Breakthrough raises gene therapy hopes

The potential to alter our own genetic make-up for ever has come a step closer, after Canadian scientists produced mice with an artificial chromosome that was passed to the animals' offspring.

The potential to alter our own genetic make-up for ever has come a step closer, after Canadian scientists produced mice with an artificial chromosome that was passed to the animals' offspring.

The experiment, which currently would be illegal in humans, marks another significant step in the progress of "gene therapy", a technology intended to ease or eradicate the effects of gene-related diseases such as cystic fibrosis.The mice were bred by a team at Chromos Molecular Systems, based in British Columbia, and had an artificial chromosome - a collection of genes - inserted into their cells while they were still embryos. That chromosome was then taken up by every cell in the mice's bodies, including the sperm and eggs. When the genetically engineered mice mated with normal mice, the chromosome, carrying its new genes, was passed on.

Such "germline" gene therapy could have a big effect on humans, since the offspring of treated patients would also get such an extra chromosome. That might lead to the eradication of diseases caused by faulty genes - but it could also lead to "designer" babies. "This is obviously going to open up the debate again in the field of germline gene therapy," said Norman Nevin, who chairs the Gene Therapy Advisory Committee in Britain.