Hereditary angioedema (HAE) is a rare hereditary disease that occurs underneath the skin (subcutaneous tissue). It causes swelling along with fluid accumulation within the skin and tissues underlying the skin. This condition is different for each individual and it depends on how often swelling occurs and how severe it gets to the location. A swelling in throat tissue needs immediate medical attention, as it may even inhibit or stop breathing due to the swollen tissue.
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What are the symptoms of hereditary angioedema (HAE)?
Swelling of the skin tissues is the main symptom of HAE. It doesn’t cause itching or any other discomforting reaction. The symptom lasts for about two to five days and decreases eventually. If a person is born with this genetic defect, it’s likely to become worse in teenage. However, in some people, HAE remains undiagnosed until their adulthood.
Some common symptoms of hereditary angioedema:
- Swelling of the skin
- Extreme fatigue
- Muscle aches
- Tingling sensation in the skin
- Abdominal pain
- Nausea and vomiting
- Shortness of breath
- Mood swings
- Swelling of the hands and feet
- Laryngeal edema that may further result in asphyxiation
What are the types or forms of hereditary angioedema (HAE)?
There are three types of hereditary angioedema. These types can be distinguished only by laboratory tests and genetic testing.
- Type I HAE is caused by low levels of C1 inhibitor protein.
- Type II HAE occurs due to normal or elevated levels of dysfunctional C1 inhibitor protein.
- Type III is known to be an estrogen-dependent form of HAE and it occurs mainly in women.
What causes hereditary angioedema (HAE)?
HAE is generally caused due to a gene, which produces a protein termed C1 inhibitor (C1-INH). This autosomal dominant gene is not able to produce enough C1 inhibitor (a protein that inhibits the complement system from self-activation) to let the body fluids escape from tiny blood vessels into different body areas. As a result, swelling occurs at any part of an individual’s body. If your parents have HAE, there are chances that even you may have inherited it.
What triggers hereditary angioedema (HAE)?
While the major cause of HAE is not clear, some of the most common reasons that trigger HAE are:
- Minor injuries
- Surgical procedures
- Dental procedures
- Cold, flu, or pneumonia
- Intermittent physical activities
- Menstrual periods
- Hormone therapy
How is hereditary angioedema (HAE) diagnosed?
Hereditary angioedema is often difficult to diagnose because of the irregularity of attacks. However, patients that have a parent with hereditary angioedema are likely to have inherited it from them. For diagnosis, a serum C4 level is checked with a screening test. Besides that, the three types of HAE are determined by genetic testing and blood tests of complement levels including C1, C2, and C4. Even Ultrasound, CT scan and X-rays are used to check the fluid accumulation in the tissues.
How to treat?
The World Allergy Organization (WAO) issued the following guidelines for HAE Types I and II in 2013:
- You need to treat all hereditary angioedema attacks as soon as possible with C1-INH, Kalbitor (ecallantide), or Firazyr (icatibant).
- Adjuvant therapy is administered in hereditary angioedema attacks when indicated.
- All HAE-I/II patients must have their have on-demand treatment for two attacks, as well as carry their on-demand treatment to show their medical history.
- Plasma-derived C1-INH is the preferred therapy for HAE-I/II attacks in children and pregnant women.
- All individuals suffering from HAE must have their history of HAE attacks and an HAE identification card.
- Even self-administration of treatment must be taught to the patients so that they can themselves treat of HAE attacks in an emergency.