/16 0.91 (0.44-1.88) 0.202 PGR rs1379130 G393G, functional consequences unknown 36% G/G 272/298 1.00 G/A 311/268 0.74 (0.56-0.96) A/A 88/108 1.01 (0.69-1.47) 0.412 PGR rs10895068 50 -UTR, creates new transcription start site, increasing expression of PR-B isoform (De Vivo et al. 2002) 4% G/G 615/619 1.00 G/A 58/59 0.89 (0.58-1.38) A/A 1/1 1.94 (0.05-80.6) 0.670 PGR rs518162 50 -UTR, SNP is located between PR-B and PR-A transcription start sites, potentially affecting PR-A/B expression (De Vivo et al. 2002) 7% G/G 580/586 1.00 G/A 93/88 1.06 (0.74-1.53) A/A 3/4 1.23 (0.21-7.06) 0.710 NR1I2 rs1523127 50 -UTR, belongs to a haplotype incl. SNPs that introduce new transcription factor binding sites (Zhang et al. 2001) 39% A/A 245/258 1.00 A/C 326/317 0.89 (0.68-1.17) C/C 98/88 0.89 (0.61-1.32) 0.450 NR1I2 rs2276706 Intronic, belongs to a haplotype incl. SNPs that introduce new transcription factor binding sites (Zhang et al. 2001) 38% G/G 251/267 1.00 G/A 329/324 0.92 (0.70-1.20) A/A 95/83 0.89 (0.60-1.31) 0.474 NR1I2 rs1464603 Intronic, functional consequences unknown 32% T/T 303/307 1.00 T/C 310/291 1.05 (0.80-1.36) C/C 65/78 1.11 (0.73-1.69) 0.608 NR1I2 rs6785049 Intronic, G allele associated with increased induction of CYP3A (Zhang et al. 2001) 38% A/A 260/264 1.00 A/G 323/313 1.00 (0.77-1.31) G/G 94/101 1.10 (0.75-1.60) 0.698 NR1I2 rs2276707 Intronic, T allele associated with increased induction of CYP3A (Zhang et al. 2001) 17% C/C 446/439 1.00 C/T 180/190 1.00 (0.75-1.32) T/T 21/24 1.19 (0.58-2.44) 0.794 NR1I2 rs1054191 30 -UTR, A allele associated with decreased induction of CYP3A (Zhang et al. 2001) 14% G/G 499/518 1.00 G/A 161/143 0.95 (0.70-1.28) A/A 17/12 0.80 (0.35-1.87) 0.581 NR1I2 rs3814057 30 -UTR, C allele associated with decreased induction of P-glycoprotein (Zhang et al. 2001) 17% A/A 458/440 1.00 A/C 177/201 1.15 (0.87-1.52) C/C 22/24 1.20 (0.60-2.41) 0.307 COMT rs4680 V158M, A allele leads to thermo-labile protein and 2-3 fold lower catalytic activity (Dawling et al. 2001) 49% G/G 171/177 1.00 A/G 343/327 0.88 (0.66-1.19) A/A 162/175 1.05 (0.74-1.48) 0.802 HSD17B1 rs605059 G313S, functional consequences unknown, C allele has been associated with lower estradiol levels (Setiawan et al. 2004) 46% T/T 199/167 1.00 T/C 330/340 1.30 (0.97-1.75) C/C 144/170 1.41 (0.99-2.01) 0.051 CYP1B1 rs1800440 N453S, G allele leads to enzyme which catalyzes hydroxylation of estradiol more efficiently (Hanna et al. 2000) 19% A/A 452/467 1.00 A/G 202/187 0.89 (0.68-1.18) G/G 26/22 0.81 (0.40-1.62) 0.342 CYP1B1 rs1056836 L432V, G allele leads to enzyme with increased activity (Shimada et al. 1999) 41% C/C 224/220 1.00 C/G 339/320 1.00 (0.75-1.32) G/G 106/128 1.31 (0.91-1.88) 0.209 CYP1B1 rs1056827 A119S, T allele leads to enzyme which catalyzes hydroxylation of estradiol more efficiently (Hanna et al. 2000) 31% G/G 317/323 1.00 G/T 304/297 0.90 (0.70-1.17) T/T 57/55 0.85 (0.54-1.35) 0.362 continued gene ESR1 (interaction ORZ1.49, 95% CI 1.04-2.13, P interactionZ0.03). 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[hide] An update on ABCB1 pharmacogenetics: insights from... Pharmacogenomics J. 2011 Oct;11(5):315-25. doi: 10.1038/tpj.2011.16. Epub 2011 May 31. Wolf SJ, Bachtiar M, Wang J, Sim TS, Chong SS, Lee CG
An update on ABCB1 pharmacogenetics: insights from a 3D model into the location and evolutionary conservation of residues corresponding to SNPs associated with drug pharmacokinetics.
Pharmacogenomics J. 2011 Oct;11(5):315-25. doi: 10.1038/tpj.2011.16. Epub 2011 May 31., [PMID:21625253]

Abstract [show]
The human ABCB1 protein, (P-glycoprotein or MDR1) is a membrane-bound glycoprotein that harnesses the energy of ATP hydrolysis to drive the unidirectional transport of substrates from the cytoplasm to the extracellular space. As a large range of therapeutic agents are known substrates of ABCB1 protein, its role in the onset of multidrug resistance has been the focus of much research. This role has been of particular interest in the field of pharmacogenomics where genetic variation within the ABCB1 gene, particularly in the form of single nucleotide polymorphisms (SNPs), is believed to contribute to inter-individual variation in ABCB1 function and drug response. In this review we provide an update on the influence of coding region SNPs within the ABCB1 gene on drug pharmacokinetics. By utilizing the crystal structure of the mouse ABCB1 homolog (Abcb1a), which is 87% homologous to the human sequence, we accompany this discussion with a graphical representation of residue location for amino acids corresponding to human ABCB1 coding region SNPs. Also, an assessment of residue conservation, which is calculated following multiple sequence alignment of 11 confirmed sequences of ABCB1 homologs, is presented and discussed. Superimposing a 'heat map' of residue homology to the Abcb1a crystal structure has permitted additional insights into both the conservation of individual residues and the conservation of their immediate surroundings. Such graphical representation of residue location and conservation supplements this update of ABCB1 pharmacogenetics to help clarify the often confounding reports on the influence of ABCB1 polymorphisms on drug pharmacokinetics and response.

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131 These are E3/61A4G (N21D), E5/266C4T (M89T), E17/1985T4C (L662R), E17/2005C4T (R669C). Login to comment
132 When in haplotype with the intensely studied SNPs E13/1236C4T (#s6), E22/2677G4T/A (#ns22) and E27/3435C4T (#s20), SNP E3/61A4G (N21D), which cannot be mapped to the 3D crystal structure, was reported to increase BODIPY-FL-paclitaxel accumulation and modulate the effect of cyclosporine A on the intracellular accumulation of BODIPY-FL-paclitaxel transport.50 However, the N21D substitution was found not to influence cyclosporine A pharmacokinetics in another study.51 In yet another study, the N21D polymorphism was reported to influence the trough but not the peak plasma levels concentration of methadone.52 Using a yeast-based assay, SNP E27/3421T4A (S1141T) (#ns33) and several SNPs that cannot be mapped to the crystal structure (E5/266C4T (M89T), E17/1985T4C (L662R), E17/2005C4T (R669C)) were reported to increase drug resistance to two or more drugs whereas SNP E27/ 3322T4C (W1108R) (#ns31) decreased drug resistance.49 Curiously, in another study, the E17/2005C4T (R669C) SNP was reported to be associated with decreased resistance to paclitaxel and etoposide in transfected LLC-PK1 cells.53 The increased resistance by SNP E17/2005C4T (R669C) was found to be reversed by SNP E27/3322T4C (W1108R) (#ns31).49 In another study using HEK293T cells, SNP E27/3421T4A (S1141T) (#ns33) was reported to be less sensitive to cyclosporine A inhibition of BODIPY-FL-paclitaxel transport.50 It was suggested that as the resistance profiles of SNPs E27/3421T4A (S1141T) (#ns33), E27/3322T4C (W1108R) (#ns31) and diplotype E27/3322T4C (W1108R)- E17/ 2005C4T (R669C)) display the largest variation across substrates, the region where S1141T (#ns33) and W1108R (#ns31) reside might contribute to the substrate discrimination activity of P-gp.49 The 3D crystal structure reveals that both S1141T (#ns33) and W1108R (#ns31) reside at the C-terminal NBD of the P-gp protein with S1141T (#ns33) residing on the outer surface and W1108R (#ns31) residing in the interior of the NBD (Figures 2b, 4d and 4e and flash movie http:// pfs.nus.edu.sg/demo_src/abcb1.html). Login to comment

[hide] Xenobiotic, bile acid, and cholesterol transporter... Pharmacol Rev. 2010 Mar;62(1):1-96. Epub 2010 Jan 26. Klaassen CD, Aleksunes LM
Xenobiotic, bile acid, and cholesterol transporters: function and regulation.
Pharmacol Rev. 2010 Mar;62(1):1-96. Epub 2010 Jan 26., [PMID:20103563]

Abstract [show]
Transporters influence the disposition of chemicals within the body by participating in absorption, distribution, and elimination. Transporters of the solute carrier family (SLC) comprise a variety of proteins, including organic cation transporters (OCT) 1 to 3, organic cation/carnitine transporters (OCTN) 1 to 3, organic anion transporters (OAT) 1 to 7, various organic anion transporting polypeptide isoforms, sodium taurocholate cotransporting polypeptide, apical sodium-dependent bile acid transporter, peptide transporters (PEPT) 1 and 2, concentrative nucleoside transporters (CNT) 1 to 3, equilibrative nucleoside transporter (ENT) 1 to 3, and multidrug and toxin extrusion transporters (MATE) 1 and 2, which mediate the uptake (except MATEs) of organic anions and cations as well as peptides and nucleosides. Efflux transporters of the ATP-binding cassette superfamily, such as ATP-binding cassette transporter A1 (ABCA1), multidrug resistance proteins (MDR) 1 and 2, bile salt export pump, multidrug resistance-associated proteins (MRP) 1 to 9, breast cancer resistance protein, and ATP-binding cassette subfamily G members 5 and 8, are responsible for the unidirectional export of endogenous and exogenous substances. Other efflux transporters [ATPase copper-transporting beta polypeptide (ATP7B) and ATPase class I type 8B member 1 (ATP8B1) as well as organic solute transporters (OST) alpha and beta] also play major roles in the transport of some endogenous chemicals across biological membranes. This review article provides a comprehensive overview of these transporters (both rodent and human) with regard to tissue distribution, subcellular localization, and substrate preferences. Because uptake and efflux transporters are expressed in multiple cell types, the roles of transporters in a variety of tissues, including the liver, kidneys, intestine, brain, heart, placenta, mammary glands, immune cells, and testes are discussed. Attention is also placed upon a variety of regulatory factors that influence transporter expression and function, including transcriptional activation and post-translational modifications as well as subcellular trafficking. Sex differences, ontogeny, and pharmacological and toxicological regulation of transporters are also addressed. Transporters are important transmembrane proteins that mediate the cellular entry and exit of a wide range of substrates throughout the body and thereby play important roles in human physiology, pharmacology, pathology, and toxicology.

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6832 Nucleotide Change Amino Acid Change In Vitro Function Protein Expression/ Localization ABCB1 MDR1 A61G N21D ↔ N.D. T307C F103L N.D. N.D. G1199A S400N 1↔ Normal C2005T R669C ↔ N.D. G2677T A893S 21↔ Normal G2677A A893T 1↔ Notmal T3421A S1141T 2↔ N.D. C3435T I1145I 2↔ N.D. G3751A V1251I 2 N.D. 2, reduced function; 1, increased function; ↔, no change in function; N.D. not determined. Login to comment

[hide] Genetic association analysis of transporters ident... Pharmacogenet Genomics. 2012 Jun;22(6):447-65. Grover S, Gourie-Devi M, Bala K, Sharma S, Kukreti R
Genetic association analysis of transporters identifies ABCC2 loci for seizure control in women with epilepsy on first-line antiepileptic drugs.
Pharmacogenet Genomics. 2012 Jun;22(6):447-65., [PMID:22565165]

Abstract [show]
OBJECTIVE: The ATP-binding cassette (ABC) superfamily of transporters is known to efflux antiepileptic drugs (AEDs) primarily in the brain, gastrointestinal tract, liver, and kidneys. In addition, they are also known to be involved in estrogen disposition and may modulate seizure susceptibility and drug response. The objective of the present study was to investigate the role of genetic variants from ABC transporters in seizure control in epilepsy patients treated with monotherapy of first-line AEDs for 12 months. METHODS: On the basis of gene coverage and functional significance, a total of 98 single nucleotide polymorphisms from ABCB1, ABCC1, and ABCC2 were genotyped in 400 patients from North India. Of these, 216 patients were eligible for therapeutic assessment. Genetic variants were compared between the 'no-seizures' and the 'recurrent-seizures' groups. Bonferroni corrections for multiple comparisons and adjustment for covariates were performed before assessment of associations. RESULTS: Functionally relevant promoter polymorphisms from ABCC2: c.-1549G>A and c.-1019A>G either considered alone or in haplotype and diplotype combinations were observed for a significant association with seizure control in women (odds ratio>3.5, P<10, power>95%). Further, low protein-expressing CGT and TGT (c.-24C>T, c.1249G>A, c.3972C>T) haplotypes were always observed to be present in combination with the AG (c.-1549G>A, c.-1019A>G) haplotype that was over-represented in women with 'no seizures'. CONCLUSION: The distribution of the associated variants supports the involvement of ABCC2 in controlling seizures in women possibly by lowering of its expression. The biological basis of this finding could be an altered interaction of ABCC2 with AEDs and estrogens. These results necessitate replication in a larger pool of patients.

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87 - 330-21247T > C Intron 1 0.005 6 rs4148731 chr7:87239329 c.-330 - 8935C > T Intron 1 0.000 7 rs9282564 chr7:87229440 c.61A > G Exon 3 (Asn21Asp) 0.000 8 rs9282565 chr7:87214875 c.239C > A Exon 5 (Ala80Glu) 0.000 9 rs28381826 chr7:87214531 c.286 + 297G > A Intron 5 0.000 10 rs1989830 chr7:87205663 c.287 - 6124C > T Intron 5 0.135 11 rs2520464 chr7:87201086 c.287 - 1547A > G Intron 5 0.409 12 rs2235023 chr7:87190452 c.827+ 127G > A Intron 9 0.000 13 rs10276036 chr7:87180198 c.1000 - 44C > T Intron 10 0.401 14 rs2229109 chr7:87179809 c.1199G > A Exon 12 (Ser400Asn) 0.000 15 rs1128503 chr7:87179601 c.1236T > C Exon 13 (Gly412Gly) 0.390 16 rs2235036 chr7:87175271 c.1795G > A Exon 16 (Ala599Thr) 0.000 17 rs2235039 chr7:87165854 c.2401G > A Exon 21 (Val801Met) 0.000 18 rs2235040 chr7:87165750 c.2481 + 24G > A Intron 21 0.155 19 rs2032581 chr7:87160810 c.2485A > G Exon 22 (Ile829Val) 0.000 20 rs2032582 chr7:87160618 c.2677T/A > G Exon 22 (Ser/Thr893Ala) 0.318 21 rs7779562 chr7:87144816 c.3085 -72G > C Intron 25 0.043 22 rs2707944 chr7:87144641 c.3188C > G Exon 26 (Ala1063Gly) 0.000 23 rs2229107 chr7:87138659 c.3421A > T Exon 27 (Thr1141Ser) 0.000 24 rs1045642 chr7:87138645 c.3435T > C Exon 27 (Ile1145Ile) m Expression and activity [28] m mRNA expression [29] Altered substrate specificity [30] 0.375 25 rs2235048 chr7:87138511 c.3489 + 80C > T Intron 27 0.381 26 rs17064 chr7:87133470 c.3932A > T 30 UTR 0.000 ABCC1 1 rs504348 chr16:16043174 rs50438C > G Near gene region k Promoter activity [31] 0.135 2 rs215106 chr16:16047542 c.48 + 3886A > G Intron 1 0.210 3 rs215049 chr16:16070768 c.48 + 27112G > C Intron 1 0.245 4 rs246220 chr16:16082128 c.49 - 19545C > G Intron 1 0.118 5 rs119774 chr16:16086833 c.49 - 14840G > A Intron 1 0.089 6 rs246217 chr16:16090354 c.49 - 11319C > A Intron 1 0.118 7 rs2014800 chr16:16099966 c.49 - 1707C > T Intron 1 0.398 8 rs41494447 chr16:16101842 c.218C > T Exon 2 (Thr73Ile) 0.000 9 rs4781712 chr16:16103232 c.226 - 401A > G Intron 2 0.355 10 rs246240 chr16:16119024 c.616 -7942A > G Intron 5 0.114 11 rs924135 chr16:16123459 c.616 - 3507A > T Intron 5 0.412 12 rs903880 chr16:16130514 c.809 + 54C > A Intron 7 0.147 13 rs8187852 chr16:16139709 c.1057G > A Exon 9 (Met353Val) 0.000 14 rs35587 chr16:16139714 c.1062T > C Exon 9 (Asn354Asn) 0.182 15 rs35592 chr16:16141823 c.1219 - 176T > C Intron 9 0.172 16 rs60782127 chr16:16142079 c.1299G > T Exon 10 (Arg433Ser) k Transport of leukotriene C4 and estrone sulfate [32] 0.008 17 rs3765129 chr16:16149901 c.1474 - 48C > T Intron 11 0.032 18 rs35597 chr16:16158034 c.1678 - 3979G > A Intron 12 0.320 19 rs35621 chr16:16168608 c.1913 - 1575C > T Intron 14 0.103 20 rs45511401 chr16:16173232 c.2012G > T Exon 16 (Gly671Val) 0.024 21 rs4148356 chr16:16177275 c.2168G > A Exon 17 (Arg723Gln) 0.000 22 rs3851713 chr16:16184873 c.2644 + 428A > T Intron 19 0.340 23 rs2239995 chr16:16192565 c.2645 - 3919G > A Intron 19 0.324 24 rs11864374 chr16:16201885 c.2871 + 1155G > A Intron 21 0.338 25 rs35529209 chr16:16205325 c.2965G > A Exon 22 (Thr989Ala) k Transport of estradiol 17b-glucuronide [32] 0.000 26 rs3887893 chr16:16205501 c.3079 + 62G > A Intron 22 0.448 27 rs13337489 chr16:16208683 c.3140G > C Exon 23 (Ser1047Cys) 0.000 28 rs2299670 chr16:16220858 c.3819 + 1090A > G Intron 26 0.399 29 rs8057331 chr16:16230411 c.4202C > T Exon 29 (Thr1401Met) 0.000 30 rs212090 chr16:16236004 c.5462T > A 30 UTR 0.357 31 rs212093 chr16:16237754 rs212093G > A Near gene region 0.429 32 rs4148382 chr16:16238494 rs4148382G > A Near gene region 0.034 ABCC2 1 g.-1774G > delG chr10:101535688 g.-1774G > delG Near gene region k Promoter activity [33] 0.000 2 rs1885301 chr10:101541053 c.-1549G > A Near gene region k Promoter activity [haplotype containing (- 1549A)-(- 24T)] [33] k Clearance of irinotecan (ABCC2*2 containing the G allele) [34] 0.379 450 Pharmacogenetics and Genomics 2012, Vol 22 No 6 Table 2 (continued) N dbSNP ida Positionb Allelesc Gene location (effect) Function MAF 3 rs2804402 chr10:101541583 c. Login to comment

[hide] Clinical response and side effects of metocloprami... J Clin Gastroenterol. 2012 Jul;46(6):494-503. doi: 10.1097/MCG.0b013e3182522624. Parkman HP, Mishra A, Jacobs M, Pathikonda M, Sachdeva P, Gaughan J, Krynetskiy E
Clinical response and side effects of metoclopramide: associations with clinical, demographic, and pharmacogenetic parameters.
J Clin Gastroenterol. 2012 Jul;46(6):494-503. doi: 10.1097/MCG.0b013e3182522624., [PMID:22688145]

Abstract [show]
OBJECTIVES: Metoclopramide is associated with variable efficacy and side effects when used in the treatment of gastroparesis. AIM: To determine associations of clinical and pharmacogenetic parameters with response and side effects to metoclopramide in patients with upper gastrointestinal symptoms suggestive of gastroparesis. METHODS: Gastroparetic patients treated with metoclopramide were enrolled. Clinical parameters recorded were age, sex, weight, diabetic status, gastric emptying result, daily dose, effectiveness, and side effects. DNA was isolated from salivary samples; 20 single nucleotide polymorphisms were genotyped in 8 candidate genes (ABCB1, ADRA1D, CYP1A2, CYP2D6, DRD2, DRD3, HTR4, KCNH2). RESULTS: One hundred gastroparetic patients treated with metoclopramide participated. Dose averaged 33+/-16 mg/d for 1.1+/-1.7 years. Responders (53 of 100 patients) were older (48+/-15 vs. 38+/-11 y; P=0.0004) and heavier (body mass index of 28+/-7 vs. 25+/-7; P=0.0125). Efficacy was associated with polymorphisms in KCNH2 (rs1805123, P=0.020) and ADRA1D (rs2236554, P=0.035) genes. Side effects, occurred in 64 patients, were more common in females (83% vs. 64%; P=0.037), nondiabetics (77% vs. 47%; P=0.004), and patients with normal gastric emptying (41% vs. 17%; P=0.015). Side effects were associated with polymorphisms in CYP2D6 (rs1080985, P=0.045; rs16947, P=0.008; rs3892097, P=0.049), KCNH2 (rs3815459, P=0.015), and serotonin 5-HT4 receptor HTR4 gene (rs9325104, P=0.026). CONCLUSIONS: Side effects to metoclopramide were more common in nondiabetic patients with normal gastric emptying. Polymorphisms in CYP2D6, KCNH2, and 5-HT4 receptor HTR4 genes were associated with side effects, whereas polymorphisms in KCNH2 and ADRA1D genes were associated with clinical response. Clinical parameters and pharmacogenetic testing may be useful in identifying patients before treatment with metoclopramide to enhance efficacy and minimize side effects.

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87 SNPs Evaluated in This Study With Corresponding Genes and Functional Consequences of Polymorphisms Genes/Alleles SNP Markers Function Effect of Genetic Polymorphism CYP2D6 rs1080985 Oxidative metabolism SNP in intron Phenotype-associated allele CYP2D6 rs16947 Oxidative metabolism Cys245Arg Phenotype-associated allele CYP2D6 rs3892097 Oxidative metabolism SNP in intron Loss of function CYP1A2 rs2069514 Oxidative metabolism Upstream region Phenotype-associated allele CYP1A2 rs762551 Oxidative metabolism Upstream region Phenotype-associated allele DRD3 rs7625282 Dopamine receptor Intron DRD2 rs1799978 Dopamine receptor Upstream region Phenotype-associated allele DRD2 rs6275 Dopamine receptor His313His Phenotype-associated allele DRD2 rs6277 Dopamine receptor Pro319Pro Phenotype-associated allele ABCB1 rs1045642 Drug transporter Ile1145Ile Decreased function ABCB1 rs9282564 Drug transporter Asn21Asp Decreased function HTR4 rs10078551 Serotonin receptor 4 Forms a haplotype HTR4 rs7713886 Serotonin receptor 4 Forms a haplotype HTR4 rs7735184 Serotonin receptor 4 SNP in intron HTR4 rs9325104 Serotonin receptor 4 SNP in intron KCNH2 rs1805123 Potassium voltage-gated channel H (eag-related), member 2 K897T Phenotype-associated allele KCNH2 rs3807375 Potassium voltage-gated channel H (eag-related), member 2 Phenotype-associated allele (QT prolongation) KCNH2 rs3815459 Potassium voltage-gated channel H (eag-related), member 2 SNP in intron Phenotype-associated allele (QT interval) ADRA1D rs2236554 Adrenergic receptor a1D 30 -UTR ADRA1D rs709024 Adrenergic receptor a1D 30 -UTR SNP indicates single nucleotide polymorphism. Login to comment

[hide] The permeability P-glycoprotein: a focus on enanti... Expert Opin Drug Metab Toxicol. 2010 Aug;6(8):953-65. Choong E, Dobrinas M, Carrupt PA, Eap CB
The permeability P-glycoprotein: a focus on enantioselectivity and brain distribution.
Expert Opin Drug Metab Toxicol. 2010 Aug;6(8):953-65., [PMID:20504109]

Abstract [show]
IMPORTANCE OF THE FIELD: The permeability glycoprotein (P-gp) is an important protein transporter involved in the disposition of many drugs with different chemical structures, but few studies have examined a possible stereoselectivity in its activity. P-gp can have a major impact on the distribution of drugs in selected organs, including the brain. Polymorphisms of the ABCB1 gene, which encodes for P-gp, can influence the kinetics of several drugs. AREAS COVERED IN THIS REVIEW: A search including publications from 1990 up to 2009 was performed on P-gp stereoselectivity and on the impact of ABCB1 polymorphisms on enantiomer brain distribution. WHAT THE READER WILL GAIN: Despite stereoselectivity not being expected because of the large variability of chemical structures of P-gp substrates, structure-activity relationships suggest different P-gp-binding sites for enantiomers. Enantioselectivity in the activity of P-gp has been demonstrated by in vitro studies and in animal models (preferential transport of one enantiomer or different inhibitory potencies towards P-gp activity between enantiomers). There is also in vivo evidence of an enantioselective drug transport at the human blood-brain barrier. TAKE HOME MESSAGE: The significant enantioselective activity of P-gp might be clinically relevant and must be taken into account in future studies.

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209 Different SNPs were associated with the phenotype of remission, and carriers of the C allele for the rs2032583 genotype had higher odds ratio for remission (7.72, 95% CI 2.8 -- 21.3) at 4 weeks Exon 7 Exon 13 Exon 11Exon 2 Exon 8 Exon 6 Exon 3 Exon 4 Exon 9 Exon 17 Exon 10 Exon 14 Exon 12 Exon 15 Exon 16 Exon 19 Exon 21 Exon 18 Exon 23 Exon 24 Exon 28 Exon 27 Exon 20 Exon 22 A893S Exon 25 Exon 26 Exon 5 N21D N183S N400S Variant (548G, Ser183) MDR1*1 (548A, Asn183) Variant (2677T, Ser893) S1141T ATP-binding domain ATP-binding domain MDR1*1 (2677g, Ala893) R492C A. B. Figure 2. Login to comment

[hide] A synonymous polymorphism in a common MDR1 (ABCB1)... Biochim Biophys Acta. 2009 May;1794(5):860-71. Epub 2009 Mar 11. Fung KL, Gottesman MM
A synonymous polymorphism in a common MDR1 (ABCB1) haplotype shapes protein function.
Biochim Biophys Acta. 2009 May;1794(5):860-71. Epub 2009 Mar 11., [PMID:19285158]

Abstract [show]
The MDR1 (ABCB1) gene encodes a membrane-bound transporter that actively effluxes a wide range of compounds from cells. The overexpression of MDR1 by multidrug-resistant cancer cells is a serious impediment to chemotherapy. MDR1 is expressed in various tissues to protect them from the adverse effect of toxins. The pharmacokinetics of drugs that are also MDR1 substrates also influence disease outcome and treatment efficacy. Although MDR1 is a well-conserved gene, there is increasing evidence that its polymorphisms affect substrate specificity. Three single nucleotide polymorphisms (SNPs) occur frequently and have strong linkage, creating a common haplotype at positions 1236C>T (G412G), 2677G>T (A893S) and 3435C>T (I1145I). The frequency of the synonymous 3435C>T polymorphism has been shown to vary significantly according to ethnicity. Existing literature suggests that the haplotype plays a role in response to drugs and disease susceptibility. This review summarizes recent findings on the 3435C>T polymorphism of MDR1 and the haplotype to which it belongs. A possible molecular mechanism of action by ribosome stalling that can change protein structure and function by altering protein folding is discussed.

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152 A study in our lab showed that common polymorphisms of MDR1 at 61ANG (N21D), 307TNC (F103L), 1199GNA (S400N), 2677GNT (A893S) and 2995GNA (A999T) do not change the transport of four MDR1 substrates when expressed at high levels in human cells [66]. Login to comment
153 A recent study by Gow et al. suggested that all of the SNPs they tested (N21D, S400N, R669C, A893S, A893T, S1141T, V1251I) produced small changes which in most cases are not statistically significant [59]. Login to comment
227 Protein function is different depending on substrate use 1236T-3435T 2677T-3435T 1236T-2677T-3435T 1236T-2677T-3435A Hung CC et al. 2008 [93] Flp-In HEK-293 Stable No difference 1236T-2677A Rhodamine 123 Calcein-AM, phenytoin, cyclosporine A, phenobarbital valproic acid, lamotrigine, carbamazepine, gabapentin, levetiracetam Certain inhibitors against Rhodamine 123 transport are less effective in double haplotype and TTT haplotype 1236T-2677T 1236T-3435T 2677A-3435T 2677T-3435T 1236T-2677A-3435T 1236T-2677T-3435T Salama NN et al. 2006 [91] LLC-PK1 Stable No apparent difference 1236T-2677T Rhodamine 123, vincristine, vinblastine Single or haplotype mutations had significant decrease in MDR1 function1236T-3435T 2677T-3435T 1236T-2677T-3435T GOW JM et al. 2008 [59] HEK-293T Transient No difference 1236T-2677T-3435T Calcein-AM, cyclosporine A, BODIPY-FL-paclitaxel TTT haplotype with N21D mutation reduces MDR1 function with BODIPY-FL-paclitaxel but not Calcein-AM. Login to comment
151 A study in our lab showed that common polymorphisms of MDR1 at 61ANG (N21D), 307TNC (F103L), 1199GNA (S400N), 2677GNT (A893S) and 2995GNA (A999T) do not change the transport of four MDR1 substrates when expressed at high levels in human cells [66]. Login to comment
226 Protein function is different depending on substrate use 1236T-3435T 2677T-3435T 1236T-2677T-3435T 1236T-2677T-3435A Hung CC et al. 2008 [93] Flp-In HEK-293 Stable No difference 1236T-2677A Rhodamine 123 Calcein-AM, phenytoin, cyclosporine A, phenobarbital valproic acid, lamotrigine, carbamazepine, gabapentin, levetiracetam Certain inhibitors against Rhodamine 123 transport are less effective in double haplotype and TTT haplotype 1236T-2677T 1236T-3435T 2677A-3435T 2677T-3435T 1236T-2677A-3435T 1236T-2677T-3435T Salama NN et al. 2006 [91] LLC-PK1 Stable No apparent difference 1236T-2677T Rhodamine 123, vincristine, vinblastine Single or haplotype mutations had significant decrease in MDR1 function 1236T-3435T 2677T-3435T 1236T-2677T-3435T GOW JM et al. 2008 [59] HEK-293T Transient No difference 1236T-2677T-3435T Calcein-AM, cyclosporine A, BODIPY-FL-paclitaxel TTT haplotype with N21D mutation reduces MDR1 function with BODIPY-FL-paclitaxel but not Calcein-AM. Login to comment

[hide] Implications of genetic polymorphisms in drug tran... Cancer Lett. 2006 Mar 8;234(1):4-33. Epub 2006 Feb 28. Kerb R
Implications of genetic polymorphisms in drug transporters for pharmacotherapy.
Cancer Lett. 2006 Mar 8;234(1):4-33. Epub 2006 Feb 28., [PMID:16504381]

Abstract [show]
Drug transporters are increasingly recognized as a key determinant of drug disposition and response. It is now widely appreciated that expression of the ATP-dependent efflux transporter, MDR1 (ABCB1, P-glycoprotein), in organs such as the gastrointestinal tract, liver and kidney significantly alters the extent of drug absorption and excretion. Moreover, expression of MDR1 at the level of the blood-brain barrier limits the entry of many drugs into the central nervous system. Given such an important role of MDR1 in the drug disposition process, it is not surprising to see increasing focus on the role of single nucleotide polymorphisms (SNPs) in this transporter as a potential determinant of interindividual variability in drug disposition and pharmacological response. However, drug transport is often the result of the concerted action of efflux and uptake pumps located both in the basolateral and apical membranes of epithelial cells. A growing list of membrane-spanning proteins involved in the in- or outward transport of a large variety of drugs has been recognized and characterized over the past few years in almost all tissues, including organic anion and cation transporters (OAT, OCT, solute carrier family SLC22A), organic anion transport proteins (OATP, solute carrier family SLCO, formerly SLC21A), and MRPs (ABCCs), other members of the ATP-binding cassette family. We are just beginning to appreciate their role for drug delivery and disposition and the contribution of genetic polymorphisms in these transport proteins to interindividual variability in the efficacy and safety for pharmacotherapy. This review summarizes the consequences of inherited differences in drug transport for pharmacotherapy. With the main focus on ABCB1, an update of recent advances is given and clinically relevant examples are used to illustrate how heritable differential drug transport can help to explain individual variability in drug response. The pharmacogenetics of other transporters is briefly introduced.

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76 Table 3 Overview of the 15 most common ABCB1 (MDR1) genetic variants Position Location Effect Allelic frequency (%) CA AS AA K129TOC 50 UTR Non-coding 5 4 7 K1GOA 50 UTR Non-coding 8 5 0 61AOG Exon 2 Asn21Asp 8 2 2.5 Exon 5-25GOT Intron 4 16 7 30 Exon 10-44AOG Exon 10 Intron 9 45 69 26 1199GOA Exon 11 Ser400Asn 2.5 0 !1 1236COT Exon 12 Synonymous 46 69 21 Exon 11C44COT Intron 12 5 0 17 Exon 12C24COT Intron 13 52 54 54 Exon 13C38AOG Intron 14 50 68 54 Exon 19C24GOA Intron 20 12 7 15 2677GOT/A Exon 21 Ala893Ser/Thr 46/2 45/7 O1 3421TOA Exon 26 Ser1141Thr 0 0 10 3435COT Exon 26 Synonymous 56 40 10 IVSC21TOC Intron 28 0 8 0 AA, African American; AS, Asian; CA, Caucasian. Login to comment
75 Table 3 Overview of the 15 most common ABCB1 (MDR1) genetic variants Position Location Effect Allelic frequency (%) CA AS AA K129TOC 50 UTR Non-coding 5 4 7 K1GOA 50 UTR Non-coding 8 5 0 61AOG Exon 2 Asn21Asp 8 2 2.5 Exon 5-25GOT Intron 4 16 7 30 Exon 10-44AOG Exon 10 Intron 9 45 69 26 1199GOA Exon 11 Ser400Asn 2.5 0 !1 1236COT Exon 12 Synonymous 46 69 21 Exon 11C44COT Intron 12 5 0 17 Exon 12C24COT Intron 13 52 54 54 Exon 13C38AOG Intron 14 50 68 54 Exon 19C24GOA Intron 20 12 7 15 2677GOT/A Exon 21 Ala893Ser/Thr 46/2 45/7 O1 3421TOA Exon 26 Ser1141Thr 0 0 10 3435COT Exon 26 Synonymous 56 40 10 IVSC21TOC Intron 28 0 8 0 AA, African American; AS, Asian; CA, Caucasian. Login to comment

[hide] MDR1 gene polymorphisms and clinical relevance. Yi Chuan Xue Bao. 2006 Feb;33(2):93-104. Li YH, Wang YH, Li Y, Yang L
MDR1 gene polymorphisms and clinical relevance.
Yi Chuan Xue Bao. 2006 Feb;33(2):93-104., [PMID:16529292]

Abstract [show]
In vivo and in vitro studies have demonstrated that P-glycoprotein (P-gp) plays a very significant role in the ADME processes (absorption, distribution, metabolism, excretion) and drug-drug interaction (DDI) of drugs in humans. P-gp is the product of multidrug resistance gene (MDR1/ABCB1). Pharmacogenomics and pharmacogenetics studies have revealed that genetic polymorphisms of MDR1 are associated with alteration in P-gp expression and function in different ethnicities and subjects. By now, 50 single nucleotide polymorphisms (SNPs) and 3 insertion/deletion polymorphisms have been found in the MDR1 gene. Some of them, such as C3435T, have been identified to be a risk factor for numerous diseases. It is believed that further understanding of the physiology and biochemistry of P-gp with respect to its genetic variations may be important for individualized pharmacotherapy. Therefore, based on the latest public information and our studies, this review focuses on the following four aspects: 1) the impact of P-gp on pharmacokinetics; 2) MDR1 genetic polymorphisms and their impacts on pharmacogenetics; 3) relationship between altered P-gp expression and function and the MDR1(C3435T) SNP, and 4) relevance of MDR1 polymorphisms to certain human diseases.

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43 The A61G mutationexpression and function (Asn21Asp) may contribute to a net charge change (basic to acidic) close to the N-terminus of P-gp, which appears to be of minor functional importance '3y1. Login to comment
52 Furthermore, Kimchi-Sarfaty and his colleagues carried out a study to characterize the functional consequences of five coding SNPs (Asn21Asp,Phel03Leu, Ser400Asn, Ala893Ser, Ala999Thr) using a vaccinia virus-based transient expression system, but it was found that the distribution and function of P-gp in the cells were similar to wild-type P-gp in the human body'431.The mechanism of these contradictory results regarding the C2677T/A and C3435T polymorphisms function is unclear until now. Login to comment
50 The A61G mutation expression and function (Asn21Asp) may contribute to a net charge change (basic to acidic) close to the N-terminus of P-gp, which appears to be of minor functional importance '3y1. Login to comment
64 Furthermore, Kimchi-Sarfaty and his colleagues carried out a study to characterize the functional consequences of five coding SNPs (Asn21Asp,Phel03Leu, Ser400Asn, Ala893Ser, Ala999Thr) using a vaccinia virus-based transient expression system, but it was found that the distribution and function of P-gp in the cells were similar to wild-type P-gp in the human body'431.The mechanism of these contradictory results regarding the C2677T/A and C3435T polymorphisms function is unclear until now. Login to comment

[hide] MDR1 Ala893 polymorphism is associated with inflam... Am J Hum Genet. 2003 Dec;73(6):1282-92. Epub 2003 Nov 7. Brant SR, Panhuysen CI, Nicolae D, Reddy DM, Bonen DK, Karaliukas R, Zhang L, Swanson E, Datta LW, Moran T, Ravenhill G, Duerr RH, Achkar JP, Karban AS, Cho JH
MDR1 Ala893 polymorphism is associated with inflammatory bowel disease.
Am J Hum Genet. 2003 Dec;73(6):1282-92. Epub 2003 Nov 7., [PMID:14610718]

Abstract [show]
Crohn disease (CD) and ulcerative colitis (UC) are overlapping chronic inflammatory bowel diseases (IBDs). Suggestive evidence for linkage at chromosome 7q has been reported for both CD and UC. Contained within this region is the gene for MDR1 (multidrug resistance), a membrane transport protein for which human polymorphisms have been reported in Ala893Ser/Thr and C3435T that alter pharmacokinetic profiles for a variety of drugs. Because mdr1 knockout mice spontaneously develop colitis, exonic regions were resequenced and tested for IBD association in a large, multicenter North American cohort. Two missense mutations, Asn21Asp and Ala893Ser/Thr, as well as the expression-associated polymorphism C3435T, described elsewhere, were genotyped in the entire cohort. Significant association of Ala893 with IBD was observed by both case-control analysis (P=.002) and the pedigree disequilibrium test (PDT [P=.00020-.00030]) but not for the Asn21Asp or C3435T polymorphisms. Significant association by PDT was observed within the subset with CD (P=.0014-.00090), with similar, nonsignificant trends in a smaller subset with UC. The Ala893Ser/Thr variant is triallelic, and the associated, common allele is Ala893, with undertransmission of the 893Ser (common) and the 893Thr (rare) variants. The Ala893 variant has decreased activity compared with the 893Ser variant; therefore, the association with human IBD is consistent with the murine model of mdr1 deficiency. Taken together, these data support the association of the common Ala893 polymorphism with IBD specifically and, more broadly, provides additional support for its contribution to interindividual pharmacogenetic variation.

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4 Two missense mutations, Asn21Asp and Ala893Ser/Thr, as well as the expression-associated polymorphism C3435T, described elsewhere, were genotyped in the entire cohort. Login to comment
5 Significant association of Ala893 with IBD was observed by both case-control analysis ( ) and the pedigreeP p .002 disequilibrium test (PDT [ ]) but not for the Asn21Asp or C3435T polymorphisms. Login to comment
41 In this article, we examine the Asn21Asp variant, as well as functionally associated polymorphisms on Ala893Ser/Thr and C3435T. Login to comment
65 The Asn21Asp (forward primer: 5-ATGGAGGAGCAAAGAAGAAG- AACTT-3; reverse primer: 5-CGCAACTATGTAAAC- TATGAAAATGAAAC-3; VIC [WT probe]: 5-AACTG- AACAATAAAAGG-3; FAM [rare probe]: 5-CTGAAC- GATAAAAGG-3) and C3435T polymorphisms (forward primer: 5 -AACAGCCGGGTGGTGTCA-3 ; reverse primer: 5 -ATGTATGTTGGCCTCCTTTGCT-3 ; VIC [WT probe]: 5 -CTCACGATCTCTTC-3 ; FAM [rare probe]: 5-CCTCACAATCTCTT-3) were genotyped using Taqman amplification and were detected using the ABI Prism 7700 Sequence Detection System. Login to comment
82 We identified four exonic SNPs: in exon 2 (A61G-Asn21Asp), exon 12 (C1236T), exon 21 (G2677T/A-Ala893Ser/Thr), and exon 26 (C3435T) (table 2). Login to comment
86 Because the Ala893Ser/Thr and C3435T polymorphisms have been associated with altered MDR1function, and because the Asn21Asp polymorphism represents a nonconserved amino acid variation that could potentially alter function, we typed these variants in a large cohort of patients with IBD to test for disease association. Login to comment
88 For the Asn21Asp variant, no evidence for IBD association was observed ( ). Login to comment
101 The combined analysis of the two ethnic groups (calculated as the sum of the individual cohort statistics) was for alleles and was for genotypes.P p .002 P p .008 Table 4 Global P Values by PDT Analysis of Exonic SNPs SNP GLOBAL P FOR PDT ANALYSIS FOR CD UC IBD Sum Average Sum Average Sum Average Asn21Asp .24 .15 .26 .56 .8 .39 Ala893Ser/Thr .0014 .00090 .29 .16 .00030 .00020 C3435T .42 .31 .93 .60 .63 .35 limited power to identify modest differences. Login to comment
110 Table 4 demonstrates the results by PDT for the Asn21Asp, Ala893Ser/ Thr, and C3435T polymorphisms among patients with CD, UC, and IBD. Login to comment
112 For the entire cohort with IBD, significant evidence for association was observed for the Ala893Ser/Thr polymorphism ( ), and no evidence was observedP p .00020-.00030 for the Asn21Asp or C3435T polymorphisms. Login to comment
113 Separate evaluation by CD and UC phenotypes showed no evidence of a CD association for the Asn21Asp or the C3435T polymorphisms. Login to comment
116 Because the numberP p .16-.29 of subjects with UC is significantly smaller than the num- Table 5 PDT Analysis of the Tri-Allelic Exon 21 SNP ALLELE TRANSMISSION P FOR PDT ANALYSIS FOR CD UC IBD Sum Average Sum Average Sum Average Ala893 Overtransmitted .0072 .0040 .31 .15 .0021 .0010 893Ser Undertransmitted .036 .028 .43 .23 .016 .0093 893Thr Undertransmitted .0046 .0046 .16 .16 .0025 .0032 Global score .0014 .00090 .29 .16 .00030 .00020 Table 6 Linkage Disequilibrium Values SNP Pair r2 Asn21Asp and Ala893Ser/Thr .10 Ala893Ser/Thr and C3435T .52 Asn21Asp and C3435T .09 ber of subjects with CD in this cohort, these trends do not support a significant association of the Ala893Ser/ Thr polymorphism with UC. Login to comment
117 In the cohort with UC, in contrast to a prior case-control study (Schwab et al. 2003), we observed no evidence for association with the 3435T polymorphism, nor was evidence observed for the Asn21Asp. Login to comment
126 Two-locus-haplotype analysis of the Asn21Asp-Ala893Ser/Thr haplotype demonstrates that the less common 21Asp variant occurs solely on the Ser893 background, which is unassociated with disease. Login to comment
135 OF HAPLOTYPES Transmitted Untransmitted Asn21Asp-Ala893Ser/Thr: Asn21-Thr893 2 17 Asn21-Ala893 203 128 Asn21-Ser893 131 188 21Asp-Ser893 48 51 Ala893Ser/Thr-C3435T: 893Thr-C3435 0 14 893Thr-3435T 2 2 Ala893-C3435 174 133 Ala893-3435T 69 51 893Ser-C3435 14 31 893Ser-3435T 130 158 NOTE.-Haplotypes were constructed using Genehunter, version 2.1; all affected individuals were included. Login to comment
6 Significant association of Ala893 with IBD was observed by both case-control analysis ( ) and the pedigree P p .002 disequilibrium test (PDT [ ]) but not for the Asn21Asp or C3435T polymorphisms. Login to comment
102 P p .002 P p .008 Table 4 Global P Values by PDT Analysis of Exonic SNPs SNP GLOBAL P FOR PDT ANALYSIS FOR CD UC IBD Sum Average Sum Average Sum Average Asn21Asp .24 .15 .26 .56 .8 .39 Ala893Ser/Thr .0014 .00090 .29 .16 .00030 .00020 C3435T .42 .31 .93 .60 .63 .35 limited power to identify modest differences. Login to comment
111 Table 4 demonstrates the results by PDT for the Asn21Asp, Ala893Ser/ Thr, and C3435T polymorphisms among patients with CD, UC, and IBD. Login to comment
114 Separate evaluation by CD and UC phenotypes showed no evidence of a CD association for the Asn21Asp or the C3435T polymorphisms. Login to comment
118 In the cohort with UC, in contrast to a prior case-control study (Schwab et al. 2003), we observed no evidence for association with the 3435T polymorphism, nor was evidence observed for the Asn21Asp. Login to comment
128 Two-locus-haplotype analysis of the Asn21Asp-Ala893Ser/Thr haplotype demonstrates that the less common 21Asp variant occurs solely on the Ser893 background, which is unassociated with disease. Login to comment
137 OF HAPLOTYPES Transmitted Untransmitted Asn21Asp-Ala893Ser/Thr: Asn21-Thr893 2 17 Asn21-Ala893 203 128 Asn21-Ser893 131 188 21Asp-Ser893 48 51 Ala893Ser/Thr-C3435T: 893Thr-C3435 0 14 893Thr-3435T 2 2 Ala893-C3435 174 133 Ala893-3435T 69 51 893Ser-C3435 14 31 893Ser-3435T 130 158 NOTE.-Haplotypes were constructed using Genehunter, version 2.1; all affected individuals were included. Login to comment

[hide] The influence of MDR1 polymorphisms on P-glycoprot... Adv Drug Deliv Rev. 2002 Nov 18;54(10):1295-310. Fromm MF
The influence of MDR1 polymorphisms on P-glycoprotein expression and function in humans.
Adv Drug Deliv Rev. 2002 Nov 18;54(10):1295-310., [PMID:12406646]

Abstract [show]
The MDR1 (ABCB1) gene product P-glycoprotein is a membrane protein, which functions as an ATP-dependent exporter of xenobiotics from cells. Its importance was first recognized because of its role in the development of multidrug resistance (MDR) of cultured tumor cells against various anticancer agents. It is now, however, well established that this transporter is not only expressed in tumor cells, but also in normal tissues with excretory function (intestine, liver, kidney). Since P-glycoprotein has a very broad substrate specificity, it determines disposition of a broad variety of drugs. Moreover, induction and inhibition of P-glycoprotein are new mechanisms for drug interactions in humans. Very recently, systematic screens of the MDR1 gene have identified multiple single nucleotide polymorphisms. Some of those appear to be associated with altered transporter function and expression. This review discusses the currently available data on the influence of MDR1 polymorphisms on P-glycoprotein tissue expression, drug disposition, treatment outcome and disease risk.

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324 `[84] X. Decleves, S. Chevillard, C. Charpentier, P. Vielh, J.L. [87] J. Shon, H. Chun, K. Kim, E. Kim, Y. Yoon, I. Jang, S. Shin, Laplanche, A new polymorphism (N21D) in the exon 2 of J. Shin, The PK and PD of fexofenadine in relation to MDR1 the human MDR1 gene encoding the P-glycoprotein, Hum. Login to comment
322 ` [84] X. Decleves, S. Chevillard, C. Charpentier, P. Vielh, J.L. [87] J. Shon, H. Chun, K. Kim, E. Kim, Y. Yoon, I. Jang, S. Shin, Laplanche, A new polymorphism (N21D) in the exon 2 of J. Shin, The PK and PD of fexofenadine in relation to MDR1 the human MDR1 gene encoding the P-glycoprotein, Hum. genetic polymorphism in Korean healthy subjects, Clin. Mutat. Login to comment

[hide] Effect of levothyroxine administration on intestin... Clin Pharmacol Ther. 2002 Sep;72(3):256-64. Siegmund W, Altmannsberger S, Paneitz A, Hecker U, Zschiesche M, Franke G, Meng W, Warzok R, Schroeder E, Sperker B, Terhaag B, Cascorbi I, Kroemer HK
Effect of levothyroxine administration on intestinal P-glycoprotein expression: consequences for drug disposition.
Clin Pharmacol Ther. 2002 Sep;72(3):256-64., [PMID:12235446]

Abstract [show]
OBJECTIVE: Thyroid function alters the pharmacokinetics of many drugs; one example is the cardiac glycoside digoxin. Because digoxin disposition is affected by intestinal expression of P-glycoprotein, we hypothesized that thyroid hormones may regulate P-glycoprotein and influence disposition of P-glycoprotein substrates. METHODS: Duodenal expression of P-glycoprotein measured by reverse transcriptase-polymerase chain reaction of MDR1 messenger ribonucleic acid (mRNA) and by immunohistochemical examination was studied in 8 healthy volunteers (4 men and 4 women; age range, 22-29 years; body weight, 59-89 kg) before and after coadministration with levothyroxine (200 microg orally for 17 days), which resulted in suppression of thyroid-stimulating hormone. The pharmacokinetics of the P-glycoprotein substrate talinolol was assessed after intravenous (30 mg) and oral (100 mg) administration. RESULTS: Duodenal MDR1 mRNA expression and immunoreactive P-glycoprotein were increased 1.4-fold (not significant; P =.078) and 3.8-fold (P <.01), respectively, after administration of levothyroxine. The changes in P-glycoprotein expression were associated with minor alterations in talinolol half-life after both oral and intravenous administration. CONCLUSIONS: Expression of intestinal P-glycoprotein in humans appears to be influenced by thyroid hormones. The functional consequences need to be addressed in patients with hyperthyroidism.

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38 MDR1 genotyping The following 10 most frequent or putatively functional single nucleotide polymorphisms of the MDR1 gene were identified as described recently: exon 2 G-1A, A61G (amino acid exchange Asn21Asp), T307C (Phe103Leu), exon 6 Cϩ139T, G1199A (Ser400Asn), C1236T, exon 17 T-76A, G2677T/A (Ala893Ser/Thr), and C3435T.18 In brief, the deoxyribonucleic acid (DNA) of venous blood was extracted by use of a standard phenol-chloroform procedure. Login to comment

[hide] Pharmacogenetics of the human drug-transporter gen... Drug Discov Today. 2001 Aug 15;6(16):835-839. Brinkmann U, Roots I, Eichelbaum M
Pharmacogenetics of the human drug-transporter gene MDR1: impact of polymorphisms on pharmacotherapy.
Drug Discov Today. 2001 Aug 15;6(16):835-839., [PMID:11495756]

Abstract [show]
The blood- and tissue-concentrations, and thus the activity, of many drugs are influenced by factors that are subject to inter-individual variation. Variables that influence blood levels are metabolizing enzymes and transporters. Transporters control drug uptake, distribution and elimination. Transport by efflux pumps such as MDR1-encoded P-glycoprotein can influence the bioavailability of drugs. Knowledge of the transporter 'status' might allow for compensation of differences in drug uptake, such as by dose adjustment, which is important for drugs with narrow therapeutic windows. So far, intestinal expression of MDR1 has been determined by cumbersome methods, such as biopsies, although recently a functional polymorphism has been identified, which discriminates individual high or low-expressor alleles. As a result, clinical trials and therapy can be adapted to the 'MDR1-status' of individual patients.

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53 For example, SNPs that change amino acids, and thus possibly have an effect on protein function, are located at position A61G (replacement of Asn with Asp at position 21 of exon 2 of Pgp), a Phe-Leu change in position 103 next to the second TMD close to a glycosylation site, and a G1199A SNP in exon 11, which causes a Ser-Asn size- and charge- change close to the first ATP-binding domain. Login to comment
68 Single nucleotide polymorphisms (SNPs) in the MDR1 gene SNP Region Number Frequency of SNPsa [%] Effect Heterozygous Homozygous Observed Estimated T-12C E1 85 11.8 0 0.4 Non-coding G-1A E2 188 11.2 0 0.4 Translation initiation A61G E2 188 17.6 0.5 0.81 Asn21Asp G-25T I4 85 26.0 3.5 2.3 G-35C I4 85 1.2 0 0.01 T307C E5 85 1.2 0 0.01 Phe103Leu C+139T I5 85 48.2 16.5 16.8 C+145T I5 85 2.4 0 0.01 G1199A E11 85 12.9 0 0.4 Ser400Asn C1236T E12 188 48.9 13.3 14.4 Gly412Gly C+44T I12 188 11.7 0 0.4 T-76A I16 85 45.9 22.4 20.3 A+137G I17 85 1.2 0 0.01 G2677T E21 83b 43.4 42.2 38.4 Ala893Ser G2995A E24 36b 11.1 0 Ala999Thr C3435T E26 537 47.7 26.4 24.1 Ile1145Ile C3396T E26 188 0.53 0 0.01 Wobble aMDR1 sequences Genbank (gb) accession numbers AC002457 and AC005068 are defined as wildtype. Login to comment

[hide] A new polymorphism (N21D) in the exon 2 of the hum... Hum Mutat. 2000 May;15(5):486. Decleves X, Chevillard S, Charpentier C, Vielh P, Laplanche JL
A new polymorphism (N21D) in the exon 2 of the human MDR1 gene encoding the P-glycoprotein.
Hum Mutat. 2000 May;15(5):486., [PMID:10790226]

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0 HUMAN MUTATION Mutation and Polymorphism Report #115 (2000) Online Mutation and Polymorphism Report Authors: Xavier Declèves , Sylvie Chevillard2 , Charlotte Charpentier1 , Philippe Vielh3 , and Jean-Louis Laplanche1 Affiliations: 1 Service de Biochimie et Biologie Moléculaire, hôpital Lariboisière, Paris, France; 2 Laboratoire de cancérogenèse expérimentale, Commissariat à l`Energie Atomique, Fontenay aux Roses, France; 3 Service de cytopathologie, Institut Curie, Paris, France Corresponding Author Address and E-mail: Xavier Declèves, Service de Biochimie et Biologie Moléculaire, hôpital Lariboisière, 2 rue Ambroise Paré 75010 Paris, France; E-mail: xavier.decleves@inserm.lrb.ap-hop-paris.fr Title : A new polymorphism (N21D) in the exon 2 of the human MDR1 gene encoding the P-glycoprotein Keywords: P-glycoprotein; multidrug resistance-1; MDR1; ABCB1 Species: Homo sapiens Change is: Polymorphism Gene/Locus Name: ATP-biding cassette B1 (multidrug resistance 1) Symbol: ABCB1 Genbank accession number: M14758 (cDNA) OMIM accession number: 171050 Locus specific database: Chromosomal location: 7q21 Inheritance: Mutation / polymorphism name Nucleotide change-Systematic name: c485A>G Amino acid change-Trivial name: N21D Mutation / polymorphism type: Missense Polymorphism frequency: Detection method: DGGE Detection conditions: Sequence of primers: Forward primer 5`-psoralen-AAGGTCGGGATGGATCTTGAA-3` Reverse primer 5`-GTTCCCACCACCATATACAA-3` PCR conditions: 30 cycles, denaturation 94°C (1 min) annealing 55°C (2 min) elongation 72°C (2 min), magnesium concentration 1.5 mM Electrophoresis: 20%-60% denaturant concentration (100% denaturant: 7M urea, 40% formamide), 58 degrees, 3 hours, 160 volts. Login to comment
20 Direct sequencing revealed a change of A to G at position 485 (cDNA sequence) leading to a change of asparagine to aspartic acid at position 21 which is located in the first intracellular domain of P-gp. Login to comment

[hide] The MDR1 (ABCB1) gene polymorphism and its clinica... Clin Pharmacokinet. 2004;43(9):553-76. Ieiri I, Takane H, Otsubo K
The MDR1 (ABCB1) gene polymorphism and its clinical implications.
Clin Pharmacokinet. 2004;43(9):553-76., [PMID:15217301]

Abstract [show]
There has been an increasing appreciation of the role of drug transporters in the pharmacokinetic and pharmacodynamic profiles of certain drugs. Among various drug transporters, P-glycoprotein, the MDR1 gene product, is one of the best studied and characterised. P-glycoprotein is expressed in normal human tissues such as liver, kidney, intestine and the endothelial cells of the blood-brain barrier. Apical (or luminal) expression of P-glycoprotein in these tissues results in reduced drug absorption from the gastrointestinal tract, enhanced drug elimination into bile and urine, and impeded entry of certain drugs into the central nervous system. The clinical relevance of P-glycoprotein depends on the localisation in human tissues (i.e. vectorial or directional movement), the therapeutic index of the substrate drug and the inherent inter- and intra-individual variability. With regard to the variability, polymorphisms of the MDR1 gene have recently been reported to be associated with alterations in disposition kinetics and interaction profiles of clinically useful drugs, including digoxin, fexofenadine, ciclosporin and talinolol. In addition, polymorphism may play a role in patients who do not respond to drug treatment. Moreover, P-glycoprotein is an important prognostic factor in malignant diseases, such as tumours of the gastrointestinal tract.A growing number of preclinical and clinical studies have demonstrated that polymorphism of the MDR1 gene may be a factor in the overall outcome of pharmacotherapy for numerous diseases. We believe that further understanding the physiology and biochemistry of P-glycoprotein with respect to its genetic variations will be important to establish individualised pharmacotherapy with various clinically used drugs.

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162 [94] Recently, a new mechanism for the drug- Sarfaty et al.[89] also investigated functional conse- grapefruit juice interaction has been reported; the quences of MDR1 polymorphisms (Asn21Asp, bioavailability and serum concentrations of fex- Phe103Leu, Ser400Asn, Ala893Ser, and ofenadine were reduced when grapefruit juice was Ala998Thr) using a vaccinia virus-based transient taken. Login to comment

[hide] Analysis of pharmacogenetic traits in two distinct... Hum Genomics. 2011 May;5(4):265-82. Ikediobi O, Aouizerat B, Xiao Y, Gandhi M, Gebhardt S, Warnich L
Analysis of pharmacogenetic traits in two distinct South African populations.
Hum Genomics. 2011 May;5(4):265-82., [PMID:21712189]

Abstract [show]
Our knowledge of pharmacogenetic variability in diverse populations is scarce, especially in sub-Saharan Africa. To bridge this gap in knowledge, we characterised population frequencies of clinically relevant pharmacogenetic traits in two distinct South African population groups. We genotyped 211 tagging single nucleotide polymorphisms (tagSNPs) in 12 genes that influence antiretroviral drug disposition, in 176 South African individuals belonging to two distinct population groups residing in the Western Cape: the Xhosa (n = 109) and Cape Mixed Ancestry (CMA) (n = 67) groups. The minor allele frequencies (MAFs) of eight tagSNPs in six genes (those encoding the ATP binding cassette sub-family B, member 1 [ABCB1], four members of the cytochrome P450 family [CYP2A7P1, CYP2C18, CYP3A4, CYP3A5] and UDP-glucuronosyltransferase 1 [UGT1A1]) were significantly different between the Xhosa and CMA populations (Bonferroni p < 0.05). Twenty-seven haplotypes were inferred in four genes (CYP2C18, CYP3A4, the gene encoding solute carrier family 22 member 6 [SLC22A6] and UGT1A1) between the two South African populations. Characterising the Xhosa and CMA population frequencies of variant alleles important for drug transport and metabolism can help to establish the clinical relevance of pharmacogenetic testing in these populations.

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73 G; N21D 0.0 0.0 0.0 NA NA 0.1 0.0 0.07 0.0 ABCB1 rs1045642 C 3435C . Login to comment

[hide] Interindividual variability in hepatic organic ani... Drug Metab Dispos. 2014 Jan;42(1):78-88. doi: 10.1124/dmd.113.053819. Epub 2013 Oct 11. Prasad B, Evers R, Gupta A, Hop CE, Salphati L, Shukla S, Ambudkar SV, Unadkat JD
Interindividual variability in hepatic organic anion-transporting polypeptides and P-glycoprotein (ABCB1) protein expression: quantification by liquid chromatography tandem mass spectroscopy and influence of genotype, age, and sex.
Drug Metab Dispos. 2014 Jan;42(1):78-88. doi: 10.1124/dmd.113.053819. Epub 2013 Oct 11., [PMID:24122874]

Abstract [show]
Interindividual variability in protein expression of organic anion-transporting polypeptides (OATPs) OATP1B1, OATP1B3, OATP2B1, and multidrug resistance-linked P-glycoprotein (P-gp) or ABCB1 was quantified in frozen human livers (n = 64) and cryopreserved human hepatocytes (n = 12) by a validated liquid chromatography tandem mass spectroscopy (LC-MS/MS) method. Membrane isolation, sample workup, and LC-MS/MS analyses were as described before by our laboratory. Briefly, total native membrane proteins, isolated from the liver tissue and cryopreserved hepatocytes, were trypsin digested and quantified by LC-MS/MS using signature peptide(s) unique to each transporter. The mean +/- S.D. (maximum/minimum range in parentheses) protein expression (fmol/microg of membrane protein) in human liver tissue was OATP1B1- 2.0 +/- 0.9 (7), OATP1B3- 1.1 +/- 0.5 (8), OATP2B1- 1 1.7 +/- 0.6 (5), and P-gp- 0.4 +/- 0.2 (8). Transporter expression in the liver tissue was comparable to that in the cryopreserved hepatocytes. Most important is that livers with SLCO1B1 (encoding OATP1B1) haplotypes *14/*14 and *14/*1a [i.e., representing single nucleotide polymorphisms (SNPs), c.388A > G, and c.463C > A] had significantly higher (P < 0.0001) protein expression than the reference haplotype (*1a/*1a). Based on these genotype-dependent protein expression data, we predicted (using Simcyp) an up to approximately 40% decrease in the mean area under the curve of rosuvastatin or repaglinide in subjects harboring these variant alleles compared with those harboring the reference alleles. SLCO1B3 (encoding OATP1B3) SNPs did not significantly affect protein expression. Age and sex were not associated with transporter protein expression. These data will facilitate the prediction of population-based human transporter-mediated drug disposition, drug-drug interactions, and interindividual variability through physiologically based pharmacokinetic modeling.

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179 TABLE 4 Frequency of OATP1B1, OATP1B3, and P-gp SNPs detected in the University of Washington (UW) liver bank Marker ID Variant Change for Variant Frequency in UW liver Bank Homozygous Variant Heterozygous Variant Wild-Type OATP1B1 rs4149015 211187G.A Promoter 0 9 53 rs2306283 388A.G N130D 10 30 22 rs11045819 463C.A P155T 4 9 49 rs4149056 521T.C V174A 1 21 40 rs4149057 571T.C L191L 16 34 12 rs2291075 597C.T F199F 10 33 19 OATP1B3 rs4149117 334G.T A112S 0 45 17 rs7311358 699A.G I233M 0 45 17 rs2053098 1557G.A A519A 0 45 17 rs3764006 1833A.G G611G 0 42 20 P-gp rs2214102 21G.A 59UTR 0 6 56 rs2235015 287-25G.T Intron 0 19 43 rs10276036 IVS9-44A.G Intron 19 31 12 rs1128503 1236C.T G412G 18 33 11 rs2032588 1350+44C.T Intron 0 7 55 rs2235033 1554+24C.T Intron 22 32 8 rs2235013 1725+38A.G Intron 21 33 8 rs9282564 61A.G N21D 7 11 45 rs2235040 2481+24G.A Intron 0 12 50 rs2032582 2677G.T, 2677G.A A893S, A893T 17 32 13 rs3213619 2129T.C 59UTR 0 4 58 rs1045642 3435C.T I1145I 22 30 10 rs17064 *89A.T 39UTR 0 7 55 rs3842 *193A.G 39UTR 0 18 44 OATP, organic anion-transporting polypeptide; P-gp, P-glycoprotein; SNP, single nucleotide polymorphisms; UW, University of Washington. Login to comment

[hide] Impact of Single Nucleotide Polymorphisms (SNPs) o... Int J Mol Sci. 2015 Aug 25;16(9):20168-82. doi: 10.3390/ijms160920168. Ruiz J, Herrero MJ, Boso V, Megias JE, Hervas D, Poveda JL, Escriva J, Pastor A, Sole A, Alino SF
Impact of Single Nucleotide Polymorphisms (SNPs) on Immunosuppressive Therapy in Lung Transplantation.
Int J Mol Sci. 2015 Aug 25;16(9):20168-82. doi: 10.3390/ijms160920168., [PMID:26307985]

Abstract [show]
Lung transplant patients present important variability in immunosuppressant blood concentrations during the first months after transplantation. Pharmacogenetics could explain part of this interindividual variability. We evaluated SNPs in genes that have previously shown correlations in other kinds of solid organ transplantation, namely ABCB1 and CYP3A5 genes with tacrolimus (Tac) and ABCC2, UGT1A9 and SLCO1B1 genes with mycophenolic acid (MPA), during the first six months after lung transplantation (51 patients). The genotype was correlated to the trough blood drug concentrations corrected for dose and body weight (C0/Dc). The ABCB1 variant in rs1045642 was associated with significantly higher Tac concentration, at six months post-transplantation (CT vs. CC). In the MPA analysis, CT patients in ABCC2 rs3740066 presented significantly lower blood concentrations than CC or TT, three months after transplantation. Other tendencies, confirming previously expected results, were found associated with the rest of studied SNPs. An interesting trend was recorded for the incidence of acute rejection according to NOD2/CARD15 rs2066844 (CT: 27.9%; CC: 12.5%). Relevant SNPs related to Tac and MPA in other solid organ transplants also seem to be related to the efficacy and safety of treatment in the complex setting of lung transplantation.

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59 There is a SNP in the ABCB1 gene, rs9282564, comprising the change Asn21Asp, due to the variation A > G, the biological effect of which has not been clearly established. Login to comment