CHI3L1 and amyotrophic lateral sclerosis: ALS patients exhibit increased levels of chitinase-like proteins, including chitotriosidase 1 (CHIT1), chitinase-3-like protein 2 (CHI3L2), and chitinase-3-like protein 1 (YKL-40), in contrast to healthy control subjects and individuals with other neurodegenerative disorders (Dreger et al., 2022; Thompson et al., 2022).