Disease Overview

Hereditary angioedema (HAE) is a debilitating, multisystem inherited disease caused by low levels of the functional plasma protein complement-1 esterase inhibitor (C1-INH).1

HAE is known to generate episodic, non-pruritic, non-pitting edema that usually involves the extremities but may affect any external body surfaces, commonly including the genitalia, the face, and the lips.2

Acute attacks of intestinal edema can result in severe abdominal pain due to mucosal swelling. However, the most serious attacks involve the larynx. Laryngeal attacks can lead to complete obstruction of the airway and death from asphyxiation.3

Types of HAE

The variants of HAE related to C1-INH function are:

  • Type I: affecting 85% of those with HAE and characterized by low antigenic and functional plasma levels of a normal C1-INH protein
  • Type II: affecting 15% of those with HAE and characterized by the presence of normal or elevated antigenic levels of a dysfunctional mutant protein together with reduced levels of the functional protein
  • Type III: affecting only female patients and characterized by normal functional levels of C1-INH, yet showing the classic signs and symptoms of HAE. 2,4

Acquired type I or type II HAE is very rare and is due to immune complexes that are usually linked to an underlying lymphoproliferative disorder.4


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Symptoms of HAE

HAE is characterized by recurrent attacks of localized edema, involving subcutaneous tissue, the intestines, the face, the hands, the feet, the genitalia, and the larynx. Read more about symptoms of HAE.

Diagnosis and treatment

HAE is a rare disease that is often misdiagnosed because its symptoms mimic those of several common conditions. Treatment includes management of acute attacks and prophylaxis. Learn more.