Genetic Testing for BRCA1 and BRCA 2

A significant number of women with breast cancer have some family history of the disease. But only 5 to 10 percent of all cases of breast cancer are due to heredity. However, you’re two to three times more likely than the average woman to develop breast cancer if a first-degree relative (your mother, sister, or daughter) has had the disease.

If more than one first-degree relative has had breast cancer, your risk is also higher. This increased risk is even greater if the relatives developed cancer either before they went through menopause or in both breasts. Certain other types of cancer, such as ovarian cancer and male breast cancer, in a family further increase the possibility that the cancer is hereditary.


Some women are vulnerable to developing breast cancer because they’re born with mutations in the BRCA1, BRCA2, or PALB2 genes. Mutations are changes in the molecular sequence of the DNA. Having certain mutations in these genes raises your breast cancer risk. A woman can inherit an abnormal gene from either her father or her mother.

These genes normally function as caretakers, helping cells repair their DNA when it becomes damaged as a normal consequence of living. Women without a BRCA mutation have two normal copies of the gene and are at a lower risk for developing breast cancer than those with the mutation. In most cases a single normal gene is sufficient for good health. But if that healthy gene is lost, leaving only the mutated copy, the cell’s ability to repair its DNA can be compromised, leading to cancer.

Defects in these genes are not associated with increased risk for every kind of cancer. However, in addition to breast cancer, women with a BRCA mutation have an increased risk of developing ovarian cancer. Men with these mutations may be at an increased risk of developing male breast cancer and prostate cancer. Other cancers may be linked to these abnormal genes in some families. We continue to learn more about where they do and don’t cause malignancy.

Genetic Testing

If you or women in your family have been diagnosed with breast cancer, you may wonder if you should be tested for genetic mutations. For most women, the answer to this question is no. Inherited gene mutations are responsible for only a small percentage of breast cancers. However, research that seeks to refine the role of testing is currently under way and could change our approach.

You and your relatives might benefit from genetic counseling and testing if:

  • several members of your family in multiple generations have had breast cancer or other forms of cancer — ovarian cancer or male breast cancer in particular
  • your breast cancer occurred at a fairly young age (under age 50)
  • your breast cancer occurred in both breasts
  • your breast cancer is triple negative, meaning it lacks the estrogen receptor, progesterone receptor, and HER2 receptor

If any of these apply to you, discuss your situation with your doctor. 

Genetic Testing & Counseling at Memorial Sloan Kettering
Memorial Sloan Kettering’s Clinical Genetics Service offers hereditary cancer risk assessment, genetic counseling, and genetic testing by specially trained genetic counselors and physicians.
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If you’re concerned about your personal or family risk for breast cancer, we invite you to meet with one of the specially trained genetic counselors and doctors in our Clinical Genetics Service. They can help you better understand your personal risk for developing breast cancer.

Together, we’ll investigate and map your family history of disease, discuss your personal risk factors, and estimate your risk for disease. We’ll also determine whether the genes BRCA1 and BRCA2 or others might be affecting your risk level. We encourage you to bring up any questions and concerns you may have about testing for mutations in these genes.

Genetic testing cannot predict whether you or a family member will develop breast cancer. It can only tell you if it’s more likely that you will.