CHI3L1 and early-onset autosomal dominant Alzheimer disease: In neurodegenerative disorders such as Alzheimer’s disease, YKL-40 is expressed in microglia and astrocytes close to Aβ plaques and is positively associated with t-tau and p-tau, signifying a key role for YKL-40 in the inflammatory processes of Alzheimer’s disease [184,185].