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Designer Babies: A Match Made In Vitro

Chicago specialist creates a number of embryos, screens them for desired traits, then implants the one that best fits the criteria.

January 19, 2003|Matt Crenson | Associated Press Writer

NEW YORK — They held a news conference not long after Adam Nash was born.

It was a small affair compared to the international media extravaganza that attended December's alleged birth of the world's first cloned human.

Maybe that's because Adam's birth had nothing to do with UFO cults, virgin births or secret laboratories in unidentified countries. But unlike the allegedly cloned "Eve," Adam offers a very real glimpse into the future of human reproduction.

For one thing, Adam has actually been proven to possess the genes that he was designed with. Even more important, those genes were not merely copied from another person's, but selected to give Adam specific traits.

"Cloning is a red herring," said Princeton University biologist Lee Silver, whose 1997 book "Remaking Eden" envisions a future when parents will have the opportunity to fiddle with their children's heredity.

Silver says two powerful scientific fields are beginning to collide in a way that will profoundly change human reproduction. As reproductive technologies are developed and refined, science's knowledge of human genetics is also exploding.

The combination of genetic knowledge with reproductive technology already allows parents to select some of the genes they pass to their children. Someday it may even enable the creation of human genes, and traits, that have never existed. It is possible that our children's children's children will be engineered to live longer and be healthier, stronger and more intelligent than any generation before them.

Adam Nash's parents already had one child when he was born in August 2000. Their daughter, Molly, suffered from a rare genetic disease called Fanconi anemia. The Nashes wanted to ensure that Adam would not inherit the genetic defect that caused his sister to have a host of birth defects, including missing thumbs and hip sockets.

But they also wanted to be sure Adam would share one of Molly's genetic characteristics. Because their daughter would die without a bone-marrow transplant, the Nashes wanted their children to have the same tissue type so that Adam could serve as Molly's donor.

With the help of Dr. Yury Verlinsky, a geneticist at the Reproductive Genetics Institute in Chicago, the Nashes created several dozen embryos by in vitro fertilization and chose one with the proper genetic characteristics.

That embryo became Adam.

Verlinsky has used the same procedure to help parents carrying genes for cystic fibrosis, hemophilia and sickle cell anemia avoid having children with those diseases. He has ensured that older mothers, whose children have a markedly increased risk of being born with Down syndrome, give birth to healthy babies. Recently, he gave a 30-year-old woman with a gene for early-onset Alzheimer's disease the opportunity to bear a child who lacks the trait.

Verlinsky doesn't modify the embryos he implants. He merely creates a number of embryos by in vitro fertilization, screens them for some desired property -- usually the absence of a particular genetic defect -- then implants the one that best fits the criteria.

So far, parents have used the procedure, which is known as PGD (preimplantation genetic diagnosis) only as a means of preventing inherited diseases in their children.

Using the technology as an enhancement to make children taller or smarter is impractical, partly because PGD merely selects among genes the two prospective parents already possess. That means that Junior's height and intelligence are limited by his parents' genetics.

Furthermore, characteristics such as height and intelligence are influenced by a large number of different genes, making it unlikely that the best ones will come together in a single embryo.

Verlinsky dismisses critics who accuse him of playing God, of creating "designer babies" and of trying to fool Mother Nature.

"We don't design nothing," he said in a thick Russian accent. "That's absolutely nonsense."

But what if scientists really could simply insert whatever genes they wanted into an embryo's DNA?

In animals, they can. Scientists have been putting genes into mice for more than 20 years by injecting DNA directly into developing embryos.

"It's more powerful in that, unlike preimplantation diagnosis, you can give the embryo traits that the parents themselves don't have," said Stuart A. Newman, professor of cell biology and anatomy at New York Medical College.

The technology has been used to create cows and goats that produce valuable drugs in their milk.

Medical researchers studying Lou Gehrig's disease have inserted a gene into rats that causes them to develop the degenerative condition.

And if their creators receive approval from the federal Food and Drug Administration, salmon that are genetically modified to grow faster may soon be on sale at U.S. grocery stores.

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