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.

Inclusion Criteria:

• Willing and able to give informed consent

• 12 years of age or older

• Willingness to provide blood/saliva and urine samples, and clinical information

• A member of an AIP family, defined as (must meet one of the following):

  1. proband: possesses an AIP pathogenic mutation and is/has been symptomatic (experienced acute attacks in the opinion of the investigator)
  2. Parents (no known HMBS mutations or heterozygote with familial mutation)
  3. First, second, or third degree relative of (a) or (b)

A member of an AIP family who possesses an AIP pathogenic mutation and is/has been symptomatic (experienced acute attacks). Parents with no known HMBS mutations or heterozygote with familial mutation or a first, second or third degree relative of the above.

Not feasible.