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Three-parent babies: scientific breakthrough or ethical breach?

ByCharlotte Gower

Feb 17, 2015

The UK is now set to become the only country in the world to legally create babies using the DNA from three different people. Last Tuesday, MPs in the House of Commons voted to amend the Human Fertilisation and Embryology Act of 2008 in order to legalise mitochondrial DNA transfer, enabling babies to be created from one father, one mother and one female egg donor. Once approved by the House of Lords, this new technique could be put into practice in 2016. It will allow women who are known carriers of defective mitochondrial DNA to be able to successfully conceive and give birth without passing on the defective mitochondrial genes to the next generation. This heralds a remarkable development in the management of genetically based diseases and has the potential to eradicate this particular defect from future populations, although it cannot prevent new mutations arising. However, this technique has been labelled by its critics as the ‘three-parent baby’ technique, and deemed an unsafe project that crosses an ethical line, since it will alter DNA in genes for multiple generations.

Mitochondrial DNA is different from chromosomal DNA. Mitochondria are organelles present in most eukaryotic cells and they have their own circular DNA. The 37 genes of mitochondria programme the energy and calcium uptake, store and release function of the mitochondria. Our cells depend heavily upon these ‘power cells’

In humans, each cell normally contains twenty-three pairs of chromosomes, meaning that we have forty-six. Twenty-three of these are inherited from the male sperm and twenty-three from the female egg. We get our inherited characteristics from chromosomal DNA, such as skin, hair and eye colour. Both sperm and egg have mitochondria. However upon fertilisation, only the mitochondria of the egg remain intact, thus we only inherit maternal mitochondria. Therefore, without this treatment, women carrying defective mitochondrial DNA will continue to pass it on down the female line for generations.

According to the United Mitochondrial Disease Foundation, “while exact numbers of children and adults suffering from mitochondrial disease are hard to determine because so many people who suffer from mitochondrial disease are frequently misdiagnosed, we now know the disease is approaching the frequency of childhood cancers”. This month, research suggested that around 2,500 women in Britain are at risk of transmitting defective mitochondrial DNA to their newborn babies.

If the Lords pass the Act, it will be legally possible to replace the mother’s own defective mitochondrial DNA with healthy mitochondrial DNA from a female donor. If successful, the newborn child would then inherit chromosomal DNA, from the mother and father as well receiving mitochondrial DNA from the female egg donor. Some critics are therefore worried about the potential for this procedure to lead the way into ‘designer babies’.

However, many argue that this change in legislation will have a profoundly progressive impact in combating mitochondrial carried diseases and furthering genetic science in general. On Monday, Lord Winston, the creator of IVF, described the technique as “no more sinister than blood transfusion”. He said that less than 0.001 per cent of the resulting child’s DNA would have been replaced in the process, and justified the development by arguing that: “We are not altering a child’s characteristics, nor enhancing humans in any way. The scientists are merely trying to ensure that a crippling and sometimes fatal disease is prevented and that future generations will not suffer this horrific sadness.”

Another argument against the development, which was voiced on Tuesday, is that it would provide the foundation for an increasing culture of ‘genetic modification’ not just for plants and animals, but humans too. David King, campaigner on behalf of the group Human Genetics Alert, said: “Once you cross the ethical line, it is very hard not to take the next step of designer babies.” However, as noted above, mitochondria have their own DNA, which does not affect characteristics such as appearance. David Cameron defended this saying: “We’re not playing god here, we’re just making sure that two parents who want a healthy baby can have one.”

As with developments in reproductive medicine, there are some stern opponents to this idea. Most prominently, the Church of England has condemned the idea as unethical and “irresponsible”. Sir Tony Baldry, who speaks on behalf of the Church of England, opined “without a clearer picture of the role that mitochondria play in the transfer of hereditary characteristics, the Church does not feel it would be responsible to change the law at this time”. Fiona Bruce, MP for Congleton, echoed this sentiment by claiming that allowing this legislation to pass would mean that there was “no going back for society”.

Most medical experts appear to be in favour, of the development. However, Dr Ted Morrow, from the University of Sussex, is not yet convinced, saying: “I have some concerns about the safety of the procedure. I’m really not happy that the reviews have been as exemplary as other people think they are.”

Despite this contestation, Tuesday proved to be an unprecedented step forward for medicine, and for all the families affected by mitochondrial carried diseases, it was a day of jubilation.

The vote in the Commons was passed with 382 MPs in favour and 128 against.


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