Investigating Disease Risk Through Direct-to-Consumer Genetic Testing

Investigating Disease Risk Through Direct-to-Consumer Genetic Testing

Genetics tell a story about who we are. It is a powerful tool that can help uncover lineages and even describe our relatedness to other organisms on earth. More importantly, it can act as a medical resource to identify genetic risk factors, predict responses to medications and to reveal variant traits.1 Because genes play a role in the development and manifestation of disease, especially rare diseases, genetic testing has been rapidly increasing in popularity. These tests are designed to look for specific variants or markers that indicate a higher risk for diseases including Alzheimer’s disease, hereditary breast and ovarian cancer, and cystic fibrosis.2 Knowing these risks can help people to make timely, economical, and informed decisions about their care. Recently, genetic testing companies have taken advantage of the low costs to directly bring partial genome sequencing to Canadian consumers. For only a few hundred dollars, these direct-to-consumer (DTC) genetic tests can offer patients access to their genomic information. By 2018, it is projected that the global genetic testing market will be worth $230 million.3 What are the risks and benefits of directly providing consumers with a lot of genetic information and little guidance on how to use it?

Medical genetic testing began around the 1950s, when tests were first being developed for Down syndrome, cystic fibrosis and Duchenne muscular dystrophy.4 Since then, the cost of sequencing the human genome has dropped precipitously from the $95 million price tag in 2001 to only $1,500 in 2016.5 Today, genetic testing is available for over 2,000 conditions over 500 laboratories in the United States.4 Each of these conditions can be detected using specific tests designed to help identify changes in chromosomes, genes or proteins. For instance, chromosomal genetic tests would be used to analyze whole chromosomes to examine large genetic changes such as trisomy 21, which causes Down syndrome. On a smaller scale, a molecular genetic test can be conducted on short lengths of DNA to identify biomarkers and variables such as BRCA1 and 2 for hereditary breast and ovarian cancer.6 It is also possible to study the proteins coded by these genes through biochemical tests for protein activity. This is extremely useful for diagnosing phenylketonuria, which if caught early, can be treated to prevent intellectual disability in infants.7 These tests are prescribed by a medical doctor or genetic counsellor who would use the patient’s family and medical history as a guideline to test for specific conditions for which the patient is at risk. It is a comprehensive process where doctors answer and advise patients on the emotional risks, including what the results say about your family members’ health, and physical risks, including how results may be disclosed or used for research purposes. After receiving the results, medical professionals help interpret the patient’s risk and provide advice on how to proceed. This process uses genetic testing to evaluate disease risk factors rather than predicting disease outcomes. It emphasizes the role of environmental influences that work together with disease as a health determinant.5

“...these tests screen for more than 80 genetic markers that can reveal everything from lactose intolerance, disease carrier status, cancer risks, and male pattern baldness.”

Over the past few years, companies like 23andMe, Pathway Genomics, and deCODE have made it possible for consumers to bypass consultation with a licensed practitioner to have direct access to their personal genetic information. These tests are advertised through televisions, magazines, and the Internet to people interested in learning more about their health to complement their healthcare plan or lead a better lifestyle. Consumers send a cheek swab or saliva sample in the mail and, in a few weeks, they receive an information package describing the results. Unlike medical testing, these tests screen for more than 80 genetic markers that can reveal everything from lactose intolerance, disease carrier status, cancer risks, and male pattern baldness.1 A large about of identifying information is generated and potentially available to insurance companies and researchers. While there is legislation protecting against genetic discrimination in employment and health insurance, companies that offer life, disability, and long-term care insurance are exempt.8 With any DTC genetic test, the onus is placed on the consumer to research what the company is doing with the genetic information it collects and how this information will be shared, if at all, with third parties. Many experts and professional organizations warn that currently, this field is vulnerable to a number of legislative loopholes and enactment of privacy and confidentiality legislation are key goals for the future.

“None of the genetic tests now offered directly to consumers have undergone premarket review by the FDA…to ensure that results are accurate, reliable, and clinically meaningful.”

There is also concern around the validity of some commercialized tests. In 2010, the director of the Food and Drug Administration (FDA), Dr. Jeffrey E. Shuren, stated that “None of the genetic tests now offered directly to consumers have undergone premarket review by the FDA…to ensure that results are accurate, reliable, and clinically meaningful.”3 From company to company, there are variations in analytical validity, which is how well the tests predicts genetic change, and clinical validity, which is how well the gene variant corresponds to the presence or absence of disease risk. Another factor to consider is how much information the test can provide about the diagnosis, treatment, management and prevention of a disease, a measurement known as clinical utility. Over the last few years, the FDA has authorized DTC testing companies like 23andMe to report on carrier status for a particular disease, but not analysis for the likelihood of an individual developing a disease.9

Many of the testing results in the personal information booklets supplied by DTC testing companies simplify complex risk analysis into a “yes” or “no” answer. These generalized fact sheets often fail to address false positives and negatives and the limitations of estimating disease risk by only looking at a small number of genes out of 20,000 genes in the human body.10 Without the judgement and clinical experience of a medical professional, it is difficult to interpret disease risk within the context of a patient’s medical and family history. These considerations have led the American College of Medical Genetics, the Federal Trade Commission and numerous other national organization to recommend the use of DTC genetic tests to be used for interest rather than medical advice. They caution that many of these tests lack scientific validity and are only meaningful in the context of a medical evaluation.11 Given that these tests can range from $100-$1,000, patients should carefully consider if the benefits are worth the physical, emotional, and financial costs.9

In the broader picture, DTC genetic testing has great potential to personalize care. It can search the genome for disease risk factors, predict responses to medications, and “carrier status” for diseases. As exciting as it is to take part in this growing field, consumers need to consider the risks caused by the lack of regulations and protective legislation. It is important to self-manage risk by seeking advice from a medical professional and researching the specific test they wish to undergo. By taking the appropriate precautions, DTC testing can be a fulfilling opportunity for self-discovery.

Works Cited:

1. Ancestry. 23andMe.

2. King RA, Rotter JI, Motulsky AG. The Genetic Basis of Common Diseases. New York, NY: Oxford University Press; 2002.

3. Su P. Direct-to-Consumer Genetic Testing: A Comprehensive View. The Yale Journal of Biology and Medicine. 2013;86(3):359-365.

4. National Institutes of Health. Genetic Tests: How it is Used for Healthcare. Published October 2010.

5. National Human Genome Research Institute. The Cost of Sequencing a Human Genome. Published July 6, 2016.

6. National Institutes of Health. BRCA1 Gene. Published October 25, 2016.

7. National Institutes of Health. Phenylketonuria. Published October 25, 2016.

8. National Institutes of Health. Help Me Understand Genetics: Genetic Testing. Published October 27, 2016.

9. Food and Drug Administration. FDA permits marketing of first direct-to-consumer genetic carrier test for Bloom syndrome. Published February 23, 2015.

10. National Human Genome Research Institute. International Consortium Completes HGP. Published October 30, 2010.

11. American College of Medicine Genetics Board of Directors. ACMG Statement on Direct-to-Consumer Genetic Testing. Genetics in Medicine. 2004; 6(1): 60.

Cite This Article:

Zhang B., Zheng K., Chan G., Ho J. Investigating Disease Risk Through Direct-to-Consumer Genetic Testing. Illustrated by K. Lee. Rare Disease Review. May 2017. DOI:10.13140/RG.2.2.30193.68961.

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