CHIT1 and neurodegenerative disease: CHIT1 levels in SMA were lower than described for ALS [13, 15, 20–23, 41] or other neurodegenerative diseases [13, 16, 18, 19, 24, 29, 42, 43], implying a minor involvement of neuroinflammation in SMA and arguing against the usefulness of CHIT1 as a disease severity biomarker for SMA.