CHI3L1 and Alzheimer disease: Lananna et al. (2020) show that the clock regulates the production of Chi3l1, which encodes for YKL-40, a glycoprotein biomarker for neuroinflammation in CSF that is increased in AD patients. The authors observed that Chi3l1 is not only regulated by the core clock, but that deletion of Chi3l1/YKL-40 reduced amyloid plaque formation and Aβ phagocytosis (Lananna et al., 2020). This exciting result suggests that deregulation of a CCG such as Chi2l1 might lead to AD pathogenesis.