NEFL and amyotrophic lateral sclerosis: We identified a set of proteins, including neurofilament light chain, neurofilament heavy chain, amyloid‐beta 1–40 and amyloid‐beta 1–42, neuropeptide Y (NPY), and ubiquitin C‐terminal hydrolase L1 (UCHL1), whose CSF levels both differed between SOD1‐ALS and the control group, and were responsive to tofersen at 3 and 6 months after treatment initiation.