Effect of UGT1A6 and UGT2B7 polymorphisms on the valproic acid serum concentration and drug-induced liver injury

Aim: Valproic acid (VPA) is a classic broad-spectrum antiepileptic drug, with significant pharmacokinetic variability. Genetic polymorphisms contribute to this variability, influencing both VPA trough serum concentration (VPA concentration) and VPA-induced liver injury. Our study aims to investigate the association between polymorphisms of uridine diphosphate glucuronyl transferase (UGT) 1A6, UGT2B7 and VPA concentration and screen for potential genetic loci affecting VPA-induced liver injury. Methods: This study included epilepsy patients treated with VPA. PCR-RFLP method was used to determine the genotypes of UGT1A6 and UGT2B7. Chemiluminescent microparticle immunoassay was used to measure VPA concentration. Multiple linear regression and logistic regression were employed to analyze factors influencing VPA concentration and VPA-induced liver injury, respectively. Results: The correlation between UGT polymorphism and VPA concentration was analyzed in 133 samples. For VPA-induced liver injury, 105 patients were analyzed, with 29 in the liver injury group and 76 in the control group. Our finding showed patients with the UGT1A6-T19G variant had significantly lower VPA concentrations compared with wild-type patients and UGT1A6-T19G, A541G, A552C and UGT2B7-C802T, G211T, A268G polymorphisms showed no impact on VPA-induced liver injury. Conclusion: This study demonstrated UGT1A6-T19G polymorphisms affected the VPA concentration, providing a theoretical basis for the individualized clinical use of VPA. UGT1A6-T19G mutation had significantly lower VPA concentrations compared with wild-type patients. UGT1A6-T19G, A541G, A552C and UGT2B7-C802T, G211T, A268G polymorphisms showed no impact on VPA-induced liver injury.