Acute intermittent porphyria

Acute intermittent porphyria is a rare inherited metabolic disorder affecting the body's production of heme, the iron-containing molecule central to hemoglobin, caused by a deficiency of the enzyme porphobilinogen deaminase. It is the most common of the group of disorders known as the acute porphyrias. The deficiency stems from mutations in the HMBS gene on chromosome 11, more than a hundred of which have been identified, and it is inherited in an autosomal dominant pattern, though only about one in ten people who carry the mutated gene ever experience an acute attack. When attacks occur they most often bring severe abdominal pain and a rapid heartbeat, sometimes alongside neurological or psychiatric symptoms, and they are typically first diagnosed around age thirty-three, more often in women than men.