Effect of Vkorc1-1639 G > A Polymorphism on Warfarin Response in East of Turkey

Objective: The aim of the present study was to investigate whether the VKORC1 -1639 G>A polymorphisms could determine differences in the warfarin dose required to maintain a therapeutic INR in patients living in east of Turkish.Methods: A total of 80 patients (45 female and 35 male) aged between 17 and 85 years (mean age 58.96 +/- 16.59 years) using warfarin for at least one month and presenting at Ataturk University Medical Faculty Outpatient Clinic between May 2009 and May 2010 were included in the study. Patients underwent genotype investigations and carrier forms of VKORC1 -1639 variants; homozygous (AA), heterozygous (GA) and wild types (GG) were determined.Results: In AA and GA groups, daily warfarin maintenance doses were statistically significant lower than in GG (p=0.010 and p=0.016, respectively). There was no significant difference between AA and GA groups regarding to warfarin dose (p>0.05). INR values were higher in GA and AA groups than in GG group and differences were statistically significant (p=0.014 and p=0.016, respectively). Also there was no difference between GA and AA gropus in terms of INR.Conclusion: In conclusion, our study verified the inter-individual variability in warfarin maintenance dose due to VKORC1-1639 G>A polymorphism in patients living in east of Turkish. In order to avoid serious bleeding events in warfarin therapy, prescription of warfarin should be done on an individual basis with consideration for the patient's genetic background.