The porphyrias are a group of rare inherited or acquired disorders of certain enzymes that normally participate in the production of porphyrins and heme. They manifest with either neurological complications or skin problems, or occasionally both. Porphyrias are classified in two ways, by symptoms and by pathophysiology. Symptomatically, acute porphyrias primarily present with nervous system involvement, often with severe abdominal pain, vomiting, neuropathy and mental disturbances. Cutaneous porphyrias present with skin manifestations often after exposure to sun due to the accumulation of excess porphyrins near the surface of the skin. Physiologically, porphyrias are classified as hepatic or erythropoietic based on the sites of accumulation of heme precursors, either in the liver or bone marrow and red blood cells. The term 'porphyria' is derived from the Greek , porphyra, meaning 'purple pigment'.
Contributions by Jfdwolff, Nunh-huh, and Cheryln.