Porphyria variegata: Study of a large kindred in the United States

Ninety-one members of a large family with porphyrla variegata were studied in the United States. Sixty-seven responded by sending stool and urine specimens for quantitation of porphyrins and precursors. Six members, in whom the cases were manifest, had either abdominal, cutaneous and/or neurologic symptoms. A cousin of the propositus died after surgery from respiratory failure during an acute attack which was precipitated by the administration of porphyrogenic drugs, Pentothal ®, Seconal ® and Nembutal ®. An additional seven members were classified as having latent cases, 13 as having probable latent cases and 11 as having questionable cases according to their porphyrin excretion pattern. Comparison of the ‘gene penetration’ in this kindred with porphyria variegata in the United States with that of the South African variety revealed a similar incidence of 50 per cent in the second and third generation. However, in the younger fourth generation, only 12 per cent of those who had a porphyric parent and were 19 years of age or older were affected. This may be explained by the possibility that in the fourth generation inapparent cases may be included among questionable cases which may be found to be latent in later years. Assays for a specific enzyme defect in porphyria variegata would help to differentiate the disease in this younger age group. A systematic investigation of a family with porphyria variegata is reported here in an attempt to show the impression of the disease that exists in the United States. The incidence of porphyria variegata in our country may be greater than recognized.