Advances in the genomics of ANCA-associated vasculitis-a view from East Asia.

Recent genome-wide association studies (GWAS) in populations of European ancestry have identified several susceptibility genes to anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The most significant association was observed in HLA-DP variants in granulomatosis with polyangiitis and proteinase 3 (PR3)-ANCA positive vasculitis, while HLA-DQ variants were strongly associated with microscopic polyangiitis (MPA) and myeloperoxidase (MPO)-ANCA positive vasculitis (MPO-AAV). In non-HLA genes, SERPINA1, PRTN3 and PTPN22 were identified as susceptibility genes to AAV. The observations in GWAS suggested the presence of shared and non-shared susceptibility genes among AAV subsets. Epidemiological features of AAV are strikingly different in the East Asian populations; the proportions of MPO-AAV among total AAV, MPO-ANCA positive patients among GPA, and patients with interstitial lung disease among total AAV are considerably higher in Japan as compared with Europe. Such population differences suggest the critical role for genetic background behind these conditions. Although no GWAS has been reported in the Asian populations so far, the association of HLA-class II alleles with MPA and MPO-AAV was identified. Future genomics studies on AAV, especially from Asian populations, will provide valuable information to elucidate the molecular mechanisms and to identify molecular targets for AAV.