The purpose of this long-term follow-up study is to collect a large group of patients with the different types of porphyria and to provide a better understanding of the natural history of these disorders. The hope is that this information will help in developing new forms of treatment.

The purpose of this study is to collect information on acute porphyria attacks that may have been caused by a medication. Individuals who have tested positive for an acute porphyria, or have been told by a doctor that they may have the disease may join this study. We are particularly interested in the following: (1) Attacks that appeared to be due to a specific medication; (2) Use of a medication that is considered risky in porphyria but caused no problems; and (3) Use of medications for which the safety profile in porphyria is unknown.

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.