Definition of Hereditary angioedema:

Hereditary angioedema is a rare but serious problem with the immune system that is passed down through families. It causes swelling, particularly of the face and airways, and abdominal cramping.

See also: Angioedema

Causes, incidence, and risk factors:

Hereditary angioedema (HAE) is caused by low levels or improper function of a protein called C1 inhibitor. This problem affects the blood vessels. People with hereditary angioedema can develop rapid swelling of the hands, feet, limbs, face, intestinal tract, larynx (voicebox), or trachea (windpipe).

Attacks of swelling can become more severe in late childhood and adolescence.

There is usually a family history of the condition. However, relatives may be unaware of previous cases, which may have been reported as an unexpected, sudden, and premature death of a parent, aunt, uncle, or grandparent.

Dental procedures, sickness (including colds and the flu), and surgery have been shown to trigger certain attacks of hereditary angioedema.

Symptoms:

• Airway blockage -- involves throat swelling and sudden hoarseness
• Repeat episodes of abdominal cramping without obvious cause
• Swelling in the arms, legs, lips, eyes, tongue, or throat
• Swelling of the intestines -- can be severe and lead to abdominal cramping, vomiting, dehydration, diarrhea, pain, and occasionally shock

There is usually no itching or hives.

Signs and tests:

Blood tests (ideally done during an episode):

• C1 inhibitor function
• C1 inhibitor level
• Complement components C4 and C2

Treatment:

Antihistamines and other treatments used for angioedema are of limited benefit in hereditary angioedema. Epinephrine should be used in life-threatening reactions.

The most effective treatment is a C1 inhibitor concentrate, but this may not be available. Fresh frozen plasma contains C1 inhibitor and will help an episode, but rarely, the swelling will become worse.

Attenuated androgens, such as danazol, can reduce the frequency and severity of attacks by increasing the production of C1 inhibitor.

Once an attack occurs, treatment includes pain relief and fluids given through a vein by an intravenous (IV) line.

Helicobacter pylori, a type of bacteria found in the stomach, can trigger abdominal attacks. Getting rid of the bacteria with antibiotic therapy decreases these abdominal attacks.

Expectations (prognosis):

Hereditary angioedema can be life threatening and treatment options are limited. How well a person does depends on the specific symptoms.

Complications:

Swelling of the airways may be deadly.

Calling your health care provider:

Call or visit your health care provider if you are considering having children and have a family history of this condition, or if you have symptoms of hereditary angioedema.

Swelling of the airway is a life-threatening emergency. If you are having difficulty breathing due to swelling, seek immediate medical attention.

Prevention:

Genetic counseling may be helpful for prospective parents with a family history of hereditary angioedema.