Hereditary angioedema

Fugitive, but often pronounced episodes of swelling, predominantly in the face, but also on the hands, feet, or in the respiratory tract: Such symptoms speak for an angioedema. This usually occurs as part of an allergic reaction, much less common is a congenital disorder underlying. However, usually additional gastrointestinal symptoms occur. The swelling is due to accumulation of water (edema) in the subcutaneous tissue; In the past, angioedema on the face was also known as Quincke's edema.

Forms of angioedema

First, two forms of angioedema need to be distinguished, since these two in principle require different treatments:

  • Angioedema is caused either by the messenger histamine (histamine-mediated angioedema), which is increasingly released in the case of an allergy or an intolerance reaction, for example against drugs. This mechanism is similar to that which occurs in hives (urticaria).
  • Much less common is the inadequate function of a particular molecule - the C1 inhibitor (angioedema due to C1 inhibitor deficiency - AAE for short), which normally slows down the immune system in uncontrolled reactions. This form is usually inherited and congenital (hereditary angioedema - short: HAE). The acquired forms of this C1 inhibitor deficiency arise either in the context of cancers of the lymphatic system or as a result of autoimmune diseases.

What are the causes of hereditary angioedema?

In patients with hereditary angioedema, the level of a protein called C1-esterase inhibitor is lowered in the blood plasma. This protein inhibits the first component of the complement system. The complement system, in turn, consists of a cascade of serum proteins that play an important role in the immune and inflammatory response of the human body.

This disorder is inherited - if a parent is affected, there is a 50 percent chance that a child will inherit the disease.

Who is affected and why?

The age at onset of HAE symptoms varies widely, but there is one peak in the first decade and a second in the second decade of life. About 75 percent of patients are symptomatic when they reach the age of 20. During puberty and early adulthood, attacks appear to be more prevalent. For example, the birth control pill is reported as the trigger of the first HAE attack in previously unremarkable patients.

Another triggering factor may be an infection, for example the not uncommon viral infection mononucleosis (Pfeiffer glandular fever).

The attacks can also occur without obvious external causes, stress, anxiety or minor injuries can provoke them. Dental treatments, for example, can contribute to mucosal swelling in the airways. In addition, other triggers have been described (for example hand swelling after mowing, writing, hammering, etc.).

Hereditary angioedema during menstruation and pregnancy

In women, menstruation and pregnancy appear to have an effect on the activity of the disease. Some women report an increase in the number of attacks during their menstruation.

During pregnancy, some patients report an increased, others a decreased frequency of attacks.

The use of oral contraceptives (birth control pills, especially those containing high levels of estrogen) or hormone-containing intrauterine devices seems to increase the incidence and severity of mucosal swelling.

Hereditary angioedema: symptoms

The typical symptoms of HAE are the temporary onset of painful, non-itchy swellings that are colorless and located in the subcutaneous tissue or acute abdominal pain with no apparent other cause.

Patients often report a feeling of tightness at the site where the edema occurs about 30 minutes to a few hours later. The swelling lasts at least four - on average between 24 and 72 hours - but can sometimes last longer.

Frequency of hereditary angioedema

The frequency of HAE attacks varies enormously. Some patients are symptom-free for a long time, and swelling occurs at frequent intervals. Other patients suffer attacks at shorter, regular intervals.

Complications of hereditary angioedema

The seizures are particularly dangerous if they occur in the respiratory tract. In this case, the mucous membrane may occlude the respiratory tract and necessitate the performance of an emergency tracheostomy (tracheotomy). Untreated mucosal swelling in the trachea is one of the leading causes of death in HAE patients.

If the HAE was previously unrecognized, a mortality of 25 to 30 percent of patients has been observed in the past. Therefore, in the case of mucous membrane swelling in the laryngeal area, immediate administration of C1-esterase inhibitor concentrate and medical treatment are absolutely necessary.

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