President Obama is planning a new $250 million precision medicine initiative to personalize care, calling it "one of the greatest opportunities for new medical breakthrough that we have ever seen." But experts say the excitement is outpacing the science, the New Yorker's Cynthia Graber writes.
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While genetic sequencing has been touted as the treatment of the future and can be helpful in detecting and treating ailments like cancer, birth defects, and diseases of unknown origin, experts say many physicians—especially generalists who treat a variety of conditions—are unprepared to read genetic tests and accurately communicate the results to patients.
Genetic testing errors are 'unfortunately common'
Mistakes like misreading pieces of DNA and diagnosing patients with false disorders are "unfortunately common," genetic specialists told Graber.
Graber offers the example of a physician at Boston Children's Hospital who ran a DNA test on a girl with a mysterious condition that made her prone to infections, and caused some developmental delays and poor coordination skills. The test results showed that the girl had a missing fragment of code on chromosome 22—which can be a sign of DiGeorge syndrome, a condition that shows symptoms similar to the girl's ailments. But when a second doctor examined the test results, he found that the missing part of chromosome 22 was not in the same location as the one that causes DiGeorge. Instead, the missing piece of DNA was "likely an insignificant genetic blip."
Aleksander Rajkovic, director of reproductive genetics at Magee-Women's Research Institute at the University of Pittsburgh, in a recent paper documented another misdiagnosis of DiGeorge based on a misreading of a genetic test.
Mistakes like those "can cause greater harm than merely stoking the anxieties of a sicker person or her parents," Graber writes.
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A 2012 study in The Cancer Journal details a case in which a woman underwent intensive surgery, including the removal of her uterus, because of a false diagnosis based on DNA test results. Similarly, prenatal screenings which use parts of fetal DNA found in the mother's bloodstream are not always definitive and can lead to misdiagnoses.
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According to Graber, many current practitioners attended medical school before the human genome was sequenced and therefore are unfamiliar with a variety ailments associated with certain genes. In fact, at the time when many current physicians went to medical school, there were fewer than 12 known genetic diseases. Now, a single panel could test for nearly 100 medical issues.
Mary Norton, a clinical geneticist in the field of high-risk obstetrics at the University of California-San Francisco, says "It's very complicated, especially for generalists, who have a million other things on their minds besides genetics."
A 2014 survey from Genetics in Medicine examined 38 studies on the subject and found that a majority of respondents said they do not fully understand test results and often are not able to devote adequate time to conversations with patients about testing options and outcomes.
And many physicians looking to educate themselves on the subject turn to information offered by testing companies. Rajkovic notes that genetic testing companies often have a motive for offering data on testing and could try to push their products on doctors without enough evidence of their efficacy. He says, "In this race to offer more value, they are jumping the gun in my opinion."
Helping doctors understand genetic testing
According to Graber, there are several initiatives underway to help doctors become more attuned to DNA sequencing.
Robert Green, a medical geneticist at Brigham and Women's Hospital and Harvard Medical School, launched a project called MedSeq, which recruits patients to have their genomes sequenced by physicians. Doctors are taught to read the results and are recorded discussing the results with their patients. Later, geneticists listen to the doctors' recorded interactions and correct any mistakes.
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MedSeq participant Martin Solomon says, "The data is going to be there. We have to figure out how to make [it] usable in a constructive way, and to make physicians comfortable with it."
Solomon compares genetics to other new technology that has infiltrated the medical world, such as electrocardiograms (EKGs). He says, "When the [EKG] was first developed about a hundred years ago, most physicians thought it was voodoo," adding, "Now, if you don't understand it, then you shouldn't be practicing medicine."
Meanwhile, Norton says, "over time everyone will come to have a better understanding of genetics, [but] it will probably be a bit worse before it gets better" (Graber, New Yorker, 2/5).
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