The UK could move a step closer to allowing IVF babies with DNA from three different people.
Techniques that give a baby DNA from a father, a mother and a woman donor to prevent inherited disorders are currently outlawed.
But the Human Fertilisation and Embryology Authority (HFEA) is due to announce what advice it plans to give the Government on the issue.
Some groups have raised ethical and safety concerns about three-people IVF.
The purpose of the procedure is to stop the transmission of defective mitochondrial DNA from mothers to their babies. Children born after the procedures would possess nuclear DNA inherited from their parents plus mitochondrial DNA from a woman donor.
Mitochondria are rod-shaped power plants in the bodies of cells that supply energy. They contain their own DNA, which is only passed down the maternal line. Faulty mitochondrial genes can lead to a wide range of serious disorders including heart malfunction, kidney and liver disease, stroke, dementia, and blindness, as well as premature death. Around 6,000 adults in the UK are believed to be affected by mitochondrial diseases.
Controversy surrounds attempts to prevent such diseases through hi-tech variations of In-Vitro Fertilisation (IVF) treatment. One technique, pronuclear transfer, involves transferring nuclear DNA out of a day-old embryonic cell containing defective mitochondria. The DNA is planted into another single-cell embryo whose mitochondria function normally.
The donor embryo's own nuclear DNA is discarded, but it still contains the normal mitochondria of the woman whose egg was fertilised to create it. As it grows, the embryo produces a baby with DNA from three sources - nuclear DNA from the original parents, plus a tiny amount of mitochondrial DNA from the woman egg donor.
Another technique, maternal spindle transfer (MST), is similar but involves transferring nuclear DNA from an unfertilised egg to a donor egg. The egg is then fertilised using the father's sperm. The issue has been the subject of a public consultation by the HFEA - the UK's fertility watchdog.
The HFEA will pass on the findings of the consultation and agree on its advice to ministers. Although such techniques are banned, they could be voted in by Parliament under existing legislation.
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