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Considering a Genetic Test?

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by Sterling Harpst
2019 PharmD Candidate

Testing Your DNA May Actually Help Make Your Medicines Work Better

Many patients have heard of the personal genetic testing kits available for purchase from websites such as 23AndMe or AncestryDNA. There are currently over 250 Direct-to-Consumer (DTC) companies providing services to analyze saliva samples and create customized reports on what your genetic information says about you.1 Advertising for these companies often include claims that DNA testing can be used to determine an individual’s ancestry, risk for getting certain diseases, or even athletic ability.

What is of interest for many patients, however, is the claim that genetic information can be used to make their medicine more effective. With all of the information being presented, it can be easy for patients to become overwhelmed and unsure of how to make sense of it all. Here’s what consumers should know about the evolving field of Pharmacogenomics.

What are genes?

Inside your body there are millions of cells carrying chromosomes. Chromosomes makes up what is referred to as your “genetic blueprint.”  These are passed on to you from your parents and are made of unique information (genes) which code for specific traits. It is thought that there are nearly 30,000 genes in the human body which determine things like eye color, skin tone, height, and even the likelihood you may get a certain disease.2

What is Pharmacogenomics?

Pharmacogenomics is a relatively new field that looks at how a person’s unique genetic material affects their response to drugs. Imagine that three people get the same disease. Conventional medicine would often recommend they be prescribed the exact same medication. This may make one patient well again very quickly but have no impact on the other two. Essentially, pharmacogenomics aims to explain why changes in genetic information cause some drugs to work differently in different people. This new and exciting field hopes to make personalized medicine a reality, resulting in better diagnoses, earlier treatment decisions, more effective medication use, and customized therapy. By combining an understanding of drugs and genes, there is hope that one day all medicine can be personalized based on a patient’s DNA.

The Limitations of Genetic Tests

Although companies make a number of claims about what information their tests can provide, there are a few limitations to consider before completing any genetic test.

Interpretation

Perhaps the biggest limitation to pharmacogenomics is our ability to fully interpret what genetic information means. Modern technology allows us to analyze tens of thousands of genes, however truly understanding that information is another challenge entirely. Imagine a dictionary full of words, except only a few pages have a definition listed for each word. This dictionary could be used to describe where pharmacogenomics currently stands. Although we have advanced tremendously in recent years, we are still far from fully understanding of the meaning of every gene.

Ability to Make Changes

While there are certain therapies that require genetic testing before use, most do not. Many of the DTC genetic tests are designed to report only information related to drug metabolism. For example, if you do not make specific chemicals necessary to break down a drug, the drug may stay in your system longer and result in side effects. If you make those same chemicals in very high amounts, that drug may not reach the intended effect because your body removes it too quickly. For the purpose of making medication changes, this is often the only result tests can provide.

Minimal Regulation

Although there are many tests available today, there is little regulation when it comes to making sure companies are producing accurate results. Claims that you will know your chances for developing diseases such as Alzheimer’s are based on likelihood, not certainty. Many companies advertise tests that can be used to customize your diet and lifestyle as well. Without well documented clinical studies to provide evidence of these statements, the Centers for Disease Control and Intervention (CDC) and Food and Drug Administration (FDA) are often hesitant to agree.3

For some of the newer or less well-known companies, there are significant concerns with the privacy of your genetic information. The Genetic Information Nondiscrimination Act (GINA) was signed into law in 2008, preventing health insurances and employers from discriminating based on genetic information.4 However, with patient permission it is still legal to sell this data, making it very important to read the privacy policies on how they will use your information before taking a test.

If You’re Considering a DTC Genetic Test

It is important to know that the FDA and CDC do not approve genetic testing in place of traditional health care evaluation. The results may provide a likelihood regarding your chance to benefit from certain medications, but the tests are not final. Often the results may not be significant enough to change anything about your medicine. Here are a few points to keep in mind:

  • Talk with your doctor first before completing any genetic test. It is important to know what they would recommend based on your specific circumstance.
  • Ask your doctor if they would be able to interpret the test with you. Some reports can be complicated and very difficult for patients to understand. Genetic counselors are healthcare professionals that are specifically trained to help interpret the meaning of genetic testing results.
  • Before making any changes to medications or lifestyle, ask the opinion of your doctor. Since test results can be challenging to understand, changes could result in dangerous consequences if made incorrectly.
  • Understand your rights regarding privacy. Before sending your DNA to anyone, it is best to know what your information will be used for. Your genetic information is personal, and you may not want companies to share that information for personal gain.

References

  1. Phillips, Andelka M. “Only a Click Away – DTC Genetics for Ancestry, Health, Love and More: A View of the Business and Regulatory Landscape.” Applied & Translational Genomics, vol. 8, 2016, pp. 16–22., doi:10.1016/j.atg.2016.01.001.
  2. “Human Genome Project Completion: Frequently Asked Questions.” National Human Genome Research Institute (NHGRI), 30 Oct. 2010, genome.gov/11006943/human-genome-project-completion-frequently-asked-questions/.
  3. “Regulation of Genetic Tests.” National Human Genome Research Institute (NHGRI), 17 Jan. 2018, genome.gov/10002335/.
  4. Su P. Direct-to-Consumer Genetic Testing: A Comprehensive View. The Yale Journal of Biology and Medicine. 2013;86(3):359-365.

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