HLA-DRB1 and systemic sclerosis: The independent SSc disease-risk association with alleles HLA-DPB1*13:01 and HLA-DRB1*11:04 appeared to be driven almost exclusively by ATA + patients, in which these alleles occurred at significantly higher frequency than in ATA − disease (HLA-DPB1*13:01 OR = 7.85, pFDR = 9.3 × 10−22; HLA-DRB1*11:04 OR = 4.13, p = 9.7 × 10−14), increasing odds of ATA + SSc disease specifically substantially above that of SSc alone (Table 3).