HLA-DRB1 and systemic sclerosis: Using expression-model eQTL SNPs, selected in the second cohort to explain expression variance, as co-factors in the first cohort to determine residual genetic association with SSc again rendered most MHC association with SSc nonsignificant (P > 5 × 10−8), except for the peaks shown in Fig. 3c centered on HLA-DPB1 and HLA-DRB1.