SERPING1 and hereditary angioedema: In some instances, HAE with normal C1-INH is associated with mutations in factor XII (F12), plasminogen (PLG), angiopoietin (ANGPT1), kininogen (KNG1), or myoferlin (MYOF) genes; however, in many cases the genetic cause of HAE with normal C1-INH is unknown [6–11].