Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) includes a group of autoimmune disorders resulting in the production of autoantibodies to neutrophil proteins (leukocyte proteins, proteinase 3 (PR3)-ANCA or myeloperoxidase proteins (MPO)-ANCA). Here, MPO is linked to anti-neutrophil cytoplasmic antibody-associated vasculitis.