BRCA2 and breast cancer: The association between increased chromosomal radiosensitivity and sporadic breast cancer risk has been reported6, and a number of DNA DSB repair genes including BRCA1, BRCA2, ATM, CHEK2, PALB2, TP53, Rad51C, Rad51D, and NBS1 have been identified as being causative of hereditary breast and ovarian cancer (HBOC)10.