Thus, ALS-CSF samples had approximately 15-fold higher enzymatic activity when compared to N-CSF and 25-fold more when compared to NALS-CSF (***p < 0.001 vs N-CSF and $$p < 0.01 vs NALS-CSF) The CHIT-1 activity did not differ significantly between NALS-CSF and N-CSF (Fig. 2a). Here, CHIT1 is linked to amyotrophic lateral sclerosis.