Originally Posted On: https://www.jscreen.org/blog/brca-gene-inheritance-explained-making-testing-decisions-for-your-family
BRCA Gene Inheritance Explained: Making Testing Decisions for Your Family
Learning that hereditary cancer risk runs in your family can feel overwhelming. Understanding BRCA gene inheritance and making decisions about genetic testing involves navigating complex emotions and information. This guide will help you know who in your family should consider testing, at what age testing is most appropriate, and what criteria healthcare providers use to determine who qualifies for BRCA genetic testing.
Understanding BRCA Gene Inheritance
BRCA1 and BRCA2 (BReast CAncer genes) prevent cancer by repairing damaged DNA. When these genes have harmful mutations, they cannot function properly, significantly increasing the risk of developing breast, ovarian, and other cancers.
How BRCA Mutations Are Passed Down
BRCA gene mutations follow an autosomal dominant inheritance pattern, which means:
- You only need to inherit one copy of the mutated gene (from either parent) to have an increased cancer risk
- Each child of someone with a BRCA mutation has a 50% chance of inheriting the mutation
- Both men and women can inherit and pass on BRCA mutations
- The mutation can come from either your mother’s or father’s side of the family
Understanding your family history on both sides is crucial when assessing your hereditary cancer risk.
Who Should Be Tested First in a Family?
When considering genetic testing for BRCA mutations within a family, starting with specific family members is most informative.
The Best Candidate for Initial Testing
The most effective approach is to test the person in your family who:
- Has been diagnosed with cancer – Testing someone who has had breast, ovarian, pancreatic, or high-risk prostate cancer will provide the most definitive information. If that person has a BRCA mutation, it helps explain their cancer diagnosis and identifies what specific mutation to look for in other family members.
- Had cancer at the youngest age – If multiple family members have had cancer, the person diagnosed at the youngest age often has the highest likelihood of carrying a hereditary mutation.
- Had the most BRCA-associated cancers – Someone who has had multiple cancers associated with BRCA mutations (such as both breast and ovarian cancer) is an ideal candidate for initial testing.
- Is the closest blood relative to those with cancer – If those with cancer are deceased or unavailable for testing, the closest living relative (child, sibling, or parent) should be tested.
Once a specific BRCA mutation is identified in one family member, others can undergo much simpler and less expensive “single-site testing” that looks only for that particular mutation. It is important to note that even when a familial mutation is identified, additional testing for mutations in other genes may still be appropriate for other family members depending on their own risk factors and family history.
At What Age Should BRCA Testing Be Considered?
The timing of genetic testing is an important consideration that depends on when the information would impact medical management.
Recommended Testing Ages
- Adults (18+ years): Testing is generally available to any adult who meets testing criteria or has a known BRCA mutation in the family.
- Young adults (18-25 years): While testing is available, medical management recommendations typically don’t begin until age 25, so some young adults wait to test until they would be able to do something with their results.
- High-risk adults age 25-35: This is when most medical management for BRCA carriers begins, including enhanced breast screening with MRI. Many carriers choose to have testing around age 25 when they start increased surveillance.
- Women approaching age 35-40: Women with BRCA1 mutations are often advised to consider risk-reducing removal of the ovaries and fallopian tubes after completing childbearing or around age 35-40, making this another time period where testing may be particularly important.
- Children under 18: Testing is generally not recommended for minors since BRCA mutations don’t typically increase childhood cancer risks, and interventions wouldn’t begin until adulthood.
The National Comprehensive Cancer Network (NCCN) provides specific guidelines for when preventive measures should begin for BRCA carriers:
- Age 25: Begin annual breast MRI screening
- Age 30: Add annual mammogram, alternating with MRI every 6 months
- Age 35-40: Consider risk-reducing salpingo-oophorectomy (removal of ovaries and fallopian tubes) for BRCA1 carriers
- Age 40-45: Consider risk-reducing salpingo-oophorectomy for BRCA2 carriers
- Some providers will recommend screening begin ten years prior to the earliest diagnosis of cancer in the family, or at the ages listed above, whichever is earlier.
These guidelines are based on recommendations from the National Comprehensive Cancer Network, which regularly updates medical management protocols as new research becomes available.
These guidelines help inform the appropriate timing for genetic testing based on when the results would lead to actionable medical decisions.
Who Meets Criteria for BRCA Testing?
Healthcare providers and insurance companies use specific guidelines to determine who should undergo BRCA testing. The National Comprehensive Cancer Network (NCCN) and other medical organizations have established criteria based on personal and family history.
Personal History Criteria
You may meet the criteria for BRCA testing if you have had the following:
- Breast cancer at age 45 or younger
- Triple-negative breast cancer at age 60 or younger
- Ovarian, fallopian tube, or primary peritoneal cancer at any age
- Male breast cancer at any age
- Metastatic or high-risk prostate cancer at any age
- Pancreatic cancer at any age
- Two separate breast cancer diagnoses, especially if the first was before age 50
- Breast cancer at any age with Ashkenazi Jewish ancestry
- A known BRCA mutation in your family
Family History Criteria
You may meet the criteria for testing based on your family history if you have the following:
- Two or more close relatives with breast cancer, with at least one diagnosed before age 50
- Three or more close relatives with breast cancer at any age
- A close relative with ovarian cancer
- A close relative with male breast cancer
- A close relative with pancreatic cancer or metastatic prostate cancer
- A close family member with a known BRCA mutation
- Ashkenazi Jewish ancestry with a close relative with breast, ovarian, or pancreatic cancer
Close relatives typically include parents, siblings, children, grandparents, aunts, uncles, nieces, and nephews on the same side of the family.
Special Population Considerations
Ashkenazi Jewish Ancestry
Individuals of Ashkenazi Jewish descent have a higher likelihood of carrying specific BRCA mutations:
- Approximately 1 in 40 people of Ashkenazi Jewish ancestry carry a BRCA mutation, compared to about 1 in 400 in the general population.
- Three specific BRCA mutations (founder mutations) account for most BRCA mutations in this population.
- Testing may be considered for individuals of Ashkenazi Jewish ancestry, even with a less significant family history.
Male BRCA Carriers
Men can carry and pass on BRCA mutations and should consider testing if:
- They have a personal history of male breast cancer, pancreatic cancer, or metastatic or high-risk prostate cancer
- They have a strong family history of BRCA-associated cancers
- They have a known BRCA mutation in the family
Remember that a man with a BRCA mutation has a 50% chance of passing it to each of his children, regardless of their gender.
Making the Decision to Test
Deciding whether and when to pursue genetic testing is deeply personal. Genetic counseling is an essential part of this process and can help you:
- Understand your personal and family risk.
- Review the benefits, limitations, and possible outcomes of testing.
- Address psychological and emotional concerns.
- Navigate insurance and financial considerations.
- Develop a personalized plan for cancer screening and prevention based on results.
Benefits of Knowing Your BRCA Status
If you test positive for a BRCA mutation, this information allows you to:
Begin
enhanced screening at a younger age to detect cancer early.- Consider risk-reducing medications or surgeries.
- Make informed reproductive decisions.
- Alert family members who may be at risk
- Qualify for specific targeted therapies if you develop cancer.
What If You Test Negative?
If you test negative for a BRCA mutation:
- With a known family mutation, your risk is similar to that of the general population, and you cannot pass the mutation on to your children.
- Without a known family mutation, a negative result may still be unclear if no one in your family with cancer has been tested.
When Family Testing May Be Limited
In some situations, accessing family medical history or testing affected relatives may not be possible:
- When family members are deceased or unavailable for testing
- When family history information is limited due to adoption or estrangement
- When family members are unwilling to share medical information or undergo testing
In these cases, multi-gene panel testing that simultaneously examines multiple cancer risk genes may be most appropriate.
Taking the Next Step
If you’re concerned about hereditary breast and ovarian cancer in your family, consider these steps:
- Gather your family history – Document cancer diagnoses on both sides of your family, including the type of cancer and age at diagnosis.
- Speak with your healthcare provider – Discuss your concerns and family history.
- Consider genetic counseling – A genetic counselor can evaluate your risk and help you decide if testing is proper.
- Understand your insurance coverage – Many insurance plans cover genetic testing for those who meet medical criteria.
For qualified individuals, Myriad Genetics offers the MyRisk Hereditary Cancer Test, which evaluates 48 genes associated with hereditary cancer risk. Various financial assistance programs are available to help make testing more accessible.
Genetic testing empowers you with information that can guide critical health decisions for you and your family. By understanding who should be tested, when testing is appropriate, and what the results mean, you can take proactive steps toward managing your hereditary cancer risk.