SERPING1 and hereditary angioedema: In HAE, mutations in the SERPING1 gene encoding C1-INH (HAE type I or II) [13] and in the FXII gene (HAE type III) [14,15] lead to insufficient regulation of the kallikrein/kinin system and thus to elevated bradykinin levels causing the typical symptoms like swelling of soft tissues due to its function as potent vasodilator [16,17].