Although the genomic “scars” present in canonical HR-related genes (eg, BRCA1, BRCA2, PALB2, RAD51C, RAD51D, and RAD51B) and their respective absence in cancers with alterations affecting DDR-related genes (eg, ATM and CHEK2) have been described, the spectrum of genomic signatures in tumors with LOF of less common HR/DDR genes, including NBN, has yet to be fully characterized. The gene discussed is CHEK2; the disease is cancer.