3. A diagnosis of acute intermittent porphyria, hereditary coproporphyria or variegate porphyria confirmed by the following criteria, which are based on the criteria for enrollment in the Longitudinal Study of the Porphyrias Consortium. For each type of porphyria, the inclusion criteria are based on 1) clinical features, 2) biochemical findings, as documented by laboratory reports (or copies) of porphyria-specific testing, and 3) molecular studies to identify a mutation in a porphyria-related gene. Equivocal biochemical measurements may require confirmatory testing. Testing for a disease-causing mutation must be attempted, but an identified mutation is not essential for enrollment, since it is known that a mutation cannot be found in a small fraction (<5%) of biochemically proven cases of porphyria.