Hereditary angioedema (HAE), also known as C1 inhibitor (C1-INH) deficiency, is a rare autosomal dominant condition. The prevalence of the disease has been estimated to be approximately 1 in 50,000,with no gender predominance and no known differences in prevalence among ethnic groups.2 HAE is characterized by the occurrence of subcutaneous and submucosal edema in any part of the skin, respiratory and gastrointestinal tracts. Edema is self-limited and more commonly occurs in the extremities. Abdominal pain, nausea and vomiting are the dominant symptoms in HAE due to constriction caused by edema of the intestinal wall and mesentery.2 Episodes of swelling may also involve the upper respiratory tract, including the tongue, pharynx and larynx. In HAE patients, laryngeal edema can be life threatening due to asphyxiation and it can occur at any age.2,3 Edema can be precipitated by minor trauma to the tissue, such as dental work, infection, certain drugs such as estrogen or angiotensin converting enzyme inhibitors, as well as emotional stress.3

HAE is caused by mutations in the SERPING1 gene (also known as C1NH), which codes for C1 inhibitor (C1-INH) protein.4 Two types of HAE that have been described according to C1-INH activity and levels. In HAE Type I, accounting for 80-85% of all patients, C1-INH protein quantity is decreased by nearly 35%.1,4 In HAE Type II, serum levels of the protein are normal or elevated, but activity is reduced. A third type, HAE III, is associated with possible X-linked dominant inheritance and has been seen primarily in women.1,2,5 The Ambry Test HAE AMPLIFIED™ is designed to detect mutations in the SERPING1 gene known to cause HAE Type I and Type II.