ABCMdb

ABCB1 p.Ser1141Thr

Predicted by SNAP2:	A: N (57%), C: D (63%), D: D (66%), E: D (66%), F: D (71%), G: D (59%), H: D (63%), I: D (71%), K: D (66%), L: D (71%), M: D (66%), N: N (53%), P: D (71%), Q: D (63%), R: D (71%), T: N (57%), V: D (66%), W: D (95%), Y: D (71%),
Predicted by PROVEAN:	A: N, C: D, D: D, E: D, F: D, G: D, H: D, I: D, K: D, L: D, M: D, N: N, P: N, Q: D, R: D, T: N, V: D, W: D, Y: D,

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[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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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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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] 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] 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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70 2650C > T exon 21 synonymous (p.L884L) Kim et al., 2001 md-v-110 rs9282563 c.2677G > T exon 21 p.A893S Kim et al., 2001 md-v-031 rs2032582 c.2677G > A exon 21 p.A893T Kim et al., 2001 md-v-109 IVS 21 + 14 - 17 delAATA intron 21 Epidauros md-v-092 IVS 21 + 49 T > C intron 21 Epidauros md-v-042 rs2032583 IVS 21 + 66 T > C intron 21 Epidauros md-v-108 IVS 26 - 156 T > C intron 25 Epidauros md-v-095 IVS 26 - 68 A > G intron 25 Epidauros md-v-164 c.3320A > C exon 26 p.Q1107P Cascorbi et al., 2002 md-v-033 c.3322T > C exon 26 p.W1108R Kroetz et al., 2003 md-v-225 c.3325C > T exon 26 p.L1109F Epidauros md-v-165 c 3364C > T exon 26 synonymous (p.A1132A) Hoffmeyer et al., 2000 md-v-034 c.3321T > A exon 26 p.S1141T Kim et al., 2001 md-v-035 c.3435C > T (Tag8) exon 26 synonymous (p.I1145I) Hoffmeyer et al., 2000 md-v-036 rs1045642 IVS 26 + 59 T > G intron 26 Epidauros md-v-097 rs2235047 IVS 26 + 80 T > C intron 26 Epidauros md-v-040 rs2235048 IVS 26 + 123_24 insCATG intron 26 Epidauros md-v-096 Tag 11 intron 27 Soranzo et al., 2004 rs1186746 Tag 12 intron 27 Soranzo et al., 2004 rs1186745 MRP1 (ABCC1) c.816G > A exon 8 synonymous (p.P272P) Epidauros mr-v-014 c.825T > C exon 8 synonymous (p.V275V) Saito et al., 2002 mr-v-015 rs246221 c.1062T > C exon 9 synonymous (p.N354N) Saito et al., 2002 mr-v-016 rs35587 c.1068G > A exon 9 synonymous (p.T356T) Epidauros mr-v-057 rs8187852 IVS 9 + 8 A > G intron 9 Saito et al., 2002 mr-v-017 rs35588 c.1303G > T exon 10 p.R433S Conrad et al., 2002 mr-v-018 IVS 10 + 64 C > T intron 10 Epidauros mr-v-019 MRP2 (ABCC2) g. Login to comment

[hide] Identification of functionally variant MDR1 allele... Clin Pharmacol Ther. 2001 Aug;70(2):189-99. Kim RB, Leake BF, Choo EF, Dresser GK, Kubba SV, Schwarz UI, Taylor A, Xie HG, McKinsey J, Zhou S, Lan LB, Schuetz JD, Schuetz EG, Wilkinson GR
Identification of functionally variant MDR1 alleles among European Americans and African Americans.
Clin Pharmacol Ther. 2001 Aug;70(2):189-99., [PMID:11503014]

Abstract [show]
MDR1 (P-glycoprotein) is an important factor in the disposition of many drugs, and the involved processes often exhibit considerable interindividual variability that may be genetically determined. Single-strand conformational polymorphism analysis and direct sequencing of exonic MDR1 deoxyribonucleic acid from 37 healthy European American and 23 healthy African American subjects identified 10 single nucleotide polymorphisms (SNPs), including 6 nonsynonymous variants, occurring in various allelic combinations. Population frequencies of the 15 identified alleles varied according to racial background. Two synonymous SNPs (C1236T in exon 12 and C3435T in exon 26) and a nonsynonymous SNP (G2677T, Ala893Ser) in exon 21 were found to be linked (MDR1*2 ) and occurred in 62% of European Americans and 13% of African Americans. In vitro expression of MDR1 encoding Ala893 (MDR1*1 ) or a site-directed Ser893 mutation (MDR1*2 ) indicated enhanced efflux of digoxin by cells expressing the MDR1-Ser893 variant. In vivo functional relevance of this SNP was assessed with the known P-glycoprotein drug substrate fexofenadine as a probe of the transporter's activity. In humans, MDR1*1 and MDR1*2 variants were associated with differences in fexofenadine levels, consistent with the in vitro data, with the area under the plasma level-time curve being almost 40% greater in the *1/*1 genotype compared with the *2/*2 and the *1/*2 heterozygotes having an intermediate value, suggesting enhanced in vivo P-glycoprotein activity among subjects with the MDR1*2 allele. Thus allelic variation in MDR1 is more common than previously recognized and involves multiple SNPs whose allelic frequencies vary between populations, and some of these SNPs are associated with altered P-glycoprotein function.

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104 In addition, a number of detected SNPs, such as A548G (Asn183Ser), C1472T (Arg492Cys), and T3421A (Ser1141Thr), represented previously undescribed nonsynonymous SNPs. 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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54 Further SNPs of the MDR1 gene were identified in Asians, an A to G transversion 41 bases upstream from the initial position of exon 1a (A-41aG) and a C to G transversion at -145 in exon 1a (C-145G) (28), as well as three nonsynonymous mutations A548G (Asn183Ser), C1474T (Arg492Cys), and T3421A (Ser1141Thr) in different ethnic populations (29, 30). 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

[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

[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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111 These ten variants included five non-synonymous sites (Ile261Val, Leu662Arg, Pro1051Ala, Ser1141Thr, and Thr1256Lys). 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

[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] 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] 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] An association study of 43 SNPs in 16 candidate ge... Pharmacogenomics J. 2005;5(6):352-8. Thompson JF, Man M, Johnson KJ, Wood LS, Lira ME, Lloyd DB, Banerjee P, Milos PM, Myrand SP, Paulauskis J, Milad MA, Sasiela WJ
An association study of 43 SNPs in 16 candidate genes with atorvastatin response.
Pharmacogenomics J. 2005;5(6):352-8., [PMID:16103896]

Abstract [show]
Variation in individual response to statin therapy has been widely studied for a potential genetic component. Multiple genes have been identified as potential modulators of statin response, but few study findings have replicated. To further examine these associations, 2735 individuals on statin therapy, half on atorvastatin and the other half divided among fluvastatin, lovastatin, pravastatin and simvastatin were genotyped for 43 SNPs in 16 genes that have been implicated in statin response. Associations with low-density lipoprotein cholesterol (LDL-C) lowering, total cholesterol lowering, HDL-C elevation and triglyceride lowering were examined. The only significant associations with LDL-C lowering were found with apoE2 in which carriers of the rare allele who took atorvastatin lowered their LDL-C by 3.5% more than those homozygous for the common allele and with rs2032582 (S893A in ABCB1) in which the two groups of homozygotes differed by 3% in LDL-C lowering. These genetic effects were smaller than those observed with the demographic variables of age and gender. The magnitude of all the differences found is sufficiently small that genetic data from these genes should not influence clinical decisions on statin administration.

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57 N ¼ 160 Cauc. N ¼ 2454 Hisp. N ¼ 85 Best P Statin Ref. ABC B1 rs2229109 7 86 824 460 Ser400Asn 0 1.2 3.8 1.8 rs2032582 7 86 805 269 Ser893Ala 40.0 89.4 56.7 60.2 rs17149694 7 86 783 310 Ser1141Thr 0 6.2 0.02 0.6 rs1045642 7 86 783 296 Ile1145Ile 50.0 79.0 48.7 50.0 0.023 Atorva 9 ABC G5 rs6720173 2 43 952 052 Gln604Glu 20.8 33.1 16.8 32.5 ABC G8 rs11887534 2 43 977 898 Asp19His 1.4 3.9 5.4 6.6 0.036 Atorva 17 rs4148211 2 43 983 394 Tyr54Cys 29.2 23.1 37.4 32.5 rs4148217 2 44 011 334 Thr400Lys 10.0 24.0 18.1 30.1 rs6544718 2 44 016 576 Val632Ala 6.9 5.9 21.8 18.7 ACE rs4331 17 58 917 784 Ala157Ala 72.2 43.2 43.8 53.0 0.005 Fluva 18 rs4341 17 58 919 722 72.2 43.8 44.0 51.9 0.005 Fluva 18 Apo AI rs670 11 116 213 623 Promoter G/A 20.8 14.4 16.4 21.1 HDLC Prava 19 ApoE rs429358 19 50 103 781 E4 (Cys130Arg) 8.3 29.0 17.7 17.7 0.043 Lova 20 rs7412 19 50 103 919 E2 (Cys176Arg) 2.8 5.0 3.7 1.2 0.01 Atorva 21 19 50 106 239 SNP17 5.6 13.5 7.3 2.4 5 CETP rs1800775 16 55 552 735 CÀ629A 51.6 57.3 48.2 48.1 HDLC Atorva 22 rs708272 16 55 553 789 TaqIB 46.8 25.7 42 42.5 HDLC Atorva 22 Cyp3A4 rs4986910 7 99 003 175 Met445Thr 0 0.9 0.8 0 0.05 Atorva 23 rs2740574 7 99 026 747 AÀ392G 4.7 56.2 3.9 11.4 0.038 Atorva 23 Cyp3A5 rs776746 7 98 915 190 *3 40.6 64.2 7.4 27.2 0.026 24 rs10264272 7 98 907 486 *6, Lys208Lys 1.6 8.7 0.07 3.2 Cyp7A1 rs3808607 8 59 575 478 33.3 56.8 39.3 31.9 0.001 Atorva 25 FDFT1 rs2686196 8 11 697 311 0 0.6 1.4 0.6 HMGCR 5 74 681 677 Asn204Ser 0.0 0.0 0.2 0.0 rs5908 5 74 687 955 Val638Ser 0.0 0.3 1.7 1.2 rs2303151 5 74 691 457 11.1 2.9 4.9 4.8 5 74 691 504 SNP29 0.0 8.5 2.8 2.9 0.003 Prava 5 LDLR rs5925 19 11 091 881 Val653Val, AvaII 40.3 23.1 47.0 56.7 0.05 Fluva 26 rs688 19 11 088 602 Asn591Asn, HincII 36.1 13.0 46.8 46.3 LIPC rs1800588 15 56 510 967 CÀ514T 40.3 49.1 23.1 45.7 0.01 Prava 27 LPL rs1801177 8 19 849 988 Asp9Asn 0 3.9 1.3 1.2 rs268 8 19 857 809 Asn291Ser 0 0.3 1.7 0.6 rs328 8 19 864 004 Ser447X 11.1 8.2 11.2 9.1 OATP C 12 21 185 236 CÀ540T 5.6 3.8 5.0 10.8 12 21 216 983 *2, Phe73Leu 0 0 0.04 0 rs2291073 12 21 217 081 25.0 52.4 8.3 10.0 rs4149036 12 21 219 007 31.9 49.4 21.0 20.5 rs2306283 12 21 221 005 Asn130Asp, *1b 61.1 74.4 40.6 40.9 PK Prava 28 rs11045819 12 21 221 080 Pro155Thr, *4 2.8 9.7 15.8 8.5 rs4149056 12 21 222 816 Val174Ala, *5 8.3 3.8 16.0 14.5 PK Prava 28 12 21 250 200 Gly488Ala, *9 0 5.0 0 0 rs4149080 12 21 268 826 29.2 15.4 17.4 15.2 12 21 283 243 Leu643Phe 1.4 5.3 5.8 3.7 The genes and SNPs examined are listed in columns 1 and 2 with dbSNP identifiers, if available. Login to comment

[hide] Drug-metabolizing enzymes: evidence for clinical u... Clin Pharmacol Ther. 2005 Dec;78(6):559-81. Andersson T, Flockhart DA, Goldstein DB, Huang SM, Kroetz DL, Milos PM, Ratain MJ, Thummel K
Drug-metabolizing enzymes: evidence for clinical utility of pharmacogenomic tests.
Clin Pharmacol Ther. 2005 Dec;78(6):559-81., [PMID:16338273]

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204 In a single report the 893Ser variant of P-glycoprotein showed a significant increase in function by use of digoxin as a substrate.170 However, with the use of a variety of substrates, other investigators have failed to find any difference in function between the reference and 893Ser variant of P-glycoprotein.164,171,172 To date, there are no functional data on the common African American Ser1141Thr variant of P-glycoprotein. 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 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] 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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3 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. Login to comment
81 In addition, the P1051A SNP was chosen because of its conservation despite a low Grantham value, and the S1141T SNP was included due to its relatively high allele frequency (11% in African Americans) and evolutionary conservation. Login to comment
82 Although A893S, S1141T, and R669C SNPs are common variants (minor allele frequency !1% in at least one major ethnic group), the remaining four chosen variants are observed only once among 494 alleles from different populations. Login to comment
92 Features of the ABCB1 Variants Analyzed in This Study SNPa Evolutionary Conservationb Chemical Dissimilarity (Grantham Valuec ) Allele Count (out of 494 Alleles) M89T 0 81 1 L662R 3 102 1 R669C 2 180 2 A893S 2 99 151 P1051A 3 27 1 W1108R 3 101 1 S1141T 3 58 23 a Positions are relative to the transcription start site and based on the cDNA sequence from GenBank accession number M14758.1 with the change V185G, which is the most common haplotype in African Americans in the Pharmacogenetics of Membrane Transporters dataset. Login to comment
109 Different P-gp variants displayed higher levels of resistance (A893S-M89T, L662R, and R669C) or lower levels of resistance (A893S, S1141T, A893S-R669C, A893S-P1051A, W1108R, and W1108R-R669C) relative to the P-gp reference (Figure 2A and 2B). Login to comment
120 In the liquid assay, three variants for daunorubicin (A893S-R669C, A893S-M89T, and R669C) and five variants for doxorubicin (A893S, S1141T, A893S-M89T, L662R, and R669C) exhibited statistically significant increases in EC50 values (p , 0.05) (Figure 2C; Table S4). Login to comment
129 The average 6 standard deviation of three measurements of relative protein levels is 103 6 19 for A893S, 83 6 17 for S1141T, 94 6 16 for A893S-R669C, 115 6 20 for A893S-M89T, 93 6 19 for L662R, 70 6 22 for A893S-P1051A, 134 6 25 for R669C, 102 6 18 for W1108R, 148 6 24 for R669C-W1108R, and 53 6 13 for frame-shifted, relative to the average of reference P-gp set to 100. Login to comment
159 Although some alleles showed similar trends of resistance for valinomycin and daunorubicin/doxorubicin, others (e.g., S1141T, W1108R, and W1108R-R669C) were qualitatively different in their resistances. Login to comment
165 Five variants (S1141T, A893S-R669C, A893S-M89T, L662R, and R669C) exhibited a statistically significant increase in EC50 or EC30 values for two or more drugs. Login to comment
174 The functional consequences of five ABCB1 polymorphisms were previously unknown: the M89T, L662R, R669C, and S1141T variants were associated with increased resistance to two or more drugs; and the W1108R variant strongly mitigated the impact of R669C on gain of P-gp function (Figures 2 and 4A). Login to comment
175 Due to its high allele frequency (11% in African Americans), the S1141T SNP in particular deserves further attention to define its clinical significance. Login to comment
189 The resistance profiles of the S1141T, W1108R, and W1108R-R669C variants showed the largest variation across substrates. Login to comment
194 Our data on functional consequences revealed that these predictions were sound: four functional SNPs (L662R, R669C, W1108R, and S1141T) scored highly on both criteria, while the two SNPs (A893S and P1051A) that showed no significant functional impact had lower scores on evolutionary conservation and chemical dissimilarity, respectively. 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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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
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
159 Three variants (A893S, A893T, and S1141T) were 30 Ϯ 5, 30 Ϯ 8, and 27 Ϯ 17%, respectively, less sensitive to cyclosporin A inhibition than reference, whereas V1251I was 65 Ϯ 26% less sensitive 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
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
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
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

[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] 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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48 Four of the 12 associated nsSNPs (E3/61A4G, E5/266C4T, E17/1985T4C and E17/2005C4T) cannot be mapped to the mouse crystal Table 1 Genetic conservation of amino acids corresponding to ABCB1 coding region SNPs 1 - rs28381804 E3/49T>C (F17L) F17 W16 S16 Y17 Y35 F39 - A42 - - G11 - - 2 - rs41304191 E3/55C>T (L19L) L19 M18 M18 I19 G37 P41 - E44 - - L13 - - 3 - rs76199854 E3/57G>A (L19L) L19 M18 M18 I19 G37 P41 - E44 - - L13 - - --51I--64H-34K93N12N02K02K12N)D12N(G>A16/3E4652829sr-4 7.832.8105P12A01K88D61D18T07T55S34G34N44N)S44N(G>A131/5E3812021sr1sn5 6 ns2 rs41315618 E5/178A>C (I60L) I60 I59 I59 A71 I86 A97 G32 G104 K26 N37 L66 27.3 46.6 1.924.6368N75G64N421Y25G711I601I19V97A97A08A)E08A(A>C932/5E5652829sr3sn7 8 - rs35810889 E5/266C>T (M89T) - M89 F89 S85 T96 I112 - - - - - - - - 9 ns4 rs61607171 E7/431T>C (I144T) TM2 I144 I145 I140 V152 N168 I176 A98 A172 L93 V97 L124 36.4 40.9 2.645.45841G121T711V691A221T002S291S671A461V961V861V)I861V(A>G205/7E32622116sr5sn01 11 s1 rs1128500 E8/540C>T (S180S) S180 S181 S176 S188 E204 S212 L136 N208 E129 E133 E160 27.3 42.0 12 ns6 rs60419673 E8/548A>G (N183S) N183 N184 N179 N191 K207 E215 Q139 Q211 K132 A136 S163 27.3 39.9 9.045.54561G831S431F312G141F712G902G391G181G681G581G)V581G(T>G455/8E1058211sr7sn31 14 s2 rs1128502 E8/555A>T (G185G) G185 G186 G181 G193 G209 G217 F141 G213 F134 S138 G165 45.5 40.9 15 s3 rs2235022 E9/729A>G (E243E) E243 E244 E239 E251 E267 E275 I199 Q271 R192 M196 S223 18.2 33.3 16 s4 rs28381867 E9/738G>A (A246A) A246 A247 A242 A254 R270 M278 E202 V274 A195 T199 Y226 9.1 34.5 17 ns8 rs36008564 E9/781A>G (I261V) C-NBD (Internal) I261 I262 I257 V267 I285 I293 V217 I289 I210 H214 I241 36.4 50.3 18 s5 rs80153317 E10/879T>C (I293I) TM5 I293 I294 I289 I301 L317 M325 L249 I321 R242 S246 F273 18.2 36.3 19 ns9 rs2229109 E12/1199G>A (S400N) N-NBD (Internal) S400 S401 S396 N408 T424 Q439 T355 V428 Q348 T350 H386 18.2 60.7 20 s6 rs1128503 E13/1236C>T (G412G) N-NBD (External) G412 G413 G408 G420 G436 K451 D367 N440 D359 N361 D398 27.3 55.9 21 s7 rs35068177 E13/1308A>G (T436T) T436 T437 T432 T44 I460 C475 V391 I464 L383 I385 I422 54.5 64.6 22 s8 rs41311775 E15/1326G>A (R442R) R442 R443 R438 R450 R466 R481 R397 R470 R389 R391 R428 100.0 54.5 23 s9 rs35633772 E15/1617C>T (I539I) I539 I540 I535 I547 I563 I578 I494 I576 L486 I489 I571 90.9 65.8 24 s10 rs60247941 E15/1632C>T (A544A) A544 A545 A540 A552 A568 A583 A499 A581 I491 A494 A576 63.6 65.1 25 s11 rs2235012 E15/1662G>C (L554L) L554 L555 L550 L562 L578 L593 L509 L591 L501 L504 L586 100.0 73.6 26 s12 rs56871767 E15/1674G>A (T558T) T558 T559 T554 T566 T582 T597 T513 T595 T505 T508 T590 100.0 78.7 27 s13 rs59697741 E15/1695C>T (S565S) S565 S566 S561 S573 S589 S604 S520 S602 S512 S515 S597 100.0 75.4 28 ns10 rs28381902 E15/1696G>A (E566K) E566 E567 E562 E574 E590 E605 E521 E603 E513 E516 E598 100.0 76.6 29 ns11 rs28381914 E16/1777C>T (R593C) R593 R594 R589 R601 R617 R632 R548 R630 T540 E543 R627 54.5 67.3 30 ns12 rs56107566 E16/1778G>A (R593H ) R593 R594 R589 R601 R617 R632 R548 R630 T540 E543 R627 54.5 67.3 31 s14 rs28381915 E16/1794C>T (I598I) I598 I599 I594 I606 I622 I637 I553 I635 I545 I548 I632 100.0 65.5 32 ns13 rs2235036 E16/1795G>A (A599T) A599 A600 A595 A607 I623 V638 C554 V636 V546 V549 F633 54.5 63.6 33 ns14 rs57001392 E16/1837G>T (D613Y) N-NBD (External) D613 D614 D609 S621 R637 Q652 E568 N650 R560 N563 D677 45.5 60.5 -0.0637E--807A516E896K496M176E856L366L266L)R266L(C>T5891/71E06975653sr-43 35 - rs35023033 E17/2005C>T (R669C) R669 R670 R665 R678 I702 D705 S662 T715 - - N743 0.0 - 36 - rs59340265 E17/2037C>T (D679D) D679 D680 D675 N688 D712 N715 S632 N725 - - E753 9.1 - 37 ns15 rs41316450 E18/2207T>A (I736K) TM7 I736 I737 V732 I745 M779 I771 V682 I820 I37 L48 V814 72.7 36.7 38 ns16 rs77144566 E19/2281A>C (A761S) TM8 A761 V763 I757 A769 V802 I796 G706 I844 I647 G655 L836 63.6 42.1 39 ns17 rs41305517 E21/2398G>A (D800N) C-NBD (Internal) D800 D801 D796 D808 H841 D835 E745 D883 S108 P112 E875 9.1 45.4 40 ns18 rs2235039 E21/2401G>A (V801M) C-NBD (External) V801 V802 V797 M809 I842 V836 V746 V884 A109 V113 M876 63.6 47.6 2.035.54409L931S531I219S447V468T078I738T528T038I928I)V928I(G>A5842/22E1852302sr91sn14 42 s15 rs28381966 E22/2505A>G (V835V) V835 V836 V831 L843 T876 T870 L780 T918 N141 T145 F911 45.5 33.0 43 ns20 rs28381967 E22/2506A>G (I836V) I836 I837 I832 I844 V877 I871 L781 V919 I142 V146 F911 63.6 28.5 7.448.18429M951M551I239L497I488D098I758I548I058I948I)M948I(G>A7452/22E03150163sr12sn44 45 s16 rs9282563 E22/2650C>T (L884L) L884 L885 L880 K892 V925 M919 R829 E967 R190 K194 I959 27.3 31.2 7.535.54289P302V991V679S838S829C439S109A988S498A398S)T/A398S(A/T>G7762/22E2852302sr22sn64 4.834.631801M203T892V5701F739G7201L5301T0001S889S399S299S)N299S(A>G5792/52E72194865sr32sn74 5.633.729801E903Q503T2801T449V4301Q2401A7001A599A0001A999A)T999A(A>G5992/52E48725527sr42sn84 49 s17 rs2235044 E26/3084G>A (P1028P) P1028 P1029 P1024 P1036 - P1063 P973 V1111 P332 V334 I1117 0.0 33.0 50 ns25 rs28401798 E26/3151C>G (P1051A) P1051 P1052 P1047 K1059 E1093 Q1086 I996 K1135 P355 P357 P1142 18.2 57.6 51 ns26 rs2707944 E26/3188G>C (G1063A) G1063 G1064 G1059 G1071 G1105 G1098 G1008 G1147 G367 G369 K1154 45.5 53.8 52 s18 rs2707943 E26/3189C>G (G1063G) G1063 G1064 G1059 G1071 G1105 G1098 G1008 G1147 G367 G369 K1154 45.5 53.8 53 ns27 rs74755520 E26/3222A>C (C1074W) C-NBD (Internal) C1074 C1075 C1070 C1082 C1116 C1109 S1019 C1158 G378 S380 S1165 63.6 67.8 54 ns28 rs57521326 E26/3262G>A (D1088N) D1088 D1089 D1084 D1096 D1130 D1123 D1033 D1172 D392 D394 D1179 100.0 53.9 55 ns29 rs41309225 E27/3295A>G (K1099E) K1099 K1100 K1095 I1107 S1141 C1134 R1044 V1183 H403 H405 I1237 18.2 38.5 56 ns30 rs55852620 E27/3320A>C (Q1107P) Q1107 Q1108 Q1103 Q1115 E1149 T1142 R1052 N1191 G411 A413 R1245 27.3 43.7 57 ns31 rs35730308 E27/3322T>C (W1108R) W1108 Q1109 W1104 Q1116 H1150 N1143 S1053 D1192 S412 S414 D1246 27.3 43.5 58 s19 rs34748655 E27/3396C>T (A1132A) C-NBD (Internal) A1132 A1133 A1128 A1140 I1174 S1167 M1077 V1216 L436 A438 K1270 27.3 56.8 59 ns32 rs41309228 E27/3410G>T (S1137I ) S1137 S1138 S1133 S1145 P1179 A1172 S1082 S1220 P440 E443 - 18.2 41.8 60 ns33 rs2229107 E27/3421T>A (S1141T) S1141 S1142 S1137 S1149 T1183 T1176 D1086 S1224 D444 R447 T1277 45.5 50.9 61 s20 rs1045642 E27/3435C>T (I1145I) C-NBD (Internal) I1145 I1146 I1141 I1153 V1187 I1180 I1090 M1228 V447 I450 V1281 72.7 57.6 62 ns34 rs59241388 E28/3502A>G (K1168E) K1168 R1169 R1164 R1176 R1210 R1203 C1113 L1251 E470 V473 N1304 27.3 61.9 63 ns35 rs41309231 E29/3669A>T (E1223D) E1223 E1224 E1219 E1231 E1265 E1258 V1168 Q1306 K525 K528 D1359 27.3 60.2 64 s21 rs2235051 E29/3747C>G (G1249G) C-NBD (Internal) G1249 G1250 G1245 G1257 G1291 G1284 G1194 G1332 G551 G554 T1392 63.6 63.0 65 ns36 rs45456698 E29/3751G>A (V1251I) V1251 V1252 V1247 V1259 I1293 V1286 V1196 I1334 I553 I556 V1394 81.8 59.2 4.957.279931T165T855T9331T1021N1921D8921T4621T2521T7521T6521T)K6521T(A>C7673/92E93412753sr73sn66 C-NBD (External) C-NBD (External) C-NBD (External) C-NBD (External) TM4 - TM9 TM10 - TM1 S. aureus TM12 N-NBD (Internal) N-NBD (External) N-NBD (Internal) C-NBD (External) TM3 C. elegans D. melanoga ster A. thaliana S. pombe # SNP (amino acid substitution) Mapped to Abcb1a domain (internal/external surface) rsNo Conservation (%)a H. Sapiens C. l. Familiaris M. Musculus G. gallus P. falciparum Amino acid residue housing SNP Individual Regional 3 structure E. coli a The conservation of residues corresponding to all coding regions SNPs was obtained following multiple sequence alignment of 11 confirmed ABCB1 homolog protein sequences. Login to comment
120 Majority of the other SNPs previously associated with drug pharmacokinetics that could be mapped to the crystal structure reside at the outer surface of the C-terminal NBD Of the eight remaining SNPs to have been associated with drug response or expression, four can be mapped to the mouse Abcb1a crystal structure based on pair-wise alignment (Supplementary Figure 1).24,25 These are E26/3151C4G (P1051A) (#ns25), E27/3322T4C (W1108R) (#ns31), E27/ 3421T4A (S1141T) (#ns33) and E29/3751G4A (V1251I) (#ns36) (Figure 2b). Login to comment
125 This Figure 4 Location and conservation of (a) E8/554G4T (G185V), (b) E12/1199G4A (S400N), (c) E26/3151C4G (P1051A), (d) E27/3322T4C (W1108R), (e) E27/3421T4A (S1141T), (f) E29/3751G4A (V1251I). 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
133 Interestingly, SNP E27/3421T4A (S1141T) (#ns33) occurs at reasonably high frequency (44%) in the African population but is not found in the non-African populations (Supplementary Table 2). Login to comment
137 This SNP is even less conserved than SNP E27/3421T4A (S1141T) (#ns33) and also less conserved than its immediate surroundings as it has an individual conservation score of only 27.3% and a regional conservation score of 43.5% (Table 1, Figure 4e). Login to comment
142 Hence, of these several SNPs that had been previously associated with functional differences, most of them (E26/3151C4G (P1051A) (#ns25), E27/3421T4A (S1141T) (#ns33) and E29/3751G4A (V1251I) (#ns36) reside at the outer surface of the C-terminal NBD except for SNP E27/ 3322T4C (W1108R) (#ns31), which resides within the interior of the C-terminal NBD (Table 1, Figure 2b and flash movie http://pfs.nus.edu.sg/demo_src/abcb1.html). Login to comment
153 Genotype data that are available for 8 of these 14 previously associated SNPs revealed that the frequencies of these SNPs differed greatly among the various populations examined with SNP E27/ 3421T4A (S1141T) (#ns33) occurring only in the African Americans (Supplementary Table 2). 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] Functional hot spots in human ATP-binding cassette... Protein Sci. 2010 Nov;19(11):2110-21. Kelly L, Fukushima H, Karchin R, Gow JM, Chinn LW, Pieper U, Segal MR, Kroetz DL, Sali A
Functional hot spots in human ATP-binding cassette transporter nucleotide binding domains.
Protein Sci. 2010 Nov;19(11):2110-21., [PMID:20799350]

Abstract [show]
The human ATP-binding cassette (ABC) transporter superfamily consists of 48 integral membrane proteins that couple the action of ATP binding and hydrolysis to the transport of diverse substrates across cellular membranes. Defects in 18 transporters have been implicated in human disease. In hundreds of cases, disease phenotypes and defects in function can be traced to nonsynonymous single nucleotide polymorphisms (nsSNPs). The functional impact of the majority of ABC transporter nsSNPs has yet to be experimentally characterized. Here, we combine experimental mutational studies with sequence and structural analysis to describe the impact of nsSNPs in human ABC transporters. First, the disease associations of 39 nsSNPs in 10 transporters were rationalized by identifying two conserved loops and a small alpha-helical region that may be involved in interdomain communication necessary for transport of substrates. Second, an approach to discriminate between disease-associated and neutral nsSNPs was developed and tailored to this superfamily. Finally, the functional impact of 40 unannotated nsSNPs in seven ABC transporters identified in 247 ethnically diverse individuals studied by the Pharmacogenetics of Membrane Transporters consortium was predicted. Three predictions were experimentally tested using human embryonic kidney epithelial (HEK) 293 cells stably transfected with the reference multidrug resistance transporter 4 and its variants to examine functional differences in transport of the antiviral drug, tenofovir. The experimental results confirmed two predictions. Our analysis provides a structural and evolutionary framework for rationalizing and predicting the functional effects of nsSNPs in this clinically important membrane transporter superfamily.

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72 Predictions of the Functional Effects of 40 nsSNPs in ABC Transporters Comon name HUGO name Mutation NBD Prediction BSEP ABCB11 E592Q NBD1 Neutral BSEP ABCB11 N591S NBD1 Neutral BSEP ABCB11 Q558H NBD1 Neutral BSEP ABCB11 V444A NBD1 Neutral BSEP ABCB11 E1186K NBD2 Disease MDR1 ABCB1 P1051A NBD2 Neutral MDR1 ABCB1 S1141T NBD2 Neutral MDR1 ABCB1 T1256K NBD2 Disease MDR1 ABCB1 V1251I NBD2 Neutral MDR1 ABCB1 W1108R NBD2 Disease MRP2 ABCC2 I670T NBD1 Disease MRP2 ABCC2 L849R NBD1 Disease MRP2 ABCC2 C1515Y NBD2 Disease MRP3 ABCC3 D770N NBD1 Neutral MRP3 ABCC3 K718M NBD1 Neutral MRP3 ABCC3 T809M NBD1 Disease MRP3 ABCC3 V765L NBD1 Disease MRP3 ABCC3 Q1365R NBD2 Disease MRP3 ABCC3 R1297H NBD2 Disease MRP3 ABCC3 R1348C NBD2 Disease MRP3 ABCC3 R1381S NBD2 Disease MRP4 ABCC4 G487E NBD1 Disease MRP4 ABCC4 K498E NBD1 Neutral MRP4 ABCC4 R1220Q NBD2 Neutral MRP4 ABCC4 T1142M NBD2 Neutral MRP4 ABCC4 V1071I NBD2 Neutral MRP6 ABCC6 I1330L NBD1 Neutral MRP6 ABCC6 I742V NBD1 Neutral MRP6 ABCC6 P664S NBD1 Neutral MRP6 ABCC6 R724K NBD1 Neutral MRP6 ABCC6 R769K NBD1 Neutral MRP6 ABCC6 A1291T NBD2 Neutral MRP6 ABCC6 E1369K NBD2 Neutral MRP6 ABCC6 G1327E NBD2 Disease MRP6 ABCC6 L1416R NBD2 Disease MRP6 ABCC6 R1268Q NBD2 Disease MRP6 ABCC6 R1461H NBD2 Disease MXR ABCG2 I206L NBD1 Neutral MXR ABCG2 P269S NBD1 Disease MXR ABCG2 Q141K NBD1 Neutral nsSNPs. Login to comment
163 In contrast, the S1141T variant showed either normal or increased transport in the yeast assay, suggesting that the transporter was functioning properly.37 This variant was correctly predicted to be neutral. Login to comment
164 Finally, in transfected HEK293T cells, the S1141T variant showed increased function, suggesting that the transporter is functioning normally, but also with substrate dependence as for the V1251I nsSNP.38 This variant was predicted correctly to be neutral. Login to comment

[hide] MDR1 C3435T polymorphism and interaction with envi... Drug Metab Pharmacokinet. 2012 Sep 11. Kiyohara C, Miyake Y, Koyanagi M, Fujimoto T, Shirasawa S, Tanaka K, Fukushima W, Sasaki S, Tsuboi Y, Yamada T, Oeda T, Shimada H, Kawamura N, Sakae N, Fukuyama H, Hirota Y, Nagai M
MDR1 C3435T polymorphism and interaction with environmental factors in risk of Parkinson's disease: a case-control study in Japan.
Drug Metab Pharmacokinet. 2012 Sep 11., [PMID:22971641]

Abstract [show]
It has been suggested that P-glycoprotein (P-gp), the product of multidrug resistance 1 (MDR1) gene, regulates the brain entry of various xenobiotics. Impaired function of P-gp may be associated with an increased risk of Parkinson's disease (PD). The aim of this study was to investigate the impact of a MDR1 C3435T polymorphism on PD risk alone or in combination with environmental factors. A total of 238 patients with PD and 368 controls were genotyped for the MDR1 C3435T polymorphism. Subjects with the TT genotype of the C3435T polymorphism showed a nonsignificantly increased risk of PD (odds ratio (OR) = 1.49, 95% confidence interval (CI) =0.85 - 2.25) compared with those with the CC genotype. A gene-environment interaction was suggested, with a combination of at least one T allele and ever drinking conferring significantly higher risk (OR = 1.83, 95% CI = 1.07 - 3.15, P = 0.029), compared with the CC genotype and never drinking. No significant interaction of smoking or occupational pesticide use with the C3435T polymorphism was observed. Our results suggest that the C3435T polymorphism may not play an important role in PD susceptibility in Japanese. Evidence of an interaction between the C3435T polymorphism and alcohol consumption was suggested.

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68 All the subjects had the same genotype (TT) for MDR1 T3421A (rs2229107, Ser1141Thr) (data not shown). Login to comment
88 The frequency of the T allele in this study was somewhat lower than that of the HapMap SNP database but similar to that of other Japanese populations (41.3 %, 40.6 % and 39.0%).11, 26, 27) All Japanese as well as all Caucasians and all Han Chinese have the same genotype (TT) for the nonsynonymous T3421A (Ser1141Thr) polymorphism.28) In this study, subjects with the TT genotype of the C3435T polymorphism had a nonsignificantly increased risk of PD (OR = 1.39, 95% CI = 0.85 - 2.25) compared with the CC genotype. 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] Comparative description of haplotype structure and... Infect Genet Evol. 2010 Jan;10(1):60-7. Epub 2009 Oct 9. Benish RL, Rodriguez B, Zimmerman PA, Mehlotra RK
Comparative description of haplotype structure and genetic diversity of MDR1 (ABCB1) in HIV-positive and HIV-negative populations.
Infect Genet Evol. 2010 Jan;10(1):60-7. Epub 2009 Oct 9., [PMID:19819348]

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Human P-glycoprotein (P-gp), encoded by MDR1 (ABCB1), is an efflux transporter with a wide specificity for substrates/drugs, including HIV protease inhibitors which are commonly used in HIV/AIDS treatment. Three single nucleotide polymorphisms (SNPs) in MDR1 have been shown to affect P-gp expression and function, and may affect HIV/AIDS treatment outcome: 1236C>T [G412G, exon-12], 2677G>T/A [A893S/T, exon-21] and 3435C>T [I1145I, exon-26]. In the present study, our aims were (i) to compare the 3-SNP MDR1 haplotype structure and genetic diversity between North American HIV-positive and HIV-negative individuals belonging to four major ethnic groups and (ii) to determine whether the haplotype structure and genetic diversity observed in these ethnically admixed populations differ from that in ethnically non-admixed populations. For these aims, we analyzed a cohort of 447 HIV/AIDS patients (White [n=193], Black [n=235], Hispanic [n=17], and Asian [n=2]). Results obtained for these patients were compared with the results for (i) HIV-negative individuals (n=356) and (ii) various HapMap and Environmental Genome Project populations. We observed that the genetic characteristics of MDR1 were largely consistent between HIV-positive and HIV-negative populations, but there were striking interethnic differences in the genetic characteristics of MDR1 in both populations. Although it appeared that the genetic characteristics of MDR1 were largely consistent between ethnically admixed and non-admixed populations, genetic characterization of the admixed populations remains to be done. Thus, our results provide useful comparative insights about the genetic characteristics of MDR1 that could be extrapolated across population groups worldwide. For a meaningful interpretation of these results regarding HIV/AIDS treatment outcome, MDR1 haplotype/diplotype structure data, genetic characterization of population admixture, and polymorphisms in other relevant drug transporter and/or metabolizing enzyme genes should be considered in future clinical studies.

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155 Thus, it is important to determine whether these interethnic genetic differences in MDR1, together with other potentially significant polymorphisms in the MDR1 coding, 1199G>A (Ser400Asn) (Woodahl et al., 2005), 571G>A (Gly191Arg) (Yang et al., 2008), and 3421T>A (Ser1141Thr) (Kroetz et al., 2003), as well as regulatory regions (Taniguchi et al., 2003; Loeuillet et al., 2007), are associated with different outcomes of protease inhibitor-based HIV/AIDS treatment. 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
154 Another study using a yeast host to express human MDR1 SNPs (M89T, L662R, R669C, A893S, W1108R, S1141T) showed increased resistance to anthracyclines, actinomycin D and valinomycin. 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