Mice do not develop an immune response to human MPO, but MPO-deficient mice injected with mouse MPO do generate an immune response, such that injection of anti-MPO IgG from these mice into wild type mice results in a pauci-immune glomerulonephritis and small vessel vasculitis comparable to human AAV disease [94]. The gene discussed is MPO; the disease is anti-neutrophil cytoplasmic antibody-associated vasculitis.