Fresh Hopes and Concerns As Fetal DNA Tests Advance

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."