To this end, MPA patients with MPO-ANCAs are more likely to develop isolated crescentic glomerulonephritis [3,4], pulmonary fibrosis and peripheral neuropathy [5,6], while MPO+-GPA patients have more frequently limited disease, without severe organ involvement, less need for cyclophosphamide or rituximab therapy and fewer relapses than those with proteinase-3 (PR3)-ANCA [7,8]. The gene discussed is MPO; the disease is microscopic polyangiitis.