Could prenatal DNA testing open Pandora's box?

NEW YORK (AP) — Imagine being pregnant and taking a simple blood test that lays bare the DNA of your fetus. And suppose that DNA could reveal not only medical conditions like Down syndrome, but also things like eye color and height. And the risk for developing depression or Alzheimer's disease. And the chances of being gay.

So far that's still science fiction. But scientists have been taking some baby steps in that direction. And some ethics experts say it's time to start talking now about what that could mean for parents and society.

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This is the second story in a two-part series on fetal DNA testing and the ethical issues raised by it.

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Scanning fetal DNA from a blood test will be "without question a major medical advance that promises to greatly improve current prenatal care," says Jaime King, an associate professor at the UC Hastings College of Law in San Francisco who studies genetic testing. But bringing it into practice "raises significant practical, legal, ethical and social challenges," she says.

"This really changes the experience of what it will be like to be pregnant and have a child," said Marcy Darnovsky of the Center for Genetics and Society in Berkeley, Calif. "I keep coming up with the word, game-changer."

She wonders if parents would withhold their commitment to a pregnancy until test results show a fetus is "good enough" to be born. And what, she asks, is good enough?

She and others worry about how well couples will be able to understand this flood of information, and just what should be revealed.

The issues have been discussed before. The DNA of a fetus has long been recoverable through medical procedures, with a small risk of miscarriage. But a blood test would be free of that risk, which should make many more women interested in it and doctors willing to test for a wider range of conditions, some experts say. And the results could come early enough to allow for an abortion before the pregnancy is even obvious.

The trigger for the new round of discussion is a couple of papers published last December. In preliminary results, two research teams showed that they could essentially reconstruct a baby's genetic makeup by recovering fragments of fetal DNA from the mother's bloodstream. That ability, plus the rapidly falling cost of analyzing DNA, would open the door to inspecting individual genes.

That would go well beyond the more accurate prenatal blood test for Down syndrome that some companies hope to market within a year.

The story behind genetics of Down syndrome

One in 1,000 American children with Down syndrome born genetic disease, although it is estimated that 90% of mothers who decide to get an early diagnosis of abortion. There are many mistakes of people with Down syndrome, parents make a rash decision to frighten. Most adults with Down syndrome marry live independently, have jobs and are now living more than fifty.

There are many ways to be genetic data damage of Down syndrome or rearranged. For example, inhas Trisomy 21, a parent has two chromosomes, chromosome 21, instead of one, what the child on both chromosomes from one parent and one received from the other parent, a total of three. The child with Down syndrome then 47 chromosomes instead of 46th This occurs in 90% of all cases of Down syndrome.

With Mosaic disorder syndrome, chromosome 21 in cell replication, in which two, three normal chromosomes damaged in some cells. People with this disorder are someCells with 46 chromosomes and some cells with 47 and whose symptoms may be less stringent.

This occurs in 2% of all cases of Down syndrome. The last type of Down syndrome is called translocation and occurs when a normal chromosome breaks in two and attaches to another chromosome. This occurs in 3-4% of the patients down.

Before pregnancy, parents with a genetic counselor to determine their risk of transmission of genetic code with Down syndrome. Sometimes run into problemsFamily, if more than a person's condition. In other cases, mothers over 35 years may have an increased risk for Down's syndrome children and in rare cases, environmental factors play a role.

Some studies show that smoking Down's syndrome, as they can on contraceptives cause the syndrome, although it is discussed in some circles. Once pregnant, a woman for ultrasound to undergo blood tests or go non-invasive amniocentesis for a more accurateEvaluation.

The severity of Down syndrome varies from person to person. There is not much of Down syndrome research in genetic differences between trisomy 21, translocation syndrome and Mosaic, at this time. However, suggests a 1991 report that children with the syndrome of Mosaic had an average IQ of 12 points more than the typical child with Down syndrome.

But some children with Down syndrome tend to be higher rated, which emphasizes the uniqueness of each child.

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Essentials Of Human Genetics Fifth Edition

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