Critically, PR3 is the autoantigen in autoimmune granulomatosis with polyangiitis (GPA), a condition characterized by the inflammatory necrosis of small-to-medium-sized blood vessels, which results from inappropriate neutrophil activation triggered by the binding of PR3-specific antineutrophil cytoplasmic antibodies (ANCAs) [109]. This evidence concerns the gene PRTN3 and granulomatosis with polyangiitis.