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.

Additional recommended knowledge

Essential Laboratory Skills Guide

What is the Sensitivity of my Balance?

Daily Visual Balance Check

Symptoms and presentation

A common symptom is very 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. People with EPP are also at increased risk to develop gallstones^[1]. 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.

Experimental treatments

As of 2007 A company in Australia named Clinuvel Pharmaceuticals Limited is performing clinical trials with a melanocyte-stimulating hormone named melanotan (which they refer to as CUV1647) for EPP. ^[2][3]

History

Erythropoietic protoporphyria was first identified in 1960 by Magnus et al at the St John's Institute of Dermatology in London.^[4]

References

1. ^ 12-160d. at Merck Manual of Diagnosis and Therapy Home Edition
2. ^ Erythropoietic - British Association of Dermatologists
3. ^ Clinuvel reports first positive Phase II clinical trial results of CUV1647 in new indication - Erythropoietic Protoporphyria (EPP)PDF
4. ^ Magnus IA, Jarrett A, Prankerd TA, Rimington C. Erythropoietic protoporphyria. A new porphyria syndrome with solar urticaria due to protoporphyrinaemia. Lancet 1961;2:448-51. PMID 13765301.

• Overview of condition at NLM Genetics Home Reference