Based on the relatively higher expression of the SIGIRR gene on human memory CD4 T cells or CD4 T cells predicted by single-cell or bulk transcriptomic analysis, memory CD4 T cells were focused on demonstrating the functions of SIGIRR in RA, although gene polymorphisms and the regulation of SIGIRR in rheumatoid arthritis have been reported in earlier studies (Drexler et al. 2010; Yang et al. 2021). The gene discussed is CD4; the disease is rheumatoid arthritis.