Low-penetrance susceptibility variants and postmenopausal oestrogen receptor positive breast cancer.

The risk of breast cancer (BC) in women is high and many factors including genetic factors increase the risk for the disease. It is revealed that the variations of low-penetrance susceptibility genes are important for carcinogenesis as they interact with the environmental and hereditary factors. Recently, the list of BC-associated common single nucleotide polymorphisms (SNPs) and chromosomal loci in low-penetrance susceptibility genes have been expanded in genomewide association studies. FGFR2, LSP1, MAP3K1, TGFB1, TOX3, 2q35 and 8q loci variations are some examples for these common SNPs. These SNPs and their association with BC risk was investigated in many different populations. Therefore in this study, we aimed to evaluate low-penetrance susceptibility SNPs; namely FGFR2 rs1219648, rs2981579, rs2981582; MAP3K1 rs889312; TOX3 rs3803662; LSP1 rs909116, rs3817198 and SLC4A7 rs4973768 together, for the firsttime in Turkish postmenopausal oestrogen receptor positive BC cases. Following the DNA isolation, multiplex PCR and matrix-assisted laser desorption/ionization mass spectrometry with time of flight measurement (MALDI-TOF) based SNP analysis were performed. MAP3K1 rs889312 SNP demonstrated the strongest association with BC risk among the other low penetrant SNPs, it was also associated with BC risk in a dominant model. Only in a ressesive model, TOX3 rs3803662 was associated with BC risk. In addition, rs4973768 CC and rs909116 CC genotypes are correlated with higher tumour size which is not reported in the literature as yet; on the other hand there are no associations between any of the other SNP genotypes and clinopathological parameters. In our opinion, MAP3K1 rs889312 may be a good BC susceptibility biomarker candidate for Turkish population.