UK Scientists Create a Three-Parent Embryo

Troll-Under-D'Bridge writes "The BBC reports that British scientists have manufactured embryos containing genetic material from a man and two women. Under the procedure developed by scientists from Newcastle University, the nuclei from a father's sperm and a mother's egg are transferred into a second woman's egg 'from which the nucleus had been removed, but which retained its mitochondria.' The research, which may 'help mothers with rare genetic disorders have healthy children,' used embryos left over from in-vitro fertilization treatment."

Three parents? Not really.

[zero_out]

The definition of biological parentage (as opposed to adopted parentage) has always been genetic. Just because the egg cell came from a third party does not make her a parent. She supplied no DNA. I'm sure that one day scientists will mix and match DNA from three human beings, but that is not what this article is about.

Re:Three parents? Not really.

[Anonymous Coward]

RTFA They're getting the mitochondrial DNA from the host egg.

Re:Three parents? Not really.

[PurpleCarrot]

Not so. Mitochondrial DNA is not contained in the nucleus, but is rather contained in the hosting cell. In a normal fertilization, this is always the mother's mitochondiral DNA, but in this case, it is the egg donor's DNA. Any mitochondrial problems the donor might have had could be expressed by the child even if the two nuclear DNA parents don't have any such issues.

Re:Three parents? Not really.

[jnaujok]

The egg donor provides mitochondrial DNA, which is not unimportant to the future health of the child. Many diseases are related to mitochondrial DNA problems.

Re:Three parents? Not really.

[joocemann]

She did contribute DNA, its Mitochondrial DNA (MtDNA). Mitochondrial DNA is unique from the rest of the genome and is not in the nucleus. It is found in the mitochondria.

All MtDNA in humans is transmitted from the mother because it is her mitochondria in the egg that will propagate into each cell as cells divide in development.

So she has contributed genes.

MtDNA from egg donor.
Maternal chromosomal DNA is from the nuclear DNA donor.
Paternal chromosomal DNA is from the sperm.

Re:Three parents? Not really.

[Anonymous Coward]

Thats incorrect, as the mitochondria do contain genetic material of their own. This may be use in situations where the 'mother' has mtDNA deffects such as Kearns-Sayre Syndrome, Leber's hereditary optic neuropathy, or Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode MELAS. So yes their would be two different females genetic material and one males, in the embryo.

Re:Not what you think

[vell0cet]

Depends on what you mean by "characteristics." At the very base level, it contributes to every other cell in the offspring's body (as the mitochondria themselves are replicated during a separate mitosis stage within the "host" cell).

At another level, the mitochondria set the rate at which the cell creates energy which directly affects the ability of the cell to regenerate, reproduce and function which can itself cause differences in gene expression.

Re:Unconscionablereligious prohibition

[Anonymous Coward]

The grief suffered by a couple with infertility diseases is as great of that of someone dying of a terminal illness.

I find your trying to equate the two is disgusting. It makes you easier to ignore as a flipping idiot. In the future, try to reject the same kind of heavy handed rhetoric you're condemning others of using.

Re:Three parents? Not really.

[sznupi]

Mitochondrial DNA is also child's DNA...

And since it greatly affects methabolism, it's one of the most important traits of an organism. Certainly can affect one of the traits you list, height.

Re:Three parents? Not really.

[Culture20]

can you imagine two identical twins where one was fat and the other skinny?

Yes I know a pair. Both are attractive, but one is single and jogs, the other is married, doesn't exercise, and eats a lot. It's not all in the genes.

Re:Not what you think

[smellsofbikes]

Not only that, but since the mitochondrial DNA only codes for a small amount of the respiration chain -- cytochrome C oxidase, ATP synthase, and some of the core proteins of the NADH reductase complex, in most eukaryotic cells -- while the nuclear DNA codes for much of the rest of the proteins in the respiration chain, you need to have an excellent match between proteins that come from two different chunks of DNA. There's no guarantee that'll happen, and there's evidence that one of the reasons cloning has such a poor success rate and so many cloned animals die young of strange damage, is precisely because of poor matching between mitochondrial and nuclear dna products, leading to oxidative damage throughout the cell and early cell death because of leakage from the poorly-functioning respiration chain.

Re:Three parents? Not really.

[element-o.p.]

It happens. Look up "epigenetics." Time Magazine had an article on the subject in January ("Why your DNA is not your destiny", or something like that), and there was a Discovery Channel program on the subject I saw a year or two ago. IIRC from the DC program, there is a breed of hamster or guinea pig or something that has a disorder that causes certain individuals to not metabolize food correctly. These individuals are always hungry, always eating and consequently much larger than average. Genetically identical twins do not always display the same trait, however. What researchers found is that DNA alone does not determine your characteristics. Without the presence of certain chemical receptors in the body, your DNA sequences can't be activated -- the DNA mode code for specific proteins to be produced, but if your body doesn't have the right chemical factories to build those proteins, they *won't* be produced (that's the really dumbed-down executive summary because IANA molecular biologist and it's been a while since I saw the program).

Okay, people are neither hamsters nor guinea pigs, but similar things happen in homo sapiens, too. Again, IIRC from the DC program mentioned above, researches found a genetic sequence that is always present in autism. However, not everyone who has the DNA sequence has autism. However, everyone that they tested who has the DNA sequence and a certain sequence of chemical receptors for that DNA sequence does, and no one they tested who has the DNA sequence for autism but a different chemical receptor sequence displayed symptoms of autism. Interesting stuff...