Fresh Hopes and Concerns As Fetal DNA Tests Advance
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.