SERPING1 and hereditary angioedema: Another types of HAE have a similar clinical picture, but with normal C1-INH level and activity and a different genetic background, namely, mutations in the gene-encoding coagulation factor XII (FXII-HAE), plasminogen (PLG-HAE), angiopoietin-1 (ANGPT1-HAE), or an unknown mechanism (U-HAE) [10].