The combination of T309G of gene MDM2 heterozygous genotype with Arg399Gln of gene XRCC1 heterozygous genotype was associated with a 3-fold increase of BC probability (OR 3.0 (95% CI 1.18–7.56)) (Table 4), which makes this combination of haplotypes a genetic risk factor of BC in Kyrgyz women. This evidence concerns the gene XRCC1 and breast cancer.