Apr 5, 2012Science and Technology
Gene sequencing may not actually be useful in determining health risks

Genetic risk prediction for disease may not be as valuable as previously thought.Over the past several years the world of disease treatment and prevention has begun focusing its efforts on identifying the underlying genetic causes behind certain illnesses, with an eye to catch these maladies before they start. Companies offer tests to predict susceptibility to a myriad of cancers and hereditary diseases. Yet, a study performed on identical twins indicates that these preemptive tests may not be as useful as they are touted to be

The study, published earlier this week in Science Translational Medicine, analyzed data on 24 diseases from 53,666 identical twins in registries from the United States, Sweden, Finland, Denmark and Norway to determine whether these gene mapping tests really predict impending illness. The study measured how often one twin, both or neither developed the subject disease, asking if those who ultimately contracted one of the 24 diseases would have been forewarned by DNA sequencing. The answer, for the most part, was no.

Of those female subjects who underwent genetic testing, more than ninety-three percent learned that they were at low risk for breast cancer. And yet, these results do not signify a lack of risk, but rather are indicative of a risk akin to that experienced by the general population. Gene sequencing could, at least in theory, identify as many as seventy-five percent of those patients predisposed to developing Alzheimer’s disease, autoimmune thyroid disease, Type 1 diabetes, and, for men, heart disease. However, with the exception of heart disease, there is currently no mechanism for preventing the onset of these diseases, or even to slow their progression.

Genetic testing is not wholly without merit, however. The quest to pinpoint the underlying genetic factors in the population’s most fatal diseases is certainly a worthwhile effort, if only to prompt a better understanding of these diseases’ origins. Such valuable information may be utilized to develop treatments and, ultimately, preventative care. 

Until such preemptive health care becomes a reality, however, there is concern that those companies selling genetic tests for serious medical conditions ought to be regulated by some means. To that end, the United Kingdom's Human Genetics Commission advises the British government regarding developments in the realm of genetic testing. The Commission has developed a preliminary set of guidelines for what is currently an unchecked private industry. 

Under this suggested new regime, those companies offering genetic testing for potentially fatal diseases would be required to offer counseling before and after the results are given, in order to better assist patients in coping with difficult news. Additionally, any claims made regarding genetic susceptibility to diseases would require a basis in scientific evidence published in reputable journals, and would also require information regarding hereditary risks in terms of the patients’ siblings and offspring. 

23andMe is one of the companies offering genetic disease risk testing.At present, the UK only deems three genetic testing sites reputable -- one of which is the US-based, a company sponsored by Google, which has over 35,000 customers worldwide.  This limited endorsement begs the question: is the US employing any regulatory efforts with regard to genetic testing services? The FDA promulgates innumerous standards for everything from meat to syringes, but are they doing anything to standardize genetic testing? It would appear not. 

When the results of genetic tests prompt patients to undergo significant life decisions, such as prophylactic mastectomies, termination of pregnancies, or prescription drug use, it would seem imperative that these tests be grounded in legitimate and verifiable scientific data. Though genetic testing is a relatively new idea, it is growing quickly -- more than 900 genetic diseases are available for clinical testing. As the industry evolves, so should the standardizing authorities. 

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