Individuals with hereditary angioedema (HAE), a rare disease most frequently associated with deficiency (HAE-C1INH-Type1) or dysfunction (HAE-C1INH-Type2) of C1 inhibitor (C1INH), continue to experience frequent misdiagnoses and long delays in diagnosis, preventing appropriate management strategies and placing the patients at continued risk of inappropriate management of painful, debilitating, and potentially fatal swelling attacks. Here, SERPING1 is linked to hereditary angioedema.