Effects of UGT1A4 genetic polymorphisms on serum lamotrigine concentrations in Chinese children with epilepsy

Lamotrigine (LTG) is widely used in the treatment of children with epilepsy. Genetic polymorphisms in genes encoding drug-metabolizing enzymes may be an important source of interindividual variability in LTG metabolism. The aim of this study was to evaluate the effects of genetic polymorphisms of uridine diphosphate glucuronosyltransferase (UGT) 1A4 (UGT1A4) gene on LTG serum concentrations in children with epilepsy. The UGT1A4 142T > G in the coding regions and −219C > T/-163G > A in the 5’-upstream regions were genotyped using polymerase chain reaction amplification followed by direct automated DNA sequencing in 148 patients treated with polytherapy with LTG and valproic acid (VPA). Our data showed that patients carrying the variant UGT1A4 -219C > T/-163G > A genotypes or alleles had significantly higher adjusted LTG concentrations than those carrying the wild-type genotypes or alleles. However, the significant association was abrogated after adjusted by age, body weight, and adjusted VPA concentration. No associations were detected between the UGT1A4 142T > G genotypes or alleles and adjusted LTG concentrations. Taken together, these results suggest that the −219C > T/-163G > A mutations in the 5’-upstream regions of the UGT1A4 gene affect LTG pharmacokinetics, with which is potentially interfered by age, body weight, and concomitant VPA administration.