By Rob Stein
Washington Post Staff Writer
Sunday, October 26, 2008
Doctors have started using powerful new DNA tests to screen fetuses for a wider range of genetic abnormalities, spotting more problem pregnancies early but stirring fears that the results will increase abortions as well as confuse and needlessly alarm many couples.
The tests, which use "gene chips" to detect much subtler chromosomal variations than standard prenatal testing can, have also triggered complaints that they mark another step toward a society that seeks to weed out aberrations in the quest for the perfect child.
Proponents argue that the tests allow couples to harness the latest molecular technology to target the most devastating genetic syndromes, alleviating their worries in some cases and in others identifying abnormalities soon enough to terminate the pregnancy or prepare to care for an afflicted baby.
But critics say the tests have not been thoroughly validated and threaten to produce a flood of murky, misleading results that will subject emotionally vulnerable couples to unnecessary anxiety, perhaps prompting some to abort healthy pregnancies.
Some worry that the technique could be used to hunt for the rapidly growing list of genetic markers that merely signal an increased risk for cancer, diabetes, mental illness, obesity, addiction and other conditions later in life. Someday, similar tests could perhaps even vet fetuses for traits associated with beauty, personality or intelligence.
"It's a classic Pandora's box," said Leslie G. Biesecker of the federal government's National Human Genome Research Institute. "Like any powerful technology, it solves some problems while at the same time creating new ones. How you use a powerful technology decides whether it's good or bad."
The testing is being introduced at a time when there is already intense debate about wider screening for Down syndrome, which is detected by examining fetal DNA obtained through amniocentesis or chorionic villus sampling.
Called comparative genomic hybridization, the new tests use "microarrays" or gene chips to search for dozens of less common, often more severe syndromes caused by subtle deletions or additions of genetic material that standard genetic analysis misses.
"We can interrogate the fetal genome to identify smaller pieces of DNA that are either added or subtracted, and many of these can cause disease," said Ronald J. Wapner of Columbia University, who is leading a $3.3 million federally funded study that is starting to evaluate the technology in 4,000 pregnancies.
Many experts say doctors should wait for the outcome of that study and possibly others before offering the testing widely. But two labs in the study -- Baylor College of Medicine in Houston and Signature Genomic Laboratories of Spokane, Wash. -- are already publicly promoting the service, and a third at Emory University in Atlanta has quietly started doing the tests.
"I believe it's ready for prime time," said Arthur L. Beaudet, who chairs Baylor's Department of Molecular and Human Genetics. "For people who want the best possible prenatal diagnosis and want the maximum information, this is the best option."
The tests, which cost about $1,600 and are not yet covered by insurance, can detect about 150 known genetic disorders that can cause physical deformities, mental retardation and a host of health and behavioral problems, he said.
"Some of these disorders are quite burdensome. They require lifelong nursing care. In some cases these children never walk, never talk, never feed themselves," Beaudet said. "It can have a major impact on the family. People say, 'I wish you had given me the opportunity to know ahead of time. It's really destroyed our lives.' That's why women want to know."
While some couples may choose to terminate a pregnancy when they get a bad result, others may decide to have the baby, and knowing the information helps them and their doctors get ready to care for the child.
"There are things we want to detect during the pregnancy so we can anticipate the medical problems once the baby is born," said Lisa G. Shaffer, Signature's president and chief executive. "That way, once they are born, they already have a diagnosis and can get the care they need as soon as possible. That's the biggest advantage."
So far most couples requesting the tests have already had a child with a genetic abnormality, have a family history of a genetic syndrome or are trying to clarify worrisome results from standard screening such as an ultrasound or conventional genetic analysis.
"Patients and obstetricians are aware that this is available and are demanding it," said David Ledbetter, a professor of human genetics at Emory.
But some couples seek the testing because they want as much information as possible.
"The concern could be because of advanced maternal age," Shaffer said. "They might go into a doctor to have amniocentesis and say, 'Is there anything I can do to rule out any chromosomal abnormalities?' And the doctor says, 'Yeah, there's this other test.' "
Roxanna Rickel and her husband decided to get the test at Baylor last spring to minimize the possibility that their baby would be born with problems.
"My husband's reaction was, 'Why not?' " said Rickel, who had unexpectedly gotten pregnant at age 47. Their test came back clear. "It's reassuring. You know you're on a path that looks like everything is good."
While uneasy that Baylor and Signature may be creating misconceptions about how many genetic conditions they can definitively rule out, Ledbetter said the results can help guide couples. "We can tell the family quite a lot," he said.
Antiabortion activists, however, fear that the tests will lead to more abortions.
"The question is, what is the information used for?" said David Prentice of the Family Research Council. "If it's for informing the parents so they can be prepared for what might come, that's great. But if it's being used for eugenics purposes -- for abortion -- we would be against it."
Even some who support a woman's right to choose an abortion question the tests, saying they will probably pick up variations that are difficult if not impossible to interpret.
"There's a lot of variation down in the DNA that as far as anyone knows today not only doesn't cause any disease or syndrome, but doesn't have any consequence whatsoever. They are part of what make us different," Biesecker said. "The trick is, you have to distinguish whether it's going to cause any disorder. We're not there yet."
Even if the abnormalities detected are in a region of DNA clearly associated with a known syndrome, it is often unclear how severely affected the child would be. Missing DNA almost always causes a syndrome. But extra DNA in the same area may or may not, or may cause a mild version. Many of the syndromes can range from devastating to barely noticeable.
"We're opening up a huge can of worms," said Caroline Ogilvie of the Guy's and St. Thomas' NHS Foundation Trust in London. "More information is not always a good thing."
"Put yourself in the place of a woman who is carrying a baby she wants," said Jan Friedman of the University of British Columbia. "You find something that may or may not be abnormal. If it's abnormal it may be very bad, or it may be normal. She doesn't know what to do about it. If she continues a pregnancy, it may be a serious abnormality. If she terminates a pregnancy, she may be terminating a normal baby."
Baylor's Beaudet and Signature's Shaffer argue that their tests are focused on abnormalities clearly associated with usually severe syndromes, producing ambiguous results in 1 percent of cases so far.
"The great majority of the time the interpretation is clear-cut," said Beaudet, whose lab has screened more than 500 pregnancies. "In those cases where it's less clear, we give the best information we can."
The labs confirm unclear results with additional testing and provide trained genetic counselors to give detailed interpretations to parents and their doctors to make sure they understand the subtleties, they say.
Advocates for the disabled worry that doctors and insurance companies will use the results to pressure parents to terminate pregnancies at any sign of potential problems.
"We want disabled children to be welcomed into the world. My fear is we're moving in the opposite direction," said Andrew Imparato, president of the American Association of People With Disabilities. "If we decide to use prenatal testing to eliminate gene-based disabilities, that's what the Nazis were trying to do, in their own crude way. I think we're saying that certain types of lives aren't worth living."
Others fear that the tests will be expanded to search for genetic markers that simply predispose children to illnesses later in life, or will someday go further in the quest for "designer" babies, noting that prospective parents are already screening embryos so they can decide whether to have a boy or a girl.
"What if suddenly everyone decided another particular characteristic was not desirable?" asked Kevin T. FitzGerald, a Georgetown University bioethicist. "How about obesity? How about a tendency toward some form of depression? I'd say it's more than a worry. It's a reality with which we need to wrestle with now."