Erythropoietic Protoporphyria: Mike and Mat’s Stories
Mike and Mat visited FDA with Dr. Robert Desnick and talked about living with Erythropoietic Protoporphyria (EPP).
EPP is a rare genetic disorder caused by a defect in the enzyme ferrochelatase, which is responsible for metabolizing protoporphyrin, a precursor of hemoglobin (the protein in red blood cells that carries oxygen). Since people with EPP cannot properly metabolize protoporphyrin, it builds up in the body and causes two primary symptoms: (1) sensitivity to light typically appearing in childhood and (2) liver disease.
Swelling, burning, itching, and redness of the skin may appear during or after exposure to sunlight, some artificial lights, and computer screens. This can cause mild to severe burning pain on exposed areas of the skin. Usually, these symptoms subside in 12 to 24 hours and heal without significant scarring or discoloration of the skin. These symptoms generally begin during childhood, and tend to be more severe in the summer and can recur throughout life. Other problems may include gallstones containing protoporphyrin and severe liver complications. The diagnosis of EPP is made by testing levels of protoporphyrin in the blood. Mutation analysis of the ferrochelatase and aminolevulinate synthase genes are available in the United States.
Shielding skin from sunlight by using protective clothing and lifestyle adjustments is recommended to reduce exposure. Because the wavelengths of light causing porphyrin-sensitized phototoxicity are chiefly in the visible spectrum, window glass is not an effective barrier. Topical sunscreens are not effective unless transmission of long ultraviolet (UV) and visible light rays is reduced by their use. Sun-blocking formulations containing zinc oxide or titanium dioxide reflect visible light and may be helpful. Induction of endogenous melanin by exposure of skin to broad- or narrow-band UVB lamps or to UVA in conjunction with a psoralen UVA photosensitizer also may increase tolerance to natural sunlight. The only treatment approved by the FDA is Lumitene, a synthetic beta-carotene formulation.
Mike talks about how he was first diagnosed with EPP. He also describes how accumulated protoporphyrin in the skin of EPP patients is affected by certain bands of light energy, which leads to the various symptoms of tingling, stinging, or burning and may be followed by redness and swelling of the skin.
Dr. Desnick discusses how EPP is diagnosed currently and the underlying genetic abnormalities associated with EPP. Mat talks about his first episode with symptoms of EPP and how difficult it was to grow up with EPP.
Mike and Mat talk about living with EPP and why and how they try to avoid exposure to light.
Dr. Desnick talks about how EPP affects the skin and liver of people who have EPP. He also describes the difference between EPP and other types of porphyria.
Mike and Mat talk about other treatments that they have tried such as beta carotene and sunscreen and their hope for finding additional treatments for EPP.