According to their target antigen they can be divided into c- (anti-PR3, elevated in tuberculosis, HIV infection, uveitis, amoebiasis, and cystic fibrosis with superinfection), p- (anti-MPO, of importance to microscopic polyangiitis, eosinophilic granulomatosis with polyangiitis, and pauci-immunen glomerulonephritis), and a-ANCA (Crohn's disease, autoimmune hepatitis) (16). The gene discussed is MPO; the disease is microscopic polyangiitis.