Related Pages Breast Cancer Home Page NCI's gateway for information about breast cancer. Genetics of Breast and Ovarian Cancer [ health professional ] Expert-reviewed information summary about the genetics of breast and ovarian cancer, including information about specific genes and family cancer syndromes. The summary also contains information about interventions that may influence the risk of developing breast and ovarian cancer in individuals who may be genetically susceptible to these diseases. Psychosocial issues associated with genetic testing are also discussed.

A gene that is mutated in some patients with the blood disease Fanconi anemia may also be a risk factor for breast cancer. Researchers estimate that certain mutations in the gene BRIP1 result in a twofold increase in breast cancer risk. This puts the gene in a class with two other breast cancer susceptibility genes, CHEK2 and ATM, which may predispose a woman to cancer only in the presence of other genetic or environmental risk factors. By comparison, mutations in the breast cancer susceptibility genes BRCA1, BRCA2, and TP53 confer a 10- to 20-fold increased risk of the disease.

Dr. Nazneen Rahman of the Institute of Cancer Research in Sutton, U.K., and her colleagues discovered the gene by analyzing proteins that interact with the proteins of known breast cancer susceptibility genes. The BRIP1 protein interacts with the breast-cancer associated protein BRCA1, according to findings published online October 10, 2006, in Nature Genetics.

The researchers screened for BRIP1 mutations in 1,212 women with breast cancer who lacked mutations in BRCA1 and BRCA2. They found nine women who had "truncating" mutations in BRIP1, which probably inactivate the BRIP1 protein; only two of 2,081 women without breast cancer in a comparison group had such mutations. Several of the BRIP1 mutations they detected had been reported in patients with Fanconi anemia.

Like other breast cancer susceptibility genes, BRIP1 may play a role in repairing damaged DNA. The researchers predict that "other genes involved in DNA repair processes may also be involved in breast cancer susceptibility." Together, the known breast cancer susceptibility genes are estimated to account for up to 25 percent of the familial, or inherited, risk of the disease, leaving most of the risk unexplained.

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