However, evidence suggests that HR-positive patients account for at least half of all BRCA 1 and/or 2 mutation carriers: 1 in 17 HR-positive patients have a germline BRCA 1 and/or 2 mutations (65% of breast cancer germline BRCA 1 and/or 2 mutation population), the majority of these would be germline BRCA2 mutations [83, 84]. Here, BRCA2 is linked to breast cancer.