Scientists have made a major IVF breakthrough which could see a host of crippling inherited diseases banished forever.
The landmark research in the US raises the prospect of wiping out diseases caused by defective genes in the mitochondria - tiny energy-generating power plants in cells.
The scientists believe it will only be a few years before they are ready to try the technique on human patients, assuming they get the funding and ethical go-ahead.
By switching around genetic material in macaque monkey eggs, the scientists effectively swapped one set of mitochondria for another. The altered eggs were used to produce four healthy monkey infants through In-Vitro Fertilisation.
In future, the same technique could be used to rid human embryos of bad mitochondria, and the diseases they cause.
Future generations would also be spared the disorders once the fix was in place, marking a controversial step forward from conventional gene therapy.
Such research is currently banned in the UK. But the new Human Fertilisation and Embryology Act, which becomes law on October 1, could open the door to similar trials with the approval of Parliament. Further primary legislation would not be needed.
About 150 known disorders are directly caused by mitochondrial mutations, some of which cause terrible disabilities or shorten life. They include muscle-wasting mitochondrial myopathies, Leber's Hereditary Optic Neuropathy which leads to blindness, nerve illnesses similar to multiple sclerosis, and conditions that damage organs, including the heart.
Mitochondrial DNA is also believed to play a role in neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntington's, as well as cancers, diabetes and infertility.
The technique developed at the Oregon National Primate Research Centre in Beaverton, US, involved transferring chromosomes from one monkey's egg to another supplied by a donor female. The donor egg's own chromosomes were removed and discarded.
