SOD1 and amyotrophic lateral sclerosis: SOD1 (G93A) mice were euthanized at both 15-weeks (early symptomatic disease stage, n = 5 per group) and 18 weeks of age (end stage, n = 10 per group), and age-matched control WT non-ALS mice (n = 4) were likewise euthanized for analysis of spinal cord.