Varghese et al. (26) were the first to report chitinases in the context of ALS; using quantitative mass spectrometry (MS) and ELISA-based validation in an independent cohort, they showed that CSF levels of CHIT1, CHI3L1, and CHI3L2 were significantly elevated in ALS patients relative to healthy controls (HCs). Here, CHI3L1 is linked to amyotrophic lateral sclerosis.