MTHFR and breast cancer: A number of studies have examined MTHFR and MTR polymorphisms [4-6,17-25] and found that variant genotypes of MTHFR C677T are associated with an increased [4,17,22-25] or decreased [5,20] risk of breast cancer, while those of MTHFR A1298C are associated with a decreased risk [24] and those of MTR A2756G with a decreased risk [6].