Hereditary angioedema (HAE) is a hereditary, special form (autosomal dominant or new mutation) of Quincke's edema. It is characterized by transient and recurrent subcutaneous and / or submucosal edema, which causes swelling of the face, limbs, larynx or gastrointestinal tract. The cause is a mutation in chromosome 11, which causes a deficiency of the C1-esterase inhibitor (C1-INH).
Three types can be distinguished.
Type I is most common, with an absolute deficiency of C1-INH.
Type II is a functional deficiency, in which a malfunction of the C1-INH in sufficient amount occurs.
Type III is extremely rare and is found mainly in women with elevated levels of estrogen (e.g. during pregnancy or while using contraceptive birth control pills). There is no C1-INH deficiency in this form.
The C1-esterase inhibitor plays a crucial role in the complement system. Among other things, it regulates the production of bradykinin. This peptide hormone is responsible for the dilatation and permeability of vessels. Dysregulation of bradykinin release leads to edema spontaneously or through certain trigger stimuli.
At the same time, smooth muscle contractions are triggered, causing cramping and pain. The skin edema is often reddened and painful but it does not itch. Triggers may be insect stings, iatrogenic interventions, stress, infections, medications or other body-damaging triggers.
An edema develops very fast, but it disappears after 3-5 days. Especially life threatening is the angioedema in the larynx, which requires immediate intervention. The first swelling attacks usually occur before the age of 30, and already infants and toddlers may be affected.