SERPING1 and hereditary angioedema: Hereditary angioedema can occur with normal C1-INH, due to mutations in other genes involved in bradykinin overproduction, e.g. factor XII (Hageman Factor), plasminogen gene, angiopoeitin-1 gene and kininogen-1 gene, but there are still many unclassified cases of hereditary angioedema (31).