Porphyria refers to a group of diseases that affect fewer than 200,000 people. Acute Hepatic Porphyria (AHP) refers to a family of rare genetic diseases characterized by potentially life-threatening attacks and, for some people, chronic (ongoing and sometimes lifelong) pain and other symptoms that interfere in their ability to live normal lives.

There are four types of AHP:

Acute Intermittent Porphyria (AIP – makes up 80% of all cases)
Variegate Porphyria (VP)
Hereditary Coproporphyria (HCP)
ALAD Deficiency Porphyria (ADP)

AHP is a hereditary disease, meaning that it can be passed from parents to children. This can occur if either one or both parents carry the defective gene, depending on the AHP type. Men and women inherit the disease equally as often; however, women tend to suffer symptoms more often than men.