Transgene dosage effects on life span. (A) Kaplan-Meier survival analysis. Transgenic animals with a lower CT signal value exhibited an increased survival time. Bonferroni correction for multiple comparisons indicated a significant difference between animal source and lifespan. Inter-sex comparisons show that collaborator derived progeny with a higher CT signal value reached the endpoint (inability to self-correct) after one year of age, while commercially derived progeny with a lower CT signal value reached the endpoint much later, beyond 1.5 years of age. ***p < 0.001. Collaborator- ♂ n = 8; Collaborator- ♀ n = 5; Commercial-♂ n = 18; Commercial-♀ n = 17. (B) Linear regression analysis reveals a negative correlation between relative mutant SOD1 copy number and lifespan (p < 0.0001). Collaborator n = 16; Commercial n = 28.