According to the CHCC classification, 55 had microscopic polyangiitis (MPA), 5 had granulomatosis with polyangiitis (GPA), 1 had eosinophilic granulomatosis with polyangiitis (EGPA), and all were positive for myeloperoxidase-ANCA (MPO-ANCA). The gene discussed is MPO; the disease is microscopic polyangiitis.