The gene expression investigations revealed the substantial down-regulation of BRCA1 (P = 0.02), CHEK2 (P = < 0.0001), BRIP1 (P = < 0.0001), and RAD51 (P = 0.01) in breast tumors compared with adjacent normal tissues (Fig. 3a). This evidence concerns the gene CHEK2 and breast neoplasm.