HLA-DPB1 and microscopic polyangiitis: The first GWAS of paediatric AAV, including 63 paediatric AAV patients (42 GPA, 15 unclassified, 6 MPA) and 315 adult controls of European ancestry, was conducted to analyse genetic susceptibility factors previously found in adult AAV, such as HLA-DP and HLA-DQ [55].