As shown in an early targeted analysis of 20 variants in FCs, 84% of BRCA1 and BRCA2 positive HBC and HBOC syndrome families harbour one of five specific PVs in these genes accounting for the high frequency of these PVs observed in BC- and OC-affected individuals in this population [35]. This evidence concerns the gene BRCA2 and Hereditary breast and ovarian cancer syndrome.