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U.S. Researchers Say Humans Could be Easier to Clone than Animals
DURHAM, North Carolina, Aug 15 (News Agencies) - Humans may have a genetic advantage that makes them easier to clone than cows, sheep, pigs and mice, researchers at Duke University Medical Center said in a study published Wednesday in Human Molecular Genetics magazine.
Humans have a genetic benefit that prevents fetal overgrowth - a major obstacle encountered in cloning animals - and cancer susceptibility, the researchers said.
"This is the first concrete genetic data showing that the cloning process could be less complicated in humans than in sheep," said Keith Killian, molecular evolutionist and primary author of the study.
The genetic benefit in humans, and other primates, stems from the presence of two activated copies of a gene called "insulin-like growth factor II receptor" (IGF2R), the study said.
Human offspring receive one functional copy from each parent, while virtually all non-primate mammals receive only one functional copy of the gene.
The difference makes such animals more prone to developing cancer and suffering from cloning complications - like overly large offspring, immature lung development, enlarged hearts and reduced immunity to disease, the researchers said.
The problems in animal cloning occur "when scientists manipulate the fledgling embryos in the laboratory... While the IGF2R gene remains intact, the 'epigeneric' markings - crucial information layered on top of the gene sequence - are inadvertently damaged and alter the way the gene functions," said Randy Jirtle, professor of radiation oncology at Duke.
He compared the IGF2R gene to computer hardware that is working properly, and its epigenetic markings to computer software that is damaged or defective.
The research appears to contradict warnings given by the general scientific community against cloning human beings, in view of the current problems encountered in cloning animals.
But, researchers opposed to human cloning expressed concern that pro-cloning scientists will use the Duke study to confirm their claims that the process would not create a disfigured or disabled human being, according to a CNN online report.
One researcher, Don Wolf, who cloned two rhesus monkeys at the Oregon Regional Primate Research Center in 1999, said in the CNN article that despite the interesting theories raised by the Duke research, it should not be seen as indicating that there is no danger in cloning humans.
Several countries worldwide have called for a ban on human cloning after Italian embryologist, Severino Antinori, told an international medical conference last week in Washington that he would soon pioneer efforts to clone humans.
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