On 25 September 2012 the Progress Educational Trust held a debate on the issues surrounding new techniques to prevent the transmission of mitochondrial disease. The event was organised in partnership with City University London's science journalism course and was supported by the Wellcome Trust.
Sir Mark Walport, director of the Wellcome Trust and soon-to-be Government Chief Scientific Adviser, chaired the event. In his opening address he emphasised the importance of the topic and, referring to the ongoing HFEA public consultation on mitochondria replacement (1), said the debate 'couldn't be more timely'.
The evening began with a parents' perspective on mitochondrial disease. We heard two moving accounts of what it is like to have an affected child, first from Liz Curtis, founder and chief executive of the Lily Foundation for Research into Mitochondrial Disease and Other Metabolic Disorders. Liz spoke about her daughter, Lily, who died when she was only eight months old, describing her shock realisation that 'in this day and age', there was nothing that could be done to try and save her daughter's life. The foundation was set up, she said, so that Lily's short life would have a purpose, to fund research and to 'support other families who had been torn apart by mitochondrial diseases'.
We then heard from Alison Maguire, research executive of the Lily Foundation, whose four year old daughter also lost her battle against mitochondrial disease. She described the disorders as 'devastating' conditions that 'no-one can do anything about', recalling her experience of doctors trying many different medicines to relieve her daughter's symptoms. 'In our opinion, any techniques being developed to prevent a child inheriting a condition like this and to stop those conditions being passed to future generations can only be a good thing', she concluded.
The next presentation was given by Mary Herbert, professor of reproductive biology at Newcastle University's Institute for Ageing and Health. Professor Herbert explained the science behind the new strategies to prevent transmission of mitochondrial diseases, namely pronuclear transfer (PNT) and maternal spindle transfer (MST). We heard how her team want to increase the efficiency of the techniques and test how the resulting embryos 'compare to embryos that have not been manipulated'.
An important point raised by Professor Herbert was the way in which damaged mitochondria are passed on during reproduction. A woman with a small number of mutations can produce healthy eggs, or those in which all of the mitochondria contain mutations, so there is 'no way of predicting how a child would be affected until later in pregnancy', she warned. This could mean 'very difficult reproductive decisions for women'.
The potential social implications for families of children born using PNT or MST were discussed next. Martin Richards, emeritus professor of family research at the University of Cambridge's Centre for Family Research, predicted that parents will have to make 'very difficult' choices if the new technologies become available. Using egg donation as an example of a current reproductive method, Professor Richards said that parents would need to consider the 'disadvantages of a new technique', against a 'well-tried and tested technology' which already produces 'healthy children' and 'happy families'.
John Wyatt, emeritus professor of ethics and neonatal paediatrics at University College London, was next to address the audience. Speaking as a paediatrician with personal experience of caring for many sick babies, he described his concerns. 'What are the genuine risks for children?' he asked, reminding us that the new techniques involve germline modification and will therefore variably affect future generations. As no mother could predict the degree to which a child may be affected, he said, would we in some instances use a potentially dangerous 'therapy' for a child who would not actually have developed the disorder? 'It is only by doing long-term follow-up studies…that you're ever going to know whether…this technology is safe'.
Professor Wyatt concluded by raising the question: 'What are the limits of biotechnology?' He spoke of the human desire for our children to inherit our good genetic characteristics but not our bad ones. 'Is it appropriate for us to use technology for this process? Is this the way we want to go?', he asked.
The final panellist was Jackie Leach Scully, professor of social ethics and bioethics at Newcastle University. Highlighting some of the ethical issues surrounding the new technologies, she spoke about safety, saying: 'As with any innovative technology, we can't know at this point whether there will be unknown, undesirable effects on the children who are born through these methods'. However, some would argue that the unknown harms would 'actually have to be pretty bad to outweigh the very known harms of having a severe mitochondrial disease'.
Professor Scully also emphasised the 'manipulative', rather than 'selective', nature of the new technologies. If they were introduced, children would, for the first time, be born following 'deliberate manipulation of their DNA', a practice not currently allowed under UK law. She argued that this could be a 'slippery slope', ending with the manipulation of nuclear DNA also being permitted. While she predicted that it would be possible to distinguish legally between the two, she warned that it could be hard to tell patients and parents that 'because their condition lies in the wrong type of DNA, you can't intervene'.
The speaker presentations were followed by questions from the audience. A major theme of the discussion was whether allowing modification of mitochondrial DNA (mtDNA) would indeed set us on a slippery slope. Professor Herbert seemed optimistic that regulations would prevent this from happening, while Professor Wyatt argued that we need 'very strong reasons' to 'cross the line' into germline transmission. An interesting point was made by Professor Marcus Pembrey when he pointed out that PNT and MST do not actually involve altering the sequence of the mtDNA. We could therefore 'draw a line' by saying that DNA should not be 'cut and spliced', he suggested.
Other audience members asked how a child's identity might be influenced by their cells containing genetic material from three people. Alison Maguire felt it would not have an effect as mtDNA has no bearing on how a child 'looks, thinks, sees and feels'. As the second woman would have no parenting role, she could simply be compared to an organ donor, she said. Her comments echoed those made earlier by Professor Herbert, who had explained that it is the genes contained in the nucleus which determine all of our heritable characteristics.
Provocative press headlines such as the Daily Mail's 'Three-parent embryos' and 'GM babies' were also mentioned. While some viewed them as frustrating, others remarked that they at least stimulate discussion by bringing the topic to the public's attention.
As the panellists summed up a lively debate, the evening was described as 'fascinating and very valuable' and we were reminded that mitochondrial diseases are 'devastating conditions' that are also a 'huge burden to the NHS'.
Finally, it was put to an audience vote. A show of hands revealed those in favour of techniques to prevent transmission of mitochondrial disease greatly outnumbered those opposed to them.