January 1, 1970 (Vol. , No. )
Taralyn Tan Ph.D. Curriculum Fellow Harvard Medical
“If you could know when and how you would die, would you want to know?” How often have we encountered this question in one form or another, be it between children at the schoolyard or depicted in film and literature? It is a query that resounds within the realm of philosophy: How do we cope with mortality? Does the certainty of knowing make it better? Or worse? And what if we cannot be given certainty at all? Is it valuable to know how you might die—to engage in an unwinnable contest of crippling probabilities that may or may not offer clues to your fate?
Science can provide no certainties about an individual’s medical fate, although some people would like to think otherwise. When the human genome was sequenced, there were definitely some who looked to the nucleotide script as ancient people looked to stars … for answers. We would like to believe that it is that simple—that our DNA sequence can give us the certainty that all of us, at some level of our human consciousness, craves. Am I destined to die of Alzheimer’s? Must I ready myself for an arduous battle against cancer? Am I one of the blessed few who will simply drift from this world in my sleep? And while genetic variants have definitely been useful—as with classically Mendelian heritable diseases and biomedical research—by and large, genetic sequence offers little more than “what if’s” and “could be’s”. They may provide an “increased chance” of this or a “decreased chance” of that, but they really don’t tell us anything concrete (or useful, for that matter) at all.
That is why I find it particularly worrisome that we are entering the age of affordable, personalized genome sequencing and do-it-yourself genetic tests. While these companies are peddling the promise of knowledge, that is not a commodity that they are actually able to deliver to consumers. Knowing that you have a gene variant that increases your chance for breast cancer, for example, does not mean that you will get breast cancer. Yet, one can easily see how such news could cause undue turmoil among members of the unscientifically-trained public. For what these kits and genome sequencings provide is but a minute glimpse behind the curtain veiling the mechanisms of gene expression. Sure, nucleotides are the “building blocks of life” and all that, but genetic sequence alone will never be capable of providing us with accurate, predictive insight regarding which medical maladies we will acquire.
For one thing, genetics aren’t everything. The “nature versus nurture” argument went by the wayside a long time ago, as it is now recognized that genetic and environmental influences coalesce to determine what occurs within our cells. Secondly, you will recall from your introductory biology classes that DNA sequence is only the first stage of gene expression. One must consider such events as RNA splicing, RNA silencing, and protein modifications (to name a few) if one hopes to attain an accurate assessment of how a gene is expressed.
Let’s also throw in the aspects of cellular context and epigenetic modifications, and you’ll soon see that any company that promises to deliver certainty (or even an accurate assessment of probabilities) regarding different medical conditions based solely on DNA sequence is simply preying upon consumers’ ignorance. In essence, they are handing consumers a single piece of a 5,000-piece puzzle, telling them that what is displayed on that one fragment is indicative of the pattern of the puzzle as a whole.
I am not the only one concerned about the less-than-honest promises of at-home genetic tests, as drugstores Walgreens and CVS both canceled their debuts of Pathway Genomics’ at-home genetic tests that were scheduled for earlier this month. This was after the Food and Drug Administration started asking for more information from Pathway Genomics about the tests. Just this week Congress got involved, as its House Energy and Commerce Committee launched its own investigation of direct-to-consumer genetic tests. So what does this mean for the future of do-it-yourself genetic testing? Will I ever be able to air-mail a swab of my saliva for my genetic read-out? Hopefully not.
The sale of a test that, by its very nature of being direct-to-consumer, can never offer “full disclosure” to the people who buy it should not be permitted. Without extensive disclaimers and interpretation from scientists or medical personnel, consumers don’t stand a chance in understanding what the test does and does not tell them about their health. I wouldn’t argue that more comprehensive genetic analysis may not be beneficial to people’s health in the future, but I think that the only appropriate place for genetic analysis is in a healthcare setting, wherein an informed professional can explain the results to the patient. It is not on a drugstore shelf. And that’s one thing about which I am certain.