Erythropoietic protoporphyria

Erythropoietic protoporphyria (EPP) is a relatively mild form of porphyria, although very painful, which arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the tissue. The severity varies significantly from individual to individual.

Both autosomal dominant and autosomal recessive inheritance have been reported with this disorder.

History
Erythropoietic protoporphyria was first identified in 1960 by Magnus et al at the St John's Institute of Dermatology in London.

Symptoms and presentation
A common symptom is painful photosensitivity, manifesting itself as a burning sensation on the surface of the skin. This usually first presents in childhood, and most often affects the face and the upper surfaces of the hands and feet. Prolonged exposure to the sun can lead to edema and blistering. After many years, chronically sun-exposed skin may become thick and wrinkled. In a small percentage of cases, protoporphyrin accumulates to toxic levels in the liver, leading to liver failure.

Treatment and prognosis
There is no cure for this disorder; however, symptoms can usually be managed by the simple expedient of limiting sun exposure. Protective clothing is also very helpful; however, since the photosensitivity results from light in the visible spectrum, most sunscreens (with the exception of light-reflecting substances such as zinc oxide) are of little use. Some individuals can decrease their sun sensitivity with daily doses of beta carotene; others gradually build a protective layer of melanin by regularly exposing themselves for short times to ultraviolet radiation. The most severe cases are sometimes treated with liver transplants. People with EPP are also at increased risk to develop gallstones.