PDAC is characterized by complex rearrangements and mitotic abnormalities, with frequent changes in the DDR pathways, including homologous recombination (HR) abnormalities in the breast cancer 1 (BRCA1), breast cancer 2 (BRCA2), Ataxia Telangiectasia Mutated (ATM) and Partner and Localizer of BRCA2 (PALB2) genes [16–18]. The gene discussed is ATM; the disease is breast cancer.