Due to the strong evidence linking ATM to radiation sensitivity in the constitutional setting [5, 6], we searched our institutional MSK-IMPACT (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets) database of 2,250 patients who underwent targeted panel sequencing to identify other patients with truncating mutations in ATM. Forty-five other patients, harboring a variety of primary malignancies, were found to have frame-shift or truncating ATM mutations. The gene discussed is ATM; the disease is cancer.