Variegate porphyria.

Variegate porphyria is an autosomal dominant inherited trait resulting in decreased activity of protoporphyrinogen oxidase. It is characterized clinically by photosensitive skin disease and a propensity to acute neurovisceral crises. The disease is found worldwide but has an exceptionally high frequency in South Africa. The gene for human protoporphyrinogen oxidase has been identified and sequenced, and several mutations in the protoporphyrinogen oxidase gene sequence have been identified. In South Africa, fewer patients now present with acute attacks, leaving a greater proportion with skin disease or asymptomatic disease. Acute attacks of variegate porphyria appear to be less easily provoked and to be milder than those associated with acute intermittent porphyria.