Homologous recombination deficiency (HRD) has been established as a predictive biomarker for PARPi therapy in ovarian cancer; furthermore, distinct HRD phenotypes correlate with somatic mutations and the epigenetic silencing of BRCA1 and BRCA2 in breast, prostate, and pancreatic cancers [26]. The gene discussed is BRCA1; the disease is hypoparathyroidism-retardation-dysmorphism syndrome.