Hereditary angioedema (HAE, is an autosomal dominant disorder characterized by episodic local subcutaneous edema and submucosal edema involving the upper respiratory and gastrointestinal tracts. There are 2 classic types of the disorder. In type I, representing 85% of patients, serum levels of C1NH are less than 35% of normal (Cicardi and Agostoni, 1996Bowen et al., 2001). In type II, the levels are normal or elevated, but the protein is nonfunctional. The 2 types are clinically indistinguishable.

See 300145 for a discussion of angioedema induced by ACE inhibitors.

Zuraw (2008) provided a detailed review of the clinical features, management, and pathogenesis of hereditary angioedema.