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, larynx (voicebox), or trachea (windpipe).

There is usually no itching or hives. Swelling of the gut can cause intestinal cramping. If swelling closes the airways, 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.

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