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 types of the disorder.

 In type I, representing 85% of patients, serum levels of C1NH are less than 35% of normal.
 In type II, the levels are normal or elevated, but the protein is nonfunctional. The two types are clinically indistinguishable.

Eiology

 hereditary angioedema is caused by mutation in the C1 inhibitor gene (C1NH) (MIM.606860).

Associations

 benign or malignant B-cell lymphoproliferative disorders -* chronic lymphocytic leukemia

• multiple myeloma

 essential cryoglobulinemia