Here, we present data on the prevalence and risk assessment of BC associated with clinically significant variants in known susceptibility genes (BRCA1, BRCA2, ATM, CHEK2, and PALB2), as well as in disputed genes with an undetermined contribution to the disease (BLM, NBN, RAD50, NBEAL1, XRCC2, MUTYH, FANCC, and so on), identified in a panel of 78 genes involved in DNA repair processes. This evidence concerns the gene CHEK2 and breast cancer.