BRCA1 and cancer: A BRCA1/2 defect-specific point mutation spectrum that shows a broad range of mutation types has been inferred from unsupervised pattern-finding in cancer genomes.11 To obtain direct causative evidence for the mutagenic effect of BRCA1/2 loss-of-function, including accurate measurements of the mutation load, experiments in isogenic BRCA1/2 mutant and non-mutant cell lines or transgenic animals are necessary.