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Hereditary Angioedema

Angioedema is the medical term for a sudden swelling of the skin or mucous membranes. It is by no means rare. In fact, it is estimated that as many as 20-25% of men and women will experience it at some point in their lives. In most cases, angioedema are related in some way to an allergic reaction and are caused by the action of the mediator substance of allergies, histamine.

There are, however, other types of swellings of the skin and mucous membranes that are not allergy-related and not mediated by histamine. These kinds of angioedema called Hereditary Angiooedema (HAE) , these swellings are much rarer and patients may suffer from them for many years before their true cause is recognised. HAE is an inherited disorder caused by a specific mutation in the affected person’s genetic code. The gene in question is responsible for the production of an enzyme known as C1- inhibitor (C1-INH). C1-INH is an important protein that regulates a variety of metabolic processes in the body. As a result of the underlying genetic mutation, persons suffering from HAE either produce too little C1-INH or a type of C1-INH that does not function properly. One of the effects of C1-INH is to prevent an excessive production of bradykinin. Virtually all patients with angioedema experience swellings of the skin. Most commonly affected are the extremities (arms, legs, hands, feet), the face and the genital organs. More than 70% of the swellings suffered by HAE patients affect the mucous membranes of the internal organs, which is reported to be extremely painful. Swelling attacks involving the mouth or neck can be life-threatening, especially when they affect the larynx.

There are two currently available options for the treatment of acute angioedema attacks: bradykinin

Icatibant (bradykinin B2-receptor antagonist):
Bradykinin, which increases the permeability of the vascular wall for fluid, is present in abnormally high quantities in patients with HAE. Icatibant blocks the bradykinin B2 receptors on the cells of the blood vessel walls, which in turn prevents the swelling caused by the actions of bradykinin. The medication is injected into the subcutaneous adipose tissue in a manner similar to that of an insulin injection.

C1- inhibitor (C1-INH) concentrate:
Patients with HAE have too little C1-inhibitor (C1-INH) or the C1-INH present in their systems does not function correctly. Because of this deficiency, the body produces excessive amounts of bradykinin, with the result that they are at risk of swelling of the skin and mucous membranes. C1-INH concentrate is either injected into a vein or administered as an intravenous infusion. It temporarily replaces the body’s own deficient C1-esterase inhibitor.

The goal of the EAACI task force “HAE “ is to improve the patient´s care by rising awareness in the general population and medical professionals (manuscripts) and by providing an international emergency card for patient´s with HAE. This card is backed up by an informative website (see the draft of site at www.hae-info.net).

For more information see www.angiooedem.net