Chitinase 3-like 1 (CHI3L1) is a member of human chitinases family. According to previous studies in literatures, increased expression of CHI3L1 has been proven to be correlated with the presence of different diseases, including cancers, autoimmune diseases, and chronic inflammatory conditions. Elevated serum levels of YKL-40 are associated with increased disease severity, poorer prognosis and shorter survival for many other diseases. When monitored over time, increases in serum YKL-40 parallel with disease progression. It can serve as an measurable marker of changes in disease status.