Answer Your Genetics Questions
What are BRCA1 and BRCA2 gene mutations?
BRCA genes are normal genes that all of us have. We believe that the normal function of the BRCA gene may be to help prevent cancers from developing. Some mutations, or abnormalities, in these genes prevent them from working properly – allowing cancers to develop. Individuals who have inherited a deleterious – or disease causing – mutation in BRCA1 or BRCA2 are at increased risk for developing breast and ovarian and other cancers.
Approximately 1 in 40 individuals of Ashkenazi Jewish descent carry an altered BRCA1 or BRCA2 gene, compared to approximately 1 in 500 individuals in the general population. The genetic mutation increases the risk of developing breast cancer and ovarian cancer. There is also a somewhat increased risk to develop other cancers such as pancreatic and prostate cancer as well as melanoma, depending on which gene is involved. In families with an inherited predisposition, cancers may occur in several family members and at younger ages than usual.
What is the difference between genetic and genomic testing?
Genetic testing usually refers to testing in a single gene or a selected group of genes. Genetic testing is usually targeted to a specific concern, even when testing includes a large panel of genes. Genomics is the study of all of the inherited traits in an organism. Genomic testing refers to testing of all of the genes. This is done when there is no specific target in mind. Sometimes genomic testing is used to try to find a cause for a constellation of symptoms or birth defects that appear to be hereditary.
What does it mean when a tumor is genetically tested?
Whenever cancer develops, it is a result of changes in DNA that occur in a particular line of cells. These DNA changes are not inherited, but accumulate slowly over time in cells, and can gradually change the way the cells function. Eventually, these changes can lead to the development of cancer. The DNA changes may be the result one’s lifestyle or habits, or may be related to an environmental exposure. Often, they happen by chance.
It helps physicians treat cancer if they know the specific DNA changes that have accumulated to cause the tumor. Most of the time, changes identified by this method are not inherited.
How do BRCA mutations affect the risk of breast and ovarian cancer in women of Jewish descent?
Both men and women can carry a BRCA mutation and will have a 50% chance of passing it to each of their children. Not everyone who inherits the mutation will develop breast cancer or ovarian cancer, but the risk is increased.
For those carrying mutations, the risk for breast cancer may reach 50-80% and for ovarian cancer, 44%, compared to the average woman’s breast cancer risk of 12% and ovarian cancer risk of 1-2%.
Women of Ashkenazi descent with breast cancer or ovarian cancer, and individuals with a family history of these cancers, may want to consider genetic counseling and testing. BRCA gene mutations have also been found in Jews of Sephardi descent as well as in individuals of all ethnic origins. These individuals may also want to consider genetic counseling and testing.
Where can I get more information about BRCA gene testing?
Before having genetic testing, you should first speak with a genetic counselor. Genetic counseling can help you understand what testing may be most appropriate for you and help you understand how the information can be useful to you. You can find genetic counselors through physicians, major medical centers’ genetics programs, cancer centers, or the National Society of Genetic Counselors at www.nsgc.org.
Should men consider being tested for BRCA mutations?
Men with a BRCA mutation also have a 50% chance of passing it to each of their children. Men who have a family history of breast and ovarian cancer in their female relatives should think about genetic testing for themselves. Additionally, men may also develop breast cancer. Since most doctors do not do routine breast examinations in men, there is no recommendation for screening with imaging in men, and because male breast exams are uncommon, it is important to identify men who may be at increased risk to develop breast cancer or other cancers, including prostate cancer.
How can I prepare for my genetic counseling appointment?
Prepare for your appointment by providing a detailed family history, including information and medical records about family members who have had cancer. Bring test results from all members of your family who have had genetic testing, especially if they are positive for the presence of a mutation.
What if I test positive for a BRCA mutation?
A positive test result indicates that you have inherited a known mutation in the BRCA1 or BRCA2 gene, which provides information about your risk of developing cancer. It cannot be used to predict if cancer will actually develop—or when. Women who test positive have a number of options they can consider to manage their risk (including screening, risk-reducing surgeries, and medications that reduce cancer risk), and they should discuss the options with a health care professional.
Do I need further genetic testing if my results of testing for BRCA1 and BRCA2 are negative?
If you tested negatively for a BRCA1 or BRCA2 mutation, it may be useful to consult with a certified genetic counselor about the utility of additional genetic testing. A variety of genetic panels are now available to test for additional genes that predispose to breast, ovarian, and other types of cancer. These genes may cause a high or more moderate risk in a variety of cancers. Your genetic counselor can advise which test makes the most sense based on your personal and family history of cancer. He/she may also be able to help choose the testing that your insurance company is most likely to cover.
The chart below describes some of the major genes that might be tested when hereditary breast and ovarian cancer is suspected. They are divided into two sections, describing high risk and moderate risk genes.
High risk genes
|Syndrome Name||Genes||Highest cancer risks||Risk somewhat increased|
|Hereditary breast and ovarian cancer||BRCA1, BRCA2||Breast and ovarian cancer||Pancreatic, prostate, melanoma, as well as other cancers|
|Lynch syndrome||MLH1, MSH2, MSH6, PMS2, EPCAM||Colon, uterine and ovarian cancer||Small intestine, gastric, urinary tract as well as other cancers|
|Li Fraumeni||TP53||Female breast cancer, sarcoma, adrenal cortical||Childhood cancers, leukemia, as well as other cancers|
|Cowden syndrome||PTEN||Breast, uterine, and thyroid cancer||Melanoma, colon, and renal cancer|
|Peutz Jeghers syndrome||STK11||Female breast, colorectal, gastric and pancreatic cancer||Small bowel, ovarian, uterine, cervical and lung cancer|
|Hereditary diffuse gastric cancer||CDH1||Diffuse gastric cancer and lobular breast cancer||Colon cancer, signet ring type|
|Neurofibromatosis||NF1||Breast cancer, central nervous system cancers||Leukemia, gastro-intestinal stromal tumors|
Moderate risk genes
|Genes||Moderate risk||Possible other risks|
|ATM||Breast cancer||Pancreatic cancer|
|BRIP1||Ovarian cancer||Breast cancer|
|CHEK2||Breast cancer||Colorectal cancer|
|PALB2||Breast cancer||Pancreatic cancer|
|RAD51C||Ovarian cancer||Breast cancer|
|RAD51D||Ovarian cancer||Breast cancer|
If genetic testing is negative, how should I be monitored?
Your health care team can help you determine the best methods for monitoring breast and ovarian health. They can also keep you apprised of developments in genetic research and testing as it becomes available. A strong family history of cancer cannot be ignored even if you do not have a BRCA1 or BRCA2 mutation, since researchers have not yet identified all mutations or genes involved in hereditary cancer.
As a cancer survivor, what are the benefits of genetic counseling and testing?
If you have been diagnosed with breast cancer or ovarian cancer, test results may influence your surgery and treatment decisions. Genetic testing can help you make decisions about ongoing screening and inform discussions with your family about potential inherited risks.
Should I get BRCA testing even if I do not have a family history?
According to the National Cancer Institute, genetic testing of individuals who have not been diagnosed with cancer is indicated when there is an existing family history. Genetic testing may also be done if someone is of Ashkenazi Jewish descent, as being of Ashkenazi Jewish descent is considered to be a significant risk factor, with or without a known family history. There are also individuals who, for a variety of reasons, may not have access to their family history. If a woman with an unknown family history has an inherited cancer risk, considering genetic counseling and testing may be appropriate.
Whether or not you have a known family history, are of Ashkenazi Jewish descent, or simply have questions about genetic testing, Sharsheret recommends that you speak to a genetic counselor to assess your risk, become better informed, and discuss your options. The Sharsheret support team is available to help you address your questions and find a genetic counselor.
To speak with a member of our support team and get connected with Sharsheret’s genetics program, click here.
For additional BRCA Genetics resources, click here.
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