ABCB1 and epilepsy: The ATP-binding cassette sub-family B member 1 (ABCB1, also known as MDR1) gene, which encodes human P-glycoprotein, can transport several AEDs.[9] In addition, previous studies have demonstrated that ABCB1 was also overexpressed in brain tissue from patients with refractory epilepsy, suggesting ABCB1 gene might be an important candidate gene responsible for refractory epilepsy.[10, 11] Siddiqui et al first reported that patients with drug-resistant epilepsy were more likely to have the CC genotype in C3435T variant, a well-known polymorphism in ABCB1 gene [12].