Hereditary angioedema
Hereditary angioedema (HAE) is a disorder that results in recurrent attacks of severe swelling. The swelling most commonly affects the arms, legs, face, intestinal tract, and airway. If the intestinal tract is affected, abdominal pain and vomiting may occur. Swelling of the airway can result in its obstruction and trouble breathing. Without preventive treatment, attacks typically occur every two weeks and last for a few days.
| Hereditary angioedema (HAE) | |
|---|---|
| Other names | Hereditary angioneurotic edema (HANE), familial angioneurotic edema |
| Swollen right hand during a hereditary angioedema attack. | |
| Specialty | Hematology |
| Symptoms | Recurrent attacks of severe swelling |
| Usual onset | Childhood |
| Duration | Attacks last a few days |
| Types | Type I, II, III |
| Causes | Genetic disorder (autosomal dominant) |
| Diagnostic method | Measuring C4 and C1-inhibitor levels. |
| Differential diagnosis | Intestinal obstruction, other types of angioedema |
| Prevention | C1 inhibitor |
| Treatment | Supportive care, medications |
| Medication | C1 inhibitor, ecallantide, icatibant |
| Prognosis | 25% risk of death if airway involved (without treatment) |
| Frequency | ~1 in 50,000 |
There are three main types of HAE. Types I and II are caused by a mutation in the SERPING1 gene, which encodes the C1 inhibitor protein, while type III is often due to a mutation in the F12 (factor XII) gene. The result is increased levels of bradykinin, which promotes swelling. The condition may be inherited in an autosomal dominant manner or occur as a new mutation. Triggers for an attack may include minor trauma or stress, but attacks often occur without any obvious preceding event. Diagnosis of types I and II is based on measurement of C4 and C1-inhibitor levels.
Management of HAE involves efforts to prevent attacks and the treatment of attacks if they occur. During an attack, supportive care such as intravenous fluids and airway support may be required. C1 inhibitor medications can be used for both prevention and treatment, while ecallantide and icatibant can be used to treat acute attacks.
HAE affects approximately 1 in 50,000 people. The condition is typically first noticed in childhood. Type I and II affected females and males equally, while type III affects females more often than males. When the airway is involved, without treatment, the risk of death is about 25%. With treatment, outcomes are generally good. The condition was first described in 1888 by Canadian physician William Osler.