HLA-DRB1 and rheumatoid arthritis: Associations of amino acid residues 10, 11, 12, 13, 33, 37, 47, 67, 70, 96 and 98 of the HLA-DRβ chain were reported in European ACPA(+) RA [33], showing slightly different association pattern from the results of this study (Figure 1B).