By Dr. Brandon Colby MD, a medical expert in the fields of genetic testing and predictive medicine. Dr. Colby is the author of Outsmart Your Genes.
We previously discussed the concept of being able to outsmart your genes. We’ll now discuss why harassing this ability will usher in a revolution in the evolution of healthcare.
There’s no point in learning your genetic risk for a particular disease because there’s nothing you can do about it.
If you discover that you are at increased risk for a disease, there are actions you can take to decrease the likelihood that you will get the disease or to limit its impact on you if it should ever manifest. And, in all cases, you will be alerted to diseases you might pass on to your children. If you know you’re at risk, there are things you can do about it!
Your genetic makeup—that is, the genes you inherited from your parents—holds the secrets to your destiny. Not only the color of your eyes and hair and your musical or athletic abilities but also thousands of other factors related to your appearance, your health, and how you interact with the world are all determined, in whole or in part, by your genetics.
Your genes determine how fast your metabolism works and how you process the calories you consume, which, in turn, determines how much fat you have around your abdomen and, to a significant degree, how much you weigh. Genetics are responsible for how your body processes medications, whether you’ll experience side effects from a particular drug, what dose you require, and whether the drug will be effective at all.
Your genetic makeup even determines your basic personality traits, such as if you’re a risk-taker, whether you are shy or outgoing, how you handle stress, and even if you’re more inclined to keep anger bottled up or to let it out. Some traits, such as eye and hair color, are determined entirely by genetic inheritance.
For other characteristics, such as intelligence and height, your genes define the range of possibilities, and nongenetic factors, such as your education and lifestyle, determine where you ultimately fall within that range.
For example, your genes may dictate that your adult height will be between 5 feet 8 inches and 5 feet 11 inches, but your actual adult height is also determined by nongenetic factors, such as the kind of nutrition you receive while growing up.
Most important, your genes, either in whole or in part, determine whether you are at risk for specific diseases. Even your risk of contracting infectious diseases, ranging from the flu to HIV, is determined in part by your genes.
With the completion of the Human Genome Project and the advent of the powerful technologies now available for DNA testing, scientists have the ability to decode and analyze your genetic makeup and predict what diseases you are at risk for developing. But unless your genetic information is made actionable, your decoded genome is no more useful than a high-tech paperweight.
Predictive medicine is the component that makes DNA testing actionable. Predictive medicine is a new medical specialty. When a physician believes that a patient needs a radiological examination such as a MRI or a CAT scan, he or she refers the patient to a doctor specifically trained in the field of radiology to perform the test.
This test is then read by the radiologist, who supplies the referring physician with a written report. The report is what makes the test actionable for the physician—which is exactly what predictive medicine does in the field of genetics. Any physician can integrate predictive medicine services into his or her practice just as he or she does radiologic exams and laboratory tests.
The DNA report provides an analysis that clearly identifies the patient’s risk for various diseases and specifies preventive measures that have been shown to decrease the risk or minimize the impact of those diseases. Even the preventive measures themselves can now be genetically tailored to your DNA.
When your doctor receives your genetic report, he or she can work with you to take actions that will minimize your risk and perhaps even prevent you from ever developing the diseases for which you are at risk. Keep this in mind: Just because you have a gene that increases your risk for a certain disease does not necessarily mean you have or will ever contract the disease.
What it does mean is that your genes predispose you to that disease. But you might also find out that you do not have any of the genes associated with a particular disease—for example, if you find you do not have any harmful changes in the genes BRCA1, BRCA2, CHEK2, ATM, and FGFR2, all of which are linked to breast cancer, you might feel significant relief. You may even discover that you have a beneficial genetic makeup that protects you from and lowers your risk of certain diseases.
One indication of the usefulness of comprehensive genetic testing in clinical care is evident from a 2009 study conducted by the director of the Centers for Disease Control and Prevention’s Office of Public Health Genomics in Atlanta (also known as the CDC).
This study, published in the journal Genetics in Medicine, found that when comprehensive genetic testing results for a patient were made available to the patient’s physician, 75 percent of physicians changed some aspect of their patient’s care “such as screening tests offered, medications or dosages prescribed, lifestyle changes recommended, frequency of follow-up appointments, or diagnoses made.”
Although the physicians were already treating these patients and had presumably taken a family history and conducted all other routine care, obtaining genetic information still made a difference in their clinical management of these patients three out of four times.
In terms of its impact on society, predictive medicine has the potential to significantly decrease the costs of healthcare. As just one example, consider the medication warfarin (Coumadin), which is one of the most widely prescribed drugs in the world and is used to thin a person’s blood in order to protect against blood clots, heart attacks, and strokes.
A senior member of the U.S. Food and Drug Administration’s economic staff stated that if it became standard practice to conduct genetic testing before prescribing warfarin, the decrease in the number of adverse reactions would result in a net healthcare savings of as much as $1 billion per year.
The power of predictive medicine lies in its ability to look at your entire genetic profile and provide you with a forewarning that you and your physician can use to change your future health for the better. You, as a healthcare consumer, are the direct beneficiary of this revolution in medicine because what you can learn about your genes today will have a profound impact on your present and future well-being.
Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of Sequencing.com and the author of Outsmart Your Genes.
Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (ACMG), an Associate of the American College of Preventive Medicine (ACPM), and a member of the National Society of Genetic Counselors (NSGC).
Kolor, K., et al. (2009). “Health Care Provider and Consumer Awareness, Perceptions, and Use of Direct-to-Consumer Personal Genomic Tests, United States, 2008.” Genet Med 11 (8): 595.
U.S. Food and Drug Administration. “Critical Path Initiative—Warfarin Dosing,” 10/13/09.
Bauer, L. O., et al. (2007). “Variation in GABRA2 Predicts Drinking Behavior in Project MATCH Subjects.” Alcohol Clin Exp Res 31 (11): 1780–1787.
Gordeeva, E. (1996). My Sergei: A Love Story. Warner Books, 255.
Goldschmidt-Clermont, P., et al. (1996). “Clues to the Death of an Olympic Champion.” Lancet 347 (9018): 1833.
Weiss, E. J., et al. (1996). “A Polymorphism of a Platelet Glycoprotein Receptor as an Inherited Risk Factor for Coronary Thrombosis.” N Engl J Med 334 (17): 1090–1094.
Bojesen, S. E., et al. (2003). “Platelet Glycoprotein IIb/IIIa PlA2/PlA2 Homozygosity Associated with Risk of Ischemic Cardiovascular Disease and Myocardial Infarction in Young Men: The Copenhagen City Heart Study.” J Am Coll Cardiol 42 (4): 661–667.
Zotz, R. B., et al. (2005). “Association of Polymorphisms of Platelet Membrane Integrins αIIbβ3 (HPA-1b/PlA2) and α2β1 (α2807TT) with Premature Myocardial Infarction.” J Thromb Haemost 3 (7): 1522–1529.