Two patients with COMT inhibitor–induced hepatic dysfunction and UGT1A9 genetic polymorphism

The authors report two cases of catechol-O-methyltransferase (COMT) inhibitor-induced asymptomatic hepatic dysfunction in women with Parkinson disease. The patients were genotyped for the UDP-glucuronosyltransferase (UGT) 1A9 gene (which encodes the main COMT inhibitor-metabolizing enzyme), and found to carry mutations leading to defective glucuronidation activity. This suggests that UGT1A9 poor metabolizer genotype(s) may be a predisposing factor for COMT inhibitor-induced hepatotoxicity