Should We Be Embracing At-Home Genetic Tests?

Should We Be Embracing At-Home Genetic Tests?
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When direct-to-consumer (DTC) genetic tests first appeared on the market, Time magazine celebrated them as the invention of the year in 2008. However, almost a decade later, their usefulness is still being critically debated. This health technology is a part of personalized medicine. It promises insights into genetic components of our health, as well as helping us potentially make better decisions.

A growing number of companies worldwide are offering DNA kits for different conditions and diseases. Users are now able to access their genetic information without involving a physician and/or an insurance company. But, is satisfying our curiosity with at-home genetic tests a good decision?

Although at-home testing is a proactive approach that has many touted benefits, experts also warn of its risks and limitations. Often, these tests produce incomplete or inaccurate information. This is particularly alarming since consumers do not always have a solid grasp of their results and can make complex health decisions without expert guidance. Moreover, genetic tests provide only partial insights.

For a better understanding of our susceptibility to a disease, other factors need to be considered as well, such as environment, family history, and lifestyle choices. Most experts agree that predictive tests, which give users information about their risk of developing a health condition, are offering novel, democratized methods of genetic testing. However, the field remains riddled with conflicting information, and hot debates between companies and regulatory bodies persist.

From Reproductive Tests to Predisposition Tests

In the past, we were more familiar with reproductive genetic tests, which gave information about a future baby’s risk of disease. Now, personal presymptomatic and predisposition tests are becoming common. Presymptomatic tests provide information about an inherited condition that can develop in people who carry a certain gene. For instance, almost all people with 40 or more repeats of the CAG segment in the Huntington gene will develop Huntington’s disease (complete penetrance). Predisposition tests, on the other hand, tell about an increased risk of developing a condition because of an existing gene mutation; there is no certainty that a person being tested will develop this condition in the future.

At-home DNA tests are marketed as both presymptomatic and predisposition tests and are performed outside of the national health-care system. If you take these tests, you need to be aware that the results are usually not black and white. Mostly, users will (only) learn about their personal risks. According to the results, they might want to adjust their behavior (e.g. eat more omega-3 fatty acids) or comply with a medical intervention (e.g. undertake regular health screenings).

How Do At-Home Genetic Tests Work?

After you purchase a DTC genetic test, the protocol for testing generally requires you to take a sample of your saliva or a swab from the inside of your cheek. Alternatively, you might need to visit a health clinic to give a blood sample. The sample is sent back to the testing company and within a few days to a few weeks, you receive the results of your DNA analysis in the form of a report.

At-home DNA tests can yield an array of information, ranging from your susceptibility to a disease and carrier status (risk of transmitting a disorder to offspring) to predictions of baldness and earwax type. Increasingly popular are nutrigenetic tests, which prescribe you a diet that is purportedly matched for you based on your DNA.

Cost of Genetic Testing Is Decreasing

Although whole genome sequencing (WGS) is still expensive, more affordable options are becoming available. For instance, it is possible to opt for a cost-effective single nucleotide polymorphism (SNP) genotyping, which maps only the locations of the genome associated with diseases. SNP genotyping can provide an estimate of your risk of developing certain conditions.

Global Industry Analysts predict that by 2018, the global market for at-home genetic testing will reach over $233 million. The three leading DTC genetic testing companies are considered to be 23andMe, Family Tree DNA, and Ancestry. In 2017, 23andMe was the first to receive FDA clearance to perform DNA analysis for 10 conditions without a doctor’s involvement.

DTC companies mostly promote their genealogy services. Packages for this type of service can be found for under $100. Including medical information generally brings the cost up, for example, 23andMe currently offers a medical+genealogy version for $199. Most DTC companies do not offer complete WGS scans.

At-Home Genetic Tests vs. Testing at the Doc’s Office

One advantage of at-home tests that appeals to many consumers is that they are anonymous. Results do not automatically become a part of your medical record. “Genetic discrimination” is something that has not been comprehensively addressed. Rightfully, some people are concerned about the potential discrimination risk these type of tests carry (e.g. being used to increase life insurance premiums). Since 2009, the Genetic Information Nondiscrimination Act has been in place in America, but there have been recent calls to strengthen it. Therefore, many see independent tests as a way to keep their genetic information private.

DTC testing has been marketed as a method that can give you control over your own health choices. However, studies show that people can be wary of genetic testing that is not performed by health professionals employed in state institutions. Lack of government regulation and possible misinterpretation of genetic information have been cited as two pitfalls of at-home DNA kits. Also, consumer protection has recently become a concern. Consumers have expressed fears that their data may be made available to other companies or used for further research without their knowledge.

Associate Professor Christine Critchley of Swinburne University in Australia and her colleagues from the University of Tasmania assessed the Australian public’s attitude towards DTC genetic tests. They were interested to know if people regard them similarly to genetic tests ordered by their health-care professionals. Their results show that people generally share the concerns of genetic experts about DTC genetic tests and are not very likely to order one. Consumers in the study had worries that included privacy breaches and lack of counseling, as well as lower accuracy compared to genetic tests ordered by doctors. On the other hand, previous studies in the United States and Russia showed a more positive attitude toward purchasing commercial genetic tests. Americans and Russians seem to be more likely to order such tests online.

Andelka Phillips from the Faculty of Law of the University of Oxford also writes about the legal challenges of internet-based genetic testing that is international in nature. Phillips observes that any improvement in data protection and information security will require international collaboration.

Accuracy and Safety the Main Downsides of At-Home Genetic Tests

The ability to accurately and reliably predict the presence (or absence) of a disease has been a main concern regarding at-home testing. Some consumers reported receiving different results from different DTC companies. A team of genetic scientists from the J. Craig Venter Institute and the Scripps Translational Science Institute performed an independent comparison of five samples analyzed by 23andMe and Navigenics.

While their results showed that the accuracy of the raw results was high, the two companies differed in their disease-risk predictions for the same individuals. Navigenics and 23andMe agreed only in two-thirds of predictions regarding relative risk for a condition. Prediction agreement was better for some diseases than others. For instance, both companies agreed when predicting the risk for celiac disease. In contrast, for seven diseases—including Crohn’s disease, type 2 diabetes and heart disease—the agreement was 50 percent or less.

Researchers attributed these discrepancies to a set of markers each company uses in their calculations. Criteria for which markers to include can differ; therefore, the results are not necessarily identical. In some cases, the predictions were at opposite ends—one company predicted an increased risk for a condition, while the other suggested a decreased risk.

Most DTC genetic testing providers operate outside of the national health-care system. Their labs are not regulated and in many cases, results lack clinical validity and utility. Inaccuracies could have significant consequences. For instance, a low-risk prediction might give you a false sense of safety, negatively influencing your lifestyle choices. We do not yet understand the exact genetic contributions to disease risk, so assuming one is in the safe zone can be harmful. Experts, therefore, suggest that in the future, there should be more involvement from knowledgeable health professionals as well as more government oversight to increase safety and reliability.

How to Cope With Negative Results

When a genetic test is ordered by a physician, a patient usually gets pre- and post-testing counseling. Despite what the DTC genetic testing companies often advertise on their websites, adequate professional support is generally not provided to their customers.

Some researchers have voiced concerns about psychological and behavioral implications of genetic testing. For example, finding out you have an increased risk of developing cancer could make you anxious or depressed (even though you may never get cancer). Test results can also reveal information to other family members who might not want to know.

However, some studies indicate that finding out negative results may not necessarily cause psychological damage. Dr. Lidewij Henneman of Vrije University in Amsterdam concluded that genetic testing is associated with little distress and that after finding out, people soon return to their previous mental outlook. Henneman did point out that health literacy is still low among consumers. Some people might overestimate the likelihood of getting a disease, which she refers to as “genetic determinism.”

A Word From Verywell

Most medical professionals state that genetic testing should only be performed when there is a medical indication; for instance, family history of a disorder or having a partner who is a carrier. Ethical questions also surround genetic testing of minors, for example, the increasingly popular testing of children’s talents. According to the European Society of Human Genetics, genetic testing on a person who cannot give consent should only be done if it has a direct benefit to him or her. Predictive testing on a child should, therefore, be performed only if there is a known risk of inheriting a disease and, even then, only if therapeutic or preventative options exist. Some argue that these same ethical standards should also apply to adults for similar reasons.

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