Functions of BRCA1 and BRCA2 in the biological response to DNA damage

Inheritance of one defective copy of either of the two breast-cancer-suscep tibility genes, BRCA1 and BRCA2, predisposes individuals to breast, ovarian and other cancers. Both genes encode very large protein products; these be ar little resemblance to one another or to other known proteins, and their precise biological functions remain uncertain. Recent studies reveal that t he BRCA proteins are required for maintenance of chromosomal stability in m ammalian cells and function in the biological response to DNA damage. The n ew work suggests that, although the phenotypic consequences of their disrup tion are similar, BRCA1 and BRCA2 play distinct roles in the mechanisms tha t lead to the repair of DNA double-strand breaks.