What is Hereditary Angioedema?

Hereditary angioedema (HAE) is a rare genetic condition that causes parts of the body to swell. This swelling often happens in the hands, feet, face, and throat. It can also happen in the stomach area.¹

These episodes of swelling are called attacks. HAE is different from an allergic reaction. Allergic swelling is due to a chemical called histamine released by immune (allergy) cells. Therefore, standard allergy drugs (antihistamines, steroids, EpiPen, etc.) do not work for HAE attacks.¹

HAE is caused by an abnormality in the bradykinin pathway – a chemical system that controls fluid movement in the body. Too much bradykinin causes fluid to leak through blood vessels, leading to swelling. Knowing the facts about this condition can help you or a loved one manage it better.^1,2

Types of HAE

There are 3 main types of HAE. Each type is caused by a different change in a gene. These gene changes involve a protein in the blood called C1 esterase inhibitor (C1-INH), which keeps bradykinin levels in check. When C1-INH does not work properly, bradykinin builds up and leads to the swelling seen in HAE attacks.^1,2

Type 1

Type 1 is the most common form of the condition. About 85 percent of people with HAE have Type 1. In this type, the body does not make enough C1-INH protein. Because there is not enough of this protein, the body cannot break down bradykinin and control swelling correctly. This leads to the sudden attacks that people experience.^1,2

Type 2

Type 2 is the next most common type of HAE. In Type 2, the body makes a normal amount of the C1-INH protein. However, the protein does not work the way it should. It is like having a key that fits in a lock but cannot turn. Because the protein is not working, it cannot break down bradykinin and stop the swelling from happening.^1,2

HAE with normal C1-INH

The third type is even more rare than types 1 and 2. It is called HAE with normal C1-INH. People with this type have normal levels of the C1-INH protein. The protein also works correctly. Researchers are still learning why swelling happens. They have found that other genes may be the cause. This type often affects more women than men. It can be triggered by things like pregnancy or certain drugs.^1,2

HAE statistics and who it affects

HAE is a very rare disease. Research estimates that HAE affects about 1 in every 50,000 people worldwide. In the United States, that is about 6,000 people living with HAE.^1-3

HAE affects people of all races and genders. Most people with HAE are born with the gene change that causes it. They often inherit it from a parent. A child has a 50 percent chance of having HAE if 1 parent has the condition. However, some people are the first in their family to have the gene. This is called a spontaneous or “de novo” genetic mutation and occurs in about 25 percent of cases.^1,2

Symptoms can start as early as childhood or during the teenage years. In about half of cases, types 1 and 2 symptoms first appear by the age of 10. Symptoms may get more frequent as a person gets older. Identifying the condition early is important for starting the right treatment.^1,3

Prognosis and outlook for people with HAE

The word prognosis means the likely course of a disease. For people with HAE, the outlook has improved greatly over the last few years. While there is no cure for HAE, there are many new treatments that can help. These drugs can stop an attack when it starts. They can also help prevent attacks from happening in the first place.^1-3

Life expectancy

Overall, people who get the right care can expect to live a normal lifespan. Modern drugs have made it much safer to live with HAE.^1-3

However, if HAE is not treated, it can be dangerous. The biggest risk is swelling in the throat (laryngeal edema). This can make it hard to breathe or swallow. If this happens, it is a medical emergency. If this happens to you or your child, dial 9-1-1 and seek immediate care.^1-3

Quality of life

HAE can be a hard condition to live with. Attacks can cause pain and keep people from their daily tasks. But new treatments are helping people take back control.^1-3

People using long-term preventive drugs report having fewer attacks.
Many people can stay active and continue working and going to school.
Doctors and support groups can help with the stress of living with a chronic disease like HAE.

A positive outlook

If you or your child has hereditary angioedema, the most important thing is to work closely with a healthcare professional. They can help you find a plan that works for you. With the right care, you can live a full and healthy life.¹

Even though there is no cure, the outlook is very positive. New drugs allow people to manage their symptoms and live a typical life. If you have HAE, you are not alone, and help is available.¹