Key Points
Î Most cases of hereditary angioedema (HAE) result from a deficiency of the
serine protease inhibitor, C1 inhibitor (C1INH). (LB)
Î HAE is caused by mutations in the C1INH gene, resulting in a C1INH
functional deficiency. (LB)
Î HAE is an autosomal dominant disease. Most patients with HAE have a
positive family history of angioedema. (A)
Î Two forms of HAE, which are indistinguishable clinically, can be diagnosed
by laboratory findings: type I HAE presents with low C1INH antigenic
and functional levels, whereas type II HAE presents with normal C1INH
antigenic levels but decreased C1INH functional levels. (A)
Î Diagnosis of type I or type II HAE requires evidence of low C1INH antigenic
or functional levels, as well as decreased C4 levels and generally normal
C1q levels. (A)
Î Onset of swelling in HAE most often begins during childhood and frequently
worsens around puberty. (C)
Î HAE is characterized by relatively prolonged attacks of angioedema involving
the extremities, genitourinary tract, abdomen, face, oropharynx or larynx. (C)
Î The primary mediator of swelling in HAE is bradykinin. (A)
Î Disease severity in HAE is highly variable, characterized by episodic rather
than continuous swelling. (D)
Î A precipitating cause for most episodes of HAE attacks is unknown, but
stress and trauma have been clearly recognized as precipitants. (D)
Î Attacks of swelling in HAE generally involve the extremities, abdomen,
genitourinary tract, face, oropharynx, or larynx and follow a stereotypical
pattern in which the swelling worsens over 24 hours, peaks, then slowly
resolves over the following 48-72 hours. (A)
Î Attacks of HAE may be preceded by a prodrome. (C)
Î HAE attacks are associated with significant potential morbidity and
potential mortality. (A)
Î Optimal management of HAE depends on early identification of patients. (D)
