Hereditary angioedema

Definition – what is hereditary angioedema?

Angioedema is a swelling of the skin and/or mucous membrane that can occur acutely and particularly in the area of the face and respiratory tract. It can last for several days. A distinction is made between a hereditary and a non-hereditary form.

Hereditary means hereditary, inherited or congenital. Hereditary angioedema is therefore a disease caused by a genetic defect that can be inherited from one generation to the next. Inheritance is autosomal-dominant, which means that the disease is transmitted regardless of gender as soon as one of the two parents is affected by it.

In about 25% of cases, however, the disease does not occur through inheritance but as a spontaneous mutation. This means that there is a spontaneous genetic change which then causes the disease. Hereditary angioedema can become life-threatening if there is a sudden severe swelling in the area of the respiratory tract. The frequency of the disease is about 1:50. 000, although in reality a higher frequency is assumed.

Causes of hereditary angioedema

The cause of hereditary angioedema is a genetic defect. This defect affects a gene that codes for a certain enzyme, i.e. it is responsible for producing this enzyme. This enzyme is called a C1 esterase inhibitor or C1 esterase inhibitor.

The consequence of the gene defect is either an enzyme deficiency or an enzyme that is present but not functional. Which factors can trigger an acute disease attack is still not sufficiently clarified. It is a fact that the enzyme C1 ester phase inhibitor plays an important role in the complement system.

This is a part of the body’s own immune system. A deficiency of this C1-esterase inhibitor leads to a kind of hypersensitivity of this part of the immune system. This triggers a cascade, at the end of which the tissue hormone bradykinin is found.

This hormone leads to an increased permeability of blood vessels (vascular permeability). This in turn leads to increased fluid escaping from the vessels into the surrounding tissue. This leads to the typical swelling of the skin and mucous membrane.