When stratifying ALS patients into SOD1 mutation subgroups, ALS patients with SOD1 D90A homozygous or heterozygous mutations combined showed significantly lower levels of CSF pNFH compared to those with SOD1 A4V heterozygous and other ALS SOD1 mutations combined (CSF pNFH; p < 0.01, CSF NFL; p > 0.05). Here, SOD1 is linked to amyotrophic lateral sclerosis.