Erythropoietic Protoporphyria (EPP), is characterized by severe pain in the skin with exposure to sunlight and some forms of artificial light.

People with protoporphyria first experience tingling, itching, or burning which is a warning sign to avoid further light exposure. With ongoing exposure, the symptoms progress to severe pain that may be followed by swelling or redness. The most common areas affected include the back of the hands and the face.

The amount of sunlight tolerance varies between people with some able to tolerate only a few minutes and others who can stay out in the sun for much longer.

Symptoms typically appear in childhood. EPP is equally common in males and females.

In EPP, a molecule called protoporphyrin (PPIX) accumulates in the bone marrow, where blood cells are made. The protoporphyrin is then transported throughout the body in the blood plasma and red blood cells. When it passes through the blood vessels in your skin, it reacts to sunlight and initiates a painful reaction that can last for several days. Protoporphyrin can also be deposited and build up in the liver and bile, which can lead to liver damage.

Symptoms are triggered when skin is exposed to sunlight and some types of artificial light. Light can be reflected off snow or water, or be coming through a window.

People can first experience tingling, itching, or burning which is like a warning sign (prodrome) to avoid further sun exposure. With ongoing exposure, the symptoms generally progress to severe pain that may be followed by swelling or redness. The most common areas affected include the back of the hands and the face.

Reactions can include:

• Severe pain and burning when skin is exposed to light

• Swelling and sometimes reddening of the skin in affected areas

• Increased sensitivity to things such as wind, temperature and light after a reaction

• Babies and young children may be irritable, cry or scream when outside or in bright light, and irritability continues once they’re brought inside

Over time, skin on knuckles and face can thicken and scar. Patients may develop thickened skin on palms and soles of feet. Rarely, skin lesions and discoloration can occur.

EPP can also cause complications related to liver and gallbladder.