However, rather than providing a growth advantage as in cancers, BRCA2 deficiency causes inviability of mouse embryos and normal mouse cells12–15, although it is not fully understood how lethality is induced in the absence of BRCA2 in otherwise normal cells and how tumor cells emerge and survive the crisis when BRCA2 is lost, which may potentially impact therapeutic approaches. The gene discussed is BRCA2; the disease is neoplasm.