Picture of Kirsten Patrick

Kirsten Patrick is Deputy Editor at CMAJ


Yesterday, after a long public consultation by the Human Fertility and Embryology Authority and a heated debate and vote in the English House of Commons, it began to seem likely that the UK will be the first country to allow the practice of mitochondrial transfer (albeit with safeguards). If the House of Lords approves it, this will result in an amendment to the UK’s 2008 law regulating IVF, embryological manipulation and pre-implantation genetic therapies. We’re effectively seeing glimmerings of a green light for the creation of ‘three-parent babies’ in the UK.

I’ve been following this process closely. Once I understood the reason WHY mitochondrial transfer is important in the prevention of certain serious diseases of mitochondrial DNA, I felt convinced that legalising it was the right thing to do. Mitochondrial diseases are heterogeneous and it is difficult to explain easily in a few sentences their cause and manifestations (but it is supremely well-described in the video I’ve embedded below). What I am talking about here is serious mitochondrial diseases that are debilitating, result in the early demise of children who get them, and for which there is no cure. It’s a cruel fate for parents and child. If a couple has one child with severe mitochondrial disease, the decision to try for another child is an agonising one. Mitochondrial DNA is inherited from the mother. If a woman has mitochondrial disease, there is a risk that when she tries to conceive naturally the disease may be passed onto her child with varying degree of severity of outcome. Up to now the legal options have been as follows:

  • No more children
  • Adopt
  • Have IVF using donor eggs (child only genetically related to its father)
  • Create embryos using IVF, then test them to see if mitochondrial disease is present – called preimplantation genetic diagnosis or PGD – and then choose to implant only embryos with ‘healthy-looking’ mitochondria (not foolproof but results in a child genetically related to both parents)
  • Fetal prenatal diagnosis or PND (also not foolproof and creates the awful situation where parents may have to consider termination of pregnancy)

Recently scientists have developed two new methods that could help to prevent mothers from passing on mitochondrial disease to their children (and their children’s children and so on). The techniques, maternal spindle transfer (MST) and pro-nuclear transfer (PNT) are beautifully and clearly described in this video.

To me and to many others this has seemed like a no-brainer.

But it’s important to consider all sides of any issue, which is why the process of coming to a decision has taken so very long. The HFEA has my greatest respect for the way in which its review and public consultation , considering all points of view and a broad range of ethical concerns, has been undertaken. There are very real considerations around issues of changing the germline of offspring, which will perpetuate through generations. Many are understandably concerned about adapting the technologies and using them in other ways to create ‘designer babies’ (although with strict regulation of the procedure and careful legislation this is unlikely).

And now the rest of the world is watching, and many are hoping…..