According to the European Academy of Allergy and Clinical Immunology (EAACI) [6], five different forms of hereditary angioedema (HAE) have been identified: HAE-1, due to C1 inhibitor (C1-INH) deficiency, characterized by low antigenic and functional C1-INH levels; HAE-2, due to C1-INH dysfunction, characterized by normal (or elevated) antigenic but low functional C1-INH levels [7,8]; HAE-FXII, characterized by mutation in the coagulation factor 12 (F12) gene [9]; HAE-ANGPT1 with mutation in the angiopoietin-1 gene [10]; HAE-PLG with mutation in the plasminogen gene [11]. The gene discussed is SERPING1; the disease is hereditary angioedema.