SOD1 and amyotrophic lateral sclerosis: Mutations in SOD1 account for about 20% of familial and 2–7% of sporadic ALS cases (alsod.iop.kcl.uk), which makes SOD1 the second most frequently mutated gene after C9ORF72 in affected Caucasians (Ajroud-Driss and Siddique, 2015; Renton et al., 2014).