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‘Sorry, but I’m not sure ‘three parent babies’ will be healthy’, says scientist

  • Christopher Exley is a British professor of bioinorganic chemistry
  • Says ‘three-parent’ technique could have disastrous consequences
  • Opposes procedure on ‘basis that it is scientific experiment, not a therapy’

Professor christopher Exley



Last week MPs voted to allow a controversial ‘three-parent’ IVF technique to prevent babies being born with mitochondrial disease. 

However, some scientists are worried that genetic tinkering in this way could have serious and unpredictable consequences. 

Here, Christopher Exley, professor of bioinorganic chemistry at the University of Keele, explains why he’s against it.

Mitochondrial replacement is a genetic experiment which could have disastrous consequences for generations. In the worst case scenario, it could create ‘monsters’.

I think the debate has become an emotional one, which the MPs have responded to, rather than about the facts. I think this is a terrible mistake.

Some scientists are worried that genetic tinkering could have serious and unpredictable consequences

Some scientists are worried that genetic tinkering could have serious and unpredictable consequences

There is no doubt that the suffering of children with mitochondrial diseases and their parents is truly heartbreaking.

The diseases, which are inherited, affect the mitochondria, which are tiny rod-like structures which make energy to power the cell. 

As a result, the mitochondria either work intermittently, or not at all, meaning that tissues or body organs cannot perform properly.

This can lead to children being born with rare and often fatal diseases such as carnitine deficiency, which prevents the body from using fats for energy.

Others may develop problems later in life, suffering muscle weakness and extreme tiredness, although the symptoms vary greatly from person to person.

With the new IVF mitochondrial procedure – which has so far only been tested on rhesus monkeys – the central part of a fertilised egg, the nucleus which contains the DNA, is put into a donor cell that’s had its own nucleus removed but has a healthy mitochondria.

But allowing scientists to go ahead with this supposedly neat solution to the problem may actually cause more distress in the long term. We simply have no idea what the risks are.

Prof. Exley says researchers are making very serious over-simplifications and assumptions

Prof. Exley says researchers are making very serious over-simplifications and assumptions

The ‘inventors’ of this therapy know very well that they cannot guarantee the outcome of their procedure, either in the very short term – for example, that the new egg will actually develop to a full-term foetus – or in the long term. 

They have no idea how any ‘new’ child, conceived in this way, might be influenced in their future health and development. Right now none of this can be known without carrying out many of these procedures and observing the consequences for decades.

The researchers are saying it is essentially fine to remove the nucleus from a fertilised egg and put it into a donor egg. (The process can also be carried out before fertilisation.)

But that is a very serious over-simplification and they are making a lot of assumptions.

What is unknown is the role played by the mother’s mitochondria in the development of a fertilised human egg. The assumption being made is that their only role is one of energy supply.

The researchers imply that mitochondria are nothing more than ‘batteries’ which you can pop in and out at will.

As lead researcher, Professor Doug Turner, of the Wellcome Trust Centre for Mitochondrial Research, has said: ‘The way people think about them are as little power stations or little batteries that produce the energy that our cells need to work.’

Our understanding of how mitochondria work  is not sufficiently advanced

Our understanding of how mitochondria work is not sufficiently advanced

I think this is misleading and has skewed the debate.

As a biologist, I know that mitochondria are far more than batteries. Mitochondria are an essential part of the whole cell.

Our understanding of how they work and influence the development of the embryo is not sufficiently advanced to know for sure.

What we do know is this. The nucleus, which carries the genetic material, the DNA, floats in a sea of fluid called cytoplasm, which contains little fragments called mitochondria.

These mitochondria metabolise nutrients in the presence of oxygen and create energy which powers the cell. Depending on where the cell is in the body, it may contain one mitochondrion or hundreds of mitochondria.

A brain cell, for example, needs a lot of energy to function properly and needs lots more mitochondria than a fat cell. Only red blood cells have no mitochondria at all.

In the process of creating energy, mitochondria create many byproducts, including chemicals called reactive oxygen species and reactive nitrogen species.

These chemicals pass through the cytoplasm and into the nucleus where they have a signalling role, telling the nucleus to do certain things, even possibly affecting the DNA that determines traits in a new baby.

We are just starting to learn more about the huge importance of mitochondria in the entire cell.

So, although we still only know the tip of the iceberg about how mitochondria influence the nucleus, it looks likely the mitochondria in your cells play a role in the development of an embryo.

Those mitochondria from the third person will be pressing all kinds of buttons on the DNA codes, just like a typist on a word processor. Depending on what keys are pressed, you get different combinations of letters, words and sentences.

Who is to say that when the nucleus is taken from the fertilised egg and placed into a foreign environment (the donor egg without its own nucleus), that this ‘cuckoo nucleus’ will develop in an identical manner in its new home?

The donor mitochondria could start interacting with the parental DNA and cause havoc.

It is wrong to assume the genetic material of the nucleus will have the overriding influence upon the subsequent development of the foetus.

It totally ignores a role for not only mitochondria in every human cell, but everything present in the original fertilised egg. It makes the assumption that the genetic material of the cuckoo nucleus will not be influenced in any way by it being in a new home.

Once this technique is allowed to go ahead, there is no going back. People born with three parents will have children themselves and the consequences may only reveal themselves decades down the line.

How many cuckoo foetuses are we prepared to abort, because they are found to be incompatible with life in the womb, to produce one cuckoo child?

How many cuckoo children are we prepared to bring into society before we can be certain that this procedure is safe and has not simply replaced one child with a terrible disease with another child or person with something which could conceivably be worse?

I strongly oppose this procedure on the basis that it is scientific experiment, not a therapy. Childless myself, and not through choice, I understand the desire to have a family of one’s own, but I am absolutely certain that it is better for a small number of people to learn to live with childlessness or adopt, than it is for this experiment to be given the go-ahead.

Interview by THEA JOURDAN


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