This result suggests that ABCC2 polymorphisms can affect valproic acid concentration and, consequently, treatment outcome in patients with epilepsy receiving valproic acid monotherapy.34 Yang et al reported that the ABCC2 rs2273697 polymorphism was significantly related to oxcarbazepine plasma concentration in the whole patient cohort and in patients stratified by age (P = 0 0.033).35 However, Shen et al36 reported that polymorphisms of ABCC2 rs2273697 were not associated with the concentrations and therapeutic efficacy of oxcarbazepine. Here, ABCC2 is linked to epilepsy.