Scientists from the US Duke University Medical Centre in Durham, North Carolina, have discovered that it may be easier to clone a human than it is to clone sheep, mice or other mammals. It is thought that this is because humans possess a single genetic difference that has not been present in other animals, the lack of which has proved an obstacle to the success of animal cloning.
The researchers, who published their findings in the journal Human Molecular Genetics, say that humans and other primates each have two working copies of a gene called insulin-like growth factor II receptor (IGF2R). One copy of the gene is passed from each parent to its offspring. It is thought that other mammals, such as sheep, pigs, cows and mice, only ever receive one functioning copy of the gene because of a process called genomic imprinting.
Having two functioning copies of the IGF2R gene is thought to help prevent fetal enlargement and susceptibility to cancer and other disorders common to cloned mammalian offspring. Keith Killian, leader of the research team, said 'this is the first concrete data showing that the cloning process could be less complicated in humans than in sheep'.