Hereditary angioedema

Hereditary angioedema (HAE) is a rare, ongoing and potentially life-threatening condition that causes episodes of swelling in the tissues of different parts of your body.

Key points

  1. Angioedema refers to swelling of the deeper layers of your skin and tissue, and hereditary means a genetic condition passed down from your parents.
  2. HAE is caused by a lack of, or a deficiency in, the gene that controls a blood protein called C1 Inhibitor. This raises the level of a chemical called bradykinin, which causes swelling.
  3. The swelling can affect your hands, feet, face, throat, airway, genitals and gut.
  4. HAE can't be cured, but there is medication to help prevent and treat the swelling.
  5. This condition affects your day to day life, so it’s important to get support for living with it.

Airway swelling is particularly dangerous and can cause death. If you or someone else has any airway swelling, call 111.

Who is affected by hereditary angioedema?

  • Between one in every 50,000 to one in 150,000 people have HAE.
  • Most people experience their first episode of HAE when they are a child or teenager.
  • Because HEA is rare, it can take a while before it is diagnosed.

What triggers an attack of hereditary angioedema?

Episodes can happen for no clear reason, but they may be caused by:

  • stress and anxiety
  • injuries or infections
  • minor operations and dental surgery
  • illnesses such as colds or flu
  • being pregnant or having your period
  • high blood pressure medication, known as ACE inhibitors.

What are the symptoms of hereditary angioedema?

The key symptom is swelling in your hands, feet, face, throat, airways, digestive tract or genitals. The swelling is not itchy, and treatments for swelling caused by allergies do not help HAE-related swelling.

If the swelling is in your gut, you will have pain, nausea and vomiting. If the swelling is in your airway, it will affect your breathing and you need to call 111.

How often these symptoms happen and how long they last varies from person to person, but they may happen once or more a month and last for two to three days.

How is hereditary angioedema diagnosed?

Your doctor will do a physical examination and refer you for blood tests to see if the swelling is caused by an allergy or the C1 esterase deficiency that causes HAE. If you do have HAE, they will refer you to a specialist.

What is the treatment for hereditary angioedema?

The treatment of angioedema depends on the severity of the episode. In most cases of mild HAE, such as mild facial swelling, the symptoms go away by themselves after a few hours or days, and they may not need treatment. 

Severe cases will require emergency treatment with a blood product called  c1 inhibitor concentrate. This is given directly into the vein. A medicine called icatibant (Firazyr®)  can also be used in emergencies for acute attacks of hereditary angioedema, but only in people with C1-esterase-inhibitor deficiency. This medication can be administered by injection by the patient or carer in an emergency, but to qualify for funding, you must meet special criteria and receive training on how to administer the injection.

If you suffer from frequent attacks, to reduce your chance of an acute attack your doctor may prescribe as a preventative either anabolic steroids (such as danazol or stanazolol) or regular c1 inhibitor concentrate. 

What self-care can I do to help with hereditary angioedema?    

  • Always take your medication to prevent episodes, and if an episode happens, take your medication for that.
  • Follow your action plan.
  • During a mild attack, try a cool shower or a cold cloth on the swelling.
  • Get support for living with HAE.

Support

HAE Australasia 
New Zealand Organisation for Rare Diseases
International HAE Facebook support group 

Learn more

The following links provide further information about hereditary angioedema. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

HAE Australasia 
Genetics Home Reference National Library of Medicine, US, 2017
Genetic and Rare Diseases Information Center US, 2011 
Angioedema DermNet New Zealand
Managing your child's HAE at school HAE Australasia, 2017
Medic Alert New Zealand
Rare Disease Day International

References

1. Hereditary and acquired C1-inhibitor-dependent angioedema: from pathophysiology to treatment Journal Annals of Medicine. 2016 Mar 26;48(4):256–267.  
2. HAE Australasia 
3. Hereditary angioedema: a brief review of new developments J Cur Med Res Op. 2014 Jan 24;30(5): 923–930.
4. Angioedema DermNet, NZ, 2006

Credits: Health Navigator Editorial Team.