Hereditary Angioedema

Hereditary angioedema, also referred to as Quincke's disease, is a rare immune system disorder. Hereditary angioedema is inherited in an autosomal dominant pattern, in which, the child inherits a faulty gene from one parent. In autosomal dominant inheritance pattern, there are 50% chances of passing the disease to the offspring. The disorder is caused due to inadequate amount of the blood protein, C1 inhibitor. The deficiency leads to swelling in different parts of body, especially the face and airways.

Causes of Hereditary Angioedema

The improper functioning or inadequate level of C1 inhibitor in the blood, causes hereditary angioedema. Swelling in the body is controlled by C1 inhibitor, whenever the body is injured. The gene associated with C1 inhibitor, SERPING1, is situated on the 11th chromosome. Mutation of this gene, leads to deficiency and dysfunction of the C1 inhibitor. This deficiency, further causes swelling in various body parts, like voice box, windpipe, hands, feet, face and intestinal tract. The swelling of the passage that joins stomach and anus, causes pain in the form of cramps. The effects can be fatal, if the swelling takes place in the windpipe. A hereditary angioedema patient may have a hitherto unnoticed family history of the disease. Surgery, dental operation and illness (like cold/flu) are also considered as some trigger factors that may cause an attack of hereditary angioedema. There are three types of hereditary angioedema, as given in the table below.

Type	Cause
Type 1	Low level of C1 inhibitor
Type 2	Normal or increased level of C1 inhibitor that does not function properly.
Type 3	Related to estrogen (female sex hormone) - only women are affected.

Symptoms of Hereditary Angioedema

Many a times, it happens that an individual born with hereditary angioedema does not show any symptom, until he/she reaches puberty. The symptoms are sudden and are referred to as an attack of hereditary angioedema. The symptoms are a result of several causes, like anxiety, illness, injury and surgery. It is noticed that the symptoms of the attack remain for at least 5 days and it takes one to three days for the swelling to reduce completely. The following list gives some of the symptoms that may be observed:

• Swelling of body parts, like legs, arms, lips, tongue or throat.
• Unexplained pain in the stomach.
• Vomiting or diarrhea, due to swelling of the intestine.
• Difficulty in swallowing, breathing, hoarseness due to swelling of airway.
Diagnosis of Hereditary Angioedema

Hereditary angioedema can be diagnosed by blood tests and genetic tests. As the swelling in the body parts can be a result of many other problems, blood and genetic tests are the only two tests that can confirm the diagnosis of hereditary angioedema. The blood test aims at finding out the amount of C1 inhibitor in the blood and verifying whether it is functioning properly or not. The gene test can help in revealing any defect in chromosome 11. If the level of C1 inhibitor is very low, then hereditary angioedema is confirmed.

Treatment for Hereditary Angioedema

The treatment for hereditary angioedema depends on the area which has swollen. Swelling of the windpipe can be serious and needs urgent treatment. Medications that are usually used to reduce swelling do not prove to be helpful, in case of hereditary angioedema. Preventive medications like danazol and oxandrolone are recommended for people who get frequent attacks of hereditary angioedema. Medications are, also available, to prevent swelling caused due to hereditary angioedema after any surgery. Some drugs are available, which can be used during an attack, i.e. soon after the swelling. Medications are available to treat the symptoms, like nausea, vomiting etc. Blood transfusion treatment is given, in some cases of hereditary angioedema.

Hereditary angioedema cases are found in 1 in 10,000-50,000 in US. Though, it is a rare genetic disorder, it may cause fatal problems. Individuals having family history of hereditary angioedema should consult their physician for preventive measures.