3. Do inherited mutations in other genes increase the risk of breast and/or ovarian tumors?

Yes. Mutations in several other genes, including TP53, PTEN, STK11/LKB1, CDH1, CHEK2, ATM, MLH1, and MSH2, have been associated with hereditary breast and/or ovarian tumors (4, 6, 7). However, the majority of hereditary breast cancers can be accounted for by inherited mutations in BRCA1 and BRCA2 (8). Overall, it has been estimated that inherited BRCA1 and BRCA2 mutations account for 5 to 10 percent of breast cancers and 10 to 15 percent of ovarian cancers among white women in the United States (6).

4. Are specific mutations in BRCA1 and BRCA2 more common in certain populations?

Yes. For example, three specific mutations, two in the BRCA1 gene and one in the BRCA2 gene, are the most common mutations found in these genes in the Ashkenazi Jewish population. In one study, 2.3 percent of participants (120 out of 5,318) carried one of these three mutations (9). This frequency is about five times higher than that found in the general population (10). It is not known whether the increased frequency of these mutations is responsible for the increased risk of breast cancer in Jewish populations compared with non-Jewish populations.

Other ethnic and geographic populations around the world, such as the Norwegian, Dutch, and Icelandic peoples, also have higher frequencies of specific BRCA1 and BRCA2 mutations.

In addition, limited data indicate that the frequencies of specific BRCA1 and BRCA2 mutations may vary among individual racial and ethnic groups in the United States, including African Americans, Hispanics, Asian Americans, and non-Hispanic whites (11–13).

This information about genetic differences between racial and ethnic groups may help health care providers in selecting the most appropriate genetic test(s) (see Question 5).

5. Are genetic tests available to detect BRCA1 and BRCA2 mutations, and how are they performed?

Yes. Several methods are available to test for BRCA1 and BRCA2 mutations (14). Most of these methods look for changes in BRCA1 and BRCA2 DNA. At least one method looks for changes in the proteins produced by these genes. Frequently, a combination of methods is used.

A blood sample is needed for these tests. The blood is drawn in a laboratory, doctor’s office, hospital, or clinic and then sent to a laboratory that specializes in the tests. It usually takes several weeks or longer to get the test results. Individuals who decide to get tested should check with their health care provider to find out when their test results might be available.

Genetic counseling is generally recommended before and after a genetic test. This counseling should be performed by a health care professional who is experienced in cancer genetics (see Question 17). Genetic counseling usually involves a risk assessment based on the individual’s personal and family medical history and discussions about the appropriateness of genetic testing, the specific test(s) that might be used and the technical accuracy of the test(s), the medical implications of a positive or a negative test result, the possibility that a test result might not be informative (an ambiguous result) (see below), the psychological risks and benefits of genetic test results, and the risk of passing a mutation to children.