Causes of HAE

Lesa
Diagnosed with
HAE in 1980

What causes hereditary angioedema (HAE) attacks?

If you or someone you care about has been diagnosed with HAE, you might be interested in knowing what causes the angioedema in an HAE attack. Scientists don’t know everything about the events that lead to an attack, but studies show that most people with HAE either do not have enough C1 esterase inhibitor (C1-INH) protein in their blood, or it doesn’t work the way it should.

When there is a C1 esterase inhibitor deficiency, or C1-INH isn’t working properly, a cascade of events occurs. Part of this cascade is increased activity of another protein called plasma kallikrein. Increased kallikrein activity leads to excess bradykinin production, which causes the swelling of an HAE attack.

Decreased C1 esterase inhibitor proteins are tied to an underlying disorder and can cause an increase in bradykinin levels and lead to HAE symptoms.

Normally, C1 esterase inhibitor helps to regulate plasma kallikrein. When there is not enough functioning C1 esterase inhibitor, the activity of plasma kallikrein increases. Too much plasma kallikrein activity triggers the release of bradykinin. Increased bradykinin levels cause blood vessels to release fluid and results in the localized swelling and pain of an HAE attack.

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