ABCMdb

ABCB1 p.Val1251Ile

Predicted by SNAP2:	A: D (85%), C: N (53%), D: D (75%), E: D (75%), F: D (66%), G: D (75%), H: D (75%), I: N (53%), K: D (75%), L: N (82%), M: N (57%), N: D (75%), P: D (80%), Q: D (71%), R: D (75%), S: D (71%), T: D (66%), W: D (95%), Y: D (75%),
Predicted by PROVEAN:	A: D, C: D, D: D, E: D, F: D, G: D, H: D, I: N, K: D, L: N, M: N, N: D, P: D, Q: D, R: D, S: D, T: D, W: D, Y: D,

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

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

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126 In addition to the possible decrease in expression levels, ATPase activity in the ABCG2 +24 Intron 20 G A +40 Intron 20 C T 2547 Exon 21 A G 849 Ile to Met 2650 Exon 21 C T 884 Syn 2677 Exon 21 G T 893 Ala to Ser 2677# Exon 21 G A 893 Ala to Thr +31 Intron 22 G A 2956 Exon 24 A G 986 Met to Val 2995 Exon 24 G A 999 Ala to Thr 3151 Exon 25 C G 1051 Pro to Ala 3320 Exon 26 A C 1107 Gln to Pro 3322 Exon 26 T C 1108 Trp to Arg 3396 Exon 26 C T 1132 Syn 3421 Exon 26 T A 1141 Ser to Thr 3435** Exon 26 C T 1145 Syn 3751 Exon 28 G A 1251 Val to Ile 3767 Exon 28 C A 1256 Thr to Lys 4030 Exon 28 G C Non-coding 4036 Exon 28 A G Non-coding +21 Intron 28 T C Table 2. Summary of common genetic variants in the ABCB1 gene (continued) *cDNA numbers are relative to the ATG site and based on the cDNA sequence from GenBank accession number M14758 with an A as the reference at position 43. Login to comment

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

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

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

[hide] 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] Additive effects of drug transporter genetic polym... Cancer Chemother Pharmacol. 2010 May;66(1):95-105. Epub 2009 Sep 22. Sai K, Saito Y, Maekawa K, Kim SR, Kaniwa N, Nishimaki-Mogami T, Sawada J, Shirao K, Hamaguchi T, Yamamoto N, Kunitoh H, Ohe Y, Yamada Y, Tamura T, Yoshida T, Matsumura Y, Ohtsu A, Saijo N, Minami H
Additive effects of drug transporter genetic polymorphisms on irinotecan pharmacokinetics/pharmacodynamics in Japanese cancer patients.
Cancer Chemother Pharmacol. 2010 May;66(1):95-105. Epub 2009 Sep 22., [PMID:19771428]

Abstract [show]
PURPOSE: Effects of genetic polymorphisms/variations of ABCB1, ABCC2, ABCG2 and SLCO1B1 in addition to "UGT1A1*28 or *6" on irinotecan pharmacokinetics/pharmacodynamics in Japanese cancer patients were investigated. METHODS: Associations between transporter haplotypes/variations along with UGT1A1*28 or *6 and SN-38 area under the time-concentration curve (AUC) or neutropenia were examined in irinotecan monotherapy (55 patients) and irinotecan-cisplatin-combination therapy (62 patients). RESULTS: Higher SN-38 AUC values were observed in ABCB1 2677G>T (A893S) (*2 group) for both regimens. Associations of grade 3/4 neutropenia were observed with ABCC2 -1774delG (*1A), ABCG2 421C>A (Q141K) and IVS12 + 49G>T ((#) IIB) and SLCO1B1 521T>C (V174A) (*15 x 17) in the irinotecan monotherapy, while they were evident only in homozygotes of ABCB1*2, ABCG2 (#) IIB, SLCO1B1*15 x 17 in the cisplatin-combination therapy. With combinations of haplotypes/variations of two or more genes, neutropenia incidence increased, but their prediction power for grade 3/4 neutropenia is still unsatisfactory. CONCLUSIONS: Certain transporter genotypes additively increased irinotecan-induced neutropenia, but their clinical importance should be further elucidated.

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86 = UGT1A1*6 or *28. a BJL contains -1789G[A, *2 (block 1) = 325G[A (E109K), *3 (block 1) = 304G[A (G102R); b *2 (block 2) contains 2677G[T (A893S); c *1b (block 3) = IVS27-182G[T, *2 (block 3) = 3751G[ A (V1251I); d *1A contains -1774delG; e IIB contains 421C[A (Q141K) and IVS12 ? Login to comment
124 patients who experienced grade 4 neutropenia ID Gene Genetic variation Nucleotide change (amino acid substitution) Haplotypea b1 ABCB1 304G[C (G102R) Block 1 *3 b2(B)b 1804G[A (D602N) Block 2 *12 b3(B)b 1342G[A (E448K) Block 2 *14 b4 3043A[G (T1015A) Block 2 *16 b5 3751G[A (V1251I) Block 3 *2 c1 ABCC2 1177C[T (R393W) *7 g1 ABCG2 376C[T (Q126X) Block 1 *4 g2 1465T[C (F489L) Block 2 *2 g3 1723C[T (R575X) Block 2 *5 s1(S)c SLCO1B1 1007C[G (P336R) s2 311T[A (M104K) u1 UGT1A1 -3279T[G, 1941C[G # 60-# IB (?/?) 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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103 A total of 30 segregating sites have not been previously described, including eight non-synonymous changes coding for the following amino acid changes: Met89Thr, Leu662Arg, Arg669Cys, Ile849Met, Pro1051Ala, Trp1108Arg, Val1251Ile, and Thr1256Lys. Login to comment
113 An additional five coding variants occurred at sites that were conserved in six of the seven species, including those resulting in the Arg669Cys, Ile849Met, Trp1108Arg, and Val1251Ile changes. Login to comment
141 Unauthorized reproduction of this article is prohibited. Table 1 Genetic variation in ABCB1 Allele frequencyd Variant cDNA NT DNA/AA AA Total CA AA AS ME PA No.a positionb changec position change (n ¼ 494) (n ¼ 200) (n ¼ 200) (n ¼ 60) (n ¼ 20) (n ¼ 14) 1.1Ã (À274) G to A Intron À1 0.006 0 0.016 0 0 0 1.2Ã (À223) C to T Intron À1 0.002 0.005 0 0 0 0 1.3Ã (À146) T to C Intron À1 0.002 0 0.005 0 0 0 1.4Ã (À60) A to T Intron À1 0.004 0 0.010 0 0 0 1.5 (À41) A to G Intron À1 0.002 0 0 0.017 0 0 1.6Ã À241 G to A Non-coding 0.002 0 0 0.017 0 0 1.7 À145 C to G Non-coding 0.002 0 0 0.017 0 0 1.8 À129 T to C Non-coding 0.060 0.051 0.071 0.036 0.100 0.071 1.9 À43 A to G Non-coding 0.012 0 0.020 0.036 0 0 1.10Ã (+140) C to A Intron 1 0.013 0.005 0.021 0 0 0.071 1.11Ã (+237) G to A Intron 1 0.004 0 0.010 0 0 0 2.1 À4 C to T Non-coding 0.004 0 0.010 0 0 0 2.2 À1 G to A Non-coding 0.036 0.080 0.005 0 0.050 0 2.3 61 A to G 21 Asn to Asp 0.045 0.080 0.025 0.017 0 0 4.1Ã (À8) C to G Intron 3 0.002 0.005 0 0 0 0 4.2Ã 266 T to C 89 Met to Thr 0.002 0.005 0 0 0 0 5.1 (À25) G to T Intron 4 0.210 0.158 0.300 0.067 0.200 0.286 8.1 729 A to G 243 Syn 0.002 0.005 0 0 0 0 8.2Ã 781 A to G 261 Ile to Val 0.006 0 0.015 0 0 0 10.1Ã (À44) A to G Intron 9 0.400 0.450 0.255 0.685 0.450 0.571 11.1Ã (À41) T to G Intron 10 0.002 0 0 0.017 0 0 11.2 1199 G to A 400 Ser to Asn 0.014 0.025 0.010 0 0 0 12.1Ã (À4) G to A Intron 11 0.002 0 0.005 0 0 0 12.2 1236 C to T 412 Syn 0.385 0.459 0.209 0.685 0.450 0.571 12.3Ã 1308 A to G 436 Syn 0.002 0 0.005 0 0 0 12.4Ã (+17) G to A Intron 12 0.008 0 0.020 0 0 0 12.5 (+44) C to T Intron 12 0.088 0.046 0.168 0 0 0 13.1 (+24) C to T Intron 13 0.530 0.521 0.542 0.540 0.450 0.571 14.1 1617 C to T 539 Syn 0.002 0.005 0 0 0 0 14.2 (+38) A to G Intron 14 0.540 0.505 0.540 0.683 0.450 0.500 15.1 (+38) G to A Intron 15 0.004 0.005 0.005 0 0 0 16.1Ã 1985 T to G 662 Leu to Arg 0.002 0.005 0 0 0 0 16.2Ã 2005 C to T 669 Arg to Cys 0.004 0 0.010 0 0 0 18.1Ã (À27) A to G Intron 17 0.008 0.010 0.005 0 0.050 0 20.1Ã (+8) C to G Intron 20 0.002 0 0.005 0 0 0 20.2 (+24) G to A Intron 20 0.126 0.121 0.150 0.067 0.200 0 20.3Ã (+40) C to T Intron 20 0.014 0 0.035 0 0 0 21.1Ã 2547 A to G 849 Ile to Met 0.002 0.005 0 0 0 0 21.2 2650 C to T 884 Syn 0.004 0.005 0.005 0 0 0 21.3a 2677 G to T 893 Ala to Ser 0.308 0.464 0.100 0.450 0.400 0.357 21.3b 2677 G to A 893 Ala to Thr 0.035 0.036 0.005 0.067 0 0.357 22.1 (+31) G to A Intron 22 0.002 0 0.005 0 0 0 25.1Ã 3151 C to G 1051 Pro to Ala 0.002 0 0.005 0 0 0 26.1Ã 3322 T to C 1108 Trp to Arg 0.002 0 0.005 0 0 0 26.2 3421 T to A 1141 Ser toThr 0.047 0 0.111 0 0.050 0 26.3 3435 C to T 1145 Syn 0.392 0.561 0.202 0.400 0.500 0.500 28.1 3751 G to A 1251 Val to Ile 0.002 0 0 0 0.050 0 28.2 3767 C to A 1256 Thr to Lys 0.002 0.005 0 0 0 0 28.3 (+21) T to C Intron 28 0.031 0 0.077 0 0 0 a Variants are numbered sequentially by exon. Login to comment
164 M89T I849M V1251I T1256K S1141TW1108R P1052AR669C A893S/T L662R Cytoplasm S400N I261V N21D Extracellular Fig. 1. 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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102 Unauthorized reproduction of this article is prohibited. Copyright(c)LippincottWilliams&Wilkins.Unauthorizedreproductionofthisarticleisprohibited. Table 2 List of SNPs and deletion/insertion of the ABCB1 gene found in a Japanese population SNP IDÃ Position Nucleotide Effect on Block Site Our SNP ID NCBI IMS-JST NT_007933.10 cDNA-based change protein Frequency Block À1 59-Flanking MPJ6_AB1057 12472341 À8104 T.C 0.003 59-Flanking MPJ6_AB1059 12472207 À7970 C.T 0.007 Block 1 59-Flanking MPJ6_AB1002 rs2188524 ssj0000008 12464608 À371 A.G 0.128 Exon 1 (59-UTR) MPJ6_AB1003 12464382 À145 C.G 0.024 Exon 1 (59-UTR) MPJ6_AB1004 rs3213619 ssj0000009 12464366 À129 T.C 0.093 Intron 1 MPJ6_AB1005 rs3214119 ssj0000010 12463753 IVS1-74 delG 0.121 Intron 3 MPJ6_AB1008 rs2235074 12459219 IVS3+36 C.T 0.093 Intron 4 MPJ6_AB1010 rs2235014 12433788 IVS4-76 T.C 0.017 Intron 4 MPJ6_AB1011 rs2235015 12433737 IVS4-25 G.T 0.086 Exon 5 MPJ6_AB1012 12433674 325 G.A E109K 0.010 Intron 5 MPJ6_AB1013 rs2235016 12433585 IVS5+76 T.G 0.055 Block 2 Intron 5 MPJ6_AB1014 rs2235018 12433538 IVS5+123 A.G 0.141 Intron 5 MPJ6_AB1015 rs2235020 12433438 IVS5+223 A.T 0.548 Intron 5 MPJ6_AB1016 rs2235021 12433437 IVS5+224 G.T 0.548 Intron 6 MPJ6_AB1017 12429839 IVS6-109 G.T 0.007 Intron 7 MPJ6_AB1018 12429545 IVS7+14 G.A 0.010 Intron 8 MPJ6_AB1020 rs1922240 ssj0000016 12417527 IVS8-106 A.G 0.348 Intron 9 MPJ6_AB1021 12414371 IVS9-44 G.A 0.445 Intron 10 MPJ6_AB1023 rs2235029 12414108 IVS10-41 T.G 0.017 Exon 12 MPJ6_AB1025 rs1128503 12413774 1236 C.T G412G (silent) 0.555 Intron 12 MPJ6_AB1052 12413643 IVS12+17 G.A 0.010 Intron 13 MPJ6_AB1026 rs2235033 ssj0000018 12413316 IVS13+24 T.C 0.445 Intron 13 MPJ6_AB1027 rs2235035 ssj0000019 12413259 IVS13+81 C.T 0.348 Intron 14 MPJ6_AB1028 rs2235013 ssj0000020 12412799 IVS14+38 G.A 0.445 Intron 15 MPJ6_AB1029 12408557 IVS15-69 T.C 0.014 Intron 16 MPJ6_AB1030 rs2235046 12408239 IVS16+73 A.G 0.452 Intron 16 MPJ6_AB1031 rs1922242 12407840 IVS16-76 T.A 0.369 Intron 18 MPJ6_AB1034 12402869 IVS18-35 G.C 0.003 Intron 20 MPJ6_AB1035 rs2235040 ssj0000027 12399923 IVS20+24 G.A 0.090 Exon 21 MPJ6_AB1036 12394791 2677 G.A A893T 0.200 Exon 21 MPJ6_AB1037 rs2032582 12394791 2677 G.T A893S 0.403 Intron 21 MPJ6_AB1038 rs2032583 ssj0000031 12394734 IVS21+49 T.C 0.090 Intron 24 MPJ6_AB1040 12379982 IVS24+16 C.T 0.031 Exon 26 MPJ6_AB1041 rs1045642 ssj0000040 12372818 3435 C.T I1145I (silent) 0.441 Intron 26 MPJ6_AB1042 rs2235047 ssj0000048 12372705 IVS26+59 T.G 0.403 Intron 26 MPJ6_AB1043 rs2235048 ssj0000049 12372684 IVS26+80 T.C 0.448 Block 3 Exon 27 MPJ6_AB1068 12369435 3587 T.G I1196S 0.003 Intron 27 MPJ6_AB1044 12369323 IVS27+63 C.G 0.003 Intron 27 MPJ6_AB1053 12368127 IVS27-189 A.G 0.007 Intron 27 MPJ6_AB1045 rs1186745 ssj0000051 12368120 IVS27-182 G.T 0.200 Intron 27 MPJ6_AB1054 12368110 IVS27-172 G.A 0.010 Intron 27 MPJ6_AB1047 rs1186744 12368106 IVS27-168 T.C 0.010 Intron 27 MPJ6_AB1048 12368105 IVS27-167 A.G 0.014 Intron 27 MPJ6_AB1055 12368090 IVS27-152 A.G 0.003 Intron 27 MPJ6_AB1049 12368057 IVS27-119 C.T 0.021 Intron 27 MPJ6_AB1056 rs2235049 12368025 IVS27-87 A.G 0.007 Intron 27 MPJ6_AB1070 12368024 IVS27-86 T.C 0.003 Intron 27 MPJ6_AB1071 12368018 IVS27-80 ins C 0.003 Exon 28 MPJ6_AB1051 12367824 3751 G.A V1251I 0.010 ÃSNP ID assigned by our project team (MPJ-6). Login to comment
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
154 The Ã2 and Ã3 haplotypes had a nonsynonymous SNP of 3751G.A (V1251I) and 3587T.G (I1196S), respectively. Login to comment
162 *1b Block 3 Site Position Nucleotide change Effect on protein Exon 27 3587 TϾG I1196S Diplotype *1a/*1a Intron 27 Intron 27 IVS27 ϩ63 Intron 27 Intron 27 Intron 27 Intron 27 Intron 27 Intron 27 Intron 27 Intron 27 Intron 27 Exon 28 IVS27 -189 IVS27 -182 IVS27 -172 IVS27 -168 IVS27 -167 IVS27 -152 IVS27 -119 IVS27 -87 IVS27 -86 IVS27 -80 3751 CϾG AϾG GϾT GϾA TϾC AϾG AϾG CϾT AϾG TϾC ins C GϾA V1251I *1a/*1b *1a/*1c *1a/*1d *1a/*1e *1a/*1f *1a/*1g *1a/*1h *1a/*1i *1a/*1j *1a/*1k *1a/*1m *1a/*1n *1a/*1p *1a/*1q ? Login to comment

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

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

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28 6, June 2004 ((c) 2004) 9040724-8741/04/0600-0904/0 (c) 2004 Plenum Publishing Corporation Table I. MDR1 Coding Variants cDNA positiona NT change DNA/AA position AA change Allele frequencyb Total (n ‫ס‬ 494) CA (n ‫ס‬ 200) AA (n ‫ס‬ 200) AS (n ‫ס‬ 60) ME (n ‫ס‬ 20) PA (n ‫ס‬ 14) 61 A to G 21 Asn to Asp 0.045 0.080 0.025 0.017 0 0 266 T to C 89 Met to Thr 0.002 0.005 0 0 0 0 729 A to G 243 Syn 0.002 0.005 0 0 0 0 781 A to G 261 Ile to Val 0.006 0 0.015 0 0 0 1199 G to A 400 Ser to Asn 0.014 0.025 0.010 0 0 0 1236 C to T 412 Syn 0.385 0.459 0.209 0.685 0.450 0.571 1308 A to G 436 Syn 0.002 0 0.005 0 0 0 1617 C to T 539 Syn 0.002 0.005 0 0 0 0 1985 T to G 662 Leu to Arg 0.002 0.005 0 0 0 0 2005 C to T 669 Arg to Cys 0.004 0 0.010 0 0 0 2547 A to G 849 Ile to Met 0.002 0.005 0 0 0 0 2650 C to T 884 Syn 0.004 0.005 0.005 0 0 0 2677 G to T 893 Ala to Ser 0.308 0.464 0.100 0.450 0.400 0.357 2677 G to A 893 Ala to Thr 0.035 0.036 0.005 0.067 0 0.357 3151 C to G 1051 Pro to Ala 0.002 0 0.005 0 0 0 3322 T to C 1108 Trp to Arg 0.002 0 0.005 0 0 0 3421 T to A 1141 Ser to Thr 0.047 0 0.111 0 0.050 0 3435 C to T 1145 Syn 0.392 0.561 0.202 0.400 0.500 0.500 3751 G to A 1251 Val to Ile 0.002 0 0 0 0.050 0 3767 C to A 1256 Thr to Lys 0.002 0.005 0 0 0 0 a cDNA numbers are relative to the ATG site and based on the cDNA sequence from GenBank accession number M14758. Login to comment

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

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

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11 Among these SNPs, only MPJ6äAB1051 resulted in an amino acid alteration, V1251I. Login to comment
37 Novel SNPs in the ABCB1 gene found in Japanese individuals SNP name AB1017 AB1018 AB1021 AB1052 AB1029 AB1040 AB1053 AB1054 AB1048 AB1055 AB1049 AB1051 Intron 6 Intron 7 Intron 9 Intron 12 Intron 15 Intron 24 Intron 27 Intron 27 Intron 27 Intron 27 Intron 27 Exon 28 Position (NTä017168.9) 7251272 7251566 7266740 7267488 7272554 7301129 7312984 7313001 7313006 7313021 7313054 7313287 Position (cDNA) IVS6 109a IVS7 +14b IVS9 44 IVS12 +17 IVS15 69 IVS24 +16 IVS27 189 IVS27 172 IVS27 167 IVS27 152 IVS27 119 3751 Nucleotide change GÀT GÀA GÀA GÀA TÀC CÀT AÀG GÀA AÀG AÀG CÀT GÀA Amino acid change V1251I Frequency, z G: 99.2 G: 99.2 G:56.7 G: 98.3 T: 98.3 C: 99.2 A: 98.3 G: 97.5 A: 98.3 A: 99.2 C: 99.2 G: 98.3 T: 0.8 A: 0.8 A:43.3 A: 1.7 C: 1.7 T: 0.8 G: 1.7 A: 2.5 G: 1.7 G: 0.8 T: 0.8 A: 1.7 a Numbers following IVS (intervening sequence) represents number of the preceding exon. Login to comment
74 Of these SNPs, only one SNP, MPJ6äAB1051 which was found in 2 subjects, introduced a nonsynonymous amino acid change (V1251I). Login to comment

[hide] Genetic variations and haplotype structures of the... Ann Hum Genet. 2006 Sep;70(Pt 5):605-22. Sai K, Itoda M, Saito Y, Kurose K, Katori N, Kaniwa N, Komamura K, Kotake T, Morishita H, Tomoike H, Kamakura S, Kitakaze M, Tamura T, Yamamoto N, Kunitoh H, Yamada Y, Ohe Y, Shimada Y, Shirao K, Minami H, Ohtsu A, Yoshida T, Saijo N, Kamatani N, Ozawa S, Sawada J
Genetic variations and haplotype structures of the ABCB1 gene in a Japanese population: an expanded haplotype block covering the distal promoter region, and associated ethnic differences.
Ann Hum Genet. 2006 Sep;70(Pt 5):605-22., [PMID:16907707]

Abstract [show]
As functional ABCB1 haplotypes were recently reported in the promoter region of the gene, we resequenced the ABCB1 distal promoter region, along with other regions (the enhancer and proximal promoter regions, and all 28 exons), in a total of 533 Japanese subjects. Linkage disequilibrium (LD) analysis based on 92 genetic variations revealed 4 LD blocks with the same make up as previously described (Blocks -1, 1, 2 and 3), except that Block 1 was expanded to include the distal promoter region, and that a new linkage between polymorphisms -1,789G>A in the distal promoter region and IVS5 + 123A>G in intron 5 was identified. We re-assigned Block 1 haplotypes, and added novel haplotypes to the other 3 blocks. The reported promoter haplotypes were further classified into several types according to tagging variations within Block 1 coding or intronic regions. Our current data reconfirm the haplotype profiles of the other three blocks, add more detailed information on functionally-important haplotypes in Block 1 and 2 in the Japanese population, and identified differences in haplotype profiles between ethnic groups. Our updated analysis of ABCB1 haplotype blocks will assist pharmacogenetic and disease-association studies carried out using Asian subjects.

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159 As observed previously, the rare haplotype groups * 2 [3751G>A (V1251I)] and * 3 [3587T>G (I1196S)] were observed at frequencies of 0.014 and 0.001, 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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4 The A893S, A893T, and V1251I variants and the N21D/ 1236CϾT/A893S/3435CϾT haplotype altered intracellular accumulation compared with reference P-gp in a substrate-dependent manner. Login to comment
55 The following variants were created from the reference ABCB1 plasmid in pCIneo: 61AϾG (N21D), 1199GϾA (S400T), 1596TϾG [a nonfunctional nucleotide-binding domain (NBD) mutant], 2005CϾT (R669C), 2677GϾA (A893T), 3421TϾA (S1141T), and 3751GϾA (V1251I). Login to comment
103 There are six polymorphic residues that meet these criteria: N21D, S400T, R669C, A893S/T, S1141T, and V1251I. Login to comment
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
163 Six of 13 previously described nonsynonymous variants were chosen for study based on an allele frequency Ͼ2%: N21D, S400N, A893S, A893T, S1141T, and V1251I. Login to comment
170 The data collected in the absence of cyclosporin A for empty vector (gray, dotted), P-gp reference (black), NBD mutant (gray), A893S (green), V1251I (blue), and haplotype N21D/1236CϾT/A893S/3534CϾT (red) are shown in a representative fluorescence histogram (a). Login to comment
171 The effects of cyclosporin A on BODIPY-FL-paclitaxel accumulation are displayed in a representative histogram in b for P-gp reference (black, shaded), A893S (green), A893T (orange), S1141T (pink), V1251I (blue), and haplotype N21D/1236CϾT/A893S/3534CϾT (red). Login to comment
189 The A893T and V1251I variants had lower intracellular levels of calcein, indicating increased efflux of calcein-AM by P-gp (Table 3). Login to comment
199 Likewise, we found that the functional effects of A893S, A893T, V1251I, and N21N/1236CϾT/A893S/3435CϾT were substrate-dependent. Login to comment
209 It should be noted that V1251I P-gp displays decreased function with BODIPY-FL-paclitaxel but increased function with calcein-AM. Login to comment
211 There is no other data on the function of the V1251I variant, and testing additional substrates may elucidate the importance of this amino acid change. 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
229 Intracellular accumulation of calcein-AM and/or BODIPY-FL-paclitaxel was altered by A893S, A893T, V1251I, and N21D/1236CϾT/A893S/3435CϾT. Login to comment

[hide] 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
139 SNP E29/3751G4A (V1251I) (#ns36) was found to increase BODIPY-FL-paclitaxel accumulation and modulate the effect of cyclosporine A on the intracellular accumulation of BODIPY-FL-paclitaxel transport.50 When mapped to the crystal structure, V1251I resides at the outer surface of the C-terminal NBD (Figures 2b and 4f). 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
143 Except for SNP E29/3751G4A (V1251I) (#ns36) with high individual conservation score (480%), the other three SNPs have below average conservation scores (o46%). Login to comment
154 Except for synonymous SNP E27/3435C4T (I1145I) (#s20) and non-synonymous SNPs E29/3751G4A (V1251I) (#ns36) and E26/3262G4A (D1088N) (#ns28), these previously associated SNPs have below average individual conservation scores (o46%) and only average regional 31 structure conservation scores (40-60%) suggesting that there is some tolerance of variability in these regions of the P-gp protein, perhaps facilitating differences in substrate specificity of the different polymorphs. 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
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
165 The V1251I variant of P-glycoprotein showed decreased transport of BODIPY-FL-paclitaxel, but increased transport of calcein-AM in an assay using transfected HEK293T cells. 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

[hide] Association between the c.3751G>a genetic variant ... Asian Pac J Cancer Prev. 2013;14(9):5361-5. Li XF, He HB, Zhu YS, He JK, Ye WW, Chen YX, Lou LQ
Association between the c.3751G>a genetic variant of MDR1 and hepatocellular carcinoma risk in a Chinese Han population.
Asian Pac J Cancer Prev. 2013;14(9):5361-5., [PMID:24175826]

Abstract [show]
The objective of this study was to evaluate the influence of a genetic variant in the multidrug resistance 1 gene (MDR1) on hepatocellular carcinoma (HCC) risk. This case-control study was conducted in a Chinese population of 645 HCC cases and 658 cancer-free controls. The genotype of the c.3751G>A genetic variant in the MDR1 gene was investigated by created restriction site-polymerase chain reaction (CRS-PCR) and DNA sequencing methods. Our data demonstrated significantly differences detected in the allelic and genotypic frequencies between HCC cases and those of cancer-free controls. Association analyses indicated that there were statistically increased risk of HCC in the homozygote comparison (AA versus (vs.) GG: OR = 2.22, 95% CI 1.51-3.27, chi(2) = 16.90, P < 0.001), dominant model (AA/GA vs. GG: OR = 1.25, 95% CI 1.00-1.55, chi(2) = 3.98, P = 0.046), recessive model (AA vs. GA/GG: OR = 2.14, 95% CI 1.47-3.09, chi(2) = 16.68, P < 0.001) and allele comparison (A vs. G: OR = 1.33, 95% CI 1.13-1.57, chi(2) = 11.66, P = 0.001). The allele-A and genotype-AA may contribute to HCC susceptibility. These preliminary findings suggest that the c.3751G>A genetic variant in the MDR1 gene is potentially related to HCC susceptibility in a Chinese Han population, and might be used as a molecular marker for evaluating HCC susceptibility.

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49 Based on the results of DNA sequence analysis, the c.3751G>Agenetic variant is a non-synonymous mutation, which caused by G toAmutations in exon29 of human MDR1 gene and led to the valine (Val) to isoleucine (Ile) amino acid replacement (p.Val1251Ile, Reference sequences GenBank IDs: NG_011513.1, NM_000927.4 and NP_000918.2). Login to comment
74 Sequence analyses indicate that this genetic variant results into the p.Val1251Ile amino acid replacement. Login to comment

[hide] Impact of Genetic Polymorphisms of ABCB1 (MDR1, P-... Clin Pharmacokinet. 2015 Jul;54(7):709-35. doi: 10.1007/s40262-015-0267-1. Wolking S, Schaeffeler E, Lerche H, Schwab M, Nies AT
Impact of Genetic Polymorphisms of ABCB1 (MDR1, P-Glycoprotein) on Drug Disposition and Potential Clinical Implications: Update of the Literature.
Clin Pharmacokinet. 2015 Jul;54(7):709-35. doi: 10.1007/s40262-015-0267-1., [PMID:25860377]

Abstract [show]
ATP-binding cassette transporter B1 (ABCB1; P-glycoprotein; multidrug resistance protein 1) is an adenosine triphosphate (ATP)-dependent efflux transporter located in the plasma membrane of many different cell types. Numerous structurally unrelated compounds, including drugs and environmental toxins, have been identified as substrates. ABCB1 limits the absorption of xenobiotics from the gut lumen, protects sensitive tissues (e.g. the brain, fetus and testes) from xenobiotics and is involved in biliary and renal secretion of its substrates. In recent years, a large number of polymorphisms of the ABCB1 [ATP-binding cassette, sub-family B (MDR/TAP), member 1] gene have been described. The variants 1236C>T (rs1128503, p.G412G), 2677G>T/A (rs2032582, p.A893S/T) and 3435C>T (rs1045642, p.I1145I) occur at high allele frequencies and create a common haplotype; therefore, they have been most widely studied. This review provides an overview of clinical studies published between 2002 and March 2015. In summary, the effect of ABCB1 variation on P-glycoprotein expression (messenger RNA and protein expression) and/or activity in various tissues (e.g. the liver, gut and heart) appears to be small. Although polymorphisms and haplotypes of ABCB1 have been associated with alterations in drug disposition and drug response, including adverse events with various ABCB1 substrates in different ethnic populations, the results have been majorly conflicting, with limited clinical relevance. Future research activities are warranted, considering a deep-sequencing approach, as well as well-designed clinical studies with appropriate sample sizes to elucidate the impact of rare ABCB1 variants and their potential consequences for effect sizes.

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67 Only a few reports have described the functional consequences of rare variants in cell models, e.g. variants 266T[C (rs35810889, p.M89T), 1199G[A/T/C (rs2229109, p.S400N/I/T), 1985T[G (rs35657960, p.L662R), 2005C[T (rs35023033, p.R669C), 3322T[C (rs35730308, p.T1108R) and 3751G[A (rs28364274, p.V1251I) [50-52]. Login to comment

[hide] Genetic polymorphisms of the multidrug resistance ... Tumour Biol. 2015 Aug;36(9):7007-15. doi: 10.1007/s13277-015-3407-1. Epub 2015 Apr 12. Wang ZC, Liu LZ, Liu XY, Hu JJ, Wu YN, Shi JY, Yang LX, Duan M, Wang XY, Zhou J, Fan J, Gao Q
Genetic polymorphisms of the multidrug resistance 1 gene MDR1 and the risk of hepatocellular carcinoma.
Tumour Biol. 2015 Aug;36(9):7007-15. doi: 10.1007/s13277-015-3407-1. Epub 2015 Apr 12., [PMID:25861753]

Abstract [show]
A possible association between multiple drug resistance 1 gene (MDR1) polymorphisms and the risk of developing hepatocellular carcinoma (HCC) is currently under debate, and evidence from various epidemiological studies has yielded controversial results. To derive a more precise estimation of the association between MDR1 polymorphisms and HCC risk, the present meta-analysis was performed. A total of 8 studies containing 11 cohorts with 4407 cases and 4436 controls were included by systematic literature search of EMBASE, PubMed, Web of Science, and CNKI. All polymorphisms were classified as mutant/wild-type alleles. In particular, the variation type, functional impact, and protein domain location of the polymorphisms were assessed and used as stratified indicators. The pooled odds ratio (OR) with 95 % confidence interval (CI) was calculated to evaluate the association. Overall, our results suggested that the mutant alleles of the MDR1 gene were associated with a significantly increased risk for HCC under all genetic models (allelic model: OR = 1.28, 95 % CI = 1.20-1.36, P < 0.001; dominant model: OR = 1.27, 95 % CI = 1.16-1.38, P < 0.001; recessive model: OR = 1.59, 95 % CI = 1.36-1.85, P < 0.001). Furthermore, increased risks for HCC were also revealed in stratified analyses by ethnicity, sample size, and quality scores of cohorts as well as variation type, functional impact, and protein domain location of polymorphisms. In conclusion, the present meta-analysis suggested that the presence of MDR1 mutant alleles might be a risk factor for HCC.

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80 Positions in different coding Table 1 Characteristics of the studies and cohorts included in the meta-analysis Name of studies Country Ethnicity Type of case/control Genotyping method Quality scores Age Male/female ratio Variant site Genotype frequency of case/control HWE Case Control Case Control 1/1 1/2 2/2 Mean SD Mean SD Chen Y [29] China Chinese HCC a /HP PCR-RFLP 6 55.8 14.7 54.5 13.9 91/9 90/10 2677G>T/A 18/19 56/53 26/28 0.492 Minoru F-1 [30] Japan Japanese HCC b /HP PCR-SSCP 8 70 7 - - 43/15 61 2677G>T/A 12/16 29/30 17/15 0.900 Minoru F-2 [30] Japan Japanese HCC b /HP PCR-SSCP 8 70 7 - - 43/15 61 3435C>T 16/14 29/39 13/8 0.023 Ren YQ [31] China Chinese HCC a /HP CRS-PCR 7 58.7 11.3 55.8 15.6 512/177 499/181 4125A>C 299/312 289/303 101/65 0.487 Gao J-1 [32] China Chinese HCC a /HP CRS-PCR 7 57.9 13.7 53.5 14.9 278/75 269/66 335T>C 141/172 150/128 62/35 0.132 Gao J-2 [32] China Chinese HCC a /HP CRS-PCR 7 57.9 13.7 53.5 14.9 278/75 269/66 3073A>C 116/155 158/139 79/41 0.261 Rui J [33] China Chinese HCC a /HP MALDI-TOF-MS 8 46 - 48 - 95/14 90/19 1236C>T 19/22 54/48 36/39 0.310 Yang D-1 [34] China Chinese HCC a /HP CRS-PCR 8 59.2 14.3 58.3 15.3 418/287 429/297 159G>T 312/342 298/308 95/76 0.591 Yang D-2 [34] China Chinese HCC a /HP CRS-PCR 8 59.2 14.3 58.3 15.3 418/287 429/297 1465C>T 294/367 306/292 105/67 0.420 Li XF [35] China Chinese HCC a /HP CRS-PCR 8 58.6 14.5 59.1 13.5 409/236 445/213 3751G>A 283/325 271/286 91/47 0.136 Wan YY [36] China Chinese HCC a /HP CRS-PCR 8 57.7 13.2 58.6 14.2 399/233 435/210 1564A>T 278/311 266/276 88/58 0.772 Total 4407 4436 1788/2055 1906/1902 713/479 1/1, 1/2, and 2/2 represent wild homozygous genotype, wild/mutant heterozygous genotype, and mutant homozygous genotype, respectively HCC hepatocellular carcinoma, HP healthy people, CHC chronic hepatitis C, CHB chronic hepatitis B, B-^ unclear, PCR-RFLP polymerase chain reaction-restriction fragment length polymorphism, PCR-SSCP polymerase chain reaction-single-strand conformation polymorphism, CRS-PCR created restriction site-polymerase chain reaction, MALDI-TOF-MS matrix-assisted laser desorption ionization timeof-flight mass spectrometry a Hepatitis B-related HCC b Hepatitis C-related HCC Table 2 Characteristics of the MDR1 polymorphisms included in the meta-analysis Studies Polymorphism site Exon location Variation type A.A. alteration FI a FI score a Feature key P. location description b P. function description b Chen Y [29] 2677G>T/A Exon 21 Nonsynonymous S893A Neutral -0.98 Topological domain Cytoplasmic ABC transmembrane type 1 S893T Low 1.66 Topological domain Cytoplasmic ABC transmembrane type 1 Minoru F-1 [30] 2677G>T/A Exon 21 Nonsynonymous S893A Neutral -0.98 Topological domain Cytoplasmic ABC transmembrane type 1 S893T Low 1.66 Topological domain Cytoplasmic ABC transmembrane type 1 Minoru F-2 [30] 3435C>T Exon 26 Synonymous - - - Topological domain Cytoplasmic ABC transporter Ren YQ [31] 4125A>C Exon 28 Nonsynonymous E1211A Low 1.805 Topological domain Cytoplasmic ABC transporter Gao J-1 [32] 335T>C 5'-UTR Noncoding - - - - - - Gao J-2 [32] 3073A>C Exon 22 Nonsynonymous L860F Medium 2.715 Transmembrane Helical ABC transmembrane type 1 Rui J [33] 1236C>T Exon 12 Synonymous - - - Topological domain Cytoplasmic ABC transporter Yang D-1 [34] 159G>T Exon 5 Synonymous - - - Transmembrane Helical ABC transmembrane type 1 Yang D-2 [34] 1465C>T Exon 14 Nonsynonymous R489C Medium 1.97 Topological domain Cytoplasmic ABC transporter Li XF [35] 3751G>A Exon 28 Nonsynonymous V1251I Neutral -0.365 Topological domain Cytoplasmic ABC transporter Wan YY [36] 1564A>T Exon 15 Nonsynonymous T522S Low 1.42 Topological domain Cytoplasmic ABC transporter A.A. amino acid, FI functional impact, ABC ATP-binding cassette a The functional impact is evaluated using online MutationAssessor.org b Location of SNP in the protein structure is assessed by Uniprot.org online service sequence subgroup analyses revealed that cytoplasmic polymorphisms correlated with a significantly higher HCC risk (cytoplasmic subgroup: OR=1.28, 95 % CI 1.19-1.37; P<0.00001), whereas transmembrane polymorphisms exhibited site-specific results (Gao J-2, 2013: OR=1.65, 95 % CI 1.32-2.05, P<0.0001; Yang D-1, 2013: OR=1.65, 95 % CI 0.98-1.33, P=0.10). Login to comment