De Wel et al. assessed neuroinflammatory biomarkers—chitotriosidase-1 (CHIT1) and chitinase-3-like protein 1 (YKL-40) in the CSF of SMA type 2 and 3 patients over 22 months of nusinersen treatment, and found that YKL-40 correlated with clinical improvements [35]. Here, CHI3L1 is linked to spinal muscular atrophy, type II.