PRTN3 and microscopic polyangiitis: Granulomatosis with polyangiitis typically displays a pattern of cytoplasmic ANCA (C-ANCA) almost exclusively as a result of antibodies directed against proteinase-3 (PR3), while microscopic polyangiitis typically shows a pattern of perinuclear ANCA (P-ANCA) targeting myeloperoxidase [17,38].