@article{02d9c7a11a46461fa861af5ccd04bd5b,
title = "VKORC1 polymorphims, haplotypes and haplotype groups on warfarin dose among African-Americans and European-Americans",
abstract = "Background: Although the influence of VKORC1 and CYP2C9 polymorphisms on warfarin response has been studied, variability in dose explained by CYP2C9 and VKORC1 is lower among African-Americans compared with European-Americans. This has lead investigators to hypothesize that assessment of VKORC1 haplotypes may help capture a greater proportion of the variability in dose for this under-represented group. However, the inadequate representation of African-Americans and the assessment of a few VKORC1 polymorphisms have hindered this effort. Methods: To determine if VKORC1 haplotypes or haplotype groups explain a higher variability in warfarin dose, we comprehensively assessed VKORC1 polymorphisms in 273 African-Americans and 302 European-Americans. The influence of VKORC1 polymorphisms, race-specific haplotypes and haplotype groups on warfarin dose was evaluated in race-stratified multivariable analyses after accounting for CYP2C9 (*2, *3, *5, *6 and *11) and clinical covariates. Results: VKORC1 explained 18% (30% with CYP2C9) variability in warfarin dose among European-Americans and 5% (8% with CYP2C9) among African-Americans. Four common haplotypes in European-Americans and twelve in African-Americans were identified. In each race VKORC1 haplotypes emerged into two groups: low-dose (Group A) and high-dose (Group B). African-Americans had a lower frequency of Group A haplotype (10.6%) compared with European-Americans (35%, p < 0.0001). The variability in dose explained by VKORC1 haplotype or haplotype groups was similar to that of a single informative polymorphism. Conclusions: Our findings support the use of CYP2C9, VKORC1 polymorphisms (rs9934438 or rs9923231) and clinical covariates to predict warfarin dose in both African- and European-Americans, A uniform set of common polymorphisms in CYP2C9 and VKORC1, and limited clinical covariates can be used to improve warfarin dose prediction for a racially diverse population.",
keywords = "African-Americans, CYP2C9, Cohort study, European-Americans, Haplotypes, Pharmacogenetics, VKORC1, Warfarin",
author = "Limdi, {Nita A.} and Beasley, {T. Mark} and Crowley, {Michael R.} and Goldstein, {Joyce A.} and Rieder, {Mark J.} and Flockhart, {David A.} and Arnett, {Donna K.} and Acton, {Ronald T.} and Nianjun Liu",
year = "2008",
doi = "10.2217/14622416.9.10.1445",
language = "English",
volume = "9",
pages = "1445--1458",
number = "10",
}