Stratifying according to MDM2 SNP309 status (SNP309TT, SNP309TG, and SNP309GG) we found the MDM4 SNP34091CC genotype (recessive model) to be significantly associated with reduced risk of breast cancer among patients carrying the SNP309GG genotype (OR = 0.41; 95% CI = 0.21–0.82; Table 2, Fig. 1B). This evidence concerns the gene MDM2 and breast carcinoma.