**Hereditary Angioedema**

Asli Gelincik and Semra Demir

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.68208

#### **Abstract**

Hereditary angioedema (HAE) is an autosomal dominantly inherited orphan disease manifested by recurrent unpredictable nonpitting and nonpruritic swelling attacks with‐ out urticarial plaques. HAE is caused by a deficiency of the C1 esterase inhibitor (C1‐inh) or decreased function of C1‐inh. Type 1 HAE, the most common form, occurs due to C1‐inh deficiency and is seen with low‐serum C1‐inh levels. In type 2 HAE, the function of C1‐inh is impaired, and in HAE with normal C1‐inh serum levels, the function of C1‐ inh is normal. HAE episodes can affect various sites in the body such as the larynx, face, extremities, gastrointestinal tract, and urogenital area. Acute episodes can be treated with C1‐inh concentrates, a kallikrein inhibitor, called ecallantide and bradykinin B2 receptor antagonist, icatibant. Depending on the frequency, severity, and location of the episodes, long‐term prophylaxis regimens with plasma‐derived C1‐inh concentrates, antifibrino‐ lytics, or 17α‐alkylated androgens can be used. C1‐inh concentrates or 17α‐alkylated androgens should be administered before dental procedures and minor or major surgical interventions to provide short‐term prophylaxis. In conclusion, HAE is a rare life‐threat‐ ening disease of which clinical presentation is highly variable and early accurate diagno‐ sis significantly prevents mortality and morbidity.

**Keywords:** hereditary angioedema, C1‐inhibitor, bradykinin, complement, orphan disease
