Understanding HAE

HAE is a rare disease that causes considerable swelling in various body tissues. A person with HAE will have the disease for life, because it is part of their genetic makeup. However, depending on the severity of the disease, some people will have many attacks each month, while others could go months or even years without a swelling attack.

Doctors refer to this kind of swelling as edema (EH deem uh). In HAE, this edema is caused by a change in a gene that codes for a single body protein. This protein is called “complement-1 esterase inhibitor.” Because this is quite a mouthful, doctors abbreviate this as C1-INH. C1-INH is part of the immune system—the part of the body that recognizes and attacks foreign invaders, such as viruses or bacteria.

C1-INH is involved in many different reactions in the immune system. Without adequate amounts of C1-INH, blood vessels can become leaky, allowing fluid to build up in the tissue. In HAE, this swelling can occur almost anywhere but often is found in one of the following body parts:

• Extremities (hands, feet, arms, legs)
• Intestines (abdomen)
• Face
• Larynx or voice box
• Genitals

In a recent survey of families with HAE, attacks of the hands, feet, and abdomen were reported most often. Unlike allergic reactions in which both sides of the body are affected, HAE attacks may involve just one side, for example just the right hand, but not the left or vice versa.

These attacks can be disabling. For example, swollen fingers may prevent the effective use of one’s hands. Swelling of the intestines usually causes severe abdominal pain.

Most serious, however, are attacks of the voice box or larynx (LAIR ingks). These laryngeal (luh RIN jee ul) attacks are most serious because they can cut off the air supply to the lungs and are therefore, life-threatening attacks.