Three parent babies - a genetic love triangle



Photo credit ALAMY

In February this year a law was passed in the UK that enables babies to be born with genetic material from three people. No, this isn’t some strange new technique for the more sexually experimental among us, it is in fact a pioneering new form of IVF that combats serious hereditary mitochondrial diseases being passed from a mother to her child; these disorders affect 1 in 200 people a year and currently have no cures.

Mitochondria are the site of respiration (energy conversion) and are found in almost all the cells in the body. Because of their essential role, damaged mitochondria can lead to a range of different problems, particularly in areas with a high energy demand such as the brain and muscles - these can present many different symptoms including severe muscle weakness, heart disease, neurological disorders and learning disabilities.

So how does it work?

Mitochondria have their own set of DNA which is essential for their function. This DNA is always inherited from the mother and so if there are mutations in the mother’s mitochondrial DNA, they will always be passed to her children. Depending on their severity, these mutations could cause disease.

There are two techniques of in vitro fertilisation (IVF) that have been developed to prevent this: pronuclear transfer and maternal spindle transfer. Both of these involve implanting the nucleus from the mother’s egg - which contains the majority of the genetic information - into a host mother’s egg with healthy mitochondria. This is fertilised by the father’s sperm either before or after the nuclear transfer.

Ok, I’ll admit “three parent baby” is a little misleading; in reality less than 1% of the child’s DNA would have come from the donor and that would be contained exclusively in the mitochondria. This means that it would have little to no effect on their appearance, IQ, personality or any other traits that you’d expect to inherit from a parent.

So this procedure will prevent babies being born with incurable diseases - that’s great, isn’t it?

There are ongoing debates surrounding this controversial new approach with some labelling it a defiance of nature and questioning its long term effects in these children. Some also fear it’ll open the gate to further genetic manipulation and the creation of ‘designer babies’.

However, following rigorous research, scientists have announced they have no evidence to indicate that these techniques are unsafe and - for now, at least - it appears to be a promising route for defeating these devastating diseases, that could benefit around 2500 women in the UK alone that carry these mitochondrial mutations.

With the first of these procedures being carried out as early as October this year, “three parent” babies could be born towards the middle of 2016. So will this be the future of medical genetics, or a disaster waiting to happen?

We’ll have to wait and see.

#IVF #Mitochondria #LucindaSinclair #Health

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