Warfarin is an anticoagulant that inhibits vitamin K-dependent clotting factors including factor (F) II, FVII, FIX and FX. Different factors can change the effect of this anticoagulant in clinic. Therefore we assessed impact of VKORC1 -1639 G>A polymorphism and demographic factors on required maintenance dose in Iranian patients under warfarin therapy. The study population included 95 patients with a mean age of 61.3 ± 12.6 years. Target INR range of 2-3 was considered for these patients. The frequency of VKORC1 -1639 G>A polymorphism was assessed by polymerase chain reaction-restriction length polymorphism (PCR-RFLP). Finally the obtain data were analyzed by SPSS software. Our study revealed that 30.5%, 49.5%, and 20% of the patients had VKORC1 (G/G), (G/A), and (A/A) genotypes, respectively. Carriers of VKORC1 G/G genotype required a higher warfarin dose as compared to A/A carriers (4.48 ± 1.32 and 2.7 ± 1.16 mg/day, respectively; P < 0.01). In addition, patients with higher age required lower warfarin therapeutic dose (r = - 0.3, P < 0.01). It seems that -1639 G>A polymorphism and demographic variables had significant effects on warfarin maintenance dose in Iranian patients under warfarin therapy.
Keywords: Bleeding; Thrombosis; Vitamin K epoxide reductase complex subunit 1; Warfarin.