In the first GWAS in AAV, Lyons et al. demonstrated that granulomatous polyangiitis (GPA, Wegener’s) and microscopic polyangiitis were genetically distinct diseases and anti-myeloperoxidase ANCA was associated with HLA-DQ while anti-proteinase 3 (anti-PR3) ANCA was associated with HLA-DP, SERPINA1, and PRTN3 (21). Here, PRTN3 is linked to microscopic polyangiitis.