Mitochondrial Replacement Hype Goes Nuclear Including by Wellcome Trust

A new paper from a UK team yesterday showed that mitochondrial replacement therapy faces a serious and difficult safety hurdle fitting with similar findings from an earlier recent study from a different team led by Dieter Egli, but the UK media and some scientists there are engaging in hype, claiming the exact opposite.

They are pushing the unscientific meme that mitochondrial replacement, also known by other terms such as 3-person IVF, has now been shown to be safe and will produce safe pregnancies. It’s a powerful example of science communication and politics gone awry.

Unfortunately the news gets worse as the wonderful UK research organization the Wellcome Trust seems to have a leading role in pushing the hype. They are promoting the misleading notion that 3-person IVF is now shown to be safe in their piece on the research (emphasis mine):

“Wellcome researchers have found that a new IVF-based technique to reduce the risk of mothers passing on mitochondrial disease to their children is likely to lead to normal pregnancies.

The idea that the new data support the expectation of normal 3-person IVF pregnancies turns reality on its head as it assumes safety and efficacy that are not supported by the actual data, which again instead point to safety problems. They are also pushing this incorrect notion about safety on Twitter too.

There’s nothing wrong with a bit of optimism in science, but this goes way too far and has spread into much of the UK media reporting on this story, which are also ignoring the Egli lab paper (for Dr. Egli’s view on this situation skip toward the end of my article). For instance, the main BBC report on the new paper used this unfortunate title:

“Three-person babies IVF technique ‘safe’”

In the text of the BBC piece it goes on to say: “The use of an IVF technique involving DNA from three people to create a baby has moved a step closer with a study that shows it is safe.”

Yes, the researchers showed a bit of an improvement in the technique in the new paper, but the data pointed overall to remaining serious safety issues that must be resolved and are not easy to address.

BBC hype mito replacement

Another “gem” from Fergus Walsh’s BBC piece went further (emphasis mine):

“The study in Nature found the technique will lead to normal pregnancies.”

It will? For sure? But again the data say the opposite.

Also doesn’t this last bit I highlighted sound a lot like the Wellcome Trust’s words? What happened to objective media reporting on science? It feels like Wellcome Trust is in charge here and the UK media are following along blindly.

For instance, a piece from Ian Sample over at The Guardian keeps to the party line as well. It too has a version of the same old meme when it writes, “the procedure was likely to produce normal pregnancies”.

What is going on here?

In the new research paper from a team led by Mary Herbert who works at the Wellcome Trust the data they report highlight the problem of carryover and/or amplification of diseased mitochondria during the process of creating a new embryo from two different women and a man via 3-person IVF. In addition to the UK media not mentioning the Egli paper, Herbert’s team also did not mention it either in their manuscript.

I asked Dr. Egli today for his view on where things stand with this technology and on the media situation in the UK, and he wrote back to me this way:

“We find ourselves on the same side of this issue.
though I support the use of this technology, I think more work is needed.
We emphasize the fact that there is one key difference to human reproduction: it is the fact that current MR techniques can lead to unstable mixtures of different mitochondrial genotypes. The uniparental inheritance of mitochondria becomes bi-parental, which does not normally occur in natural reproduction. So we do not know the consequences and behavior of such mixtures. I think it must be avoided for the technique to be reliable and safe. And I think it needs to be shown experimentally that heteroplasmy can reliable be avoided before clinical application of the technique. An unintended clinical result would be a huge setback for the field, and I think it’s better to figure these things out in cell culture than in a human being.
I do not see a problem with the genetic recombination between nuclear and mitochondrial alleles, something that is inherent to reproduction and compatibility is continuously selected for. It’s really the data that we saw that convinced me there is reason for caution when mixtures at even very low levels are induced. It was not a result that we were looking for, but we thought it deserves attention and we put quite an effort into what could easily have been dismissed. Interestingly, the British group confirms that exact finding in their paper. Regulators will not miss that fact even if the media may not all cover the full complexity of the topic.”


I have great respect for Dr. Egli and he is an expert on this area of science. His sober and balanced words carry major scientific weight for global policy considerations on 3-person IVF. By contrast, hype is harmful to both science and patients because it sows false hope and breaks trust.

Why do I care about this if I’m not a researcher directly working on it? It’s important that science be reported accurately. Also, frankly I’m concerned that children produced using this technique could be seriously or even fatally harmed by the method itself if someone pulls the trigger prematurely.

To be clear, I could support mitochondrial replacement in the future as I have no particular objection to it in principle. If the technique can be further refined in coming years and there are additional data that more conclusively indicate a solid expectation of safety and efficacy, I will probably come on board as a supporter because mitochondrial disease is an extremely serious even if rare health issue.

But the reality is that the science isn’t there today so let’s not pretend otherwise.

4 thoughts on “Mitochondrial Replacement Hype Goes Nuclear Including by Wellcome Trust”

  1. Hi Marcel,
    I’m not sure why they are pushing so hard except that maybe they feel they have to justify their abundant funding and live up to their past words that set up high expectations. It’s a risky path for not only those doing the hype, but also puts patients and families at risk.

  2. @Philip, I really appreciate your feedback and your perspective on this situation. My sense is that overstating how the translational science is going, as we saw in the last 24 or so hours from some quarters, helps no one in the long run.

  3. Hello Dr Knoepfler, great insight as always.

    Do you think the article(s) like yesterday’s fail to elucidate on the risks involved around the carryover of diseased mitochondria? Information portrayed by media just seem to completely ignore the conclusions on these papers. I think it’s funny how they even dare to use the word “likely”. As if “likely” was descriptive enough to assure safety on the manipulation of humans. Why do you think technology for rare diseases through non-validated procedures is being pushed so hard? It just seems weird.

  4. Well-stated, Paul. As a patient advocacy organization focused on mitochondrial disorders it is important we (UMDF) provide our community a balanced message that informs and manages expectations. Our position is that the technique should only be made clinically available as an option when shown to be safe and efficacious (with proper regulatory oversight). The recent Egli paper clearly demonstrates the need for further pre-clinical research. Philip Yeske, UMDF

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