TOP1 and systemic sclerosis: This study challengingly attempted to identify and characterize the relation of self-antigenic (RIANFKIEPPGLFRGRGNHP) peptide from Top1 protein in selective binding with HLA-DRB1*08:02, HLA-DRB1*11:01, HLA-DRB1*11:04, HLA-DRB5*01:02 or HLA-DRB1*01:01 which could individually contribute to SSc disease risk at different levels.