To test the hypothesis that polymorphisms in antioxidant genes are more susceptible to sperm DNA damage and male infertility, we examined 11 single-nucleotide polymorphisms from six antioxidant genes (GPX1, CAT, PON1, NQO1, SOD2/MnSOD, and SOD3) in 580 infertility cases and 580 controls from a Chinese population-based case-control study (NJMU Infertility Study). Genotypes were determined using the OpenArray platform. Sperm DNA fragmentation was detected using the Tdt-mediated dUTP nick-end labeling assay, and the level of 8-hydroxydeoxyguanosine (8-OHdG) in sperm DNA was measured using immunofluorescence. The adjusted odds ratio and 95% confidence interval (CI) were estimated using unconditional logistic regression. The results indicated that the PON1 Arg192Glu (rs662) and SOD2 Val16Ala (rs4880) variant genotypes were associated with a significantly higher risk of male infertility. In addition, subjects carrying variant genotypes of both loci had a twofold (95% CI, 1.42-2.90) increase in the risk of male infertility, indicating a significant gene-gene interaction between these two loci (P for multiplicative interaction=0.045). Moreover, linear regression analysis showed that individuals carrying the PON1 Arg192Glu (rs662) or SOD2 Val16Ala (rs4880) variants have significantly higher levels of sperm DNA fragmentation and 8-OHdG. These data suggest that genetic variations in antioxidant genes may contribute to oxidative sperm DNA damage and male infertility.
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