What are the different types of HAE?

Type 1 HAE, Type 2 HAE, and HAE with normal C1-INH.

People with Type 2 HAE have enough C1-INH, but it doesn’t work correctly.

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CANVAS: AN HAE OVERVIEW

Hereditary angioedema (HAE) is a rare genetic condition that can cause unpredictable, severe, and even life-threatening swelling attacks in various parts of the body.¹

Causes and Genetics of HAE

The body makes a protein called a C1 esterase inhibitor (C1‑INH), which plays a role in controlling swelling.
People with HAE typically have low levels of C1‑INH, or their C1‑INH does not work as well as it should.²

Genes give the body instructions to make proteins.
The SERPING1 gene tells the body how to make the C1‑INH protein. HAE is usually caused by changes in this gene.³

Other genes provide instructions for different proteins that also play a role in controlling swelling. Learn more about the science of HAE attacks: HAE Illustrated.

HAE can run in families. If one parent has HAE, their child has a 50/50 chance of having it too.⁴

Sometimes a person can be the first in their family to have HAE. This happens in about 25% of cases.⁵

Types of HAE

Type I HAE:
People with Type I HAE don’t have enough C1-INH. This is the most common type of HAE.¹

Type II HAE:
People with this type have enough C1-INH, but it doesn’t work correctly.¹

HAE with normal C1‑INH:
In some cases, C1‑INH levels are normal. The cause is unknown, and research continues so we can better understand why this happens.⁴

Go Beyond the Basics

See the Full Impact of HAE

Stay Informed

References:

Ghazi A, Grant JA. Hereditary angioedema: epidemiology, management, and role of icatibant. Biologics. 2013;7:103-113. doi:10.2147/BTT.S27566
Wedner HJ. Hereditary angioedema: pathophysiology (HAE type I, HAE type II, and HAE nC1-INH). Allergy Asthma Proc. 2020;41(Suppl 1):S14-S17. doi:10.2500/aap.2020.41.200081
De Maat S, Hofman ZLM, Maas C. Hereditary angioedema: the plasma contact system out of control. J Thromb Haemost. 2018;16(9):1674-1685. doi:10.1111/jth.14209
Busse PJ, Christiansen SC, Riedl MA, et al. US HAEA Medical Advisory Board 2020 guidelines for the Management of Hereditary Angioedema. J Allergy Clin Immunol Pract. 2021;9(1):132-150.e3. doi:10.1016/j.jaip.2020.08.046
Zuraw BL. Clinical practice. Hereditary angioedema. N Engl J Med. 2008;359(10):1027-1036. doi:10.1056/NEJMcp0803977

This information is for educational purposes only and is not intended to constitute medical advice. For all healthcare decisions, talk with your healthcare team.