In addition, three of the HLA-DRB1 AA positions (37, 58, and 74) are close to sites (30, 60, and 74) which have been described to play a role in binding the consensus antigenic peptide of the topoisomerase I epitope, auto-antibodies to which define the ATA+ subgroup of SSc patients49. This evidence concerns the gene HLA-DRB1 and systemic sclerosis.