Whole Genome Sequencing: Changing The Way We Look At Health And Illness


What if you could look into the future and manage or even prevent an illness before it occurs? Whole Genome Sequencing (WGS) is taking personalized healthcare to a whole new level. It's about identifying your particular genetic variations - what makes you different from other people and what makes your body respond to a virus or to a medication differently than someone else. It can also reveal if you have a genetic predisposition to a disease - invaluable knowledge which can prompt early intervention and treatment.

The One and Only You

Each species has its own genome. The human genome consists of over 20,000 genes. These genes are made up of DNA expressed in the form of sequences of letters. Your DNA is the blueprint for your body - instructions for how you develop, function, and age. They also influence how we respond to things in our environment like germs and pollutants. What makes you different from everyone else is the fact that every individual has his or her unique genome sequence, complete with individual variations and mutations.

Whole genome sequencing enables scientists to analyze your entire DNA using high resolution, next generation sequencing techniques. Long before the human genome was mapped in 2003, genetic testing was available to detect single gene mutations responsible for an inherited disease like sickle cell anemia or for mutations that are risk factors for developing a disease like breast cancer.

A more recent form of genetic testing, single nucleotide polymorphisms (SNP) testing, focuses on analyzing genetic variations of within the human genome. The good thing about SNP testing is that it provides you with information regarding multiple genetic risk factors for such things as drug reactions, cardiovascular disease, and rheumatoid arthritis. It can also aid in tailoring diet and exercise programs. Gene segments analyzed by SNP testing can give your healthcare practitioner insight into how your genes influence your eating behavior and your body's response to physical activity. That said, researchers are finding that numerous gene segments play a role in your risk of developing disease, so looking at just one gene segment won't reflect your overall genetic risk. SNP testing is, however, an excellent way to identify factors that have the potential to negatively impact your health.

In comparison, WGS looks at all of your DNA, generating a huge amount of data. This data must then be analyzed in order to extract useful, actionable information - that is, what the test results mean for your health or your children's health given what scientists currently know about the human genome. As more people have their genome sequenced and more genome comparisons are made, new light will be shed on the implications of genetic variations with respect to the true risk of developing a disease or contracting an infectious illness.

Should You Have Your Genome Sequenced?

Getting your whole genome sequenced involves genetic counseling and obtaining a blood or saliva sample. The sample is then sequenced, analyzed, and the results interpreted. Although the field of WGS is growing at a very fast pace and testing has become less expensive, the clinical significance of much of the information gleaned from WGS is still not fully understood. So, should you get tested?

Currently, genetic testing in individuals with certain forms of cancer is advantageous as it helps physicians choose the best chemotherapy regimen for that person - one that effectively fights the cancer while minimizing the side effects. Similarly, WGS can detect abnormalities in how the body metabolizes medications, leading to a more appropriate selection of drugs and better drug dosing. For couples planning to start a family, but whose family medical history includes genetic disease, WGS provides valuable information about the risk of passing on a disease to the next generation.

In some cases, WGS can identify genetic abnormalities for which early intervention is warranted.1 It can also prove to be an important diagnostic tool in someone with severe health problems or with a family history of medical illnesses.2 ln healthy individuals, however, less than 2 % will be found to have a genetic mutation that requires treatment or continued surveillance. 3 In about 20% of all people who undergo WGS, a genetic mutation will be detected, but it's still uncertain if they will definitely go on to develop the disease.3 That's due in part to the fact that things other than our DNA - like diet and the environment - influence our susceptibility to disease.

One of the most important questions to ask yourself before being tested is: Are you prepared to learn that you may have a genetic mutation for an incurable disease? To better address this situation, WGS testing allows individuals to opt out of receiving certain test results. It's also important to keep in mind that the current state of WGS has its limitations. Testing positive for a certain gene doesn't mean you'll definitely go on to develop that disease. Similarly, a negative result doesn't mean you won't be at risk of developing that disease at a later date. WGS testing is being continually refined to make it more sensitive and more accurate, but it is a snapshot of your DNA at one point in time.

Here are a few other things to consider when contemplating WGS testing:

Advantages:

  • WGS can identify disease-causing genetic variations that would otherwise not be detected.

  • WGS may aid in diagnosing the cause of severe health problems

  • WGS can identify which drugs are safe and effective for you to use.

  • Your sequenced genome can contribute to the growing body of knowledge of health and illness, should you elect to share your results.

Disadvantages:

  • Federal laws like the Genetic Information Nondiscrimination Act exist for protection against discrimination from employers and health insurance companies, but not from life, disability, or long-term care insurance companies.

  • Not every company that does WGS protects your genetic information the same way. The Presidential Commission for the Study of Bioethical Issues recommends that "Accessible whole genome sequence data should be stripped of traditional identifiers whenever possible to inhibit recognition or re-identification."4 If you choose to do WGS, be sure you fully understand how your data will be kept confidential.5

  • Emotional stress and unnecessary or excessive testing may result from the knowledge that you have a genetic variation. Remember, having a genetic predisposition for a disease doesn't mean you will definitely go on to develop that disease.

WGS is rapidly shaping the future of how we prevent, diagnose, and treat illness and most researchers agree that WGS will eventually become a routine part of our health care. But you don't have to wait for your WGS findings to take control of your health. Basic steps like eating well, exercising, and reducing environmental stressors and pollutants go a long way toward optimizing your genetic - and overall - health. You can also choose to have just segments of your genes tested through SNP testing. If you would like more information on ways you can improve your health, please contact us today.

References

1 "When should we all have our genome sequenced?" 10.31.2013 by Main J. Khoury. CDC.gov/genomics/blog

2 "Whole-genome sequencing in health care". Recommendations of the European Society of Human Genetics. European Journal of Human Genetics (2013) 21, 580-584.

3 "Should healthy people have their genome sequenced?" www.wsj.com 2/15/2013

4 Presidential Commission for the Study of Bioethical Issues. Privacy and Progress in Whole Genome Sequencing. October 2012.

5 Niemiec, E & Howard, HC. Ethical issues in consumer genome sequencing: Use of consumer's samples and data. Applied & Translational Genomics. 2016 Mar; 8:23-30.

The contents of this blog are intended for educational purposes only. The information presented here is not a substitute for proper medical attention, diagnosis, or treatment by a qualified healthcare professional. Always seek the advice of your healthcare provider before starting or making any changes to an existing treatment plan, exercise program or dietary regimen, and before using nutritional supplements.

~ Dr. Sarah Williams ~ Concord & Nantucket, Massachusetts ~

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