Guest commentary: Direct-to-consumer genetic testing--Helpful or harmful?

Personalized or precision medicine is the future for many complex diseases, but simply giving a patient knowledge of their genetic predisposition to a disease is not enough

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Genetic testing for disease predisposition is constantly on the rise, with companies like 23andMe and Futura Genetics gaining in popularity among consumers. The purpose behind direct-to-consumer genetic testing is to help reduce the likelihood of developing serious health conditions, with a focus on using genetic information to motivate healthier lifestyles and take preventive action. According to a recent study from Cambridge University’s Health and Behavior Research Unit, however, knowing their genetic risk of disease doesn’t necessarily motivate people to change their behavior.
The Cambridge study found that consumers becoming aware of their genetic risk for certain diseases wasn’t enough to get them to change their lifestyles accordingly—e.g., quit smoking, eat better or exercise more—stating, “Expectations that communicating DNA-based risk estimates changes behavior are not supported by existing evidence.” The study posited that “personalized medicine” based on genetic testing can only truly be effective when individuals who carry a certain risk to develop a disease take steps to make a lifestyle change in attempts to thwart the disease—and that direct-to-consumer genetic testing may actually be detrimental, as it could distract patients from evidence-based research and instead rely only on their odds based on genetic tests to make sustainable health decisions.
Personalized or precision medicine is the future for many complex diseases, such as cancer, and genetic testing plays a key role in that approach. However, giving a patient knowledge of their genetic predisposition to a disease—even if they take action to avoid or manage the disease—is not enough. The key is to ensure that the information gathered through genetic testing is used effectively.
Pros and cons of consumer genetic testing
Consumer genetic testing has the potential to provide significant benefits to patients if the information is leveraged in an educated manner. For example, if the test shows that a person has an increased risk of diabetes due to genetic predisposition in his family or HLA type, he can take steps to reduce his risk or delay the onset, such as having his blood checked regularly, watching his weight and exercising regularly. If people take the tests seriously and are well educated on the consequences of related good or poor behaviors, direct-to-consumer genetic testing can be very beneficial as well as cost-saving. Additionally, as more drugs and their combinations are being developed with companion diagnostics, genetic tests are critical to determining whether a patient is a candidate for a certain drug treatment or not.
On the other hand, these kinds of tests can actually be harmful if used in a vacuum, without any information to guide a patient’s decisions. A genetic test on its own cannot provide a well-supported diagnosis for any kind of disease, so there is the potential for consumers to misread the severity of their test results and believe they are in harm’s way—or conversely, not understand the full weight of their risk factors—if they don’t have the whole picture and the results explained to them.
For example, consider a person who takes a genetic test and finds that she is at risk for going blind in a few years. She is insecure about what that means, so decides to wait and see what happens, rather than see her doctor and get on a path to interfere with or manage the disease, e.g. through early and minor interventions, before it becomes clinically imminent. The genetic test can’t provide any benefit if the patient does not take action to hinder the disease.
On the opposite end of the spectrum, some consumers may overestimate their risk factors for a disease and take extreme measures to prevent it. For example, when Angelina Jolie tested positive for the BRCA1 gene, she elected to have a preventative mastectomy. Jolie took this action to preserve her health, maybe not only for her own good, but also for her family. But the fact that she didn’t want to have more children and could afford to have reconstructive plastic surgery may have made the decision a bit easier than it would be for a young woman without these financial resources, and who still wants to get married and have a family. If that latter woman tests positive for the BRCA1 gene and is left alone to handle that information, how does she decide what to do, and what does that mean for her and her family? Will she choose to have a preventative mastectomy and continue on with her life as normal? Decide not to get into a relationship or have children for fear of getting cancer? Tell her female family members that they might be at risk as well? A preventative procedure may not actually be necessary for this woman, depending on the host of other health factors at play, but she may choose this route anyway if basing her decision solely on the genetic test.
There could be serious impact on a patient if given genetic information without any other context with which to make a decision. Preventative measures are an increasingly important piece of managing disease risk in the future, but the decision to take that action needs to be made in a realistic, well-educated way, versus the more radical approach of taking a genetic test and then making a decision based solely on that information.
Genetic testing only tells half the story
In order to make a well-informed decision, it’s important to remember that a genetic code is just a genetic code consisting of four letters. Like words on a page coming together to form a meaning that can be read and understood, genetic information only becomes meaningful when correlated with other relevant information. Whether it’s a direct-to-consumer test for information gathering or a test performed by a doctor as part of a clinical trial, genetic data must be analyzed in conjunction with other information, such as protein data, morphology information and clinical outcomes, so that the whole picture of a patient can be seen.
Particularly in oncology, genetic data combined with accurate, quantifiable tissue data facilitates better biomarker identification and the development of companion diagnostics, helps researchers identify the right therapeutic molecules to move through the pipeline and ultimately enables pharmaceutical companies to develop and bring targeted drugs to market faster—all of which are critical to improving the treatment of patients.
Toward precision medicine
Consumer genetic testing can be beneficial as long as the information is used appropriately. It can certainly help support advances in precision medicine, which includes making use of diagnostic information to not only develop new therapies, but also help guide the use of the best available drugs and drug combinations for a patient. In order for consumer testing to be effective, however, several things are needed:
  1. A healthcare specialist needs to be involved to help the patient take the next step. The questions raised by genetic tests should be answered in a conscious and well-educated way, and no lay person can be expected to do that on their own (Google is a great resource, but not an expert opinion). As the Cambridge study mentioned, if left to interpret the results on their own, patients could be distracted by genetic tests and rely solely on their genetics rather than on evidence-based research to make health decisions. Consumer testing can be detrimental if patients are left alone with a very serious healthcare decision, so there needs to be a safety net with these tests.
  2. More information needs to be provided. Genetic testing alone is not sufficient, either in the drug discovery and development setting or in the consumer setting. Health decisions need to be based on the full picture of a patient, and genetic data needs to be correlated with cancer tissue data, previous treatments, lifestyle and other information in order to get that full view. As the Cambridge study noted, just having knowledge of a relative risk factor does not necessarily prompt a behavioral change to reduce that risk. The best way to combat this cognitive dissonance among patients is to provide more information; for example, instead of simply saying “You have a gene amplified that can cause cancer,” saying “You have a family history and genetic predisposition, you have high blood pressure and you smoke cigarettes, so you are at a very high risk of developing lung cancer” may better encourage patients to take action. The more information a patient or health specialist can collect and compare, the better informed and compliant they will be.
  3. Genetic data should be maximized. Ultimately, if consumers are sharing the results of their genetic tests with their doctors or other healthcare professionals, this (big) data would be most helpful if it made its way back to the lab to help inform the drug discovery and development process. With all valid concerns around personal data safety and data integrity, patients suffering from a life-threatening disease are usually willing to share for their own personal benefit.
As the industry moves toward precision medicine and healthcare, fully understanding the patient and making decisions accordingly, whether it’s the use of a drug or a behavioral change, is key.

Dr. Ralf Huss is chief medical officer of Definiens and has more than 20 years of training and experience in histopathology and cancer research. Prior to joining Definiens, he also served as global head of histopathology and tissue biomarkers at Roche Diagnostics.

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