CHI3L1 and dementia: Furthermore, protein levels in CSF may depend on APOE ε4 genotype, which has been reported for beta secretase-1 [BACE1] [14] and chitinase-3-like protein 1 [YKL40] [15], both proteins associated with AD-type dementia, and so, it is plausible that APOE ε4 genotype may influence other protein markers in the CSF as well.