Scientists have successfully transplanted human chromosomes into mice, a first that promises to transform medical research into the genetic causes of disease. The mice were genetically engineered to carry a copy of human chromosome 21, a string of about 250 genes. About one in a thousand people are born with an extra copy of the chromosome, a genetic hiccup that causes Down's syndrome.and,
Genetic studies of the mice will help scientists to nail down which genes give rise to medical conditions which are prevalent among people with Down's syndrome, such as impaired brain development, heart defects, behavioural abnormalities, Alzheimer's disease and leukaemia.
Medical researchers yesterday hailed the work as a "tour de force", but critics accused the team of pushing the boundaries of genetic manipulation too far and blurring the distinction of what was biologically human.
But according to David King, of the pressure group Human Genetics Alert, the potential breakthrough comes at too high a cost. "Creating organisms with whole chromosomes from another species is genetic engineering taken to another level....but...
"Before, researchers have said they're not making big changes because they're only inserting the odd gene into animals. If you're talking about creating something with a whole human chromosome in it, you have to ask is this really a mouse any more? Is it starting to be a new species, a hybrid between a mouse and a human? If more chromosomes are put in, are we going to have to start giving these things pseudo human rights?"
Dr Tybulewicz added: "There's nothing more obviously humanlike about these mice than any others. If you were to see them, you'd not be able to tell they are different to a normal one."
But perhaps this notion of animal mixed with man isn't that far fetched after all. Like I always say, there's never anything new under the sun: