Genetic factors including human leukocyte antigen gene (HLA) (Nepom et al., 2010), interleukin genes (IL23R, IL6, IL17, and IL12B) (Chabaud, Fossiez, Taupin, & Miossec, 1998; Chang et al., 2010), autoimmune regulator gene (AIRE) (José‐Raúl et al., 2013), protein tyrosine phosphatase 22 (PTPN22) gene (Hinks et al., 2010), and solute carrier family 22 member 4 (SLC22A4) (Newman et al., 2010) have been implicated in the pathogenesis of RA. This evidence concerns the gene SLC22A4 and rheumatoid arthritis.