In contrast to the CHEK2-deficient cancers, BRCA1/2-deficient cancers did not present with mutational signature SBS1 (0/28 cancers; 0%; P < .05), and a minority presented with mutational signature SBS5 (11/28 cancers; 39%; P < .05; Figure 1, D). This evidence concerns the gene CHEK2 and cancer.