SERPING1 and hereditary angioedema: In the vast majority of cases, HAE is caused by the causative mutations in complement 1 (C1) inhibitor gene (SERPING1) that leads to C1-esterase inhibitor (C1-INH) deficiency (type I) or dysfunction (type II), resulting in uncontrolled activation of kallikrein–kinin system and overproduction of bradykinin [4, 5].