October 20, 2004
Proposal To Make Child With Three Genetic Parents

Some British scientists have proposed the use of in vitro fertilization techniques that will create a child with 3 genetic parents where one of the parents donates only mitochondrial DNA (mtDNA).

The research application from Doug Turnbull and Mary Herbert at the University of Newcastle will be decided upon by the UK's regulatory body, the Human Fertilisation and Embryology Authority, over the next few weeks. The procedure would involve fertilising a woman's egg by in-vitro fertilisation outside the body and transplanting the fertilised nucleus to an egg from another woman which has had its nucleus removed.

The resulting baby would have mitochondrial DNA from the woman who donated the egg. The nuclear DNA would be an even split between the two original parents who provided and fertilized the first egg. Since the nucleus of humans has about 2.9 billion DNA letters and the mitochondrial DNA has only 16,569 DNA letters the amount of DNA contribution by the egg donor will be extremely small. Those 16,539 letters code for 13 genes that are involved in the mitochondrion's breaking down of sugar to produce the energy molecules NADH and ATP.

The chief value of this technique is that it would allow women who have diseases caused by harmful mitochondrial DNA mutations to have offspring that do not suffer from their mother's mutation. Also, there is evidence that mitochondrial DNA variations have an influence on life expectancy. So one can imagine future parents wanting to select mtDNA to give to one's child that would add a one or two decades to their life expectancy.

In a broader context this is one step down a much longer road where children will be born who have many genetic parents. In the future with more advanced technqiues for manipulating cells (perhaps using microfluidics) the 23 pairs of individual nuclear chromosomes that make up a single cell's DNA complement could be taken from different people to combine in the nucleus of a single embryonic cell. That cell could then develop into a full adult. Once it becomes possible to extract and insert individual chromosomes the nuclear DNA for a single embryo could be built using chromosomes taken from 46 different people.

The ability to combine chromosomes from lots of different people is one of the ways that people will create kids who combine many different most desired features into individual people. This will have the effect of speeding up human evolution because as desired features are more rapidly selected for then of course less desired features will be just as rapidly selected against.

In Western societies I expect women will be doing most of the selecting of DNA donors. In some other societies men will be doing more of the selecting. Given the differences in male and female ideals and the differences in ideals between societies it seems reasonable to expect a greater divergence in the genetically determined and influenced characteristics in people in different parts of the world. Though perhaps in some qualities there will be a convergence as, for instance, blond hair and blue eyes are popular in so many places.

My guess is that higher IQ will be universally popular. But in other cognitive characteristics I expect to see divergences between populations. For example, not all populations will place equal value on introversion versus extroversion. Similarly, I expect to see differences between societies in choices for genetic variations that influence the tendency to be faithful in marriage. Some societies will want more masculine men or feminine women than other societies.

Share |      Randall Parker, 2004 October 20 02:48 PM  Biotech Reproduction

David N. St. John said at October 21, 2004 12:29 AM:

Randall, as far as I know, this is a new development, but it is not a new idea, not by a long shot. Read Robert A. Heinlein's "Time Enough for Love", about the creation of one of Lazarus Long's "granddaughters".

Randall Parker said at October 21, 2004 2:05 AM:

David, Quite right. This is not a new idea. But it is beginning to happen in real life. On some topics I get reactions along the line that some idea I discuss is just science fiction that might happen in the distant future or might never happen. I post the reports on the beginnings of big changes because I want to get across the idea that humanity is going to change more in the 21st century than it has changed in the last ten thousand years. Lots of people are quite unaware that we are on the brink of huge changes.

Just how genetic engineering will play out is one of the great mysteries about our future. What will people choose to do to their offspring? It is an incredibly important question. What problems will happen as a result?

Garson Poole said at October 21, 2004 1:56 PM:

An earlier attempt to perform this type of procedure led to multiple miscarriages as described in this article at the BetterHumans website. Here is an excerpt: "... the technique led to three embryos that developed to the point where they had a detectable heartbeat. To protect the mother's safety, doctors eliminated one embryo after a month. One remaining fetus then died at 24 weeks and the other died at 29 weeks. It's not clear whether the technique led to the miscarriages, but Grifo and colleagues say that it did not, and that the failure was a result of complications from multiple pregnancy."

Interestingly, a mammal with three parents will not be a new creation. For example, the original mammal clone Dolly had three genetic parents. The nuclear DNA of Dolly was from the sheep that was cloned (a Finn Dorset ewe) and hence it was created from the DNA of two parents. The mitochondrial DNA was provided by a donor egg from another sheep (a Scottish Blackface ewe). That donor was the third parent. The proposed experiment of the UK researchers would create a child using a donor egg to obtain mitochondria but the child would of course not be a clone.

Anti-aging researcher Aubrey de Grey suggests an interesting and radical approach to genetic problems in mitochondria in this article. He says, "rather than fixing mitochondrial mutations, we can obviate them. We can make copies of those 13 genes (in the mitochondria), and put these (suitably modified) copies into the chromosomes in the nucleus.... Genes in our chromosomes are very, very much better protected from mutations than the mitochondrial DNA."

Another intriguing approach to creating children while trying to avoid severe genetic defects is opened up by recent results concerning reproductive stem cells. Biologists used to think that no egg stem cell source existed in adult female mammals, and that the supply of eggs was limited to those present at birth. Now, researchers believe that new egg follicles are being created well into adult life from stem cells. See this article article.
This means that genetic modifications to egg stem cells can be used to create eggs for procreation. Also, genetic modifications in sperm stem cells can be used to create sperm for procreation.

LEPORE ROSANNA said at March 7, 2005 10:01 AM:

Sono italiana,abito a Torino,sono affetta da menopausa precoce,non produco più ovociti.C'è la possibilità di concepire un figlio con una parte del mio patrimonio genetico ed il patrimonio genetico di mio marito?Si stanno eseguendo degli studi in Europa?Dove ed a chi posso rivolgermi?

10135 TORINO (Italy)

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