Cox proportional hazards models were constructed incorporating available first‐visit clinical characteristics known to be associated with survival in ALS (disease duration at sampling, age at onset, bulbar versus spinal symptom onset, and sex), along with pNFH and LC–MS/MS UCHL1 and CHIT1, with and without disability progression rate as an additional variable (Figure 4). This evidence concerns the gene CHIT1 and amyotrophic lateral sclerosis.