If our estimates of breast cancer risk are correct, then women carrying the ATM c.7271T > G variant would be at sufficiently high risk to warrant screening for at least this variant in multiple-case families without mutations in BRCA1 or BRCA2. If such a variant is identified, these women could be counseled in a manner similar to that with BRCA2 carriers, and those affected with breast cancer might also be candidates for treatment with PARP inhibitors in a manner similar to that with BRCA1 and BRCA2 carriers. This evidence concerns the gene BRCA2 and breast cancer.