SERPING1 and angioedema: If the patient has (1) recurrent angioedema without hives, (2) C1-INH levels within normal limits, (3) exclusion of medication-associated angioedema, such as ACEi, nonsteroidal anti-inflammatory drugs (NSAIDs), and tissue plasminogen activator, (4) no response to mast cell therapies, and (5) a response to B2 bradykinin receptor antagonists, then this diagnosis is supported [9].