CHEK2 and breast cancer: Estimates are that about 1.1–1.7% of women with breast cancer have a PV in CHEK2, 1.4–2.1% in BRCA1, 1.6–2.2% in BRCA2, 0.87–1% in ATM, and 0.84–0.87% in PALB2, with other genes less than 1% [98,100].