ANCA have been reported to be causally involved in the pathogenesis of WG; the autoantibody titer correlates with disease activity [8], and ANCA directly activate a wide variety of inflammatory functions in neutrophils, such as the secretion of oxygen radicals, proteases, and lipid mediators, once PR3 is expressed on the leukocyte surface [9-12] under inflammatory conditions. The gene discussed is PRTN3; the disease is granulomatosis with polyangiitis.