Severe radiotoxicity in an allogeneic transplant recipient with a heterozygous ATM mutation

Patients receiving radiotherapy often experience toxicity of the skin and mucous membranes. While radiotherapy is a mainstay of myeloablative conditioning for allogeneic hematopoietic stem cell transplantation (ASCT), no risk factors for radiotoxicity have been identified in this setting. Here, we report on a patient with excessive radiation‐induced toxicity after ASCT who carried a heterozygous mutation in the Ataxia telangiectasia mutated (ATM) gene. This is the first case to suggest a genetic basis for increased radiotoxicity after myeloablative ASCT.