Coproporphyrinogen Oxidase（CPOX) which is localized to the internal membrane space of erythrocytes takes part in the 6th phase of heme biosynthesis. CPOX catalyzes the oxidative decarboxylation of propionic acid side chains of rings A and B of coproporphyrinogen III. Mutations in human CPOX gene forecast the clinical result of the disease， with either hepatic hereditary coproporphyria or hematological manifestations of erythropoietic harderoporphyria.
