CHI3L1 and rheumatoid arthritis: Cartilage glycoprotein 39 (chitinase 3–like 1), which is found in the serum and synovium of patients with RA and patients with osteoarthritis, shows a tendency to be correlated with disease severity (30), and therefore, it was interesting to find more of its transcript in the patients whose disease extended to oligoarticular JIA in this study.