CHI3L1 and proximal spinal muscular atrophy: The regression model, adjusted for age and sex, analyzing YKL-40 (also known as Chitinase 3-like 1) levels in CSF, revealed no significant differences between CSF samples of the healthy control group (control: 173.32 ± 11.39 ng/mL) and the non-treated adult SMA patient samples (SMA(Pre): 88.16 ± 6.50 ng/mL) related to the group effect [F(1,54) = 0.243, p = 0.624].