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Limitations of the 23andMe BRCA1/2 Test

With Genetic Counselor Katherine Zimmerman, MSPH, LCGC

In recent years, the accessibility of genetic testing has expanded, allowing individuals to explore their ancestry, health predispositions, and even potential risks for hereditary conditions. 23andMe, a prominent player in the direct-to-consumer genetic testing market, even offers a test specifically designed to identify mutations in the BRCA1 and BRCA2 genes that are associated with increased risk of breast, ovarian and other cancers. But while the allure of uncovering potential health risks is unsurprising, it is crucial to understand the very real limitations of these direct-to-consumer tests and why it’s important to keep a licensed healthcare provider in the loop.

What are the BRCA1 and BRCA2 genes?	A digital rendering of a DNA double-helix.

The BRCA1 and BRCA2 genes play a crucial role in the body's defense against the formation of tumors. Mutations in these genes can compromise that defense, significantly increasing the risk of developing breast, ovarian, and other cancers. It can also be a sign of Hereditary Breast and Ovarian Cancer (HBOC) syndrome, an inherited condition marked by increased likelihood of these specific cancers occurring.

Traditionally, BRCA testing has been conducted in clinical settings, involving rigorous analysis and counseling by healthcare professionals, including genetic counselors.

The 23andMe Approach & Its Limitations

23andMe's BRCA1/2 test is part of its broader health and ancestry DNA testing service. Users provide a saliva sample, which is then analyzed to identify specific genetic variants associated with an elevated risk of breast and ovarian cancers. The results are presented directly to the consumer through an online platform.

Regulatory Concerns with 23andMe

The U.S. Food and Drug Administration (FDA) has also expressed concerns about the accuracy and reliability of direct-to-consumer genetic tests, including those offered by 23andMe. Direct-to-consumer genetic tests, such as 23andMe, have a higher false positive and false negative rate than clinical-grade genetic tests.

In fact, if an individual is identified to have a BRCA1/2 mutation on 23andMe, most insurance companies will still require confirmation testing from a clinical grade genetic testing lab.

However, there are serious limitations to this test that consumers should be aware of:

  • A Limited Analysis: The 23andMe test only analyzes a limited number of known BRCA1/2 variants, potentially missing other relevant mutations that could contribute to cancer risk. Even the company’s new test, which analyzes a total of 44 BRCA1/2 gene mutations, only accounts for a mere fraction of the total known mutations in these genes.
  • Risk of Misinterpretation and Lack of Counseling: Interpreting genetic test results demands a nuanced understanding of complex genetic information, and genetic counselors play a pivotal role in explaining those results, discussing potential health implications, and helping individuals make informed decisions. Without proper guidance from healthcare professionals, there's a risk of misinterpretation, undue anxiety or even false reassurance based on incomplete or misunderstood information.
    Unlike clinical genetic testing, 23andMe's service lacks the personalized counseling that is crucial for individuals found to carry harmful mutations. And with the limited scope of its test, results may provide a false sense of security if it fails to detect mutations associated with increased cancer risks. This false reassurance could dissuade individuals from seeking further testing or treatment.
  • An Incomplete Genetic Picture: Hereditary cancer risks extend well beyond the BRCA1 and BRCA2 genes, even for breast and ovarian cancers. Moreover, the broader spectrum of hereditary cancer risks encompasses a multitude of genes beyond those specifically tied to breast cancer, including those associated with colorectal, prostate, and pancreatic cancers, among others, each contributing to an intricate and multifaceted genetic picture. Direct-to-consumer tests do not account for these.

Approach With Caution

So while the idea of uncovering genetic predispositions to cancer through a simple home-based test is undoubtedly appealing, it is essential to approach the 23andMe BRCA1/2 test, and other direct-to-consumer tests, with caution. The limitations in scope, potential for misinterpretation, and absence of professional counseling raise significant concerns about its use in guiding healthcare decisions.

For individuals seeking a comprehensive understanding of their genetic cancer risk, consulting with healthcare professionals and undergoing thorough clinical testing remains the most prudent approach.

If you have a personal or family history of cancer, or received a positive 23andMe result, consult with a certified genetic counselor who specialized in oncology. To learn more about genetic counseling at Sarasota Memorial or to schedule an appointment with a Sarasota Memorial Genetic Counselor, click here or call (941) 917-2005.

Written by Katherine Zimmerman, MSPH, LCGC, a licensed and certified oncology genetic counselor at Sarasota Memorial Hospital’s Brian D. Jellison Cancer Institute.

Posted: Jan 30, 2024,
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