Guide to porphyrias. A historical and clinical perspective.

Porphyrias are a group of inherited disorders of heme biosynthesis classified as neurovisceral, cutaneous, or mixed. A deficiency of any of the 8 enzymes in the biosynthetic pathway can lead to a variety of clinical symptoms. Classification depends on the defective enzyme. Porphyrias often are misdiagnosed because patients have vague symptoms. However, acute forms of porphyria can be life-threatening, so it is important to make an accurate diagnosis and initiate proper medical management. We discuss the history, pathogenesis, clinical manifestations, diagnosis, and treatment of porphyrias and then briefly describe the 8 types of porphyrias and their distinguishing features.