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

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, or airway (larynx or trachea).

Unlike an allergic reaction, there is usually no itching or hives. Swelling of the gut can cause intestinal cramping. If swelling closes the airway, it can be deadly. 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 just been reported as an unexpected, sudden, and premature death of a parent, aunt, uncle, or grandparent.

Many attacks occur without reason. However, anxiety, stress, sickness (including colds and the flu), and surgery have been shown to trigger certain attacks of hereditary angioedema. Dental procedures increase the risk of attacks in patients with HAE.

• Swelling in the arms, legs, lips, eyes, tongue, or throat
• Airway blockage (involves throat swelling and sudden hoarseness)
• Repeat episodes of abdominal cramping without obvious cause
• Intestinal swelling can be severe and include vomiting, dehydration, pain, and occasionally shock

• Decreased C1 inhibiting factor activity
• Decreased C4 and C2 levels

Antihistamines and other related treatments are of limited benefit in hereditary angioedema.

Attenuated androgens, which are derivatives of normal sex hormones, can reduce the frequency and severity of attacks.

Once an attack occurs, treatment includes pain relief and fluids given by an intravenous (IV) line. A new treatment called C1-inhibitor concentrate is being tested.

Hereditary angioedema can be life threatening and treatment options are limited. It is very important that patient avoid triggers, such as anxiety and trauma. How well a person does depends on the individual's specific symptoms.

Swelling of the airways may be deadly.

Call 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.

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

Weiler CR, van Dellen RG. Genetic test indications and interpretations in patients with hereditary angioedema. Mayo Clin Proc. 2006 Jul;81(7):958-72. Review.

Levi M, Choi G, Picavet C, Hack CE. Self-administration of C1-inhibitor concentrate in patients with hereditary or acquired angioedema caused by C1-inhibitor deficiency. J Allergy Clin Immunol. 2006 Apr;117(4):904-8. Epub 2006 Feb 14.

Bork K, Barnstedt SE. Treatment of 193 episodes of laryngeal edema with C1 inhibitor concentrate in patients with hereditary angioedema. Arch Intern Med. 2001; 161(5):714-8.