The rare genetic light disorder means that when skin comes into contact with the visible, coloured parts of sunlight, it causes neuropathic pain and triggers burns.
In patients, when exposed to sunlight, a precursor of the red blood pigment, protoporphyrin, is deposited in blood vessels.
Energy from visible light is absorbed and triggers a chemical reaction, which the person affected perceives as severe pain and which appears as burns on the skin.
