The United Kingdom looks set to be the first country to give the legal go-ahead for IVF treatment that would combine genetic material from three people.

The technique, known as mitochondrial transfer, would be designed to stop mothers passing on particular types of genetics-based disorders. The disorders involve faults in mitochondria, known informally as cellular power plants. They generate energy for cells and contribute towards the way cells grow and eventually die.

The IVF options are made possible because mitochondria (#9 in the picture above) is stored in the outer layer of cells, outside the nucleus. The basic principle of the proposed technique would be to create one embryo combining the egg and sperm of a mother and father, and a second embryo combining the father’s sperm and a donor’s egg. Within a day, the nucleus would be removed from both embryos, with the nucleus from the “parent” embryo placed into the “empty” egg of the “donor” embryo.

The resulting embryo (which would be implanted in the mother’s womb) would thus combine the genetic material of the parents with the donor’s healthy mitochondria.

Although several media reports have used the expression “three parent child”, doctors argue this creates an unfair impression. They stress that the child’s hereditary genetic characteristics would come entirely from the mother and father and not the donor.

The process has been tested in animals, but not in humans, so will need further testing before it can be approved. However, for the most part the objections to the technique are ethical. One issue is that, depending on how you view it, at least one of the two embryos would be intentionally created and then destroyed.

Another problem is that the changes would be passed down to future descendants of the child born as a result of the treatment. In principle that’s precisely the point and would mean removing the risk of the genetic disorder continuing to pass through the generations. However, critics argue that it’s irresponsible to take the risk of creating any new problems that would then be passed down.

The Human Fertilisation and Embryology Authority, which oversees IVF in the UK, has conducted a public consultation which found broad approval. The country’s chief medical officer had now advised the government to begin work on the regulations needed to make such treatment legal. The current plan is to publish the regulations this fall, then have politicians debate and voted upon next year.