ATM and breast cancer: There is also evidence that a subset of ATM missense variants is associated with risk of multiple cancers including breast, prostate, and pancreatic cancer.8 9 The risk for BC appears to be restricted to a subset of missense variants lying in the FRAP-ATM-TRRAP (FAT) and phosphatidylinositol 3-kinase (PI3K) domains of ATM; for these variants, the risk appears to be comparable with the risks for PTVs.5 9