Guo X, et al. - Given that increased breast cancer risk results from pathogenic variants in susceptibility genes, researchers used 831 breast cancer cases and 839 controls of Chinese women in this study to define coding variants related to breast cancer risk. They performed whole exome sequencing in genomic DNA samples from the participants. Taking together data from 7,204 breast cancer cases and 9,593 controls, they found a missense variant (rs139379666, P2974L) in the ATM gene for breast cancer risk. ATM function was disrupted by this novel mutation conferring to breast cancer risk.