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|