Overview of epidemiology, pathophysiology, and disease progression in hereditary angioedema.

Hereditary angioedema (HAE) is an autosomal dominant disease caused by a deficiency in functional C1 inhibitor affecting an estimated 1 in 50,000 individuals in the United States. The disease is characterized by recurrent episodes of nonpruritic swelling of the hands, feet, arms, legs, trunk, face, genitalia, bowels, and larynx beginning in childhood or adolescence and continuing throughout the patient's lifetime. There is significant variability in both the severity and frequency of edema attacks. Untreated patients may suffer an attack as often as every few days, while patients undergoing prophylactic therapy may be symptom free for a decade or more. Although disease awareness has increased following the US Food and Drug Administration approval in 2009 of a new treatment for acute HAE attacks, delayed diagnosis, misdiagnosis, and inappropriate treatment remain significant problems. This article reviews the pathophysiology, symptoms and clinical course, and diagnostic challenges of HAE.