Science

One Child, Three Parents?

Imagine growing up having not two, but three genetic parents – one father and two mothers. Impossible? Actually, this may soon become a reality, with new research being developed to combat mitochondrial diseases.

Mitochondria are parts of your cells that are the ‘power stations’ – they provide energy for every cell of your body, allowing your body and your organs to function. Most of your DNA – genetic inherited information from your parents that makes up much of who you are – is contained in your nucleus – the ‘control room’ of your cells. But your mitochondria also contain some DNA, which means they can be the cause of inherited diseases.

Damaged or faulty mitochondria can cause serious diseases, due to problems in your muscles, your heart or even your brain, affecting around 6,000 adults in the UK. The DNA in the nucleus of your cells is made up of a mix of genetic information from both your parents, but your mitochondria is only inherited from your mother: this is known as matrilineal inheritance. This means that any mutations a mother may have in her mitochondria she will pass onto her children. It’s also unpredictable – even if a mother has a very mild form of a mitochondrial disease, you can’t predict how severe the disease will be in her children; it may be much worse, or non-existent.

Your mitochondria also contain some DNA, which means they can be the cause of inherited diseases.

But for parents in this position, there may be answer. New techniques have been developed to allow mothers to carry a healthy child without the risk of disease, by a process known as ‘3 parent IVF’. It works by transferring the genetic information from the nucleus contained in either an egg or embryo with damaged mitochondria into a donor egg from a woman with healthy mitochondria. The embryo would be fertilised by the father’s sperm either before or after the transfer. This means the child would contain DNA from three parents: the vast majority of DNA from the mother and father, and mitochondrial DNA from the donor.

This is literally the cutting edge of science, but also of ethics: the treatment, although deemed safe, is still illegal. Although the ‘designer baby’ argument is not really an issue here, there’s still the ethics in destroying and modifying embryos. There’s also the child to consider – he or she could grow up with identity issues, and would the donor mother have any parental responsibilities or rights towards the child? Future generations would also be affected as the DNA in the mitochondria could be passed on down generation to generation, a permanent modification.

This means the child would contain DNA from three parents: the vast majority of DNA from the mother and father, and mitochondrial DNA from the donor.

In 2012, the Human Fertilisation and Embryological Authority (HFEA) ran public surveys, consultations and events to help judge what the public thought about the treatment and ethical considerations involved and they are due to release their findings this year. If they’re positive, Britain may be the first country to legalise the treatment, although it’ll be a number of years before any trials would begin.

This treatment may be triumph in clinical terms, but as with all controversial methods regarding genetic manipulation and the life of a potential human, it must go hand in hand with the social and ethical issues that will ultimately decide its fate.

Faiza Peeran

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Image: Duncan Hull via Flickr

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