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Freeing us from our cells: avoiding inherited mitochondrial disease

8 October 2012
Appeared in BioNews 676

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.

Medical Frontiers: Debating Mitochondria Replacement
Human Fertilisation and Embryology Authority |  17 September 2012
21 March 2013 - by Sandy Starr 
Mitochondrial replacement therapy, where a small amount of a mother's genetic material is swapped with material from a donor during IVF to avoid passing on heritable illnesses, enjoys the 'general support' of the public, the UK's fertility regulator says...
7 January 2013 - by Dr Peter Mills 
How valuable are emerging biotechnologies? Of all the questions about the prospects of the life sciences, this is the one that UK policy makers seem most eager to answer...
3 December 2012 - by Dr Iain Brassington 
Under the law as it stands in the UK, only 'permitted' embryos may be implanted into a woman. Permitted embryos are those that have not been genetically modified, and are not formed from genetically modified gametes...
19 November 2012 - by Sandy Starr 
At the beginning of this year, the Human Fertilisation and Embryology Authority was asked to consult the public on proposed new techniques to avoid the transmission of mitochondrial disease. The resulting public consultation is being conducted in several different ways including two public events, the first of which I attended...
19 November 2012 - by Professor Mary Herbert 
The energy required for our cells to function properly is mainly produced by mitochondria. Mitochondria are tiny structures within our cells, which contain their own DNA. The mitochondrial DNA (mtDNA) encodes a small number of the many proteins required to produce energy efficiently. Mutations in mtDNA cause a broad spectrum of diseases and degenerative disorders, which can be fatal....
17 September 2012 - by Dr Sophie Pryor 
The UK's Human Fertilisation and Embryology Authority (HFEA) has launched a public consultation on the social and ethical impact of new methods that could prevent the transmission of some incurable mitochondrial diseases....
17 September 2012 - by Sarah Norcross 
Mitochondria don't normally get much press attention, they like to keep a low profile generating energy in the cells and leave nuclear DNA to grab the headlines...
25 June 2012 - by Dr Virginia Bolton 
Predictably, the publication of the Nuffield Council on Bioethics' report supporting further research into a technique to prevent inheritance of mitochondrial disease prompted a flurry of publicity. Equally predictably, nearly every newspaper - whether broadsheet or tabloid - went for the sensationalist angle and used the 'three-parent IVF' tag in their headline...
18 June 2012 - by Dr Geoff Watts 
The Nuffield Council on Bioethics has published a new report: 'Novel techniques for the prevention of mitochondrial DNA disorders: an ethical review'. Dr Geoff Watts, chair of the working party that wrote it, offers some personal reflections on a few of its key conclusions...
12 June 2012 - by Antony Starza-Allen 
The Nuffield Council on Bioethics has published a review of the ethical issues raised by proposed IVF techniques, which aim to prevent the transmission of faulty mtDNA from mother to child. The report concludes the techniques are ethically permissible, provided further research establishes their safety....
Dad Says, "No Way" ( - 09/10/2012)
Our daughter has a mitochondrial disease. However, I think this procedure is medically unsound and theologically wrong. Explanations on my blog:
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