Acute hepatic porphyrias represent a sub-group of porphyrias (see this term) characterized by the occurrence of neuro-visceral attacks with or without cutaneous manifestations. Acute hepatic porphyrias encompass four diseases: acute intermittent porphyria (the most common), variagate porphyria, hereditary coproporphyria, and hereditary deficit of delta-aminolevulinic acid dehydratase (extremely rare) (see these terms).