Background: This study was designed to verify whether the glutathione S-transferase (GST) genotypes affect mild hepatotoxicity in valproic acid (VPA)-treated patients.
Methods: The association between the GSTM1 and GSTT1 genotypes, and the levels of aminotransferases and total bilirubin was retrospectively investigated in 149 Japanese epileptic patients treated with VPA.
Results: The adjusted odds ratio (OR) of the GSTM1- vs. GSTM1+ genotype and the GSTM1-/GSTT1-vs. GSTM1+/GSTT1+ genotypes for gamma-glutamyltransferase (GGT) increase over the upper limit of normal were 2.8 [95% confidence interval (CI): 1.1-7.2] and 6.5 (95% CI: 1.5-28.0), respectively. The GSTT1 genotypes alone did not significantly affect the liver function tests. The alanine aminotransferase, aspartate aminotransferase and (gamma-glutamyltransferase) GGT levels in patients treated with VPA >6 months were significantly higher in the GSTM1- than GSTM1+ genotype. The GGT levels were significantly higher in the older subjects receiving polytherapy, and the effects of the polytherapy and age were greater in the GSTM1- genotype.
Conclusions: The GSTM1- and GSTM1-/GSTT1- genotypes may be a genetic risk factor for the increase of GGT in VPA-treated patients. However, it was not possible to clarify whether the GGT increase was caused by VPA-induced hepatotoxicity or not.