Criteria for diagnosis of HAE-nC1-INH include: (1) a history of recurrent angioedema in the absence of associated hives or use of medication known to cause angioedema; (2) documented normal or near normal C4, C1-INH and C1 -INH function, and (3) either a genetic variant associated with the disease or a family history of angioedema and documented lack of efficacy of chronic high-dose antihistamine therapy [7]. The gene discussed is SERPING1; the disease is angioedema.