Associations between MDR1 C3435T polymorphism and drug-resistant epilepsy in the Polish population.

Epilepsy is a common neurological disorder. About one-third of epileptic patients demonstrate multidrug resistance (MDR) phenotype and develop drug-resistant epilepsy (DRE). Single nucleotide polymorphism (SNP) C3435T (rs1045642), identified in the MDR1 gene, is associated with an increased intestinal expression of P-glycoprotein (P-gp) which affects the levels of anti-epileptic drugs in plasma. The reported study was designed to explore associations between the MDR1-C3435T gene SNP and the risk of DRE in the Polish population. The C3435T polymorphism of MDR1 gene was investigated by the PCR-RFLP technique in 74 patients with DRE and 70 age- and sex-matched non-DRE controls. Blood samples were obtained from patients with drug-resistant epilepsy, treated at the Department of Neurological Surgery, Medical University in Warsaw between the years 2011 and 2012. Odds ratios (ORs) and 95 % confidence intervals (CIs) were calculated for each genotype and allele. Genotype distribution of C3435T polymorphism of MDR1 gene was compared between the DRE patients and controls with significant differences (p < 0.05) between the two investigated groups. A possible association was observed between DRE and the presence of 3435C allele. The 3435C allele was found in 69 % of DRE cases and in 48 % of the used controls. The variant 3435T allele of MDR1 decreased the risk of drug-resistant epilepsy [odds ratio (OR) 0.41; 95 % confidence interval (CI) 0.26-0.67]. The results indicate that the C3435T polymorphism of MDR1 gene may be associated with the incidence of DRE observed in the Polish population.