“[T]he revolution in using DNA to read people’s medical future is turning out to be more hype than hope,” she writes.
The latest study to “throw cold water” on the usefulness of DNA in predicting disease comes from a paper in the May 12 issue of the Journal of the American Medical Association, reports Begley. It found that adding two newly discovered “Alzheimer’s genes” (ones found to be more common to people with the disease) to Alzheimer’s traditional risk factors (such as age, gender and the existence or not of a well-established Alzheimer’s-linked gene variant, apoE) did not help predict whether someone would eventually develop the disease.
Or, as the study’s authors put it, knowledge that individuals had the new genes was not “clinically useful” (although the genes may help scientists better understand the neurobiological pathways of the disease, and thus lead to new ways to treat it).
(In fact, the study also found that omitting apoE from the risk model and using only age and gender reduced the model’s accuracy only slightly.)
“The finding that adding Alzheimer’s-risk genes to plain old age, sex and apoE status does not improve the accuracy of disease prediction seems to defy everything the public is being told about the dawn of a new era of personalized medicine, in which knowing our genomes will tip us off about what diseases we are most at risk for,” writes Begley. “Such genome-based forecasting is deemed vastly superior to such antediluvian methods as family history. And it is the basis for the explosion in consumer-based genome testing, such as that offered by 23andme, Navigenics and Pathway Genomics, whose plan to sell its saliva-swab DNA collection kits at Walgreens stores was shot down by the FDA last week.”
There are some rare applications of genomic information that have proved to be very useful, Begley adds, such as the ability of a child with leukemia to metabolize chemotherapy. But, as Boston endocrinologist and human geneticist Dr. David Altschuler told Begley, using an individual’s genome to assess disease risk is “overhyped.”
“If you ask what percentage of diagnostic tests in the history of medicine have been helpful, the answer is very few,” Altsculer said. “There is a long history of new technologies being applied broadly beyond their utility.”
“Second thoughts are clearly setting in,” writes Begley. “… Last year, geneticist Steve Jones of University College London wrote in The Daily Telegraph that despite the billions of dollars that governments, industry and foundations have poured into genomics and personalized medicine, ‘the mountain has labored and brought forth a mouse,’ one that will have little effect on how medicine is practiced, let alone predicting someone’s risk of disease.”