By doing so, we confirmed the MDM4 SNP34091CC/MDM2 SNP309 GG genotype to associated with reduced risk of breast cancer (OR = 0.47; 95% CI = 0.24–0.92, when compared with the highest risk genotype (MDM4 SNP34091AA/MDM2 SNP309GG), data not shown). This evidence concerns the gene MDM4 and breast cancer.