HAE is a very rare and potentially life-threatening genetic condition.

In the absence of sufficient functional C1-INH, there is inadequate inhibition of factor XIIa, factor XIIf and kallikrein, resulting in a dramatically augmented formation of bradykinin, the mediator of the swelling characteristic of HAE.

HAE symptoms include episodes of swelling in various body parts including the hands, feet, face, and airway. In addition, patients often have bouts of excruciating abdominal pain, nausea, and vomiting that is caused by swelling in the intestinal wall. Airway swelling is particularly dangerous and can lead to death by asphyxiation.