Distinct HLA and non‐HLA associations in different subtypes of ANCA‐associated vasculitides in North India

Aim Antineutrophil cytoplasmic antibody‐associated vasculitis (AAV) is an autoimmune disease characterized by necrotizing small vessel vasculitis that can affect various organs and present multiple symptoms. Susceptibility to AAV is multifactorial and most likely caused by an amalgamation of genetic and environmental factors. The aim of the present study was to explore the distribution of human leukocyte antigen (HLA)‐DRB1/DQB1, protein tyrosine phosphatase non‐receptor type 22 (PTPN22) and cytotoxic T‐Lymphocyte‐associated protein 4 (CTLA‐4) polymorphisms in North Indian AAV patients and their associations with clinical and pathological characteristics associated with the disease. Methods A total of 150 AAV patients and 150 healthy controls were recruited. The clinical classification showed 128 as granulomatosis with polyangiitis (GPA) and 21 as microscopic polyangiitis. Only 1 case of eosinophilic granulomatosis with polyangiitis was encountered, which was excluded from analysis. HLA‐DRB1/DQB1 alleles were determined by polymerase chain reaction‐sequence‐specific primer (PCR‐SSP) method and single nucleotide variant genotyping for CTLA‐4 and PTPN22 was done by simple probe‐based SNP arrays. Results A significant predispositional association of DRB1*03 and DQB1*02 alleles, were confirmed in proteinase 3 (PR3)‐AAV patients, whereas DRB1*10, DRB1*14 and DQB1*05 were protective alleles in AAV, PR3‐AAV and GPA patients. GG genotype of CTLA‐4 + 49A/G was increased in patients as compared to controls and showed an association with AAV, PR3‐AAV and GPA patients. Conclusion The study indicated strong genetic associations were linked with PR3 antineutrophil cytoplasmic antibody specificity and it appears that PR3‐AAV and MPO‐AAV have distinct genetic backgrounds.