Hereditary Angioedema: Frequently Asked Questions

Hereditary Angioedema is a genetic conditionated illness clinically characterized by : episodes of edema in body parts high airways edema gastrointestinal edema. HAE is caused by a genetic defect of C1 inhibitor esterase (C1-INH). HAE is rare, occuring in about 1/10,000 to 1/50,000 individuals. Without therapy, the mortality rate is 20-30%.

HAE is caused by a genetic defect on chromosome 11, which leads to a deficiency of the protein C1 esterase inhibitor (C1-INH). This protein is part of a system known as the complement system, which is involved in the complex interaction leading to immune and inflammatory reactions in the body. Among other things, C1-INH reduces production of the tissue hormone bradykinin. If insufficient C1-INH is available, bradykinin concentrations increase and an episode of swelling can occur. There are three types of HAE. ...

Hereditary angioedema (HAE) is a rare inherited disease characterised by recurrent episodes of swelling (edema). Episodes of HAE can affect different areas of the skin and internal organs. Episodes affecting the larynx or tongue are particularly dangerous and can cause death by suffocation if left untreated. About every third patient has at least one life-threatening episode of this type in his lifetime.

Most cases of angioedema are not HAE because swelling attacks are typically caused by something other than C1-inhibitor deficiency, usually an allergic reaction. Laboratory analysis of blood samples or genetic testing is required to establish the HAE diagnosis. There are two specific blood tests that confirm HAE: C1-inhibitor quantitative (antigenic) C1-inhibitor functional common form of the disease--Type I--is characterized by low quantitative levels of C1-inhibitor and affects about 85% of patients. ...

Most attacks occur spontaneously with no apparent reason, however anxiety, stress, minor trauma, surgery, and illnesses such as colds and flu have been cited as triggers. Trauma to the oral cavity caused by dental procedures make HAE patients particularly vulnerable to airway attacks. Patients have also reported swelling in extremities following typing, prolonged writing, pushing a lawn mower, hammering, shoveling, and other physical activities. ...

Patients often report tingling or tightness at the site where edema will occur thirty minutes to several hours later. In some cases, this sensation can be present twelve to twenty four hours before the onset of swelling. Approximately one fourth of HAE patients experience a flat, non itching red blotchy rash both before and during an attack. The edema itself usually lasts for twenty four to seventy two hours, but the length of an attack can range from four hours to four or more days.

Swelling of the extremities is uncomfortable and, according to some patients, can be painful and debilitating depending on the location of the edema. Attacks that involve the face and throat must be taken seriously and medical treatment should be sought without delay. Swelling of the throat can close the air passage and cause death by suffocation. The symptoms of an impending airway obstruction include difficulty swallowing and a change in voice pitch. ...

Fortunately, most prepubescent children with HAE do not suffer from frequent attacks and infrequent flares affecting the abdomen can be managed by using pain relievers and anti nausea agents. The small number of severely affected children who experience frequent and severe attacks must be managed on a case by case basis. ...

The age of HAE onset varies considerably, however, in one study, half of the patients reported onset of their symptoms by the age of seven, and over two thirds became symptomatic by the age of thirteen. There also seems to be an increased frequency of attacks during puberty or adolescence.