A recent study confirmed previous reports that PR3-ANCA+ but not MPO-ANCA+ disease is associated with gene variants in HLA-DPA1 and DPB1. A tri-allelic HLA-DPB1 haplotype explained much of the genetic risk in patients with AAV. This evidence concerns the gene PRTN3 and anti-neutrophil cytoplasmic antibody-associated vasculitis.