What is HAE?

Hereditary Angioedema (HAE) is a rare genetic condition that is potentially life-threatening and occurs in about 1 in 30,000 to 1 in 50,000 people. Symptoms include recurrent episodes of edema (swelling) in various parts of the body including hands, feet, abdominal and airway. Additionally, patients experience excruciating abdominal pain, nausea and vomiting during episodes of swelling in the intestinal wall. Severity of attacks vary greatly, swelling of the airway is particularly dangerous and can be fatal.

Patients with HAE have a defect in a gene that regulates a protein that is present in the bloodstream, called C1 inhibitor protein. This protein is normally involved in regulating blood-systems involved in inflammatory response and coagulation. A defect in the gene may lead to a non-functional C1 inhibitor protein or inadequate production of the protein, and results in a biochemical imbalance causing fluid to be released from capillaries into surrounding tissue and thus causing episodes of edema.


HAE is passed on in families as it is hereditary. A child of an HAE parent has a 50 percent possibility of inheriting the condition, however, there are many cases where patients have the disease due to a spontaneous mutation in a gene, in these cases there is no previous family history. Due to HAE being a very rare condition, patients may go years without diagnosis or treatment as symptoms of HAE are often misdiagnosed.