HLA-DRB1 and systemic sclerosis: Some of the biological themes, prominently represented by the genes positively correlating between skin and PBC transcriptome in SSc patients and controls, included genes encoding ribosomal proteins (e.g., RPL14, RPS12, RPS26 and RPS23), interferon-inducible proteins (e.g., IFI27, MX1, OAS2 and HERC5), and HLA class I (HLA-A, HLA-C and HLA-H) and II (HLA-DPB1, HLA-DQB1, HLA-DRB1 and HLA-DRB4).