Abstract
The mechanism of regulation of heme biosynthesis is of great interest for both biological and medical reasons. The hepatic and eythropoietic porphyrias are shown to be hereditary or acquired disorders characterized by defects in specific enzymes of the heme biosynthetic pathway. In addition, several other diseases can be associated with a defect of heme biosynthesis. Heme has become well established in the treatment of acute porphyrias. In recent years, heme has been used increasingly for the treatment of other heme deficiency states as well.