ATD-induced ANCA-positive patients more frequently had MPO-ANCA, ANA, AHA, IgM aCL, concomitant presence of both IgM and IgG aCL, IgM anti-β2 GP I, cryoglobulinemia and decreased C4 (Table 3). The gene discussed is C4A; the disease is autoimmune hemolytic anemia.