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Hereditary Angioedema

Hereditary angioedema (HAE) is a rare but serious genetic disorder.

It is largely caused by a deficiency or malfunction of the certain proteins (C1 esterase inhibitors) in the blood. The condition causes recurrent episodes of swelling, particularly of the face and the upper airways, and abdominal pain.

Hereditary angioedema is similar to allergic angioedema, with the rapid swelling of areas beneath the skin. However, hives don’t appear, and the causes are different.

Hereditary angioedema results from the low level or malfunction of the C1 esterase inhibitors, the proteins that help to regulate the normal flow of fluids in blood vessels. Rapid swelling of tissues happens when blood or lymphatic fluid leaks and accumulates outside the vessels. The condition is usually passed down from generation to generation in a family.

Dental procedures, illnesses (such as colds and the flu), surgery, infections, medications (such as aspirin or NSAIDs), hormonal changes, and emotional stress may trigger attacks. The attack often involves the same part of the body as the triggering factor, like dental work may bring on symptoms around the face or throat.

Edema usually develops gradually over a couple of days, peaks over the first 24 hours, and subsides within 72 hours. However, some episodes of swelling may seem spontaneous and persist for a week.


Symptoms usually start during childhood and become more severe later in adolescence. Attacks could happen regularly every month or may be random. Between the attacks, a patient could be completely well.

SKIN SWELLING. Typically, swelling occurs around the face, lips, tongue, hands or feet, and genitals and resolves in 1 to 3 days. Hives do not occur.

AIRWAYS SWELLING. The membrane lining of the mouth, throat, and the upper airways swell causing trouble breathing, swallowing, and talking. These are the most dangerous symptoms because they can lead to suffocation. If symptoms are severe and sudden, you should seek medical attention immediately.

ABDOMINAL SWELLING. Swelling in the GI tract can often be an overlooked condition in people with undiagnosed HAE. When the lining of the digestive tract is affected, it can lead to nausea, vomiting, severe abdominal cramps, are diarrhea.


As this is a life-threatening condition, a proper and timely diagnosis is crucial. If angioedema is encountered without urticaria (itchy hives), laboratory analysis of blood or genetic samples are required to establish a diagnosis: C4 level and C1 inhibitor level/function tests. A specialist will also consider the appearance of the symptoms, a patient diary, and family and medical history.


Conventional treatment, such as antihistamines and corticosteroids that treat allergic angioedema doesn't work well for HAE. For routine prophylaxis, injections with the active substance of the C1 inhibitor are given to replace the deficient protein in severely affected patients.

Because the symptoms and severity of hereditary angioedema vary greatly, many patients are required individualized care to manage the condition.

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