Multigene panel (MGP) studies of known HBOC genes in large mixed patient cohorts suggest a pathogenic and/or likely pathogenic variant (PV) prevalence of approximately 8% in BC cases and 16% in OC cases; with PVs in BRCA1 and BRCA2 (BRCA1/2) accounting for approximately 50% and 80% of the total PVs respectively (Table S1) [3, 4]. The gene discussed is BRCA1; the disease is breast cancer.