CHEK2 and breast cancer: Within the cohort of 83 subjects with BC, we detected 13 pathogenic or likely pathogenic heterozygous germline variants (ACMG class 4–5; i.e., nonsense, frameshift, missense, [consensus] splice site variants, or copy number aberrations) in 10 unrelated patients and 9 genes [ATM (n = 3), CDKN2A (n = 1), CHEK2 (n = 1), FANCI (n = 1), PALB2 (n = 2), PMS2 (n = 1), RECQL4 (n = 2), RUNX1 (n = 1), and WRN (n = 1)].