The porphyrias

Abstract

The porphyrias are caused by hereditary defects in the synthesis of heme. Each porphyria is characterized by a unique enzyme defect and measurable elevations of specific heme precursors. While qualitatively normal, these precursors accumulate to cause protean signs and symptoms. Photosensitivity should raise the suspicion of a porphyria, especially in a child or a young adult. The skin, teeth and eyes may provide clues to the diagnosis in some cases.