Genetic susceptibility to breast and ovarian cancer.

5-10% of women with breast cancer carry an inherited mutation in either the BRCA1 or BRCA2 genes. These genes confer a very high lifetime risk of breast cancer, ovarian cancer (especially BRCA1) and male breast cancer (especially BRCA2). These genes are large, of essentially unknown function, and surprisingly, play a very small role in the development of tumors in non-predisposed individuals. These genes have now been cloned, a highly automated genetic test developed and high risk populations have been screened to establish the utility of the test. The value to women and preliminary clinically recommendations are discussed.