In the very near future, we’ll all be able to have our entire genome – all our genetic information – mapped for under $1,000. This is an astonishing scientific development. The Human Genome Project cost billions. Soon, you’ll be able to get your very own genome sequenced for the price of a laptop.
It has been suggested that this technological advance will usher in a new health-care “revolution.” It will allow us, or so it’s promised, to individualize health-care treatments and preventive strategies – an approach often called “personalized medicine.” It will allow us to become fully aware of our genetic shortcomings and the diseases for which we’re at increased genetic risk, thus providing the impetuous to adopt healthier lifestyles.
But will having your personal genome available really revolutionize your health-care world? Will you be able to use this information to significantly improve your chances of avoiding the most common chronic diseases? Not likely.
Tangible benefits will be (and have been) achieved. But, for the most part, these advances are likely to be incremental in nature – which, history tells us, is the way scientific progress usually unfolds.
Why this “we are not in a revolution” message? Overselling the benefits of personal genomics can hurt the science, by creating unrealistic expectations, and distract us from other, more effective areas of health promotion.
The relationship between our genome and disease is far more complicated than originally anticipated. Indeed, the more we learn about the human genome, the less we seem to know. For example, results from a major international initiative to explore all the elements of our genome (the ENCODE project) found that, despite decades-old conventional wisdom that much of our genome was nothing but “junk DNA,” as much as 80 per cent of our genome likely has some biological function. This work hints that things are much more convoluted than expected. So much so that one of ENCODE’s lead researchers, Yale’s Mark Gerstein, was quoted as saying that it’s “like opening a wire closet and seeing a hairball of wires.”
Given this complexity, it’s no surprise that the personal health value of genomic information, particularly in relation to common diseases, remains questionable. Beyond the comparatively rare single-gene diseases (Huntington’s, cystic fibrosis etc.) and a handful of relatively predictive cancer genes, the kind of genetic information you get from a personal genome scan simply isn’t that predictive, especially when compared with the prognostic tools we already have – such as the weigh scale, tape measure and blood pressure cuff.
Perhaps more important, there isn’t much we can do with the genetic information. While progress is being made in areas such as pharmacogenetics – tailoring drug therapies based on an individual’s genes – the advances haven’t come at revolutionary speed. For example, a study published a few months ago, described as the “largest body of pharmacogenetic data available to date,” found that, in the context of depression drugs, “none of the more than 500,000 genetic markers predicted treatment outcome.” These results are, as suggested by the study authors, pretty sobering.
What about lifestyle change? The promotion of healthier lifestyles and preventive strategies are some of the most often articulated benefits of personal genomics. But there’s little evidence that people can and will change their behaviour based on genetic risk information. A 2011 systematic review of all the available data found that the communication of genetic risk information “may have little or no effect on behaviour.” And a 2012 study found that “genomic profiling for cancer risk prediction” is unlikely to have any significant impact on health.
You don’t need to get your genome decoded to know you should exercise regularly, eat lots of fruits and vegetables and maintain a healthy weight. These are the kind of basic strategies (and the good sense to be born to wealthy and well-educated parents) that have the biggest impact. These actions don’t need to be “personalized” through a high-tech and largely uninterpretable test.
For more than two decades, we’ve been told that we’re in the midst of a genetic revolution. I’m still waiting. Meantime, if we really want to revolutionize our health, we should all put down the gene sequencers, fries and pop, pick up an apple and go for a brisk walk.
Timothy Caulfield is Canada Research Chair in Health, Law and Policy at the University of Alberta and author of The Cure for Everything: Untangling the Twisted Messages about Health, Fitness and Happiness.
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