Prevention of murine erythropoietic protoporphyria-associated skin photosensitivity and liver disease by dermal and hepatic ferrochelatase.

Erythropoietic protoporphyria (EPP) is caused by a defect in ferrochelatase, leading to the accumulation of protoporphyrin predominantly in erythrocytes and hepatocytes, and resulting in skin photosensitivity upon leaching of blood protoporphyrin into the skin. Some patients also develop severe liver damage. Because the respective contributions of hepatic and erythrocytic protoporphyrin to the pathophysiology of EPP remain unclear, we investigated this question using the murine model of EPP.

Long-term treatment of erythropoietic protoporphyria with cysteine.

A Phase III 3 year placebo-controlled trial, in which patients were blinded as to when placebo was given, was conducted to determine if the administration of L-cysteine-HCl was effective in preventing or ameliorating the photosensitivity associated with erythropoietic protoporphyria. Forty-seven patients participated in the trial. Placebo was administered in the first month of the trial and then 500 mg of cysteine was given in two divided doses per day for the duration of the study.