HLA-DPB1 and granulomatosis with polyangiitis: This approach resulted in the identification of 33 variants associated with GPA and MPA that were located in or in close to candidate genes, such as PTPN22, CTLA4, RING1, and the HLA-DP locus, or were carried by previously not-significant genes taking part in either immune or inflammatory responses, such as the retinoid X receptor beta (RXRB), serpin family A member 1 (SERPINA1), toll-like receptor 9 (TLR9), and the HLA-DQ locus.