title: Genetic and clinical predictors of warfarin dose requirements in African Americans.
abstract: The objective of this study was to determine whether, in African-American patients, additional vitamin K oxidoreductase complex subunit 1 (VKORC1), cytochrome P450 2C9 (CYP2C9), CYP4F2, or apolipoprotein E (APOE) polymorphisms contribute to variability in the warfarin maintenance dose beyond what is attributable to the CYP2C9*2 and *3 alleles and the VKORC1 -1639G>A genotype. In a cohort of 226 African-American patients, weekly warfarin dose requirements were lower in those with the CYP2C9*8 allele (34 (30-47) mg; P = 0.023) and the CYP2C9 *2, *3, *5, *6, or *11 allele (33(28-40 mg); P < 0.001) as compared with those with the CYP2C9*1/*1 genotype (43 (35-56) mg). The combination of CYP2C9 alleles, VKORC1 -1639G>A genotype, and clinical variables explained 36% of the interpatient variability in warfarin dose requirements. By comparison, a model without the CYP2C9*5, *6, *8, and *11 alleles explained 30% of the variability in dose. No other VKORC1, CYP4F2, or APOE polymorphism contributed to the variance. The inclusion of additional CYP2C9 variants may improve the predictive ability of warfarin dosing algorithms for African Americans.
authors.affiliation: Department of Pharmacy Practice, University of Illinois at Chicago, Chicago, Illinois, USA. humma@uic.edu
authors.forename: L H
authors.initials: LH
authors.lastname: Cavallari
authors.forename: T Y
authors.initials: TY
authors.lastname: Langaee
authors.forename: K M
authors.initials: KM
authors.lastname: Momary
authors.forename: N L
authors.initials: NL
authors.lastname: Shapiro
authors.forename: E A
authors.initials: EA
authors.lastname: Nutescu
authors.forename: W A
authors.initials: WA
authors.lastname: Coty
authors.forename: M A G
authors.initials: MA
authors.lastname: Viana
authors.forename: S R
authors.initials: SR
authors.lastname: Patel
authors.forename: J A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000328:Adult; D001741:Black or African American / Q000235:genetics; D000368:Aged; D000465:Algorithms; D000483:Alleles; D000925:Anticoagulants / Q000008:administration & dosage*; D001057:Apolipoproteins E / Q000235:genetics*; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D065729:Cytochrome P-450 CYP2C9; D004305:Dose-Response Relationship, Drug; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D006899:Mixed Function Oxygenases / Q000235:genetics*; D011110:Polymorphism, Genetic; D064417:Vitamin K Epoxide Reductases; D014859:Warfarin / Q000008:administration & dosage*
chemical_list: D000925:Anticoagulants; D001057:Apolipoproteins E; D014859:Warfarin; D006899:Mixed Function Oxygenases; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C578523:VKORC1 protein, human; D064417:Vitamin K Epoxide Reductases