Across all 15 CPGs there was an almost equitable division of the number of positive (n = 1.54) and negative (n = 1.51) subsequent cascade tests per index case identified, although some of these were confirmatory tests of relatives with appropriate cancer or phenotype (e.g., breast or ovarian cancer for BRCA1/2 or typical Cowden features for PTEN). This evidence concerns the gene BRCA1 and cancer.