BRCA1 and breast cancer: Conversely, Hereditary Breast and Ovarian Cancer (HBOC) syndrome demonstrates much lower rates of de novo mutations, reflecting a relatively more stable pattern of inheritance, as demonstrated in a comprehensive cohort study that included 12,805 consecutive unrelated patients diagnosed with breast cancer (BC) and/or ovarian cancer (OC), where only 0.4% of patients (3/801; CI 0.1–1.1%) carried a de novo BRCA1 variant and 0.1% (1/726; CI 0.02–0.8%) harbored BRCA2 de novo [4].