Babies made using three people's DNA are born free of mitochondrial disease
91 comments
·July 16, 2025MrDrDr
gus_massa
It's inheritable so it's more than a liver transplant.
I agree that DNA in mitochondria is much smaller than DNA in the nucleus. But in each person there are many mitochondria and they nay have slightly different DNA. And the DNA in mitochondria has a different variation than the DNA in the nucleus. So it's difficult to weight both.
Can we say 2.1 parents? A long time ago I read that most binary classifications are not completely binaries, it's just that 2 options cover almost all the cases. (Are virus alive?) I guess integer classifications also have hidden corner cases.
I also remember from a biology book that in a lab they mixed two blastula(?) of small lizards(?) or something like that. They had different skin color and the baby had patches of both colors. Does that count as 2 or 4 parents?
tialaramex
Certainly Mother Nature is not obliged to have simple easy to understand binaries where it would be convenient for us and so if we think we see such a binary we should keep in mind that maybe we hallucinated it into existence because it was convenient and that's all.
throwaway106382
Who has to pay child support?
w10-1
So mother and father contribute the nucleus, and donor egg has everything else-- which is a lot more than mitochondria.
DNA required by mitochondria are both in the mitochondria and in the nucleus. This seems to show there is no co-evolution of the two; or the genetic distance of the donor might matter.
Still TBD whether other problems arise. If they do, I wonder if the affected person has any ability to get medical records of the other subjects, to compare diagnoses or treatments, notwithstanding privacy protections.
throwawaymaths
> DNA required by mitochondria
DNA that codes for proteins that are required by the mitochondria...
The DNA in the nucleus itself does not make its way to the mitochondria.
> This seems to show there is no co-evolution of the two
There is plenty of co-evolution between the two. But the idea that the genetic distance between donors doesn't matter is pretty substantiated by the fact that people of two races can have children.
le-mark
Clever. So they fertilize an egg from the mother and another egg from a donor with the fathers sperm. Then they yank out the donor/father “pro nuclei” and replace it with the pro nuclei from mother/father egg. Thus the child ends up with the donor’s mitochondria.
SoftTalker
This will run into objections from those who believe that life begins at conception. I can imagine this procedure being illegal in many jurisdictions.
svieira
I am pretty sure most people would not be all right with organ donation a la The Island. The fact that the person is vulnerable and invisible doesn't make it better.
sigmoid10
This procedure is already banned in the US, despite the fact that it was pioneered in New York.
mcintyre1994
I heard from the news in the UK that it’s currently only allowed in the UK and one other country, which I think might have been Australia.
khazhoux
Which is strange because I spoke with God last week and he told me he is ok with this procedure.
JLemay
This is such an incredible breakthrough and a huge win for science and families alike, however its sad that despite decades of work there is still no cure for mitochondrial disease. But the chance to preventing it being passed on is still such a major improvement. Also it’s sad that only the uk is capable of doing this atm bc it was the first country in the world to introduce laws to allow their creation after a vote in Parliament in 2015, while other countries were debating that it would open the doors to genetically-modified "designer" babies
FL33TW00D
The UK leads in this space as a previous PM had his newborn die of a genetic disease.
Amazing the domino effect.
FerretFred
It is an incredible breakthrough and if it prevents disease then all well and good, but are our Administrative Systems set up to handle such an arrangement?
maxerickson
Sure. The mitochondrial donor can be treated as a source of tissue and you are all done.
im3w1l
Cells can exchange mitochondria so in theory it might be possible to flood the body with healthy mitochondria and get them to slowly take over.
yorwba
I would expect that to activate the immune system. "the unique components of mitochondria, when exposed, reveal their prokaryotic history and are recognized as foreign by innate immune receptors triggering an inflammatory response." https://pmc.ncbi.nlm.nih.gov/articles/PMC6218307/
Maybe if you suppress the immune system, introduce working mitochondria, and then stop taking the immunosuppressants, any mitochondria that are still outside cells get cleaned up and the ones that got absorbed are shielded and can do their job.
inglor_cz
Maybe we can find some way to deliver mitochondria right into the cells.
dr_dshiv
Mitochondrial health is definitely going to be a big theme in the coming years.
foxyv
In vivo zygote mitochonrial transplantation. Neat! This is going to add an interesting exception to matrilineal DNA testing in the future.
Another thought, what about three parent households engaging in IVF? Will this be an option to have 3 biological parents regardless of disease? How will we keep records properly? What are the legal consequences? Do mitochondrial parents need to pay child support?
perilunar
The amount of mitochondrial DNA is tiny though (~0.1%, according to the article), and not particularly unique to any individual, since it is passed down lately unchanged apart from the occasional mutation. There's no point having 3 biological parents unless there's a bad mutation in the mother's mitochondrial DNA.
null
thaumasiotes
> In vivo zygote mitochonrial transplantation. Neat!
Absolutely not. This is in vitro:
>> The eggs from both the mother and the donor are fertilised in the lab with the dad's sperm.
In vivo would make no sense.
Out_of_Characte
>In vivo would make no sense.
It would certainly be one of the more stranger ways to explain the birds and the bees
null
999900000999
Wouldn't it be significantly easier to just use the donor's egg here ?
Or adopt?
This feels a bit narcissistic. If you and your partner determine you have genetic traits you'd rather not have, you have the option of not having biological children.
This just feels like it's going to open Pandora's box. You and your partner are short and near sighted, edit in some height and vision.
You're partner has ethnic traits they don't want to pass on ? Just edit those out.
This feels like something that's going to start well intentioned, but snowball into very strange outcomes.
God forbid this ever comes to America's profit driven health system. The rich would have the option to edit in "better" traits. Gattica here we come
daedrdev
Humanity has discarded natural selection thanks to modern medicine. Gene mutations that would have meant someone didn't survive now can be treated.
The cold truth is that it is thus inevitable that in the future humanity will need gene modification to avoid the spreading of harmful mutations. This is what they are doing here, especially since mitochondrial DNA is inherited directly from the mother means that any problems will be propagated to all future generation unlike normal genes.
attemptone
>Humanity has discarded natural selection thanks to modern medicine. Gene mutations that would have meant someone didn't survive now can be treated.
There is still selection going on and it is difficult to argue that it is not natural. The pressures we are exposed to are just not consistent with some idealized natural state and thus seem "unnatural".
Be careful, "natural selection" is a specific descriptor that describes a selection process that is contrasted by "artificial selection". The second one comes up from time to time in human context; we call it "eugenics".
wizzwizz4
It's not really a "cold" truth: eugenics isn't inherently bad, it's just us humans have an annoying cultural problem where we do horrible horrible things (including, but not limited to, genocide) whenever anyone tries to attempt eugenics. (It might be "human nature" preventing us from ever doing eugenics ethically, but all the evil eugenicists have a shared cultural background, so it's hard to tell.)
From this perspective, techniques that are technically eugenics, but can't feasibly be used in evil ways, are unambiguous progress. I'm wary of gene editing, but the technique described in the article doesn't seem like a slippery slope to me.
daedrdev
I just think people are going to heavily disagree what is moral and immoral eugenics. Like there was an article here recently about how there was drama with gene editing to remove blindness in one's children in the blind community
martin-t
There is no _we_.
There are people who have a deep emotional need to control other people's lives and use all available tools to do that.
There are also people who don't have that need at all and would very much like to use the same tools to improve themselves or their children.
These are two separate groups but "we" are limiting the second group's access to tools in order to prevent the first group from misusing it.
In fact, some people tabooize the tools and intentionally attack even the second group for using them because they either afraid of the first group or, more often, because they are not even aware there are different types of people with different motivations and driving needs.
HPsquared
Mate selection is, consciously or otherwise, based on these considerations already.
laurent_du
Why is any of that a bad thing?
mpalmer
This feels like something that's going to start well intentioned, but snowball into very strange outcomes.
gedy
I doubt problems would be unique to America, many parts Asia are more aggressive with selective births and distorting sex ratios already, I suspect this will be readily embraced and with the much larger populations will be more an impact.
HPsquared
I think Fisher's Principle will assert itself in those cases where the balance is disturbed currently. People will see how "excess males" don't have as good outcomes as "scarce females".
morkalork
It's definitely not unique to America, in fact America is in some ways only catching up to other countries. What is considered legal and ethical in say Mexico or Brazil if you have money is a lot looser than in the USA. IVF clinics happily advertise that they let you do sex selection.
inglor_cz
"near sighted, edit in some vision"
And? I suspect that when the first glasses were made, someone complained about people playing God, too: why do you want to correct your eyesight when you were not intended to see well by the Almighty?
Correction of genetic problems early on seems a lot better than various complicated treatments down the line.
"Strange" often means just "we are not used to it", but the next generations will take such things for absolutely granted.
It is no less strange that I, a Central European, am talking to an American in almost real time and free of charge, and can read his replies. That would be indeed very strange to anyone prior to 1995 or so.
And yeah, this connectedness has downsides as well, but we may work on them.
999900000999
What's a genetic "problem" ?
In some Asian countries modifying your eyes to look white is a common practice. You could easily end up with biracial people editing out some of their more ethnic features for the next generation.
Not to mention their might be some mistakes along the way. You can't git reset --hard a human.
As imperfect as humans are, that's what makes us human.
Now if as a consenting adult you want to modify yourself, laser eye surgery, etc, go ahead.
inglor_cz
What about leaving this to the parents? Does the rest of the society (in practice: busibodies who have enough time to care) have a standing to stop them? Why should anyone worship their ethnic features? That strikes me as extra dystopian.
Obviously there are degrees to what is considered a problem.
Few people would argue for leaving Huntington's or ALS-related code in. That is just cruel.
There are deaf activists who protest any attempts to cure deafness, but I would say most people won't agree with them either.
Eye color may not be a problem per se, but does not strike me as particularly important either - unless the state is based on some neo-racist ideology, it probably should not regulate this.
IMHO the real zone of shadows begins at outright enhancements, especially those that will have downsides. Maybe a certain gene sequence taken from bats or whales will confer high resistance to cancer, but at the cost of XXX or YYY. This is the sort of decision that will be really hard.
mrweasel
> Or adopt?
Adopt who? There is almost no children available for adoption, only highly handicapped children who needs an auxiliary family.
Might be easier with a donor egg, but where are you going to get that? Egg donation is highly regulated and many would find it hard to get a donor. Of course this solution also requires a donor egg, so you'd already need to have that available.
stephendause
> There is almost no children available for adoption
This is not true, at least in the United States. For one thing, there are many children in foster care who want to be adopted. It is also possible, though difficult and expensive, to adopt infants from mothers giving up their children for adoption as well. I am not saying it's an easy option or that everyone should do it, but it is an option.
kenjackson
In the US would this be considered abortion by pro-life activists?
blargthorwars
I'm prolife. Perhaps. You're destroying one human in this process.
Some of us are a bit more comfortable with IVF-like processes because the intent is to foster human life rather than take it, just as it's acceptable to cause an abortion in the process of saving a mother.
N1ckFG
Afaik it's a misconception that MRT necessarily involves the destruction of an embryo. The spindle transfer method transplants the mother's egg's DNA into the donor's egg before fertilization, so only one embryo is ever created. The UK trials exclusively used the older pronuclear transfer method, where two embryos are created and the donor's is destroyed, because the journey to full regulatory approval took about a decade and embryos are currently safer to freeze and thaw than eggs. In a hypothetical scenario where MRT became as widely available as IVF, this would not need to be the case for new patients.
perching_aix
> You're destroying one human in this process.
How so? They're removing the pro-nuclei before they fuse (which is when a new human, specifically their first sovereign cell and their DNA, would be formed). So even if you consider life to start at conception, this is precisely just before that still, so there's no human being destroyed here - unless I misunderstand the biology going on (or the article is not correct).
hylaride
> Some of us are a bit more comfortable with IVF-like processes because the intent is to foster human life rather than take it, just as it's acceptable to cause an abortion in the process of saving a mother.
But that (fostering human life) is also not a settled debate if the laws in some states are any indication. But debate is hard in jurisdictions where minority opinion can hold sway (like in Florida where a referendum hit 57% for enshrining a right to abortion).
While I'm resolutely pro-choice and don't consider a fertilized cell to be "human", (before I continue I want to be clear, I 100% support these types of procedures in the article) there is eventually going to be a grey area where debate needs to happen before we hit Gattaca-style dystopian editing.
PS This is not meant to argue against your view per se, which I disagree with but respect. I mean to illustrate how very quickly this gets messy and rational debate flies out the window. But that's the same with anything political in today's climate... :-/
sneak
Being anti-abortion (what you call pro-life) doesn’t also automatically mean that you share the belief that human life and the associated rights thereof begin at the instant of fertilization.
It seems you mean to imply that you are against the destruction of a fertilized viable embryo, but then the rest of your message seems to suggest that it isn’t that important.
karel-3d
There is a gamut of what is pro-life, pro-lifers themselves don't agree with each other on IVF.
(the same as with pro-choicers and third trimester abortions for example)
bpodgursky
Only the extreme fringe is willing to go to bat against IVF. Maybe 10%.
basisword
I think it's higher than that. The Catholic Church is against IVF. Although not all its followers will stick to all its teachings a significant number will.
olddustytrail
It's not dogma, it's just advice. And I think the vast majority of people would just ignore it.
Frankly, advice on having children from celibate men doesn't need special consideration from women.
I say this as someone who was at least raised Catholic and still has an affection for the faith.
msgodel
Where I came from (rural and very conservative) everyone is 100% against IVF and frankly, religion aside, I'm not sure it's good. There are certainly ways to abuse it and there's a certain kind of person it's popular with.
bpodgursky
I don't believe you.
Where did you come from?
nkrisc
> there's a certain kind of person it's popular with.
People who have trouble naturally conceiving a child?
hndevnufties
[dead]
hndevnufties
[flagged]
I think it would be better to describe this as an ‘organelle’ transplant as it would be easier for people to understand and discuss. Yes there is a donor (egg) and yes the new child will pass on the mitochondria to her children. But calling it a 3 person baby is unhelpful and misleading as IMO mitochondria DNA is of a different category to chromosomal DNA.