CHEK2 (OMIM 604373) is a tumor-suppressor gene that is involved in DNA repair in response to cellular DNA damage.1 There is clear evidence that individuals with heterozygous CHEK2 deleterious germline variants are associated with an increased risk for female breast cancer and prostate cancer, and elevated risks for a variety of other cancers (eg, colorectal, kidney, bladder, leukemia/lymphoma, and thyroid) have been observed.2,3 In general, germline pathogenic truncating variants (PTV) (eg, c.1100del p.[Thr367fs]) are associated with an increased risk of cancer. This evidence concerns the gene CHEK2 and breast cancer.