EPP is a rare condition, and the most acute indication for which we are exploring a clinical treatment with afamelanotide. Simply put, EPP is an absolute light intolerance brought about by a build up of photosensitive compounds in the skin of the sufferer.
It manifests itself during or after exposure to sunlight as swelling, burning, itching and redness of the skin. The major symptom however, and the most difficult to live with, is extreme and intense pain following exposure to light (particularly blue light, 400-410nm).
EPP is an hereditary genetic condition that mostly becomes active during childhood, but is difficult to diagnose in the young. This is because younger sufferers often do not experience the visible symptoms of swelling and redness of the skin, just intense pain. Because of this they can be mis-diagnosed, referred to psychologists or have their reactions suspected to be behavioural.
It tends to effect sufferers most noticeably on their face and hands, areas that are often exposed to light. Repeated or extreme reactions to light and the damage brought about by phototoxic reactions can result in varying degrees of scarring and thickening of the skin.
Study and understanding of EPP is made difficult by both its rarity and difficulties in diagnosis, but progress is being made.
It appears that the body’s natural production of heme is central to EPP. Heme carries out many essential functions in the body, one of which is the transportation of oxygen via haemoglobin. It is created in red cells and its synthesis relies on the interaction of enzymes and various molecules to create the porphyrin we call heme.
The development of heme involves several stages of synthesis before completion. EPP sufferer’s bodies are unable to finish this synthesis, resulting in a buildup of incomplete heme molecules. These molecules are known as protoporphyrin (PPIX) and they gather in the skin. PPIX molecules are highly photosensitive, meaning that when exposed to light they become phototoxic, and begin reacting destructively.
We have seen that afamelanotide may be of great benefit to those diagnosed with EPP by providing photoprotection of the skin. Our hope is that with treatment, EPP sufferers will be able to lead fuller and more active outdoor lives, without the constant risk of cutaneous phototoxic reactions.
References:
http://en.wikipedia.org/wiki/Erythropoietic_protoporphyria
http://photoprotection.clinuvel.com/node/41
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