In RA, we observed that the expression of miR-124-3p was downregulated in purified CD4+ cells isolated from PBMCs of patients and negatively correlated with the expression of YY1 and the clinical biomarker anti-CCP, implying that miR-124-3p might be a potential biomarker for clinical diagnosis of RA. The gene discussed is CD4; the disease is rheumatoid arthritis.