One reason that might explain why cloned animals die so often, or are grossly over large is because the genes get disrupted when stem cells are cultured in the lab. This discovery rings new alarms about the dangers of cloning humans say researchers in the United States. " It's probably a bad idea," says Kevin Eggan, one of the tea that made the discovery at Whitehead institute for Biomedical Research at the Massachusetts Institute of Technology in Cambridge, Massachusetts.
Even when cloned animals look normal, the team found, they still harboured genetic disruptions from the cell culturing process that could pose unseen dangers. .
"Disruption of those genes in humans could cause things like mental retardation,"says Eggan. "It surely assa yet more evidence that there should be a universal moratorium against copying people;" says Ian Wilmut, the scientist who cloned Dolly the sheep at Roslin Institute.
in Edinburgh. "How can anybody take the risk of cloning a baby when the outcome is unpredictable?".
They found that a lot of the disruption occurred when the embryonic stem cells were being cultured in the lab, not because of the cloning or IVF process, this is what they found when that examined the six genes linked with embryonic development. The gene alterations were related to a phenomenon called "imprinting". Embryos gets a copy of genes from both parents mostly, and imprinting causes a gene from just one parent and not the other to be switched on. Even amongst "daughter" cells all grown in culture from the same "parent" embryonic stem cell, investigators found widely varying patterns of imprinting in four of six genes. Eggan says that there is no obvious was to alter the culturing process to prevent the disruptions: "it shows that cloners need to pay very careful attention to how they culture cells before cloning.".
No experiments have been carried out to assess whether imprinting is affected in adult cells cloning case.