The association of MPA with MPO-ANCA is reported to be in the range of 40–80%, and MPA with MPO-ANCA is noted to be frequently associated with necrotizing glomerulonephritis and/or pulmonary capillaritis, namely, a pulmonary-renal syndrome similar to that observed in Goodpasture syndrome or WG [3, 4]. The gene discussed is MPO; the disease is granulomatosis with polyangiitis.