CHI3L1 and myeloid sarcoma: Linear regression models of cNfL (ln[cNfL] = 0.0243∗Age + 5.2043), sNfL (ln[sNfL] = 0.0177∗Age + 0.9696) and CHI3L1 (ln[CHI3L1] = 0.0172∗Age + 3.8088) with age as an independent variable were used to predict the healthy, age-related levels of these biomarkers for all MS patients according to their age at time of sample collection.