Conditioned association analysis for genetic markers across the MHC genomic region on ten independent C4 eQTL SNPs rendered most association to SSc nonsignificant (P > 5 × 10−8), except for a peak around HLA-DPB1, the initial association of which was enhanced by conditioning (Fig. 3b). The gene discussed is HLA-DPB1; the disease is systemic sclerosis.