CHI3L1 and in situ carcinoma: The discrepancy between our study and theirs might be related to a lower sample size that precluded them for obtaining statistical significance, and/or to the presence of CIS patients in the study cohort in which, disability was low, and if existent, the underlying mechanisms of progression that determine an increase in CSF biomarkers of advanced disease, such as CHI3L1, might also be underrepresented.