CHIT1 and amyotrophic lateral sclerosis: Chitotriosidase 1 (CHIT1) reflects microglial activity, and is detectable at increased levels in the CSF of ALS patients, also correlating with disease progression rate (PR) and survival.11,12 Several analytes measurable using routine clinical assays have also shown potential value as biomarkers in ALS, including acute phase proteins: C-reactive protein (CRP), complement, ferritin,13–17 and the skeletal muscle marker creatine kinase (CK).18,19