This document summarizes a study that investigated genetic differences between two types of ANCA-associated vasculitis (AAV): granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). The study analyzed over 1,200 AAV patients and found that GPA has a strong correlation with proteinase-3 (PR3) ANCA while MPA correlates with myeloperoxidase (MPO) ANCA. The study identified genetic variants in the MHC region of chromosome 6 and the SERPINA1 gene that are associated with PR3-positive AAV. It also found a SNP in the HLA-DQ locus linked to MPO-positive AAV. These genetic differences between