SOD1 and amyotrophic lateral sclerosis: The SOD1 mutation accounts for a minority (<2%) of ALS patients (Rosen et al., 1993) and, importantly, SOD1 cases do not display the pathological hallmark of ALS, namely TAR DNA binding protein 43 proteinopathy, that is found in >97% of ALS cases (Neumann et al., 2006; Kwiatkowski et al., 2009).