PRTN3 and microscopic polyangiitis: ANCA: anti-neutrophil cytoplasmic antibody, GPA: granulomatosis with polyangiitis, MPA: microscopic polyangiitis, AAV: ANCA-associated vasculitis, RTX: rituximab, CYC: cyclophosphamide, AZA: azathioprine, PR3-ANCA: proteinase 3 anti-neutrophil cytoplasmic antibody, IV: intravenous, WG: Wegener's granulomatosis