Associations between the C3435T polymorphism of the ABCB1 gene and drug resistance in epilepsy: a meta-analysis

Objective: A meta-analysis was performed to comprehensively evaluate the correlations between the C3435T polymorphism of ABCB1 (the ATP-binding cassette, subfamily B, member 1 transporter gene) and drug resistance in epilepsy. Methods: Inclusion and exclusion criteria and a strategy for searching original literature were developed and utilized to search Chinese and non-Chinese databases. Research reports discussing correlations between the ABCB1 C3435T polymorphism and patient responses to anti-epileptic drug (AED) therapy were collected. Comparisons and comprehensive quantitative analyses were conducted using an allele model (C vs. T), and a genotype model (CC vs. CT+TT). In addition, subgroup analyses were performed that divided the included studies according to the race of the study subjects (Asian or Caucasian), based on the geographical region in which each study was conducted. Results: The meta-analysis included a total of 23 publications that examined a total of 3,912 drug-resistant epileptic patients and 4,419 epileptic patients for whom drug treatment was effective. The included studies did not exhibit publication bias. Statistical analyses revealed that the C3435T polymorphism was not significantly correlated with drug resistance in epilepsy. The random-effects model comparing the C and T alleles produced an odds ratio (OR) of 1.10 with a 95% confidence interval (CI) of 0.98-1.25 and P = 0.46. Subgroup analyses suggested that in Caucasian population there are significant differences between resistance group (RN) and control group (N) in both allele model (C vs T: OR = 1.13; 95% CI: 1.03-1.25) and genotype model (CC vs CT+TT: OR = 1.27; 95% CI: 1.08-1.50). Conclusion: The ABCB1 C3435T polymorphism is associated with drug resistance in epilepsy in Caucasian population.