Maintenance of genome stability is of crucial importance to cellular and organismal survival. Double-strand breaks (DSBs) are highly toxic legions that can lead to loss or amplification of genetic information, chromosomal translocations, neoplastic transformation and cell death1. To counteract these lesions and mitigate their consequences, cells activate a complex network of repair and signaling pathways, collectively known as the DNA damage response (DDR)2. The DDR coordinates diverse processes such as cell-cycle checkpoint signaling cascades, localized chromatin modifications and functions of multiprotein DNA repair complexes. Individuals born with a defective DDR have syndromes with diverse sequelae, including cancer
predisposition, neurodegeneration and immunodeficiency.