This is the case of a 68-year-old male patient who developed MPO-positive ANCA vasculitis with accelerated chronic kidney disease, proteinuria, microhematuria, and interstitial lung disease. He was treated with pulse methylprednisolone, rituximab (375 mg/m2 x 4 doses), and oral prednisone taper. The gene discussed is MPO; the disease is vasculitis.