This study proposes to identify the predisposing/protective modifying genes that underlie the acute attacks in symptomatic patients with Acute Intermittent Porphyria (AIP), an autosomal dominant inborn error of heme biosynthesis.

The objective of this protocol is to conduct a longitudinal multidisciplinary investigation of the human porphyrias including the natural history, morbidity, pregnancy outcomes, and mortality in people with these disorders.