Prevalence of UGT1A6 polymorphisms in children with epilepsy on valproate monotherapy

Background: Valproate is a commonly used anticonvulsant drug. Uridine 5′-diphospho (UDP)-glucuronosyltransferase (UGT) contributes to around 50% of valproate metabolism and its polymorphisms may be important for explaining the considerable variation in valproate levels in patients with epilepsy. Aim: This study was aimed to analyze the genetic polymorphisms of UGT1A6 in Indian children with epilepsy and their potential influence on the pharmacokinetics of valproate. Setting and Design: This cross-sectional study was carried out in the Department of Pediatrics, All India Institutes of Medical Sciences (AIIMS), New Delhi, between March 2011 and July 2012. Materials and Methods: Children aged 3-12 years diagnosed with epilepsy on valproate monotherapy for at least 1 month were enrolled. They underwent a detailed clinical examination. The UGT1A6 polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Random samples were checked by genetic sequencing. The steady-state plasma concentrations of valproate were measured by High Performance Liquid Chromatography (HPLC) and associated with UGT1A6 polymorphisms. Results: A total of 80 children were studied. The prevalence of UGT1A6 T19G was as follows: TT (45%), TG (38.8%), and GG (16.3%); that of UGT1A6 A541G was: AA (48.8%), AG (38.8%), and GG (12.5%); and that of UGT1A6 A552C was: AA (43.8%), AC (40%), and CC (16.3%). The association between valproate doses or standardized serum valproate concentration and the various UGT1A6 genotypes could not be studied reliably in this small study population. Conclusions: The frequencies of UGT1A6 geneotypes and alleles were reported in the study population.