If you or your child has been newly diagnosed with hereditary angioedema (HAE), it’s normal to feel confused and worried about what it all means. And even if you’ve been living with HAE for a while, you might not be fully aware of what’s going on in your body when you have an attack.

We’ve compiled this list of HAE terms and definitions that you might hear or read about to reduce any uncertainty — and make things a little bit easier to understand.

The most common type of HAE. People with this type have low levels of C1 inhibitor.

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This is similar to type I, but people with this type have normal or high C1 inhibitor levels that don’t function properly.

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Formerly known as type III HAE. This type is rare and not well understood, but C1 inhibitor levels are normal and function correctly.

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Preventative therapy. This is an ongoing treatment you take to prevent HAE attacks.

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Treatment for acute HAE attacks. This is a treatment you take as an attack occurs.

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This gene provides instructions for making the C1 inhibitor protein. Mistakes in the SERPING1 gene lead to HAE types I and II.

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A protein that helps control inflammation. HAE occurs when protein levels are low or don’t function properly.

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A life-threatening condition where you aren’t able to receive oxygen. This can be due to swelling of the throat.

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Swelling in your body’s tissues that is usually the result of disease or medication. It’s most noticeable in the ankles, legs, feet, and arms.

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Bradykinin is a vasodilator, a compound that opens up the blood vessels. Excessive amounts of bradykinin are produced during an HAE attack.

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The physician to first describe hereditary angioedema.

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Describes how a disease develops.

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A doctor who treats blood conditions.

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A doctor who treats disorders of the immune system.

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A condition in which someone has trouble swallowing. This can be caused by swelling of the throat from HAE.

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A disorder that results in difficulty speaking that can be caused by swelling of the throat.

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When the mutated gene of a disorder is a dominant gene. This means there’s a greater chance of passing a disorder down through families.

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A surgical procedure that is performed if a condition or other trauma has affected your ability to breathe.

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