Hereditary angioedema (HAE) is a rare disease
characterized by localized swelling, inflammation and pain.
It is estimated that HAE affects between 1 in 10,000 and 1 in 50,000 people worldwide.
Most people with HAE either do not have enough of a protein called C1 esterase inhibitor (C1-INH) or this protein does not work as it should.
Because of this, at times, the body makes too much of another protein called bradykinin. Having too much bradykinin allows water and other fluids to leak out of the blood vessels and into areas of the body where they shouldn’t. Bradykinin is thought to be responsible for the characteristic HAE symptoms of localized swelling, inflammation and pain.
Heredity and HAE
HAE is called “hereditary” because literature suggests that about 75% of cases are passed down through families. Still, about 25% of people with HAE have no family history at all. These cases result from a genetic change that happens spontaneously. Once the spontaneous change happens, it can be passed on to children.
Types of HAE
There are two main types of HAE, called type 1 and type 2.
- Type 1 is the most common form. People with type 1 do not make enough of the protein C1-INH, so circulating levels in the blood are too low.
- People with HAE type 2 have normal, or even higher, levels of C1-INH, but this protein does not work as it should.