A Systematic Review of ABCB1 Polymorphisms and Antiseizure Medication Resistance: Insights from Effect Size and Study Power Analysis.

The most investigated ABCB1 single-nucleotide polymorphisms (SNPs) related to antiseizure medication resistance are rs1045642 (c.3435C>T, p.Ile1145=), rs2032582 (c.2677G>T/A, p.Ala893Ser/Thr), and rs1128503 (c.1236C>T, p.Gly412=). We conducted a literature review to evaluate the genotype frequencies of rs1045642, rs2032582, and rs1128503 SNPs in different ancestries among the drug-resistant and drug-responsive epilepsy groups. Furthermore, we performed effect size and study power analyses and determined the expected sample size to reach a study power of 0.8 for each conducted research. High and very high statistical power for the rs1045642, rs2032582, and rs1128503 polymorphisms was achieved in 58.0, 60.7, and 31.8% of the studies, respectively. The effect sizes (ES) of rs1045642, rs2032582, and rs1128503 ranged from 0.03-1.04, 0.06-0.92, and 0.04-0.64, respectively. The required sample sizes for rs1045642, rs2032582, and rs1128503 ranged from 9-13,000, 12-2600, and 24-5700 participants, respectively. None of the polymorphisms showed a statistically significant association with antiseizure medication resistance in the forest plots. Our analysis provides valuable guidance for future genetic association studies in the field of drug-resistant epilepsy.