CSF levels of inflammatory cytokines, such as IL-1β, IL-6 and others, are increased in PD (Mogi et al., 1996; Chen et al., 2018), and the CSF α-synuclein level is associated with that of inflammation markers such as IL-1β (Hu et al., 2015), serum amyloid A (SAA), IL-8 and chitinase-3-like protein 1 (YKL-40) (Hall et al., 2018) in PD. Here, CHI3L1 is linked to Parkinson disease.