SOD1 and amyotrophic lateral sclerosis: The SOD1G93A DL model has about 10 copies of the mutant SOD1 gene and a longer life span (39–42 weeks) than the SOD1G93A 1Gur/J mice (19–23 weeks) used in our study, which have higher copy numbers of the mutant SOD1 gene (18 copies) and exhibit accelerated onset of the ALS phenotype (14–16th week onset compared to 34th week onset in the SOD1G93A DL model) [23,24].