CHEK2 and breast cancer: Genes with PVs demonstrating statistically significant associations with breast cancer included BRCA1/2, ATM, CHEK2, PALB2, BARD1, BRIP1, RAD51C, RAD51D, NBN, CDH1, NF1, TP53, CDKN2A, and MSH6. While PVs in most of these genes were associated with two- to fivefold increased risks of breast cancer, several genes were significantly associated with increased breast cancer risk <twofold (BRIP1, MSH6, NBN, and RAD51C).