Hereditary angioedema (HAE) is a condition characterized by recurrent episodes of angioedema affecting the upper airway, bowel wall, or skin, which typically last two to four days. The angioedema of HAE is mediated by bradykinin and does not respond to epinephrine, antihistamines, or glucocorticoids. Instead, first-line therapies for HAE act by replacing the C1 inhibitor (C1INH) that is deficient or dysfunctional in this disease or by inhibiting the production or function of bradykinin. HAE affects men and women equally. There are no known racial predilections. Although symptoms often begin in childhood, the disease is commonly diagnosed during puberty or early adulthood, when attacks become more frequent. An attack of HAE usually involves one site at a time (skin, viscera, or larynx). A prodrome of fatigue or erythematous rash is noticed by some patients. Attacks build in severity for 24 hours and then subside over the next 24 to 72 hours. Once attacks have begun, they generally continue throughout the patient's life, although the frequency of attacks can be dramatically reduced by therapy. The mortality rate for patients with HAE, despite effective therapies, has been estimated to be as high as 13 percent.
