Hereditary angioedema(HAE) Disorder characterized by recurrent episodes of severe swelling (angioedema). 3 main types of HAE. Type I and II are caused by a mutation in the SERPING1 gene that makes the C1 inhibitor protein while type III is often due to a mutation of the factor KhII gene. This results in increased amounts of bradykinin which promotes swelling. Distinguishing b/w HAE & AAE( Acquired angioedema): C1q levels normal-HAE C1q levels low-AAE Type 1 HAE-Low C1-INH level & low C4 level Type 2 HAE- Normal or elevated C1-INH level & low C4 level. Function of C1-INH is reduced in both type 1 & 2 HAE.