Acute intermittent porphyria (AIP) is a rare autosomal dominant metabolic disorder affecting the production of heme, the oxygen-binding prosthetic group of hemoglobin. It is characterized by a deficiency of the enzyme porphobilinogen deaminase. Acute intermittent porphyria is the second most common form of porphyria (porphyria cutanea tarda being the most common). Its incidence is estimated to be between 5 and 10 in 100,000, but this is likely underestimated because of positive cases not being induced, and long periods of latency, with an estimation that it is latent in 90% of cases.