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Open letter to UK Parliament: avoid historic mistake on rushing human genetic modification

24 November 2014
By Dr Paul Knoepfler
Associate Professor at UC Davis School of Medicine
Appeared in BioNews 781

Dear UK Parliament and Science and Technology Committee,

I am writing to you about your deliberations on 'mitochondrial donation' (also known as three-parent technology) intended for the purpose of preventing heritable mitochondrial disorders. I am concerned about the Department of Health's recent draft regulations that would allow three-parent experiments to go forward and the possibility that the UK Parliament may vote to allow it.

This experimental technology has a noble goal, but in my opinion there are too many unanswered questions and risks that remain to allow it to proceed at this time. In fact, I believe that moving forward with it would most likely be a tragic mistake for the UK.

Who am I and why do I oppose this technology?

I am a stem cell and developmental biology researcher who is an Associate Professor at UC Davis School of Medicine. Here I speak for myself and not my institution. I have no personal or professional stake in whether this three-parent technology proceeds or not. In fact, if anything my publicly opposing this technology poses possible downsides to me because some colleagues in my field are strong advocates of the technology. My lab conducts embryonic and induced pluripotent stem cell research in addition to our cancer studies and I'm a supporter of IVF as a means for infertile couples to have children. Therefore, I am not some kind of radical extremist or luddite, but rather a concerned scientist with what I feel are rather logical, common sense concerns about mitochondrial transfer technology and the heritable human genetic modification that it always would produce.

While a recent FDA hearing by an advisory committee here in the US took what I view as an appropriately cautious approach to three-parent technology, I am concerned that the UK may soon approve this technology without first seeing evidence that the potential risks and problems have been addressed successfully in concrete ways. I would respectfully ask, 'what's the rush?'

The FDA hearing articulated numerous unresolved concerns and the FDA Committee Chair, Dr Evan Snyder, concluded: 'I think there was a sense of the committee that at this particular point in time, there was probably not enough data either in animals or in vitro to conclusively move on to human trials.'

Of course the UK could take a different path than the US and the rest of the world. And it is certainly attractive to be an innovator in the biomedical field. But is it really in the interests of the UK to go out on this particularly high-risk limb all alone? Have the problematic issues raised at the US FDA hearing including by concerned scientists been addressed by the UK or elsewhere? The evidence strongly indicates the answer to these questions is 'no'. The UK and the specific leaders making this decision, should they rush forward on this, could well find themselves on the wrong side of history on this one, with horrible consequences.

What are the concerns?

There are numerous serious risks associated with this technology. These include most notably the possibility that developmentally disabled or deceased babies will be produced. As an objective scientist, I believe the odds of this happening are at least equal to the chance that this technology will succeed in preventing mitochondrial disorders. In fact, there are precedents that would suggest that negative outcomes are reasonably likely.

In the 1990s, fertility clinics in the US, China, and elsewhere performed human reproductive procedures similar to what is being proposed now [1-5]. While the goal in those experiments was to simply create babies for infertile couples and not specifically to deal with mitochondrial disorders, the technologies employed are largely alike. In fact, these 1990s procedures were far simpler and less invasive (they only involved transfer of some oocyte cytoplasm) than what is being proposed now with mitochondrial therapies where an entire nucleus or set of chromatin is moved from one cell to another, where an entire nucleus has also been removed.

The end result from these human reproductive experiments in the 1990s was a mixture of outcomes including not only seemingly healthy children (thank goodness), but also miscarriages, a child with severe developmental disability, and chromosomal aberrations. These are very real, concerning possible outcomes for the proposed human mitochondrial transfer technology today and in the future should it be allowed to proceed.

Animal studies have yielded variable outcomes including some concerning results. Although today's mitochondrial transfer technology may be relatively improved, there is no clear evidence that these kinds of potential negative outcomes in humans could most often be avoided with new technology.

Scientists around the world have identified several more specific risky elements to the proposed experiments including, but not limited to:

  • epigenetic harm caused by nuclear transfer, etc. (as I myself discussed)
  • mito-nuclear mismatch (Reinhardt, et al.)
  • impact of mitochondria on traits i.e. not just metabolic function (Dowling, also New Scientist here and here)
  • preferential replication of even tiny amounts of carryover mutated mtDNA (Burgstaller, et al.)

What are the alternatives? Preimplantation genetic diagnosis (PGD) is a powerful technology that can help many (although admittedly not all) families dealing with this situation in an effective manner.

Proponents of three-parent technology have adopted several, nonscientific, non-medically-based tactics to attempt to minimise concerns about it such as those I articulated above.

For example, the proponents claim incorrectly that 'mitochondrial donation' is not human genetic modification. It is in fact genetic modification. Notably, the first team to ever make this kind of technology work unambiguously stated in their paper that it was genetic modification: 'This report is the first case of human germline genetic modification resulting in normal healthy children.'

The proponents of three-parent technology also incorrectly claim that the concerns about it or risks associated with it are just hypothetical, although in reality the concerns based on past experiences discussed earlier are quite concrete and real.

Proponents also might be overly optimistic about the chances that the technology will frequently prevent mitochondrial disorders in humans.

A scientific reality often passed over in this discussion is that while mitochondria have been studied for decades, the field of studying the mitochondrial genome is in its infancy and is far too new to support a major human intervention that involves the mitochondrial genome. The interactions between the mitochondrial genome and the nuclear genome are also only poorly understood today. It would be rash and premature to proceed with human mitochondrial transfer now given how primitive our knowledge is in this area at this time.

Even if hypothetically this technology might help avoid some people from having mitochondrial disorders (and that's a big if), the bottom line is that there is an equal or arguably greater chance that it will tragically produce very ill or deceased babies.

Overall, the UK would most likely be making an historic mistake by allowing three-parent technology to proceed in the near future. Please wait on this critical decision for the additional information needed to make wise choice in the long run.


Paul Knoepfler, Ph.D.

This letter was first published on the Knoepfler Lab Stem Cell Blog:


1) Babies Born in Experiments Have Genes From 3 People
New York Times |  5 May 2001
2) The girl with three biological parents
BBC News |  1 September 2014
3) Reproductive medicine: The power of three
Nature News |  21 May 2014
4) Human fertility experiment prompts wrath
Nature News |  14 October 2003
5) Pregnancy derived from human nuclear transfer
Fertility and Sterility |  1 September 2003
27 April 2015 - by Ayala Ochert 
Chinese scientists report the first-ever genetic modification of human embryos using the CRISPR/Cas9 gene-editing technique, confirming rumours that these highly controversial experiments were underway...
16 February 2015 - by Professor Frances Flinter 
Over the last 30 years I have met some remarkable families, from whom I have learned about the rewards and challenges of caring for relatives with incurable genetic conditions....
16 February 2015 - by Philippa Taylor 
In a recent Progress Educational Trust debate, 'Mitochondrial Donation: Is It Safe? Is It Ethical?', I spoke about the ethical issues raised by techniques to avoid the passing on of inherited mitochondrial disorders...
2 February 2015 - by Rebecca Carr 
A group of researchers, including five Nobel laureates, has urged the UK's Parliament to legislate for mitochondrial donation...
2 February 2015 - by Dr Iain Brassington 
It seems to have happened very quickly: it was only in 2012 that the public consultation process about allowing mitochondrial donation to be used on humans was underway; and now – if you'll allow the pun – the first child to have benefitted from them could be conceivable in the next few months...
29 September 2014 - by Professor Frances Flinter 
Robust debate about the pros and cons of mitochondrial donation is essential, but the clinical reality of mitochondrial disorders is stark. Couples who have lost a child affected by a serious maternally-inherited mitochondrial disorder may have limited reproductive options...
15 September 2014 - by Geoff Brindle 
It is every parent's nightmare to lose a son or daughter, whatever age they may be; particularly when it is to an illness or disease for which there is no treatment or cure...
4 August 2014 - by Siobhan Chan 
The UK Government has been accused of deliberately misleading the public in order to win approval over its plans to implement mitochondrial replacement techniques in IVF...
28 July 2014 - by Dr Rachel Montgomery 
The UK Government has announced that regulations around the use of mitochondrial replacement techniques will be presented to Parliament in the next few months...
Mitichondrial transplants ( - 24/11/2014)
What we do know with certainty is that if we don't act babies will definitely suffer and die or live unnecessarily damaged lives. These are transplants of organelles not parentage and nothing to do with core genetic identity. Fear of the risk of bad consequences is not evidence nor is it reason to apathetically fail to attempt to cure otherwise certain disease or disability.  People should be identified by their potential to achieve & enjoy life and not stereotyped and constrained by their possession of curable illness. Counsels of cowardly mystical despair don't save lives.
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