Avoiding mitochondrial DNA disorders
Avoiding mitochondrial DNA disorders
by Louise Ogden, Web Editor at the British Science Association
Inherited mitochondrial disorders have been making the headlines a lot recently. The announcement at the start of this year by the Wellcome Trust that they were giving £4.4 million towards a new Wellcome Centre for Mitochondrial Research in Newcastle, was coupled with the announcement by the Secretaries of State for Health and for Business, Innovation and Skills that the Human Fertilisation and Embryology Authority (HFEA) and Sciencewise-ERC were to seek the “public views on emerging IVF techniques designed to prevent the transmission of mitochondrial disease.”
With that consultation now underway, the debate has been gathering speed, with news outlets using the oft-criticised phrasing “Three-parent babies”, to describe the techniques under scrutiny – pronuclear transfer and maternal spindle transfer.
Pronuclear transfer (PNT) involves taking the nucleus of a day old embryo made from the egg and sperm of the parents and transferring it into an embryo, created from a donor egg and the father’s sperm, which has had its nucleus removed. This embryo would then have all of the nuclear genetic material of the parents, but would only have the healthy mitochondria of the donor.
The second technique, maternal spindle transfer (MST), is very similar to PNT except that it involves transferring the spindle of chromosomes from the mother’s unfertilised egg into a donor egg that has had its spindle removed. This egg can then be fertilised by the father’s sperm to create an embryo with healthy mitochondria.
But under current law, both these techniques would be illegal. Ultimately, if one or both of these techniques were to be introduced as fertility treatments, there would need to be a change in the law, meaning this decision is not just about the ethical and social implications, it’s also about the legal ones.
Two weeks ago, Progress Educational Trust held a public debate at City University London to address some of these issues. Chaired by Sir Mark Walport, the outgoing Director of the Wellcome Trust and the incoming Government Chief Scientific Advisor, he opened the discussion by explaining the complexities of the topic and the different facets of the arguments.
It’s easy to forget that there are families who suffer every day because of the effects of inherited mitochondrial diseases. The debate last week, however, was opened by two mothers who had lost children due to inherited mitochondrial diseases, Liz Curtis and Alison Maguire, both of whom are now involved with the charity, the Lily Foundation for Research into Mitochondrial Disease and Other Metabolic Disorders.
Their stories were difficult to listen to and it was clear that both women believed that these techniques should be used as treatments in the future if proven safe and effective.
One of the issues with these techniques is identifying the women who are affected. Both Liz and Alison did not know that they had mitochondria with mutated DNA until their children were born, and in fact Liz had two older children, neither of whom had been affected. But unless a women’s mitochondrial DNA is completely sequenced, there is no way to identify any issues before their child is affected, unless of course there has been a family history of the disorders.
The debate also focussed on the possible social and identity issues of a child born using one of these techniques. Technically, the child would have the genetic material of three different people, although only a tiny fraction would come from the donor mitochondria. Professor Martin Richards from the University of Cambridge’s Centre for Family Research doesn’t believe that this would cause any identity issues in a child.
“Three parent children are hardly unique now - there are many different situations where three parents are at least socially connected to the child,” he explained, whether through egg donation, sperm donation, or surrogacy. His main concern was that the parents wouldn’t tell the children the true story of their origins, meaning they could have an “identity crisis” later in life if they were to find out unexpectedly.
He also argued that ultimately egg donation would be an effective fertility treatment for these families, although that would mean a child wouldn’t have any of the genetic material from their mother. Until long term ,generational studies are completed, Prof Richards just doesn’t think it’s worth the risk when alternatives already exist for families affected in this way.
Professor John Wyatt from UCL echoed these sentiments asking what will happen to “the children of the children of the children?” He questioned whether the UK could be affected by “reproductive tourism” if it were one of a few countries that offered the treatment to women. This could lead to strains on the health service, issues with immigration and potentially issues with international politics.
Ethically speaking, Prof Wyatt was also concerned that because not all children are badly affected by mitochondrial DNA mutations, and some aren’t affected at all, that the treatment could end up being used when no intervention was needed.
“We all want our kids to inherit our good bits and not our bad bits,” he said. “But is technology the right way to go about this?”
Professor Jackie Leach Scully from Newcastle University raised the point that if the treatment was offered on the NHS, how easy would it be to tell parents that have children affected by nuclear DNA mutations that they can’t be helped for any other children they have, because they “fall on the wrong side on the line”?
This has been an argument in the media as well as at the debate last week. Who’s to say that if the law was changed and mitochondrial replacement was introduced as a legitimate fertility treatment, that that won’t lead to a future debate about nuclear DNA mutations being treated, ushering us on to the “slippery slope” of increasingly invasive genetic intervention?
The HFEA and Sciencewise consultation will run until the end of this year, and it will form a basis for what parliament ultimately decides to do about mitochondrial replacement techniques. Clearly the science and technology will improve, especially now that the new research centre has been confirmed, but just because we have the scientific ability to do something does not necessarily mean we have the social or ethical right to do so. It’s only with the public’s input, the full scientific facts and the experiences of those affected by the disorders, that that decision can be made.
To have your say on mitochondrial replacement techniques, visit the HFEA website to find out more about the upcoming public debates or to fill in the online questionnaire. The consultation closes on 7 December.
Sciencewise-ERC is the UK’s national centre for public dialogue in policy making involving science and technology issues. The British Science Association is working in partnership with Sciencewise acting as the public face and engaging the public in emerging science issues.