1) Two eggs are fertilised with sperm, creating an embryo from the intended parents and another from the donors 2) The pronuclei, which contain genetic information, are removed from both embryos but only the parents’ is kept 3) A healthy embryo is created by adding the parents’ pronuclei to the donor embryo, which is finally implanted into the womb
Concerns about the safety of a pioneering therapy that would create babies with DNA from three people have been raised by researchers. The advanced form of IVF could eliminate debilitating and potentially fatal mitochondrial diseases.
Writing in the journal Science, the group warned that the mix of DNA could lead to damaging side-effects. The expert panel that reviewed the safety of the technique said the risks described would be “trivial”.
The UK is leading the world in the field of “mitochondrial replacement”. Draft regulations to allow the procedure on a case-by-case basis will be produced this year and some estimate that therapies could be offered within two years.
Mitochondria are the tiny, biological “power stations” that provide nearly every cell, which make up the body, with energy. They are passed from a mother, through the egg, to her child. But if the mother has defective mitochondria then it leaves the child starved of energy, resulting in muscle weakness, blindness and heart failure. In the most severe cases it is fatal and some families have lost multiple children to the condition. The proposed therapy aims to replace the defective mitochondria with those from a donor egg.
But mitochondria have their own DNA, albeit a tiny fraction of the total. It means a baby would have genetic information from mum, dad and a second woman’s mitochondria.
The concerns raised – by scientists at the University of Sheffield, the University of Sussex and Monash University in Australia – are about a poor match between the mitochondrial DNA and that from the parents. They said there was an interaction between the DNA in the mitochondria and the rest which is packaged in a cell’s nucleus. Their studies on fruit flies suggested that a poor match of genetic information between the nucleus and mitochondria could affect fertility, learning and behaviour.
“Describing it as like changing the batteries in a camera is too simplistic,” Dr Klaus Reinhardt from the University of Sheffield told the BBC. He added : “It is not at all our intention to be a roadblock, we think it is fantastic that for women affected there could be a cure. “We have pointed out one or two points which need to be looked at.” Via Warning of three-person IVF ‘risks’.