In comparison with the control by multivariate regression analyses considering the age, the GPNMB level was high in the ALS-fast group (p < 0.001) and the CHI3L2 level was high in the ALS-fast and ALS-intermediate groups (both p < 0.05) (Supplementary Figure S1). Here, CHI3L2 is linked to amyotrophic lateral sclerosis.