Causes of HAE

“I learn everything I can about HAE  and how it might affect me.”

Lesa — Diagnosed with HAE in 1980

Discover what causes HAE

Although not all is known about the events that induce angioedema attacks in hereditary angioedema (HAE), studies show that most people with HAE either do not have enough of an important protein called C1 esterase inhibitor or it doesn't work the way it should.

When there isn't enough C1 esterase inhibitor in the blood, or it isn't working properly, a cascade of events occurs. Part of this cascade is increased activity of another protein, called plasma kallikrein.

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

Kallikrein activity leads to excess bradykinin production, which causes the HAE attack

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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