<h4>Background</h4>ANCA-associated vasculitides (AAV) are small-vessel inflammatory disorders characterized by the presence of anti-neutrophil cytoplasmic antibodies (ANCA), including those against proteinase 3 (PR3) and myeloperoxidase (MPO). The gene discussed is PRTN3; the disease is anti-neutrophil cytoplasmic antibody-associated vasculitis.