Our data support the hypothesis that germline DNA CNV is a genetic factor contributing to breast cancer predisposition, which is in accord with the findings of other studies indicating CNVs as risk factors in cancer, including neuroblastoma [19], colorectal cancer [22,23], hepatocellular carcinoma [44], aggressive prostate cancer [20], nasopharyngeal carcinoma[45]and BRCA1-associated ovarian cancer[38]. This evidence concerns the gene BRCA1 and breast cancer.