These include synaptic proteins such as neurogranin and glial activation-related biomarkers, i.e., Chitinase 3-like 1 (YKL40) and soluble form of the triggering receptor expressed on myeloid cells 2 (sTREM2), which have been extensively investigated both in AD and PD [242,243,244]. This evidence concerns the gene CHI3L1 and Parkinson disease.