Guo X, et al. - Given an increased risk for breast cancer in correlation to pathogenic variants in susceptibility genes, researchers sought coding variants related to breast cancer risk by conducting whole-exome sequencing in genomic DNA samples from 831 breast cancer cases and 839 controls of Chinese women. In addition, among 4,580 breast cancer cases and 6,695 controls, they genotyped samples using whole exome-chip arrays. A replication study was also undertaken using a Multi-Ethnic Global Array in samples from 1,793 breast cases and 2,059 controls. Combing data from 7,204 breast cancer cases and 9,593 controls, a missense variant (rs139379666, P2974L; AF = 0.09% for breast cancer cases, but none for controls) was found in the ATM gene for breast cancer risk. As per observation, the risk allele vs the reference allele, led to significant disruption of the activity of homologous recombination-mediated double-strand breaks repair efficiency. Findings thereby found a novel mutation that disturbs ATM function, conferring to breast cancer risk.