What Are The BRCA1 and BRCA2 Genes?
BRCA genetic testing has revolutionized the world of breast cancer screening and treatment. BRCA1 was discovered in 1994 by geneticist Mary-Clare King working under the National Institute of Health. Her work was recently documented in a movie called Decoding Annie Parker with Helen Hunt in the role of Mary-Clare King.
Following her breakthrough in BCRA genetic testing, NIH scientists further identified another gene mutation, BRCA2. These two genes help protect the body from developing cancer by producing tumor-suppressing proteins which repair damaged DNA and stabilize the cell’s genetic material. BRCA1 and BRCA2 mutations increase the risk of female breast and ovarian cancer because DNA damage may not be repaired properly which can lead to these and other cancers.
Specific inherited mutations in BRCA1 and BRCA2 increase the risk of female breast and ovarian cancers, and they have been associated with increased risks of several additional types of cancer. Together, BRCA1 and BRCA2 mutations account for about 20 to 25 percent of hereditary breast cancers and about 5 to 10 percent of all breast cancers and 15 percent of ovarian cancers. Breast cancers associated with BRCA1 and BRCA2 mutations tend to develop at a younger age than their non hereditary counterparts. A harmful BRCA1 or BRCA2 mutation can be inherited from a person’s mother or father. Each child from a parent who carries the mutation in one of these genes has a 50 percent chance of inheriting the mutation.
Do I Need BRCA Genetic Testing
Harmful mutations of BRCA genes are relatively rare in the general population so generalized testing is not indicated. A health care provider can help determine whether genetic testing is appropriate by exploring an individual’s personal and family history of cancer and other factors such as ethnicity, as BRCA1 and BRCA2 mutations are more common in certain populations.
Factors that indicate BRCA gene testing should be done include:
- A family history of cancer.
- Multiple cases of breast cancers in the family.
- Having both breast and ovarian cancer.
- Having cancer in both breasts.
- Cancer diagnosed before the age of 50.
- Male breast cancer in a family.
- Ashkenazi Jewish ethnicity.
BRCA genetic testing can easily be done with a painless saliva test or a blood sample. It usually takes about a month to receive the results. The BRCA1 and BRCA2 gene mutation testing results can be; positive for carrying the mutated gene, negative (no evidence of the gene mutation) or inconclusive.
What Does A Positive BRCA1 Or BRCA2 Genetic Test Result Mean?
A positive test result indicates that a person has inherited a known harmful mutation in BRCA1 or BRCA2 gene and therefore, has an increased risk of developing certain cancers. However, a positive test result cannot tell whether a person will or when an individual will actually develop cancer. For example, some women who inherit a harmful BRCA1 or BRCA2 mutation will never develop breast or ovarian cancer.
A positive genetic test result may also have important health and social implications for family members, including future generations. Genetic tests can reveal information not only about the person being tested but also about that person’s relatives:
- Men and women who inherit a harmful BRCA1 Or BRCA2 mutation, whether or not they develop cancer themselves, may pass the mutation on to their children. Each child has a 50 percent chance of inheriting a parent’s mutation.
- If a person learns that he or she has inherited a harmful BRCA1 or BRCA2 mutation, this will mean that each of his or her full siblings has a 50 percent chance of having inherited the mutation as well.
BRCA gene screening is the first step to determining what actions to take should the test be positive. Those testing positive will benefit from enhanced diagnostic screening such as MRI, Ultrasound and Mammography. These advanced screening methods can be carried out more frequently, and started as young as 25 years old, as determined by you and your physician.
In certain cases, risk reducing surgery to remove ovaries, fallopian tubes or one or both breasts might be considered. The use of certain drugs, such as Tamoxifen, can decrease the risk of developing cancer by suppressing estrogen or other hormones.
What Does A Negative BRCA1 Or BRCA2 Test Result Mean?
A negative test result can be more difficult to understand than a positive result because what the result means partly depends on an individual’s family history of cancer and whether a BRCA1 or BRCA2 mutation has been identified in a blood relative.
If a close (blood) relative of the tested person is known to carry a harmful BRCA1 or BRCA2 mutation, a negative test result is clear: it means that person does not carry the harmful mutation and thus cannot pass it on to their children. Such a test result is called a true negative. A person with such a test result is currently thought to have the same risk of cancer as someone in the general population.
If the tested person has a family history that suggests the possibility of having a harmful BRCA1 or BRCA2 mutation but complete gene testing identifies no such mutation in the family, a negative result is less clear. The likelihood that genetic testing will miss a known harmful BRCA1 or BRCA2 mutation is very low, but it could happen. Scientists have not yet discovered all the potential harmful BRCA1 and BRCA2 mutations. Therefore, it is possible that a person in this scenario with a “negative” test result actually has an unknown harmful BRCA1 or BRCA2 mutation that has not been identified.
What Does An Inconclusive BRCA1 Or BRCA2 Test Result Mean?
Sometimes, a genetic test finds a change in the BRCA1 or BRCA2 gene that has not been previously associated with cancer. This type of test result may be described as “ambiguous” because it isn’t known whether this specific gene change affects a person’s risk of developing cancer.
What Are Some Of The Benefits Of BRCA Genetic Testing?
There can be benefits to BRCA genetic testing, regardless of whether a person receives a positive or a negative result. The potential benefits of a true negative result include a sense of relief regarding the future risk of cancer, learning that one’s children are not at risk of inheriting the family’s cancer susceptibility, and the possibility that special checkups, tests, or preventive surgeries may not be needed.
A positive test result may bring relief by resolving uncertainty regarding future cancer risk and may allow people to make informed decisions about their future, including taking steps to reduce their cancer risk. In addition, people who have a positive test result may choose to participate in medical research that could help reduce deaths from hereditary breast and ovarian cancer.
What Are Some Of The Possible Harms Of BRCA Genetic Testing?
Being screened for BRCA gene mutations has no medical risk but can have potential consequences on a person’s emotions, social relationships, finances, and medical choices. People who know they carry a mutation of the BRCA gene might feel anxious, depressed, or angry and may have trouble making choices about whether to have preventative surgery or not. BRCA genetic testing can create tension within families. Because of this it is recommended that those considering gene testing receive genetic counseling to help with the questions and decisions that will result either way.
People who receive a negative test result may experience “survivor guilt,” caused by the knowledge that they likely do not have an increased risk of developing a disease that affects one or more their loved ones. Because genetic testing can reveal information about more than one family member, the emotions caused by test results can create tension within families. Test results can also affect personal life choices, such as decisions about career, marriage, and childbearing.
Finally, there is a small chance that test results may not be accurate, leading people to make decisions based on incorrect information. Although inaccurate results are unlikely, people with these concerns should address them with their doctor or genetic counselor.