BRCA1 and breast cancer: However, it was shown that although itplays a critical role in the double-strand DNA break repair, GEN1 would not make anyappreciable contribution to breast cancer susceptibility through acting as a high-or intermediate-penetrance breast cancer predisposition gene, such as BRCA1, BRCA2,CHEK2, ATM, BRIP1, and PALB2 [26].