Acute intermittent porphyria
Acute intermittent porphyria (AIP) is caused by a partial deficiency of the enzyme porphobilinogen deaminase (PBGD), also known as hydroxymethylbilane synthase (HMBS), which is inherited as an autosomal dominant trait, leading to the accumulation of porphyrin precursors.
AIP can be triggered or worsened by hormonal contraceptives, particularly those containing estrogen and/or progesterone, due to the potential for these hormones to increase the activity of an enzyme involved in porphyrin synthesis, leading to a buildup of toxic precursors.