What is hereditary
angioedema (HAE)?

HAE causes repeated episodes of spontaneous swelling that can occur at any time and in almost any part of the body but more predominantly in the hands, feet, face, airway (throat) and internal organs. HAE is not an allergy or allergic reaction.

What causes HAE?

HAE is the result of a genetic mutation caused by a deficiency of the blood protein functional C1 esterase inhibitor (C1-INH). It is an autosomal dominant inheritable disease which means that if one of the parents has HAE, their children (male and female) will have a 50% chance of inheriting the disorder.

The absence of family history does not rule out the HAE diagnosis though as the disease can manifest itself by a spontaneous mutation of the C1-inhibitor gene (de novo mutation). These patients can pass on the defective gene to their offspring.

Types of HAE

There are different types of HAE:

  • Type 1
  • Type 2
  • HAE with normal functioning C1-INH

Symptoms and Triggers

Emotional factors (e.g. exam stress, relationship problems), small surgical procedures (e.g. dental works, stitches) and hormonal fluctuations (e.g. during pregnancy, puberty or menstruation) are sometimes enough to cause a swelling episode. It is also possible that ACE inhibitors, which are used to lower blood pressure, can prompt an episode. Other potential causes include infections, insect bites, alcohol, certain foods, heat and cold. Often, the exact cause of an episode is unknown.

HAE symptoms can manifest themselves at a very early age, but there are also examples of this occurring later in life. As incidents of choking can occur within families with HAE, making a timely diagnosis is extra important.

Check your signs and symptoms

Know your triggers

People with HAE often suffer from abdominal pain/cramps, nausea and vomiting caused by painful swelling of the intestinal wall. Acute, life-threatening swelling can also occur in the trachea or throat, in this case a doctor should be contacted immediately, because of the high risk of asphyxiation.

Some patients report experiencing prodomal symptoms (meaning early symptoms) to an episode in the form of painless rings on their arms, back or chest or tingling sensations. The severity and frequency of episodes varies. HAE-related swelling does not itch.

HAE symptoms are often confused with those of other conditions. For example, colic-like cramps, diarrhoea and vomiting are confused with gastrointestinal disorders or appendicitis and swelling in the hands or face are confused with an allergic reaction.

How is HAE diagnosed?

Due to the complexity of the disease and its potential risks, it is essential that HAE patients receive an accurate diagnosis early in life. The diversity of symptoms and their similarity to other conditions and/or other types of angioedema lead to confusion among those physicians who are not familiar with HAE.
In the United Kingdom, the expert centres have sufficient specialised, comprehensive care to make a reliable diagnosis. Diagnosis is obtained by laboratory tests of a blood sample. The blood of HAE patients show a decreased concentration of C1-inhibitor and/or reduced activity of C1-inhibitor. Next to that the concentration of C4 antigen levels is measured.
Important: A timely diagnosis can improve your quality of life!

Treatment options

Several therapies are available for HAE: acute therapy (on demand, when attack is distinguishable progressed), preventive (prophylactic) therapy and individual replacement therapy (very early symptoms of an acute attack present).
While there is currently no known cure for HAE, untreated HAE episodes can last up to five days.

HAE attacks cannot be treated with antihistamines, epinephrine, corticosteroids or adrenaline. It is extremely important for each patient to seek guidance on individualised treatment, since the way HAE manifests itself differs per individual, even within the same family, different treatments are applicable.

Due to technological advances, the products are becoming safer and there are various therapies available for treating the C1-inhibitor deficiency.

The following is an overview of the therapies available in the United Kingdom:

Bradykinin antagonist
This therapy blocks bradykinin, an oligopeptide triggering the swelling associated with the HAE symptoms. This medication is used for the acute treatment of HAE episodes in children (≥ 2 years), adolescents and adults.

Plasma-derived C1 esterase inhibitor
This therapy replaces the missing or not functioning C1-inhibitor protein in patients with a C1-inhibitor deficiency. It comes from plasma (blood) donations. This medication is licensed for the treatment and prevention of HAE episodes in children, adolescents and adults.

Recombinant human C1 esterase inhibitor
The recombinant C1 therapy replaces the missing or not functioning C1-inhibitor protein in patients with C1-inhibitor deficiency. Recombinant means that this therapy is not made from human plasma. This medication is authorized for the treatment of acute HAE attacks in adolescents and adults due to C1 esterase inhibitor deficiency.