HLA-DPA1 and rheumatoid arthritis: Previous studies found that rs1431403 genetic variations exist in the intronic region of HLA‐DPA1 and HLA‐DPB1 genes and are involved in autoimmune diseases including rheumatoid arthritis and type 1 diabetes, and in immunodeficiencies such as HIV (Ferreira et al., 2010; Yang, Chang, Liang, Lin, & Wang, 2012).