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Cloning carries grave risks: research
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SCIENTISTS say evidence is mounting that creating healthy animals through cloning is more difficult than they had expected, and they call on some researchers to stop thinking of cloning humans, the New York Times reported on Sunday.
The clones that have been produced, the newspaper said, often have problems severe enough -- developmental delays, heart defects, lung problems and malfunctioning immune systems -- to give pause to anyone thinking of cloning a human being.
For example, some mouse clones grow fat, sometimes enormously obese, even though they are given exactly the same amount of food as otherwise identical mice that are not the products of cloning. The fat mice seem fine until an age that would be equivalent of 30 for a person, when their weight starts to soar, said Dr Yanagimachi, a University of Hawaii researcher who first cloned these animals and has studied consequences of cloning in them.
Cloned mice also tend to have developmental abnormalities, taking longer to reach milestones like eye opening and ear twitching, Dr Yanagimachi has found.
Cow clones are often born with enlarged hearts or lungs that do not develop properly, said Dr Mark Westhusin, a cloning expert at Texas A&M University. Dolly the Sheep, the first animal cloned from an adult sheep's somatic cell, while apparently healthy, grew fat and had to be separated from the other sheep and put on a diet.
All the evidence so far, scientists say, indicates that the breathtakingly rapid reprogramming in cloning can introduce random errors into the clone's DNA, subtly altering individual genes with consequences that can halt embryo or fetal development, killing the clone. Or the gene alterations may be fatal soon after birth or lead to major medical problems later in life.
Some scientists say they shudder to think what might happen if human beings are cloned with today's techniques. "It would be reckless and irresponsible," said Dr Brigid Hogan, a professor of cell biology at Vanderbilt University Medical Centre.
Nevertheless, two fertility experts, Dr Panayiotis Zavos of the Andrology Institute, and Dr Severino Antinori, a fertility doctor in Rome, say that they want to clone a human.(Xinhua)
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