SOD1 and amyotrophic lateral sclerosis: Unbiased hierarchical clustering performed with the 91 proteins commonly detected in both biofluids showed a clear separation between the CSF and serum proteome, but could not cluster the samples according to the 3 groups of individuals (healthy controls, SOD1‐ALS baseline, and SOD1‐ALS tofersen; Fig. S1A–C).