“All illnesses have some hereditary contribution,” said Dr. Francis Collins, director of the National Institutes of Health (NIH) and former director of the National Human Genome Research Institute (NHGRI). “Genetics loads the gun and environment pulls the trigger.” It is a common misperception that a person’s genetics somehow determines his or her future, and that understanding the human genome is comparable to accessing the source code of a complex software program that can be reverse engineered to understand how everything works and then be fixed, prevented or controlled. As with all genetic discussions, this one is a bit more complex and cannot be distilled to one paragraph. In this light, Pathway feels it is necessary to further examine this topic by discussing the common misperception of genetic testing as being deterministic, when essentially it is predictive.
The current American political and social context is perfectly aligned with this line of discourse, because it is with this misunderstanding that the U.S. Government Accountability Office (GAO) questions the value of genetic testing when its report to the Subcommittee on Oversight and Investigations revealed, “Donor 4 had a pacemaker implanted 13 years ago to treat atrial fibrillation. However, [23andme] and [Decode] found that he was at below-average risk for developing atrial fibrillation, and [Pathway] and [Navigenics] claimed that he was at average risk.” The implication is that our collective analysis of his genetic risk must be wrong, simply because he has worn a pacemaker for 13 years. The problem with this conclusion is that genetics does not work in a vacuum, and environment and lifestyle pose a large role in the development of a health condition such as atrial fibrillation.
The first item to address is that this dialogue is focused on genetic testing to estimate risk for complex health conditions, such as colon cancer and atrial fibrillation, and is generally not applied to carrier status testing, drug response, or other types of genetic testing. Complex conditions have multiple possible causes in addition to genetics, including environment, lifestyle, and family history. The risks for many complex diseases can be mitigated by making informed personal health choices.
The Genetic Misperception
It seems probable that much of the misunderstanding originates from science fiction and entertainment media, where omnipotent governments or diabolical scientists manipulate genetics to exercise greater control over the world. This can make for great entertainment and thoughtful consideration of our future, but in this context, reality is much different from fiction. When used for assessing risk of complex health conditions, genetic information is more accurately considered as an additional tool to be used in making more informed health assessments and plans for prevention. While a family history of heart disease does not guarantee that every child and grandchild will get the disease, it is a valuable tool in encouraging future generations to make lifestyle changes for better health.
Perhaps the best way to poignantly illustrate the difference between predictive and deterministic is through an analogy. Every evening, meteorologists on the local news inform the community of the weather to expect for the coming days. Based on a scientific analysis of weather patterns and meteorological conditions, these educated meteorologists might tell us there is a “60% chance of rain on Tuesday,” or to “Expect sunny and 70 over the weekend.” Is this prediction to be used as fact? Not necessarily, as that particular Tuesday may very well bear no rain, and the weekend may turn out to be partly cloudy and a chilly 60 degrees. Collectively, it is safe to conclude that we would agree that weather reports are to be used as predictors to inform, and not to be seen as foretelling the precise future. The point here is that while these meteorologists may have been slightly incorrect in their predictions, it does not make the meteorological predictions useless – we still pack umbrellas and plan events with friends and family based on the best information that we have.
Bringing this back to complex health conditions and genetics, learning that one does not have known genetic risks that contribute to cardiovascular disease is not an excuse to enjoy a cigarette with every helping of red meat. On the other side of the spectrum, learning that one has an increased risk of cancer is no reason to throw in the towel and surrender to your ultimate destiny. The information from personal genetic testing can and should be used as a motivational tool to encourage people to make good health decisions.
Some critics claim that there is nothing in a genetic test that cannot be determined from a comprehensive analysis of one’s family history. This assertion is clearly an appeal to tradition and can only serve as a catalyst for stagnation. Only a few decades ago, the common medical practice was to not inform patients of the diagnostic details surrounding a terminal illness, such as cancer. Either out of respect or out of lack of knowledge, many people were reported as having died of old age or something broad such as heart problems. The consequence of this practice has led to a lack of understanding. It has not provided the people of this current generation, who are largely concerned with preventive health, with the information to understand their individual risk of conditions such as breast cancer, heart attack or Alzheimer’s disease. That said, the medical community’s current role in responsibly informing patients of these matters has dramatically improved. Using a person’s genetic information to further investigate the propensity for a complex disease is another piece of the health and wellness puzzle, which can be integrated in preventive health care.
The Oxford English Dictionary defines predictive medicine as “the branch of medical science or practice concerned with the prediction of the occurrence or course of disease in individual patients.” It is with this definition that we, as a culture, and our government need to view personal genetic testing.
Simply stated, as it relates to complex health conditions, personal genetic testing is predictive, and not deterministic, and it can be used as an additional piece of the puzzle. The perception that genetic testing is not useful because of its predictive nature is a fallacy.
Finally, this brings us back to the GAO report’s “Donor 4,” the colon cancer survivor who also had a pacemaker implanted 13 years ago. While the predictive nature of our genetic testing may have been imperfect for atrial fibrillation, Pathway, 23andme, and Navigenics each interpreted his genetic data to suggest an “Increased Susceptibility,” “Elevated,” and “Above Average” respectively for colon cancer. In respect to this individual’s privacy, we will not reveal what his lifestyle survey and family history suggested about his risk for this health condition, but the reports from all three companies clearly and consistently indicated increased genetic risk.
Pathway envisions a health system in which people such as GAO’s “Donor 4” use their genetic information, coupled with family history, lifestyle and environmental factors, to make informed health decisions and never have to suffer from complex health conditions that their genetic makeup has loaded in their guns.