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Is Genetic Testing a Good Way to Detect or Prevent Disease?

Holistic Health

Is Genetic Testing a Good Way to Detect or Prevent Disease?

Have you seen the ads for at-home genetic testing or have friends and family who’ve done it and found out really interesting things about their health and ancestry? If you are considering genetic testing and are curious to learn more, you are in the right place. 

In conventional medicine, genetic testing is typically limited to those genes known to be the cause of disease, which actually impacts a very small percentage of the population. In functional medicine, however, we can use genetic testing in a variety of ways to support our goals of preventing disease and helping you to achieve your most optimal state of health. 

Genetic testing is still quite new and new information emerges each day. There is a lot to consider when deciding about testing for yourself and that’s exactly what I’m going to unpack for you today. 

In this article, you’ll learn more about:

Let’s get started!

What Is Genetic Testing? 

When we talk about genetics, it’s important to remember the goal of the gene. Genes, found as part of your DNA, code for proteins that cells make that are responsible for process that happens in the body. Think of it this way: your DNA is like the cookbook and the genes are the recipes.  

The human genome was sequenced by the Human Genome Project, beginning in 1990 with the full sequence revealed in 2003. The genome sequence essentially provides a blueprint for building a human by revealing over 3 billion DNA bases in a specific pattern, 23 pairs of chromosomes and then arranged into around 20,000 – 25,000 genes!

It’s because of this technology, that genetic testing is now available. We can look at your specific DNA sequence to identify specific changes that have occurred in chromosomes, genes or proteins. This is at the heart of genetic testing and helps me, as your functional medicine clinician, to confirm or eliminate suspected genetic conditions or estimate the chances of passing on certain genetics to your kids. This information is helpful in a variety of cases. 

What Diseases Can Be Detected Through Genetic Testing?

This is kind of a loaded question, you see, there are different types of genetic testing that look at different things. 

The first type of genetic testing is the kind that tests for genes linked to disease risk and confirm a diagnosis. Examples of these include: Fragile X, Cystic Fibrosis or Huntington’s. 

This type of genetic testing also includes the genetic testing of your baby while you are pregnant that is offered during the first trimester. It is known as chorionic villus sampling, or CVS, where a sample of the placental tissue is obtained and chromosomes are tested in order to detect genetic defects or disorders.  

These are tests that are typically provided through a provider or a laboratory company and may be accompanied by genetic counseling. This type of testing reveals true cases where genetics play the key role in disease process and you can’t change the genes themselves. 

Much of the other genetic testing that you’ll see on the market today, including home genetic testing kits, look for slight alterations in a gene, called a SNP or single nucleotide polymorphisms. The detection of SNPs doesn’t focus on diagnosing a disease (or treating or curing it), but gives us clues as to your personal biochemistry, nutrient status and risks for developing disease, especially the diseases related to lifestyle. 

This is the type of genetic testing we do here in The Fork Functional Medicine is available through providers and labs but also as direct to consumer at home genetic testing. 

This testing estimates the genetic risk for Parkinson’s, detects the BRCA genes associated with breast cancer or the APOE variants associated with Alzheimer’s, as some examples. This might be helpful information if you have a family history and are working to prevent disease. 

This type of testing gives us clues about how your body is functioning. I like to look at MTHFR, COMT and other SNPs to get an idea of your methylation status and how you are detoxifying. From this perspective, genetic testing is for educational purposes to better understand biochemical function. However, since SNPs are not diagnostic, it’s important to not treat the SNP, but instead use it as once piece of a bigger puzzle in order to treat my patient. 

It is possible to have SNPs but good biochemical function or to have no SNPs for a gene, but poor function. The genetics only tell part of the story. Why? It has to do with epigenetics and how genes are expressed, or how genes are switched on or off. News flash: it’s your lifestyle and environment that determines what genes are expressed and which ones aren’t. And much of this is in your control – what you eat, how you move, how you handle stress, your sleep, your exposure to toxins and more. 

How Accurate is Genetic Testing? Is Home Genetic Testing Reliable?

I’m often asked the question how accurate is genetic testing? Or how reliable is genetic testing?  

All labs preforming genetic testing are subject to Clinical Laboratory Improvement Amendments (CLIA) or stricter state requirements. CLIA standards are in place to ensure the analytical validity of genetic tests. It is difficult to determine the quality of direct to the public testing because some of these providers are not CLIA-certified. 

When patients have the raw genetic data from an at home genetic test, such as 23andme, we use that information in our clinic. The two labs we most often use are MaxGen and Stratagene to generate a genetic report. Both labs are CLIA certified. 

23andme states that its testing has greater than 99% accuracy, and each variant also showed greater than 99% reproducibility when tested under different laboratory conditions. 

All genetic tests claim to be reliable and still we learn new things daily and there are errors so this is not yet a perfect process. Furthermore, this is a complex question that depends upon what you are looking for. I suggest speaking to your functional medicine provider for the best guidance in determining which test is best for you.  

Here's the bottom line: The most reliable genetic testing is the one that will give you the most tools for your proactive health care journey! 

Nocebo Definition, What is the Nocebo Effect?

Some people tell me they are not ready for the information provided in genetic testing or, when they receive the information their beliefs about their body and health change. 

You may be familiar with the placebo effect, where you believe you are getting a treatment and you have a positive result. But, what is the nocebo effect? The nocebo effect is the opposite. It’s where you believe or expect a negative outcome, and that’s what happens. Both the placebo and nocebo effects are valid in medicine and it just goes to show how powerful the mind is when it comes to health. We can’t underestimate the mind-body connection. 

Scientists discovered that the placebo and nocebo effects apply to genetic testing. As it turns out, a person being told they have the genetic predisposition for obesity reduces motivation for exercise and when told they have the gene for protection against obesity they begin feeling more full from meals and naturally eating less. 

This begs the question… when the side effects of perceived risk are greater than actual risk is it always appropriate to reveal genetic risks?  This speaks to an ethical dilemma. I always discuss this with patients prior to testing and suggest you discuss testing with your provider prior to conducting it. It’s important to understand the information you will be provided with and how it might affect you when making the decision about testing. The information can be overwhelming and sometimes disconcerting and a warm body with answers and explanations is incredibly comforting and valuable. Remember, it’s my job to help put the results into the context of the whole person.

What To Do With Genetic Test Results

Those of us who practice functional medicine are collectively the pioneers or early adopters of the newest and most cutting-edge ideas in health care. Functional medicine providers have embraced genetic testing as an important part of their toolbox for uncovering potential root causes of diseases and potential dysfunctions. 

Here are some ways I use genetic testing results in my practice:

How this genetic information is used is of great magnitude. It’s important for providers and consumers alike to realize that while we can garnish valuable information that facilitates understanding and guides steps, the presence of a single gene variant alone has very little value in predicting disease. 

One study looked at uses of genetic testing in cancer prevention. The author writes: “Predicting the risks for any individual of developing future disease introduces the possibility of mitigating the cancer risk by one or more intervention. Intervention may be a modification to lifestyle, early or more frequent cancer surveillance or potentially life changing major surgery. However… this is complex and not something all can do…“

A meta-analysis looking at behavior changes and psychological responses in people after receiving direct-to-consumer genetic test results (such as 23andme) gives us some data on these issues. The study reports 23% had a positive lifestyle change as a result of testing (such as changes to diet, exercise, or quitting smoking), 7% had preventative checks or testing done, 33% shared their results with their doctor and 50% shared with family. From a psychological perspective, the study reported that anxiety and stress were low and faded over time. The study concludes that direct-to-consumer testing has potential for the right person when paired with appropriate support and follow up. 

So, again, we need to look at the whole picture (not just a single SNP), which includes the environment, lifestyle and daily health habits. 

So as you weigh the pros and cons of genetic testing for yourself, it’s important to consider what type of testing is the best fit, how you will use the results and know that I am here to support you through the entire process. Remember that much of your gene expression is in your control through your lifestyle choices. Here is to your highest potential of health!


  1. Eccles, D.M. (2019). EJS-1-Uses of genetic testing for cancer prevention. Annals of Oncology. 30(6), vi4. Abstract: 
  2. Stewart, K., Wesselius, A., Schreurs, M., Schols, A., & Zeegers, M. P. (2018). Behavioural changes, sharing behaviour and psychological responses after receiving direct-to-consumer genetic test results: a systematic review and meta-analysis. Journal of community genetics, 9(1), 1–18. Full text: 


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