It used to be said that 2 is company and 3 a crowd. Maybe not when it comes to IVF given a recent study that is certain to spark debate:

Embryos containing DNA from a man and two women have been created by scientists at Newcastle University. They say their research, published in the journal Nature, has the potential to help mothers with rare genetic disorders have healthy children.

The aim is to prevent damaged DNA in mitochondria – the “batteries” which power the cell – from being passed on by the mother.

IVF clinics are not currently permitted to carry out the procedure. Around one in 200 children is born each year with mutations in the mitochondrial DNA. In most cases this causes only mild disease, sometimes without symptoms. But around one in 6,500 children is born with mitochondrial disease, which can cause serious and often fatal conditions, including muscular weakness, blindness and heart failure.

If the Newcastle results are taken forward to medical application, they need to be applied under very strict controls, and only where serious disease is otherwise likely to result. The scientists have developed a technique which would potentially allow them to replace defective mitochondria during IVF.

The research, funded by the Muscular Dystrophy Campaign, Medical Research Council and the Wellcome Trust, used newly fertilised eggs left over from IVF treatment. The nuclei from the father’s sperm and the mother’s egg, which contain the parents’ DNA, were removed, leaving behind the faulty mitochondria. The nuclei were put into another egg from which the nucleus had been removed, but which retained its mitochondria. This new embryo contained the genes from both parents plus a tiny amount of mitochondrial DNA from the donor egg.

“What we’ve done is like changing the battery on a laptop,” said lead author Professor Doug Turnbull. “The energy supply now works properly, but none of the information on the hard drive has been changed. “A child born using this method would have correctly functioning mitochondria, but in every other respect would get all their genetic information from their father and mother.”

Expect the usual suspects to recoil at the thought of this and to roll out the parade of horribles of what would occur if the government allowed such a treatment (e.g. hybrid human-animal embryos). Hopefully we will not see the customary knee-jerk reaction to this development and cool heads will prevail in evaluating the efficacy and appropriateness of this technique.