C3435T polymorphism of MDR1 gene with warfarin resistance

Background: Some patients show warfarin resistance needing more than 70 mg of warfarin per week. In this study, we examined if C3435T polymorphism of MDR1 gene could be a factor of warfarin resistance. Methods: We examined 196 blood specimens from the patients who took warfarin more than 42 mg/week for at least 1 year. The subjects consisted of 74 European Americans, 59 African Americans, 42 Hispanic Americans and 21 Asian Americans. Genotype of C3435T polymorphism was determined by using real-time polymerase chain reaction (PCR). Results: Ninety (45.9%) of the 196 patients had C3435T genotype and the remaining patients had 0435C genotype (35.7%) and T3435T genotype (18.4%). Mean dose of warfarin of patients with C3435C, C3435T and T3435T genotypes were 59.5 mg/week, 56.9 mg/week and 55.6 mg/week, respectively. There was no statistical difference in the dose of warfarin between the 3 genotypes within each race. Conclusion: Our results suggest that C3435T polymorphism of MDR1 gene is not associated with warfarin resistance. (C) 2013 Published by Elsevier B.V.