An increased risk for malignancy, in particular, female breast cancer, among individuals heterozygous for germline ATM mutations has been reported in many studies [7,8], but in a recent study, the increased breast cancer risk of the heterozygous mutation carriers in A-T families was seen only in the mothers of the A-T patients [9], while another study reported that the breast cancer risk in A-T families was associated specifically with mutations located in the binding domains of the ATM protein [10]. This evidence concerns the gene ATM and breast cancer.