The reason may be that in the process of chronic inflammation of RA joint, a large number of CD4+ T cells migrate and infiltrate into inflammatory sites in peripheral blood, resulting in the decrease of depletion of this T cell subset in peripheral blood of patients, while the decrease of CD4+ T cells leads to a relatively higher proportion of CD8+ T cells [36, 37]. The gene discussed is CD4; the disease is rheumatoid arthritis.