Chitotriosidase (CHIT1): An elevated level of CHIT1 in the cerebrospinal fluid (CSF) of ALS patients has been indicated, and CHIT1 level in CSF may exert an additional effect in the prognosis of ALS patients with a short history of symptoms that are difficult to identify [166]. This evidence concerns the gene CHIT1 and amyotrophic lateral sclerosis.