SOD1 and amyotrophic lateral sclerosis: A limitation of the study is certainly the use of only female mice as gender differences are described for sporadic and familial ALS patients [67] as well as for human SOD1 mice [68] and could therefore possibly have an impact on the variability of the results, as it is already described for SOD1G93A mice on an C57BL/6 background [45].