| 1. |
- Perera, Minoli A., et al.
(författare)
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Genetic variants associated with warfarin dose in African-American individuals : a genome-wide association study
- 2013
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 382:9894, s. 790-796
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Tidskriftsartikel (refereegranskat)abstract
- Background VKORC1 and CYP2C9 are important contributors to warfarin dose variability, but explain less variability for individuals of African descent than for those of European or Asian descent. We aimed to identify additional variants contributing to warfarin dose requirements in African Americans. Methods We did a genome-wide association study of discovery and replication cohorts. Samples from African-American adults (aged >= 18 years) who were taking a stable maintenance dose of warfarin were obtained at International Warfarin Pharmacogenetics Consortium (IWPC) sites and the University of Alabama at Birmingham (Birmingham, AL, USA). Patients enrolled at IWPC sites but who were not used for discovery made up the independent replication cohort. All participants were genotyped. We did a stepwise conditional analysis, conditioning first for VKORC1 -1639G -> A, followed by the composite genotype of CYP2C9*2 and CYP2C9*3. We prespecified a genome-wide significance threshold of p<5x10(-8) in the discovery cohort and p<0.0038 in the replication cohort. Findings The discovery cohort contained 533 participants and the replication cohort 432 participants. After the prespecified conditioning in the discovery cohort, we identified an association between a novel single nucleotide polymorphism in the CYP2C cluster on chromosome 10 (rs12777823) and warfarin dose requirement that reached genome-wide significance (p=1.51x10(-8)). This association was confirmed in the replication cohort (p=5.04x10(-5)); analysis of the two cohorts together produced a p value of 4.5x10(-12). Individuals heterozygous for the rs12777823 A allele need a dose reduction of 6.92 mg/week and those homozygous 9.34 mg/week. Regression analysis showed that the inclusion of rs12777823 significantly improves warfarin dose variability explained by the IWPC dosing algorithm (21% relative improvement). Interpretation A novel CYP2C single nucleotide polymorphism exerts a clinically relevant effect on warfarin dose in African Americans, independent of CYP2C9*2 and CYP2C9*3. Incorporation of this variant into pharmacogenetic dosing algorithms could improve warfarin dose prediction in this population.
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| 2. |
- Parra, Esteban J., et al.
(författare)
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Genome-wide association study of warfarin maintenance dose in a Brazilian sample
- 2015
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Ingår i: Pharmacogenomics (London). - : Future Medicine Ltd. - 1462-2416 .- 1744-8042. ; 16:11, s. 1253-1263
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Extreme discordant phenotype and genome-wide association (GWA) approaches were combined to explore the role of genetic variants on warfarin dose requirement in Brazilians. Methods: Patients receiving low (<= 20 mg/week; n = 180) or high stable warfarin doses (>= 42.5 mg/week; n = 187) were genotyped with Affymetrix Axiom (R) Biobank arrays. Imputation was carried out using data from the combined 1000 Genomes project. Results: Genome-wide signals (p <= 5 x 10(-8)) were identified in the well-known VKORC1 (lead SNP, rs749671; OR: 20.4; p = 1.08 x 10(-33)) and CYP2C9 (lead SNP, rs9332238, OR: 6.8 and p = 4.4 x 10(-13)) regions. The rs9332238 polymorphism is in virtually perfect LD with CYP2C9*2 (rs1799853) and CYP2C9*3 (rs1057910). No other genome-wide significant regions were identified in the study. Conclusion: We confirmed the important role of VKORC1 and CYP2C9 polymorphisms in warfarin dose.
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| 3. |
- Cavallari, Larisa H., et al.
(författare)
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Association of the GGCX (CAA) 16/17 repeat polymorphism with higher warfarin dose requirements in African Americans
- 2012
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Ingår i: Pharmacogenetics & Genomics. - 1744-6872 .- 1744-6880. ; 22:2, s. 152-158
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Tidskriftsartikel (refereegranskat)abstract
- Objective Little is known about genetic contributors to higher than usual warfarin dose requirements, particularly for African Americans. This study tested the hypothesis that the gamma-glutamyl carboxylase (GGCX) genotype contributes to warfarin dose requirements greater than 7.5 mg/day in an African American population.Methods A total of 338 African Americans on a stable dose of warfarin were enrolled. The GGCX rs10654848 (CAA) n, rs12714145 (G>A), and rs699664 (p.R325Q); VKORC1 c.-1639G>A and rs61162043; and CYP2C9*2, *3, *5, *8, *11, and rs7089580 genotypes were tested for their association with dose requirements greater than 7.5mg/day alone and in the context of other variables known to influence dose variability.Results The GGCX rs10654848 (CAA) 16 or 17 repeat occurred at a frequency of 2.6% in African Americans and was overrepresented among patients requiring greater than 7.5 mg/day versus those who required lower doses (12 vs. 3%, P = 0.003; odds ratio 4.0, 95% confidence interval, 1.5-10.5). The GGCX rs10654848 genotype remained associated with high dose requirements on regression analysis including age, body size, and VKORC1 genotype. On linear regression, the GGCX rs10654848 genotype explained 2% of the overall variability in warfarin dose in African Americans. An examination of the GGCX rs10654848 genotype in warfarin-treated Caucasians revealed a (CAA) 16 repeat frequency of only 0.27% (P = 0.008 compared with African Americans).Conclusion These data support the GGCX rs10654848 genotype as a predictor of higher than usual warfarin doses in African Americans, who have a 10-fold higher frequency of the (CAA) 16/17 repeat compared with Caucasians. Pharmacogenetics and Genomics 22: 152-158 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.
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| 4. |
- Sangkuhl, Katrin, et al.
(författare)
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PharmVar GeneFocus : CYP2C9
- 2021
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Ingår i: Clinical Pharmacology and Therapeutics. - : John Wiley & Sons. - 0009-9236 .- 1532-6535. ; 110:3, s. 662-676
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Tidskriftsartikel (refereegranskat)abstract
- The Pharmacogene Variation Consortium (PharmVar) catalogues star (*) allele nomenclature for the polymorphic human CYP2C9 gene. Genetic variation within the CYP2C9 gene locus impacts the metabolism or bioactivation of many clinically important drugs, including nonsteroidal anti-inflammatory drugs, phenytoin, antidiabetic agents, and angiotensin receptor blockers. Variable CYP2C9 activity is of particular importance regarding efficacy and safety of warfarin and siponimod as indicated in their package inserts. This GeneFocus provides a comprehensive overview and summary of CYP2C9 and describes how haplotype information catalogued by PharmVar is utilized by the Pharmacogenomics Knowledgebase and the Clinical Pharmacogenetics Implementation Consortium.
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| 5. |
- Takahashi, Harumi, et al.
(författare)
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Correlations between the enantio- and regio-selective metabolisms of warfarin
- 2017
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Ingår i: Pharmacogenomics (London). - : Future Medicine Ltd. - 1462-2416 .- 1744-8042. ; 18:2, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To clarify whether the activities of multiple CYPs associated with warfarin metabolism would be correlated with each other. Methods: Oral clearances (CLpo) of warfarin enantiomers were estimated in 378 Chinese, Caucasians and African-Americans. The partial metabolic clearances (CLm) for 7-hydroxywarfarin enantiomers were also measured. In addition, CLpo and CLm were determined in a patient on warfarin and rifampicin. Results: Correlations between CLpo for warfarin enantiomers existed across the three populations. In addition, there was a significant correlation between the CLm for 7-hydroxylation of warfarin enantiomers. Under induced conditions by rifampicin, there were significant correlations between the enantio-and regio-selective metabolisms of warfarin. Conclusion: Metabolic activities of CYP2C9, CYP1A2 and CYP3A4 may be regulated by common transcriptional mechanism(s).
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