Protoporphyria.

Human protoporphyria results from mutations in the ferrochelatase gene. Heritable deficiency of ferrochelatase causes overproduction of protoporphyrin IX, principally in the erythron. Photosensitivity is a universal feature of protoporphyria but hepatic clearance of the hydrophobic protoporphyrin molecule with excretion in bile may lead to precipitation within biliary pathways. Thus cholestatic injury and protoporphyrin gallstones occur. Minor hepatic abnormalities are frequent, but at least 30 patients have been reported with a progressive liver disease that requires transplantation. Fulminant hepatic disease appears to be recessively inherited in some pedigrees. Hazards of liver transplantation include tissue photolysis, hemolysis, and an unexplained neurological syndrome, but most of the 15 patients reported after transplantation have survived for several months to > 6 years. Aspects of protoporphyria, its pathogenesis and contemporary therapeutic strategies are considered, with emphasis on hepatic sequelae.