The methylation level of cg04537602 in RA was positively correlated with C‐reactive protein (CRP) (r = .16, p = .01), and in RA patients aged 60 years and above, cg04537602 methylation levels were positively correlated with CRP (r = .31, p = 4.7 × 10−4), tender joint count (r = .21, p = .02), visual analog scales score (r = .21, p = .02), Disease Activity Score in 28 joints (DAS28) using the CRP level DAS28‐CRP (r = .27, p = 2.1 × 10−3), and DAS28‐ESR (r = .22, p = .01). The gene discussed is ESR1; the disease is rheumatoid arthritis.