Understanding the Mechanism of the Disproportionately Reduced C1-Esterase Inhibitor (C1-INH) Levels in Hereditary Angioedema (HAE)

HAE is an autosomal dominant disorder caused by defects in the SERPING1 gene. HAE patients maintain one functional wild-type SERPING1 allele, therefore at least 50% of the normal C1-INH value is expected. However, serum antigen levels of C1-INH in HAE patients are usually 5-30% of normal. We hypothesize that the type of SERPING1 mutations and their impact on C1-INH protein structure and function lead to the variable degrees of C1-INH level in HAE patients.