Association of MDR1 (C3435T) Polymorphism and Resistance to Carbamazepine in Epileptic Patients from Turkey

Abstract

We investigated the prevalence of this multidrug resistance 1 gene (MDR1) polymorphism in drug-responsive versus drug-resistant epilepsy patients treated with carbamazepine (CBZ), which is a substrate of this protein. We genotyped the C3435T variant of MDR1 in 97 patients treated with CBZ monotherapy who had been on stable doses for more than 1 month. Our control group included 174 healthy individuals. Plasma CBZ concentrations were also measured using fluorescence polarization immunoassay. We could not demonstrate any statistically significant relationship with the genotypes among drug-resistant patients (n = 44). The frequency of the homozygous mutant (TT) genotype was 15% in drug-responsive patients, 11.3% in drug-resistant patients and 25.8% in the control group. We also did not observe any significant correlation between the presence of a specific allele and CBZ plasma level/dose index. Our study did not support any significant association between the MDR1 (C3435T) polymorphism and resistance to CBZ in epilepsy patients from Turkey.