CHEK2 and breast cancer: It is well established that knowledge of carriership is of clinical importance, since increased surveillance and prophylactic surgery leads to significantly reduced morbidity and mortality [4, 6, 20], especially for women harboring pathogenic variants in BRCA1, BRCA2, or PALB2. Out of the early-onset breast cancer patients who had previously undergone genetic testing, 19.6% were carriers of pathogenic variants in ATM, BARD1, BRCA1, BRCA2, CHEK2, or PALB2. In the current study, 9.7% of the women were identified as carriers of pathogenic variants in these six breast cancer susceptibility genes.