In RA, IRF4 is an essential transcription factor for Th17 cell differentiation, regulating Th17 cell differentiation and the secretion of inflammatory cytokines (Biswas et al., 2010; van Hamburg and Tas, 2018); and the IRF4 gene single nucleotide polymorphisms are associated with RA susceptibility (López-Isac et al., 2016). Here, IRF4 is linked to rheumatoid arthritis.