Levels of NFL and CHIT1 were elevated in the first-visit CSF samples of patients with ALS compared with healthy controls (NFL mean 13 994.7 pg/ml ALS, 1729.2 pg/ml healthy control, P < 0.001; CHIT1 ALS 6869.4 pg/ml, healthy control 843.5 pg/ml, P < 0.001) and disease controls (NFL 2742.9 pg/ml, P < 0.001; CHIT1 2194.1 g/ml, P < 0.001). This evidence concerns the gene NEFL and amyotrophic lateral sclerosis.