In addition, in our study, we observed positive correlations with laboratory parameters commonly used in RA, such as ACPAs and ESR, and clinical parameters, such as HAQ-Di and DAS28-ESR, suggesting that elevated YKL-39 could be associated with persistent inflammatory status in RA patients who do not respond to treatment and their prognosis. The gene discussed is CHI3L2; the disease is rheumatoid arthritis.