Abstract: Objective: To investigate the association between EPHX1 rs4653436（G＞A） polymorphism and inter-individual warfarin maintenance dose. Methods: The genotypes of 217 patients with stable warfarin dose were determined by using of a PCR/DHPLC genotyping assay. The warfarin maintenance doses were compared among patients with different genotypes. Results: In the total of 217 patients, the numbers of GG, GA and AA genotype were 141, 72 and 4, with the frequencies of 64.4%, 32.9% and 1.8%, respectively. The frequencies of G and A allele were 81.6% and 18.4%, respectively. The mean stable doses of patients with GG, GA and AA genotype were 2.84±1.19 mg/d, 2.91±1.09 mg/d and 2.66±1.29 mg/d respectively. There was no significant difference (P=0.483) in mean stable dose among the three genotype groups (P=0.856). Conclusion: EPHX1 rs4653436（G＞A）polymorphism may be not a genetic factor that influence the inter-individual warfarin maintenance dose.

Key words: EPHX1, genotyping, warfarin, personalized medicine