Looking for the Telltale Gene

A new genetic test allows parents to peer into their unborn children's medical future. Are we ready for this knowledge? A Columbia study looks for answers.

by Claudia Kalb Published Spring 2013
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Photographs by Jörg Meyer

Ana Zeletz, a former pediatric nurse from South Orange, New Jersey, didn’t think twice about participating in Wapner’s study. When she was thirteen weeks pregnant, an ultrasound had revealed extra fluid behind her baby’s neck, which sometimes indicates Down syndrome. A standard chromosomal test had come back normal, which ruled out Down syndrome as an explanation. But the new microarray test found a small DNA deletion that has been linked to kidney problems, diabetes, cognitive and developmental delays, and reproductive-system malformations.

Nobody could tell Zeletz precisely how her child would be affected, or even if she would be. “It was definitely heartbreaking,” says Zeletz. “But my husband and I decided we could deal with this.”

Jillian was born in October 2010, nearly seven pounds and, by all appearances, healthy. But the parents and their doctors were on the lookout for any signs of trouble. Eventually, they found some: Jillian displayed problems walking independently in her second year. So Zeletz and her husband, Stu, enrolled her in physical therapy when she was just seventeen months old. They say the microarray-test results encouraged them to seek those services, whereas they might otherwise have shrugged off Jillian’s motor delays as an example of the natural variety that exists in the timing of child-development milestones.

“I feel like it did help,” says Zeletz. “If other issues come up, I won’t be having to say to someone, ‘No, there really is a problem; she won’t grow out of it.’ It will give me more confidence in my gut instincts, and we won’t ever be chasing the problem. We’ll always be ahead of it. That does offer peace of mind.”

A science in its infancy

Human DNA is notoriously imperfect. Everyone’s genes contain typos, and most are harmless. In the Columbia study, 88 percent of the deletions and duplications detected in the genome were known to be benign.

Now that more and more DNA flaws are being linked with diseases, a new question arises: what are the chances that a flaw will lead to its associated disease? Few DNA mistakes harm us in ways that are consistent and easily traceable, like the way an extra copy of chromosome 21 will cause Down syndrome. Consider the tangled web of genetic factors involved in autism, for example. Scientists now suspect that variations in more than two hundred genes can contribute to the disorder. A child need not have all these genes to develop autism; nor does it seem likely that the presence of any one of them can ensure that he will be afflicted. Rather, a child may develop the condition only if he is carrying one or more of these broken genes and then is exposed to certain pollutants, viral infections, or chemicals that amplify the genes’ pathogenic effects.

One day, scientists hope, we will understand how these factors interact. Then a pediatrician may be able to tell a parent, based upon a child’s unique genetic profile, which environmental risks to most carefully avoid.

Wapner clearly sees his work as contributing to this future of personalized medicine. “Microarray testing will help us get to the point where we’ll be able to alter the course of a child’s health before any illness is even apparent,” he says.

Scientists are nowhere near this point yet, however. Neurological and developmental disorders in particular are proving difficult to trace to their genetic origins. In the case of autism, for example, geneticists have so far identified only 10 to 20 percent of the total number of genes thought to be involved in the condition. None of these genes is understood well enough to base any prognoses upon.

“There are limitations to what we can predict,” says Ashley Mills, the genetic counselor. “That is true of nearly all genetic conditions. We cannot completely predict how that baby is going to develop and live.”

Few of the women who took part in the Columbia study were prepared to deal with this type of ambiguity. This is apparent from follow-up interviews that the researchers conducted with some of the seventy-nine women whose unborn children were found to be carrying potentially dangerous mutations. In the interviews, many of the women said that when they agreed to participate they had failed to appreciate how murky the results could be.

“You know, they’re telling me there’s something wrong, but they can’t tell me what,” said one woman. “We wanted to know what that would mean for our son in the future. And they really couldn’t tell us.”

Said another: “I started to get really panicky that the child that I was carrying was going to be severely autistic, with seizures and schizophrenia. I would look online, and I met with a geneticist and talked to an autism expert. And frankly, nobody could really tell me. I ended up going to a crisis counselor because it was very stressful.”

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