[Familial and sporadic porphyria cutanea symptomatica (author's transl)].

The measurement of erythrocyte uroporphyrinogen decarboxylase is an easy method to divide porphyria cutanea symptomatica into two different types: (1) a familial type in which erythrocyte urodecarboxylase activity is reduced by about 50% in the patient and in apparently healthy members of his family, the inheritance pattern being consistent with an autosomal dominant trait; and (2) a more widespread sporadic type, with normal erythrocyte urodecarboxylase activity. In the familial type, the enzyme deficiency was found to be present in all tissues examined, whereas in the sporadic type it appears to be restricted to the liver.