HLA-DRB1 and rheumatoid arthritis: High-resolution HLA allele class I (A, B, and C) and class II (DQB1 and DRB1) distribution was assessed by NGS in pre-RA (n = 59), in FDR (n = 50), and HC (n = 78) in order to perform association studies between (i) pre-RA vs. HC; (ii) FDR vs. HC; and (iii) pre-RA vs. FDR (Figure 3).