When it comes to understanding inherited colorectal cancer risks, are all genetic tests the same?

Clinical genetic testing – the process of examining our hereditary makeup in a laboratory to help diagnose, treat and even predict disease - has evolved to become a critical component of medical practice and research. But now, with the advent of direct-to-consumer (DTC) genetic tests, people are being offered quick and easy genetic information through the mail.

DTC genetic testing has become quite popular over the last couple of years, and continues to be heavily promoted. Listen to your favorite podcast or watch primetime TV, and you’re sure to hear an ad promoting the benefits of at-home genetic testing to trace your ancestors.

Fun, interesting and harmless, right? Not always. Lately, some DTC tests have started to offer testing for the risk of certain inherited diseases, those that can be passed down in families through genetic material, from generation to generation.

For example, DTC companies are now offering testing that providers some information related to hereditary risks for certain cancers, like colorectal cancer. 

But is this type of genetic test the best choice to assess your risk for colorectal cancer?

Clinical genetic testing is the better choice for assessing inherited disease risk

Rising interest in DTC genetic tests for the detection of inherited diseases like cancer has been accompanied by increasing concern regarding a high number of false-positive results – those that incorrectly indicate a disease is present when it’s not! In fact, the results of a 2018 study conducted by Ambry Genetics and published in Genetics in Medicine, documented a 40 percent incidence of false positive DTC test results.

Given this margin of error, the much greater accuracy of clinical genetic testing performed in a CLIA-approved* laboratory far outweighs the convenience of DTC testing. And there are other significant advantages as well:

  • Healthcare provider involvement from Day 1: Your healthcare provider knows you as a person, and is invested in your care. They’ll be at your side from the beginning to interpret your results, counsel you on next steps, and manage your future care.
  • State-of-the-art Technology: Clinical genetic testing is able to dig deeper and look farther because it utilizes advanced technology specifically designed to detect and evaluate mutations across multiple genes associated with a number of cancers, as well as other inherited diseases.

To illustrate, picture your genome – the unique combination of genetic material that makes you “you” – as a book. DTC tests typically use a basic technology called a SNP array, which can only check for a few specific genetic mutations linked to colon cancer, missing many others that are important to test. Just like a spell checker that can only detect a handful of commonly misspelled words, SNP technology can only test for a handful of common genetic spelling errors and may miss others, even in the same gene! This testing also may only look at a couple of genes related to hereditary colorectal cancer, when there are many other important genes to test.

Compare that to clinical genetic testing, which uses a more comprehensive technology called “next generation sequencing (NGS).”  NGS works like a spell checker on steroids, able to detect all sorts of misspellings, grammatical errors, or parts of the book that have been added or deleted.

When it comes to detecting your risk for colon cancer, which kind of test would you rather have?

I’ve already taken a DTC test for hereditary colorectal cancer, and have the results. What should I do now?

For reasons that are now obvious, if you’ve taken a DTC genetic test and received a positive result saying that you are at an increased risk for colorectal or other cancers, it’s recommended that you speak with a genetic counselor or your healthcare provider regarding follow-up clinical testing to verify the accuracy of your results.

If your DTC results are negative, but you have a personal and/or family history of colorectal or other cancers, make sure you talk to your healthcare provider to find out if clinical genetic testing might be right for you.

Don’t take chances with your health!

DTC testing can be entertaining and fascinating, but as you now understand, it’s not really sufficient for the most thorough assessment of your risk for hereditary cancer.  To help alleviate this problem, Ambry Genetics has recently joined forces with My Gene Counsel (MGC), a digital health company that provides easy-to-understand genetic testing reports. Together, Ambry and MGC will combine capabilities to offer the first One-Stop Solution for the verification of DTC genetic test results, combined with proper genetic counseling for consumers determined to be at high risk for hereditary forms of cancer. To learn more about the program visit: mygenecounsel.com/onestop.

Want more information? Visit www.ambrygen.com/patients to learn more about hereditary cancer and clinical genetic testing. To locate a genetic counselor near you visit www.nsgc.org/page/find-a-genetic-counselor.

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Ambry is committed to delivering the most accurate genetic test results possible. Learn more about our products today.

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The information, including but not limited to, text, graphics, images and other material contained on this blog are for informational purposes only. The purpose of this blog is to promote broad understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this blog. Ambry Genetics Corporation does not recommend or endorse any specific tests, physicians, products, procedures, opinions or other information that may be mentioned on this blog. Reliance on any information appearing on this blog is solely at your own risk.