PRTN3 and granulomatosis with polyangiitis: MPA is primarily associated with myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA), whereas granulomatosis with polyangiitis is mainly linked to proteinase 3 (PR3)-ANCA.[1] Typically, MPA involves renal manifestations such as hematuria, proteinuria, and a rapid decline in renal function.