SERPING1 and hereditary angioedema: HAE is divided into 3 types: (1) HAE-I, caused by a C1-INH gene mutation resulting in low levels or absence of antigenic and functional C1-INH; (2) HAE-II, caused by a C1-INH gene mutation resulting in a normal or high C1-INH antigen level but reduced enzymatic activity and a low functional C1-INH level; (3) estrogen-dependent HAE, which has normal C1-INH levels and function and normal genetic analysis, but a direct correlation with estrogen levels.