This thesis examined how variable the effects of changes in cSOD activity were on phenotypes across genetic backgrounds and between sexes. Analysis of variance (ANOVA), and the effect size partial eta squared (η2p) were used to partition the amount of variation attributable to sex, cSOD activity, and genetic background across the distal and proximal phenotypes assayed. The absence of cSOD activity results in pervasive changes in phenotypic expression, and these changes are only slightly modified by sex or genetic background. Higher levels of cSOD activity generally result in phenotypic expression closer to wild-type levels, though phenotypes were more susceptible to modification depending on sex and genetic background when some cSOD activity was present. Results here indicate that the cSOD-null syndrome is pervasive, and the significant influence of sex and genetic background across phenotypes supports the utilization of both sexes and multiple genetic backgrounds in genetic analyses.