Valproate-induced hepatic failure in a case of cytochrome c oxidase deficiency.

We report a 3 year-old girl with a myoclonic epilepsy. A fatal hepatic failure occurred after 3 months of valproate (VPA) therapy. In this patient, a defect of cytochrome c oxidase (COX) was demonstrated in her circulating lymphocytes. The enzyme was also found to be deficient in post-mortem liver and in cultured skin fibroblasts. However, a fully functional respiratory chain was found in muscle. VPA administration apparently triggered the hepatic failure, given this patient's background of partial COX deficiency.