Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) are a group of systemic vasculitis characterized by autoantibodies against neutrophil cytoplasmic antigens (proteinase 3 PR3-ANCA and myeloperoxidase MPO-ANCA) and inflammation of small vessels. This evidence concerns the gene MPO and anti-neutrophil cytoplasmic antibody-associated vasculitis.