SOD1 and amyotrophic lateral sclerosis: The majority of ALS cases arise sporadically (sALS), but approximately 10% of cases are familial (fALS) (Leblond et al., 2014), and mutations in the gene encoding cytosolic superoxide dismutase 1 (SOD1) cause 20% of fALS cases (Rosen et al., 1993).