HLA-DPB1 and systemic sclerosis: On the other hand, the HLA region (6p21.3), especially the HLA-DPB1 and DPB2, was consistently identified as the gene region most strongly associated with SSc by GWAS, and this association was most prominent in SSc patients with anti-topo I antibody [45], but it remains controversial if the primarily associated genes were located within HLA or non-HLA genes.