Although the mitochondrial localization of mutant SOD1 has been discussed by Bergemalm and colleagues [47] by considering the amount of mitochondrial mutant SOD1 in murine ALS models as a potential artifact due to the high copy numbers of the transgene, the role of mitochondrial SOD1 in ALS aetiology has been established in different non-SOD1 ALS models [48]. This evidence concerns the gene SOD1 and amyotrophic lateral sclerosis.