According to the ANCA test results, forty-five cases (25.86%) of the 174 AAV patients were ANCA-negative, one hundred and nineteen cases (68.39%) were MPO-ANCA-positive, seven cases (4.02%) were PR3-ANCA-positive, and three cases (1.72%) were MPO-ANCA and PR3-ANCA double-positive. The gene discussed is MPO; the disease is anti-neutrophil cytoplasmic antibody-associated vasculitis.