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Hereditary Angioedema (HAE)

The Hereditary Angioedema Center at UC San Diego Health is dedicated to diagnosing and treating patients with diverse forms of swelling attacks caused by hereditary angioedema (HAE) – a rare, frequently misdiagnosed and poorly understood genetic condition.

The center was established with support from the U.S. Hereditary Angioedema Association to serve as a national referral center for the 6,000 to 8,000 people in the U.S. with this potentially life-threatening condition.

The center provides:

  • Early, reliable diagnosis of HAE due to C1INH protein deficiency.
  • A treatment plan tailored to the your condition and lifestyle.
  • Education on self-administering treatment at home during a swelling attack.
  • Education on non-drug approaches to improve quality of life.
  • Opportunity to participate in clinical trials of new therapies.   

What is Hereditary Angioedema?

Hereditary angioedema refers to a type of swelling caused by deficient or improper function of C1-inhibitor, a protein that prevents fluid from leaking from blood vessels. When there is not enough C1-inhibitor, or it is dysfunctional, episodic severe swelling of the skin including the hands, feet, face, or genitals can occur.

Swelling of the intestines may also occur, which can cause debilitating abdominal pain.

Swelling of mucuos membranes of the mouth, tongue, or throat from HAE can be life-threatening due to obstruction of the airway.

Types of HAE

There are three types of hereditary angioedema:

  1. HAE Type 1: Associated with insufficient production of C1-inhibitor protein. Most common type, responsible for 85 percent of HAE cases.
  2. HAE Type 2: Normal or high amounts of C1-inhibitor protein are produced but protein does not function properly. As a result, fluid leaks from blood vessels into surrounding tissue. Responsible for 15 percent of HAE cases.
  3. HAE with normal C1INH (Type 3): A small group of people, predominantly female, have swelling episodes characteristic of HAE, yet their C1-inhibitor protein levels are normal and appear to be functional. This type of HAE is very rare and the cause is poorly understood.


In about 80 percent of people with hereditary angioedema, the genetic defect is inherited.

In the other 20 percent, the disease is caused by a spontaneous mutation of the C1-inhibitor gene during conception.


HAE causes swelling, often of the skin (especially the face, throat, hands, feet and genitals). The affected area may become painful and red. You may also experience skin tingling or tightness.

Due to the nature of the disease, swelling can also occur in the intestines, causing various types of episodic and unpredictable abdominal pain, which may be confused with irritable bowel syndrome, inflammatory bowel disease, gynecological conditions or appendicitis.

How long do swelling attacks last?

The frequency, severity and location of swelling varies greatly among individuals. Acute events generally take several hours to develop and can last two to four days. If swelling occurs in the throat, you may experience difficulty breathing or swallowing. If the attack is severe and improperly treated, the swelling can be lethal.

When do attacks usually begin?

About half of all people experience their first swelling attacks by the age of seven, and more than two-thirds of patients have symptoms by the age of 13, according to the U.S. Hereditary Angioedema Association.


There are three specific blood tests used to diagnose HAE Type 1 and HAE Type 2.

The first test measures a person’s C4 serum level. C4 levels are decreased during attacks and typically remain low between attacks.

The second and third tests measure the quantity and functionality of C1-inhibitor protein.

There is currently no good diagnostic test for HAE with normal C1INH (Type 3).


People with swelling attacks caused by HAE do not respond to medications that are administered to people with most other forms of angioedema or allergies (e.g., antihistamines, corticosteroids and epinephrine).

There are currently several medications that can help treat and prevent HAE symptoms and swelling attacks.

Our team will help you sift through the growing number of new treatment options and identify an optimal management plan for your condition. This often includes instruction on how to self-administer medication at home during an acute attack.

Why is knowing how to self-administer important?

Self-administered acute care can often be given more quickly and therefore reduce episodes of potentially disabling swelling more rapidly. Ultimately, this means fewer emergency room visits and greater peace of mind.

Do non-drug approaches for HAE work?

In some instances, individuals with HAE may benefit from non-drug approaches as part of the management plan.

While more research is necessary, addressing the mental health components of HAE may be important in improving individual quality of life. Of particular interest is helping patients find and practice techniques that can help them lower their stress levels, since stress, in some people, can trigger or exacerbate swelling attacks.

Appointments and Referrals

    • 858-657-5350
    La Jolla


    Meet Our HAE Specialists

    U.S. Hereditary Angioedema Association

    UC San Diego and the U.S. Hereditary Angioedema Association have partnered to create a comprehensive angioedema center. bulletLearn more.

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