HPD and liver failure: Nitisinone, which inhibits the HGA-producing enzyme 4-hydroxyphenylpyruvate dioxygenase (HPPD; EC 1.13.11.27), has been the licensed treatment for hereditary tyrosinaemia type 1 (HT-1; OMIM #276700) since 2002, where fumarylacetoacetate hydroxylase (FAH; EC 3.7.1.2) deficiency results in liver failure, hepatocellular carcinoma and renal tubular dysfunction (17).