For this study, we selected the TRIM9 gene as a breast cancer specific methylation marker by referring to the methylation array database and observed TRIM9 hypermethylation in 92 % (11/12) of the BCCs and 68 % (13/19) of breast tumor tissues but not in any of the normal breast epithelial cell line (HMEC) cells or normal breast tissues. The gene discussed is TRIM9; the disease is breast cancer.