What is acquired angioedema (AAE) due to C1 inhibitor (C1-INH) deficiency (C1-INH-AAE)?

Updated: May 20, 2020
  • Author: Amanda T Moon, MD; Chief Editor: William D James, MD  more...
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Acquired angioedema (AAE) due to acquired C1-inhibitor (C1-INH) deficiency (C1-INH-AAE) is a rare disorder caused by acquired consumption of C1-INH. It is clinically characterized by recurrent episodes of nonpitting asymmetric edema of the face, lips, tongue, limbs, and genitals; severe abdominal pain due to edema of the gastrointestinal mucosa; and life-threatening edema of the upper respiratory tract. It is not associated with urticaria and is not an immunoglobulin E (IgE)‒mediated process.

Acquired angioedema was first described by Caldwell et al in 1972. The three key elements that initially characterized acquired angioedema were acquired deficiency of C1-INH, hyperactivation of the classic pathway of human complement, and recurrent angioedema symptoms. [1]

Two distinct syndromes are described below. Both types of acquired angioedema (AAE) without urticaria are characterized by painless, nonpruritic, nonpitting swelling of the skin. They are classified into 2 forms: acquired angioedema type I (AAE-I) and acquired angioedema type II (AAE-II).

Acquired angioedema type I is associated with other diseases, most commonly B-cell lymphoproliferative disorders. Acquired angioedema type II is an autoimmune process defined by the presence of an autoantibody directed against the C1 inhibitor molecule (C1-INH).

See the image below.

Angioedema secondary to ACE inhibitors. Angioedema secondary to ACE inhibitors.

Go to Angioedema, Pediatric Angioedema, Acute Angioedema, and Hereditary Angioedema for complete information on this topic.

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