WHAT IS HAE
Hereditary Angioedema is a rare, potentially life-threatening genetic condition that affects approximately 1 in 50 000 people. HAE is NOT an allergy or an allergic reaction.
HAE patients often experience their first attack during childhood or adolescence.
HAE is characterised by angioedema (swelling) in various parts of the body. Swelling can occur almost anywhere in the body, including:
Patients with HAE often suffer excruciating abdominal pain, nausea, and vomiting caused by swelling in the intestinal wall. Swelling of the airway or throat can cause death by asphyxiation.
Approximately 85% of patients with HAE have a genetic defect that causes a deficiency in the plasma protein C1-esterase Inhibitor (C1-INH). Some patients have normal or elevated levels of C1-inhibitor but the protein doesn’t function properly so has abnormal functional levels. It is less commonly seen in people who have normal and functional levels of C1-INH.
Without enough or properly functioning C1 inhibitor, a sequence of events occurs that results in an HAE attack. An enzyme in the blood called kallikrein becomes uncontrolled, triggering the overproduction of a peptide known as bradykinin. Excess bradykinin causes the blood vessels to leak fluid into the surrounding tissues, leading to fluid build-up and the swelling that people with HAE experience.
This is an important differentiating feature of HAE when compared with allergic reactions, which are primarily mediated by histamine.