Association between manganese superoxide dismutase (MnSOD) gene polymorphism and breast cancer risk

Superoxide dismutases play a key role in the detoxification of superoxide r adicals and thus protect cells from damage induced by free radicals. Within mitochondria manganese superoxide dismutase (MnSOD) provides a major defen ce against oxidative damage by reactive oxygen species. Polymorphism in the mitochondrial targeting sequence of MnSOD has recently been associated wit h risk of breast cancer. We examined this in a study population consisting of 483 breast cancer cases and 482 controls, all of Finnish Caucasian origi n, Odds ratios (OR) and 95% confidence intervals (95% CIs) were estimated b y unconditional logistic regression. MnSOD genotypes containing the variant A allele were found to be associated with a 1.5-fold (95% CI 1.1-2.0) incr eased risk of breast cancer compared with those with the homozygous wild-ty pe genotype (MnSOD VV). This finding supports the proposal that MnSOD genot ypes may modify individual breast cancer risk.