SERPING1 and neoplasm: C1-INH-AAE is caused (i) by a hyperactivation of the classical convertase combined with the presence of anti-C1-INH antibodies or (ii) secondary to a tumour proliferation, dysglobulinemia or an autoimmune disease, with a hypothesized proteolytic consumption of C1-INH; AAE symptoms can precede proliferation diagnoses by many years.