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Researchers Discount a Caution In Debate Over Cloned Humans

By Sheryl Gay Stolberg, New York Times

1 March 1997: In the highly charged debate over human cloning, experts cite deformities and deaths in cloned animals as evidence that making genetic replicas of people would be dangerous. Now scientists at Duke University are challenging this idea.

The researchers found that human beings possess a genetic characteristic that prevents fetuses from growing overly large, a major problem in the cloning of sheep, cows, pigs and mice. They say this subtle genetic difference also makes people less vulnerable to cancer.

"We are protected from cancer and also it is going to be easier to clone us than a mouse or a sheep," said Dr. Randy Jirtle, a professor of radiation oncology at Duke University Medical Center who is an author of the study. He said he was not advocating cloning as a means of reproduction, adding, ''We are just presenting information.''

But leading experts in animal cloning disputed Dr. Jirtle's conclusions. They said fetal overgrowth is not the only problem they must contend with and cautioned against interpreting the Duke study to mean it would be safe to create babies by cloning.

"The authors have allowed themselves to over-interpret their interesting results," said Dr. Ian Wilmut, who as director of the Roslin Institute in Scotland led the effort to clone Dolly the sheep, the first mammal cloned from an adult.

The Duke study, published in the Aug. 15 issue of the journal Human Molecular Genetics, comes just one week after Dr. Wilmut and other scientists gathered at the National Academy of Sciences in Washington for an all-day symposium at which three researchers said they would attempt to clone humans.

Opponents of reproductive cloning worry that these researchers may rely on the Duke study to make their case. ''They have used anything, however peripheral or tangential, to advance their cause,'' said Dr. Thomas Murray, president of The Hastings Center, a bioethics institute. ''But it makes their claims that they are going to clone a healthy child no more plausible than before.''

The study traced the evolution of a particular gene that governs the suppression of tumors, and also fetal growth. Dr. Jirtle said sheep, pigs, mice and virtually all nonprimate mammals inherit only one functional copy of this gene because of a phenomenon known as imprinting. But humans, he said, inherit two working copies, making abnormalities much less likely.