Genes implicated in hereditary breast cancer syndromes.

The medical histories of breast cancer-prone families have been described for over a century. The pattern of breast cancer occurrences in these families is most consistent with an autosomal dominant mode of inheritance. The location of a gene that could explain the pattern of transmission of the breast cancer trait in families averaging early (pre-menopausal) onset of breast cancer was reported in 1990. Since then, two genes have been identified: BRCA1 and BRCA2. Germ-line mutations in these two genes confer susceptibility to breast (female and male) and ovarian cancer, and account for a significant proportion of hereditary breast cancer in two cancer syndromes: site-specific breast cancer and the breast-ovarian cancer syndrome. Other hereditary syndromes that feature breast cancer are Li-Fraumeni syndrome, Cowden disease, and ataxia telangiectasia, whose carriers have been shown to harbor germ-line mutations in TP53, PTEN, and ATM, respectively. There may be other genetic factors that contribute to hereditary breast cancer, since not all families with multiple cases of breast cancer harbor germ-line BRCA1 or BRCA2 mutations. Host factors (such as lifestyle choices) and other genes may modulate risk of breast cancer in mutation carriers.