According to data from 2018–2021, approximately 13.1% of women will be diagnosed with female breast cancer at some point during their lifetime.
Genetic factors, including mutations in the BRCA1 and BRCA2 genes, significantly elevate the risk of both breast and ovarian cancers. These mutations are crucial indicators for assessing cancer risk, but how can genetic testing help understand this risk?
This blog will explain the BRCA testing process, methods for detecting mutations, and the role of genetic counseling in managing cancer risk.
We’ll also look at the benefits of RNA sequencing in BRCA testing and highlight how Biostate AI provides a reliable and affordable solution.
Understanding BRCA Genes and Their Role in Cancer Research
BRCA1 (Breast Cancer gene 1) and BRCA2 (Breast Cancer gene 2) are vital for maintaining cell genomic stability. These genes function as tumor suppressors, producing proteins that help repair damaged DNA and prevent harmful mutations from accumulating.
| Genomic stability refers to the cell’s ability to maintain the correct structure and sequence of its DNA over time. This stability is crucial because DNA contains cell growth, division, and repair instructions. |
Each individual inherits one copy of BRCA1 and BRCA2 from each parent. When these genes function correctly, they help protect against cancer. However, mutations in these genes can significantly raise the chances of developing the disease.
Here are the two types in detail.
1. Breast Cancer gene 1 (BRCA1)
BRCA1 is located on chromosome 17 (17q21). The BRCA1 protein is crucial in repairing damaged DNA, regulating transcription, and controlling the cell cycle.
Mutations in the BRCA1 gene are strongly linked to an increased risk of breast and ovarian cancers. Women with BRCA1 mutations have a lifetime breast cancer risk of 60% or higher. The lifetime risk of developing ovarian cancer is estimated to be between 39-58%.
In addition to breast and ovarian cancers, BRCA1 mutations have also been linked to other types, with a 5% risk of pancreatic cancer and a 7-26% risk of prostate cancer.
2. Breast Cancer gene 2 (BRCA2)
BRCA2 is located on chromosome 13 (13q12.3). The BRCA2 protein is essential for repairing double-strand DNA breaks through a process called homologous recombination.
Mutations in the BRCA2 gene increase the risk of breast and ovarian cancers. Women with BRCA2 mutations face a lifetime breast cancer risk exceeding 60% and a 13-29% risk of developing ovarian cancer.
BRCA2 mutations are also associated with a 5%–10% risk of pancreatic cancer and a 19%–61% risk of prostate cancer. Men with a harmful BRCA2 mutation have a 1.8%–7.1% chance of developing breast cancer by the age of 70.
Understanding the functions and risks associated with BRCA1 and BRCA2 mutations highlights the importance of accurate detection methods. Identifying these mutations early can be crucial in assessing cancer risk and guiding preventive strategies.
Methods to Detect BRCA1 and BRCA2 Mutations
Accurately identifying BRCA1 and BRCA2 mutations is essential for understanding cancer risk. Researchers combine multiple methods to improve accuracy and efficiency in mutation detection.
Step 1: PCR Primers and Exon Coverage
The first step involves amplifying specific exon regions of the BRCA1 and BRCA2 genes using polymerase chain reaction (PCR). This process targets key coding regions where mutations are more likely to occur.
- 34 PCR reactions were performed to cover 24 exons of BRCA1.
- 52 PCR reactions were performed to cover 27 exons of BRCA2.
To improve mutation detection, primers were designed at least 50 base pairs away from exon-intron boundaries to capture potential splice junction mutations. Non-coding exons 1 and 4 of BRCA1 and exon 1 of BRCA2 were generally excluded to focus on coding regions with higher mutation impact.
| NoteExons: Exons are the parts of a gene that contain the instructions for building proteins. Exons are crucial because they directly affect how proteins are formed and function.Introns: Introns are non-coding sections within a gene.Exon-Intron Boundaries: This refers to the junction where an exon meets an intron. During RNA processing, the cell must correctly identify these boundaries to remove introns and join the exons together. Splice Junction Mutation: A splice junction mutation is a genetic change that disrupts the normal cutting and joining (splicing) of exons during RNA processing. |
Step 2: Scanning Techniques for Efficient Screening
Since DNA sequencing is costly and time-consuming, researchers first use scanning techniques to identify regions with potential mutations. These methods provide a faster, more cost-effective way to narrow suspicious areas before sequencing. Standard scanning techniques include:
- Single-Strand Conformation Polymorphism (SSCP)
- Restriction Endonuclease Fingerprinting (REF)-SSCP
- Conformation-Sensitive Gel Electrophoresis (CSGE)
- Fluorescence-Based Conformation-Sensitive Gel Electrophoresis (F-CSGE)
- Two-Dimensional Gene Scanning (TDGS)
- Protein Truncation Test (PTT)
- Denaturing High-Performance Liquid Chromatography (DHPLC)
Step 3: Direct DNA Sequencing
Once scanning techniques identify potential mutation sites, direct DNA sequencing is performed to locate and characterize the mutations precisely. This method is considered the gold standard for accuracy but is reserved for confirming identified regions to save time and resources.
Step 4: Laboratory Approach (Combining Techniques for Accuracy)
In practice, researchers may combine these methods to improve efficiency. For example, one study used CSGE as a primary screening method to detect potential exons with mutations. DNA sequencing was then performed on those flagged regions to confirm and describe the mutations in detail.
| Conformation-sensitive gel Electrophoresis (CSGE) detects DNA mutations by identifying structural differences between normal (homoduplex) and mismatched (heteroduplex) DNA strands, which move differently through a gel. |
Combining PCR amplification, scanning techniques, and DNA sequencing provides a structured and effective approach to detecting BRCA1 and BRCA2 mutations. This method improves accuracy while balancing cost and efficiency in genetic testing.
Laboratory techniques are essential for precise BRCA mutation detection, but at-home options like direct-to-consumer (DTC) genetic testing have made genetic insights more accessible.
What Is Direct-to-Consumer (DTC) Genetic Testing and How Does It Work?
Direct-to-consumer (DTC) genetic testing is an at-home option that provides insights into one’s genetic makeup without the need to visit a doctor or clinic.
These tests are designed to be simple, convenient, and accessible to anyone interested in learning more about their ancestry, health risks, or traits.
Here’s how it works.
1. Ordering a Test Kit
Individuals can purchase DTC kits online or from retail stores. These kits are designed to provide insights into various aspects of genetics, such as ancestry, health risks, or inherited traits. Depending on the provider, some tests may focus on specific genes, like BRCA1 and BRCA2, while others offer broader insights.
2. Sample Collection
Most DTC kits require a saliva sample, though some may involve a blood sample. Instructions for sample collection are usually provided in the kit. After collecting the sample, individuals must securely package and mail it to the company’s designated laboratory for analysis.
3. Laboratory Analysis
Once the sample reaches the laboratory, specialists examine the DNA for specific genetic markers or variants. Some tests analyze targeted genes, while others may conduct more comprehensive sequencing, such as whole exome sequencing, to detect a wider range of genetic changes.
4. Result Reporting
Results are typically delivered through a secure online portal. Reports may include ancestry, potential health risks, or inherited traits. While these reports can provide valuable insights, they may require careful interpretation, mainly if complex genetic information is involved.
5. Genetic Counseling
Genetic counseling is strongly recommended for individuals pursuing DTC testing. Counselors can help explain the results, assess whether additional testing is necessary, and provide guidance on the next steps. Since some DTC tests may miss specific mutations, counseling can help ensure individuals receive accurate information about their genetic risks.
DTC genetic testing offers a convenient way to gain insights into one’s genetic profile. However, understanding the results, especially for BRCA mutations, requires careful interpretation and informed decision-making.
BRCA Test Results and Risk Management
Understanding BRCA test results is essential for making informed decisions about cancer risk management. Here’s a detailed overview of result types, their meanings, and recommended actions.
1. Positive Result (Harmful Change Present)
A positive result indicates a harmful mutation (pathogenic variant) in the BRCA1 or BRCA2 gene, which is linked to an increased risk of certain cancers.
A. Risk Management
For women, this includes starting breast cancer screening at a younger age with MRI (with or without contrast) alongside mammography. There is no proven effective screening for ovarian cancer.
While transvaginal ultrasound and CA-125 tests were previously used, they have not been shown to improve long-term survival.
For men, screening options should be discussed with a healthcare provider. Annual breast and prostate cancer screening may be considered, particularly for BRCA2 carriers. Prostate screening may also be considered for BRCA1 carriers.
Those with a close relative diagnosed with pancreatic cancer may be advised to undergo screening using ultrasound or MRI/magnetic retrograde cholangiopancreatography.
B. Risk-Reducing Surgery
For women, options include bilateral risk-reducing mastectomy (removal of both breasts) and/or bilateral risk-reducing salpingo-oophorectomy (removal of the ovaries and fallopian tubes).
Salpingectomy (removal of fallopian tubes while preserving ovaries until menopause) is being studied as an alternative option.
2. Negative Result (No Harmful Change Present)
A negative result means no harmful mutation was found in the BRCA1 or BRCA2 gene. Its significance depends on your family history.
If a known family mutation exists, a negative result means you did not inherit that specific mutation, and your cancer risk is considered the same as the general population.
If no known family mutation exists, the result does not provide additional information about your cancer risk beyond family history and other risk factors.
Risk Management
Continue with standard cancer screening based on your age and family history. For tailored guidance, speak to your healthcare provider.
3. Variant of Uncertain Significance (VUS)
A VUS result indicates a genetic change was found in BRCA1 or BRCA2, but its impact on cancer risk is unclear.
Risk Management
If you receive a Variant of Uncertain Significance (VUS) result, your cancer risk management should be based on your family history and other known risk factors until the VUS is reclassified. Genetic counseling is strongly recommended to help you understand your result, assess your risk, and guide you on appropriate screening or preventive steps.
A genetic counselor can explain what a VUS means, how it differs from other findings, and whether additional testing may be helpful. They also guide managing your risk and discussing implications with family members to support informed decisions about your care.
4. Invalid Result
An invalid result means the test was incomplete or produced unreliable data, often due to issues like insufficient DNA in the sample or technical errors during processing. Submitting a new sample and repeating the test is necessary in such cases.
It’s also helpful to carefully follow the lab’s sample collection instructions to improve the chances of obtaining a valid result. If concerns persist, consulting a healthcare provider or genetic counselor can provide further guidance.
Disclaimer: This blog is for educational purposes only and should not be considered medical advice. Please consult with your healthcare provider for personalized guidance and recommendations.
Limitations of DTC
While genetic testing can provide valuable insights, it’s important to recognize its limitations, especially regarding BRCA testing through direct-to-consumer (DTC) platforms. These tests may not offer a complete picture of your genetic risk.
Understanding these limitations is crucial to ensuring that you don’t rely solely on the results but take a more informed approach to managing your health. Here are some key considerations.
1. Incomplete Testing
Not all DTC tests assess every possible harmful mutation in the BRCA1 and BRCA2 genes. While some tests focus on the most common mutations, particularly those found in specific populations, they may miss less common but still significant genetic alterations.
This could lead to false-negative results, where a person with a harmful mutation may incorrectly receive a “negative” test result. This incomplete testing can give a false sense of security, potentially delaying necessary preventive measures or treatments.
2. Lack of Genetic Counseling
DTC testing does not provide access to genetic counseling, which is essential for understanding test results and their limitations. Without counseling, individuals may misinterpret results or be unsure of the next steps, such as additional testing or preventive measures. Counselors also offer emotional support, helping individuals process the psychological impact of the results.
DTC genetic testing can offer valuable insights, but it has limitations. To make informed decisions, individuals should cautiously approach DTC testing and seek professional support when needed.
Winding Up!
Understanding BRCA mutations is essential for assessing cancer risk, and genetic testing is key to identifying them. However, mutations alone don’t provide complete insight. RNA sequencing offers profound insights into how these mutations affect gene expression and cellular functions.
- RNA-seq reveals BRCA1 and BRCA2 gene expression changes, highlighting disrupted gene activity.
- It detects faulty RNA splicing caused by BRCA mutations, possibly leading to non-functional proteins.
- RNA-seq identifies how BRCA mutations affect other DNA repair and cell regulation genes.
- It compares gene activity in healthy and cancerous tissues to uncover mutation-driven changes.
At Biostate AI, we specialize in advanced RNA sequencing technology to enhance understanding of BRCA mutations. Our services provide a more comprehensive approach to cancer risk management by revealing how gene activity contributes to cancer development.
Our affordable RNA sequencing services allow researchers to explore the biological effects of BRCA mutations, giving clearer insights for informed, data-driven decisions.
Get a quote for your research today, and our team will help you unlock deeper insights into BRCA mutations and cancer risk management with our advanced RNA sequencing services.
FAQs
- Who should consider BRCA testing?
A: Individuals with a family history of breast, ovarian, pancreatic, or prostate cancer, especially if diagnosed at a young age, may benefit from BRCA testing.
- Can men have BRCA mutations?
A: Yes, men with BRCA mutations have an increased risk of prostate, breast, and pancreatic cancers, along with the potential to pass the mutation to their children.
- Is BRCA testing recommended during pregnancy?
A: BRCA testing can be done during pregnancy, but results are unlikely to impact immediate prenatal care. Genetic counseling is advised before making decisions.
- Are BRCA mutations common in the general population?
A: BRCA mutations are rare in the general population but more common in individuals of Ashkenazi Jewish descent and those with a strong family cancer history.
- Does insurance cover BRCA testing?
A: Coverage varies by provider and risk factors. However, individuals who meet specific medical guidelines, such as a family history of BRCA-related cancers, may qualify for coverage.
Sources
National Cancer Institute
PubMed: Am J Hum Genet: 12.6
PubMed: Blood: 22.13