CHI3L1 and obesity due to melanocortin 4 receptor deficiency: Coincidentally, CHI3L1 and chitin enhances obese inflammation and upregulates the plasma levels of pro-inflammatory glycoprotein YKL-40 according to recent publications [89,92], hence revealing the specific inflammatory regulatory role of CHI3L1 in obese populations and validating the potential relationships between obesity and psychiatric diseases mediated by CHI3L1.