CSF levels of glial fibrillary acidic protein (GFAP) and chitinase-3-like protein 1 (YKL-40), biomarkers of astrocyte reactivity [8, 11], are consistently elevated in the dementia phase of AD [12], and in some other brain disorders such as multiple sclerosis [13, 14]. This evidence concerns the gene CHI3L1 and multiple sclerosis.