What is HAE?

Hereditary angioedema (HAE)
is a rare genetic disease

HAE can cause repeated attacks of swelling that can be painful and disabling. HAE is called "hereditary" because it usually runs in families. So, what causes HAE?

Typically, people with HAE are either missing an important protein in their blood called C1-inhibitor, or it doesn’t work the way it should. This can cause another protein, kallikrein, to become overactive. This increase in kallikrein activity results in too much bradykinin, the substance that causes HAE attacks.

TAKHZYRO decreases plasma kallikrein activity. See how it works here.

Lexi

How is HAE diagnosed?

For people who have a family member with HAE, getting a diagnosis can be pretty straightforward. For people who have never heard of HAE, getting a diagnosis can be more difficult.

It can help to know what HAE is, what symptoms to be on the lookout for and what kind of doctor can help with a diagnosis. The US Hereditary Angioedema Association can help you find an HAE specialist.

To know for certain that you have HAE, a blood test is recommended. Your doctor will measure your levels of the proteins C4 and C1 esterase inhibitor. Testing can also help to differentiate between HAE Type I and HAE Type II.

Understanding HAE Type I and II

Most people with HAE (about 85%) have HAE Type I. Some patients with HAE (about 15%) have HAE Type II. Doctors need a blood test to show whether a patient has HAE Type I or Type II because they can look very similar to one another. They both cause swelling attacks in different locations throughout the body, and both types occur because of a genetic mutation.

Type I

Low level of C1-INH
C1-INH functions normally
Most common (~85% of people with HAE)

Type II

Normal level of C1-INH
C1-INH doesn't function normally
Less common (~15% of people with HAE)

What are the challenges in diagnosis?

ONLY

25^%

diagnosed
within 1 year*

47^%

undiagnosed
for 10 or more years*

*According to a 2015 survey of 106 people with HAE Type I or II

It's thought that only 1 in 10,000 to 1 in 50,000 people in the world have HAE. And it’s estimated that about 6,000 people have HAE in the United States. HAE is rare, and many doctors may never encounter a patient with HAE. However, there is a need for more members of the medical community to learn how to recognize, diagnose, and treat it.

It’s not unusual for people with HAE to go for years after they start experiencing symptoms before seeing a doctor who can correctly diagnosis them with HAE. In 2017, a survey of 445 people with HAE showed the average delay in diagnoses was 8.4 years.

Can HAE be misdiagnosed?

Because HAE symptoms can look very similar to the symptoms of other, more common conditions, it can be easy to misdiagnose. In a 2010 survey of 313 people with HAE, up to 65% of the participants had been misdiagnosed with another condition prior to receiving their HAE diagnosis:

Most commonly, skin attacks were mistaken for other skin conditions, like contact dermatitis, which can cause the skin to become irritated and swollen
Abdominal attacks were also confused with appendicitis or irritable bowel syndrome

What can getting misdiagnosed with another condition mean?

It can take longer to get an accurate HAE diagnosis
People who are undiagnosed are at greater risk of receiving the wrong treatment
In an emergency situation, like an HAE attack affecting the airway, getting the wrong treatment has the potential to be life-threatening

TAKHZYRO was studied to see if it could help prevent HAE attacks.

See the study

Learn about HAE symptoms and attack triggers.

More HAE info