In this study, to further clarify the phenotype variability among different mutant SOD1-expressing ALS mouse models on different genetic backgrounds, we newly generated congenic lines of SOD1G93A and SOD1H46R mice as well as those lacking Als2 on a FVB/N (FVB) background, and conducted a comparative analysis of gross phenotypes in these mutants with different genetic backgrounds. The gene discussed is ALS2; the disease is amyotrophic lateral sclerosis.