Germline genetic abnormalities in the tumor suppressors BRCA1 and BRCA2 predispose to hereditary breast and ovarian cancer (HBOC) in an autosomal-dominant manner. BRCA1 and BRCA2 are important for DNA repair, when mutated, chromosomal DNA accumulates further mutations that fuels tumorigenesis. Clinical genetic laboratory testing of individuals at risk identifies HBOC predisposing gene variants, which is crucial to guide between several management options for the condition. Furthermore, precise information regarding pathogenic variants supports treatment choices in the event of cancer development.