CHEK2 and breast cancer: All three relatives also carried a likely pathogenic variant in CHEK2, c.593–1G>T (rs786203229), a gene that confers a moderate risk of breast cancer, and possibly other tumor types, including CRC.37,38 In this family, the carriers of the two variants did not develop particularly aggressive phenotypes, two of them having developed CRC late in life (ages 60 and 73).