In addition, these studies have also shown that different AAV subtypes such as granulomatosis with polyangiitis (Wegener's, GPA) and microscopic polyangiitis (MPA) are underpinned by distinct genetic risk factors, with GPA being associated with HLA-DP, SERPINA1 (encoding α1-antitrypsin), PRTN3 (encoding proteinase-3, PR3, the main GPA-related autoantigen) and SEMA6A (semaphorin 6A), whereas MPA has been mainly associated with HLA-DQ.