[Uroporphyrinogen decarboxylase in erythrocytes: studies on the primary genetic enzyme defect in chronic hepatic porphyria (author's transl)].

In chronic hepatic porphyria, including the clinical phase, porphyria cutanea tarda, the activity of uroporphyrinogen decarboxylase is decreased not only in the liver, but also in the erythrocytes. The synonomous decrease in the enzymic activity in liver and erythrocytes in both familial and sporadic hepatic porphyria shows that the disturbance of this enzyme is the primary genetic defect of this condition; inheritance of the defect is probably autosomal and dominant. The clinical manifestation of disturbances of porphyrin metabolism are precipitated, however, by additional factors, such as liver damage, alcohol, oestrogens and neoplastic growths. In the absence of these other pathogenic influences, the enzyme defect is compensated and does not result in disturbances of haem or haemoglobin synthesis, either in the liver or the bone marrow.