CHEK2 and breast cancer: Furthermore, an increasing list of other genes have been shown to have rarer germ-line variants that are associated with strongly increased EOBC risk; these include ATM, PALB2, CHEK2, PTEN, and TP53.14 Some centers now test for these variants in individuals with otherwise unexplained strong family histories of BC, and may offer increased and earlier monitoring for BC if variants are identified.15