PRTN3 and microscopic polyangiitis: c-ANCA directed against proteinase-3 (PR3) is associated with granulomatosis with polyangiitis (GPA), while p-ANCA is typically directed against myeloperoxidase (MPO) and is commonly detected in microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA) and pauci-immune idiopathic crescentic glomerulonephritis [7].