A genome-wide scan for common genetic variants with a large influence on warfarin maintenance dose.
Warfarin dosing is correlated with polymorphisms in vitamin K epoxide reductase complex 1 (VKORC1) and the cytochrome P450 2C9 (CYP2C9) genes. Recently, the FDA revised warfarin labeling to raise physician awareness about these genetic effects. Randomized clinical trials are underway to test genetically based dosing algorithms. It is thus important to determine whether common single nucleotide polymorphisms (SNPs) in other gene(s) have a large effect on warfarin dosing. A retrospective genome-wide association study was designed to identify polymorphisms that could explain a large fraction of the dose variance. White patients from an index warfarin population (n = 181) and 2 independent replication patient populations (n = 374) were studied. From the approximately 550 000 polymorphisms tested, the most significant independent effect was associated with VKORC1 polymorphisms (P = 6.2 x 10(-13)) in the index patients. CYP2C9 (rs1057910 CYP2C9*3) and rs4917639) was associated with dose at moderate significance levels (P approximately 10(-4)). Replication polymorphisms (355 SNPs) from the index study did not show any significant effects in the replication patient sets. We conclude that common SNPs with large effects on warfarin dose are unlikely to be discovered outside of the CYP2C9 and VKORC1 genes. Randomized clinical trials that account for these 2 genes should therefore produce results that are definitive and broadly applicable.
Cooper
Gregory M
GM
Department of Genome Sciences, University of Washington, Seattle, WA98195, USA.
Johnson
Julie A
JA
Langaee
Taimour Y
TY
Feng
Hua
H
Stanaway
Ian B
IB
Schwarz
Ute I
UI
Ritchie
Marylyn D
MD
Stein
C Michael
CM
Roden
Dan M
DM
Smith
Joshua D
JD
Veenstra
David L
DL
Rettie
Allan E
AE
Rieder
Mark J
MJ
D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics; D065729:Cytochrome P-450 CYP2C9; D023281:Genomics / Q000379:methods*; D005838:Genotype; D006801:Humans; D006899:Mixed Function Oxygenases / Q000235:genetics; D010597:Pharmacogenetics / Q000379:methods; D020641:Polymorphism, Single Nucleotide; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D064417:Vitamin K Epoxide Reductases; D014859:Warfarin / Q000008:administration & dosage*
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