4,23,46 As previously noted, there is a comparatively limited understanding of individual breast cancer risk associated with mutations in genes other than BRCA1 and BRCA2. However, the presence of mutations in PALB2, ATM, truncating mutations in CHEK2, and possibly other genes are likely to be associated with lifetime breast cancer risks of greater than 20% and therefore, in the United States, at least support a decision for enhanced surveillance with annual mammography with tomosynthesis and breast MRI with contrast. This evidence concerns the gene CHEK2 and breast cancer.