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The sequencing of a person's DNA is now a routine task. This reality has left doctors looking for ways to put technology to work.
Ten years ago, a renowned federal scientist said, "Whether you like it or not, full sequencing of newborns is not far off." Dr. Francis Collins, who made this statement, has been leading the National Institutes of Health for a decade. But his prophecy did not come true for both scientific and practical reasons.
Scientists have discovered that, until now, complete genetic reading would be a poor substitute for the traditional blood test that babies get at birth to screen for diseases.
Even when genetic tests provide useful information, they can also raise troubling questions.
One of the main concerns with genetic testing of newborns is how families will receive the results and make sense of them.
Christine Kim, a graduate student studying international health, volunteered for a study at the University of North Carolina at Chapel Hill to explore this issue.
"I think it's your first [child]you want to be as prepared as possible, even if there is no way to actually prepare for that experience, "she said.
After the birth of her baby, the infant has pbaded the standard blood test to screen for rare genetic disorders. The baby also received a cotton swab on the cheek so that the researchers could sequence all his genes. (This test is called exome sequencing, which decodes about 2% of a person 's DNA, the part containing the genes but not, for example, the code that governs it. gene expression.)
The blood test and the gene badysis gave the baby an irreproachable state of health. But the next question was more delicate: Should Kim and her husband know which genes might affect their child later in life?
"On the possibility that they have identified something, would we need to put it in his medical record?" Kim wondered. "What does this mean for future health insurance?"
It is currently illegal to base health insurance coverage on genetic information, but Kim and her husband are worried about efforts to weaken these protections. Life insurance and long-term care can also be at risk.
They thought about the ethics of penetration into another person's genes. "Should we have access to this information?" she wondered. On the other hand, learning their baby's genes would also tell them something about theirs. "It may be selfish, but I was also very curious about it," she said.
And this information has turned out to be revealing. Kim said the couple's baby was wearing a genetic variant that put her at high risk of illness in adulthood. For reasons of confidentiality, she did not want to be more specific. And Kim learned that if the baby had this variant, she had it too. This made her more vigilant about her own health.
"I gave this information to my family and it was suggested that my sisters and my mother also get tested," she said.
This was not the goal of neonatal genetic screening, but it is certainly a consequence. And that plays into the discussion about the opportunity to do routine sequencing of newborn DNA.
Cynthia Powell from UNC participated in the study, whose results were published in June The pediatric journal. She concluded that parents should have the opportunity to make informed choices about the number of pieces of information to be received – only the basics about their newborn or anything that could be realized in the years to come. (Parents have not learned the existence of genetic variants that are difficult to act on, such as those that increase the risk of developing Alzheimer's disease.)
"We found that most people who were given the choice, about 70% of people, wanted information on all categories offered," Powell said. This proportion may be high because the research team recruited people who were curious at first, but it is clear that this information is in demand.
However, the study by Powell and others show that, despite their high technicality, genetic tests are far worse than conventional heel tests for detecting metabolic disorders such as phenylketonuria. These conditions are the main reason why newborns undergo a blood test at birth.
Simple and inexpensive blood tests detect the actual biochemical defect which is a sure sign of these metabolic disorders.
In many cases of genetic testing, it is not as easy to identify the underlying genetic flaw. A disorder can be caused by several genetic variants, and these variants may belong to different genes. Many have not been cataloged yet.
Scientists have discovered an even deeper problem. Simply having one of these problematic variants is not necessarily enough to determine if a child is actually developing a metabolic disease.
It turns out that other variants can sometimes come into play in a way that scientists have not yet understood. "This really opens up a new Pandora's box," said Dr. Jennifer Puck of the University of California at San Francisco.
So, DNA testing will not replace standard tests without a lot of research.
Nevertheless, there are reasons to consider the DNA test as a routine supplement.
"There are no other tests for which we do not have a screening test," Powell said. "Conditions that may predispose a child to cancer or other potentially treatable neurological conditions."
Powell and Puck spoke at a meeting organized by the NIH in late June to examine the prospects for newborn genetic testing.
Dr. Robert Green, from Brigham Hospital and Women's Hospital in Boston, expressed the following opinion: "If sequencing reveals health risks at any point in life, and if it's good, it's best to do it early. "
Why wait to find potentially useful information, he asked his colleagues.
One of the reasons not to participate in genetic testing at birth is that, unlike blood tests, these genetic tests may be fraught with concerns about privacy and personal preferences, as Kim discovered. .
And Puck said it would be a mistake to bring all these thorny issues to the neonatal screening programs that are now so widely adopted that parents are not even asked about them.
"The newborn screening programs we have are enjoying great public trust," she told the NIH meeting. "And we must preserve that trust."
Additional DNA testing would also be discriminatory, she said, as they are not covered by public health insurance for the poor.
"We can no longer follow everyone," she said, "and I do not think it's okay that only the rich people are being followed up and that the rest of our population is left behind. "
Scientists at the meeting agreed that there may be good reasons to sequence genes if a child was sick and doctors did not know why. It's the story that Patricia Bbad, of Greensboro, California, told me about her son, Aiden.
"During the first eight weeks of his life, he did not gain weight properly and we continued to see a doctor," she said. "And finally, my husband and I kept looking in his eyes, and we noticed white opacity, we knew it would probably be a cataract."
This condition required emergency eye surgery. Aiden also had other problems, including hearing loss and low muscle tone. At the age of 2, he seemed to have a rare disease.
"So we did see it by a geneticist locally, and they found nothing," she said.
The Bbades learned about genetic testing at Chapel Hill and enrolled.
Aiden's test revealed that he was suffering from a serious genetic disease called Lowe's Syndrome, which could have a potentially devastating effect on everything from kidneys to intellect.
It is not known why his previous genetic test failed the diagnosis.
The diagnosis was bad news, but at least they had an answer.
"You cry a life that you thought was something different from what it is," Bbad said. "So it was very difficult, very difficult."
As a result of the diagnosis, she added new specialists to the list of Aiden's doctors. But more importantly for the family, the diagnosis has changed its vision.
"I decided to say that it happened for we instead of at we, "she said. And that powerful word really changed my life. Because I think of it as if I were blessed and that I had the opportunity to love a soul so special, that changed so many people that it was has encountered such a positivity. "
Aiden lives her life with so much joy, she says.
"I think I'm worried more," Bbad said. "Now, I live just in the moment every day."
This revelation is far from the aspiration of genetic testing to transform child care, but it is a step in that direction.
You can contact NPR Scientific Correspondent Richard Harris at [email protected].
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