HLA-DRB1 and systemic sclerosis: Considering associations with autoantibodies, HLA-DQA1*01:01, DQB1*05:01 and DRB1*01:01 were seen at significantly increased frequency in ACA + compared with ACA − SSc (HLA-DQA1*01:01 OR = 2.58, p = 4.5 × 10−15; HLA-DQB1*05:01 OR = 2.39, p = 3.2 × 10−12; HLA-DRB1*01:01 OR = 2.15, p = 1.5 × 10−8 in the meta-analysis cohort), and reduced frequency in ATA + relative to ATA − disease (HLA-DQA1*01:01 OR = 0.3, pFDR = 2.4 × 10−9; HLA-DQB1*05:01 OR = 0.38, pFDR = 1.7 × 10−6; HLA-DRB1*01:01 OR = 0.42, p = 0.0001; Table 3).