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Mitochondrial diseases could be cured by a simple micro-transplant.
Mitochondrial disease can be cured by a simple micro-transplant. Photograph: Ben Birchall/PA
Mitochondrial disease can be cured by a simple micro-transplant. Photograph: Ben Birchall/PA

Mitochondrial disease kills 150 children a year. A micro-transplant can cure it

This article is more than 9 years old

Parliament will debate allowing the treatment of mitochondrial diseases with micro-transplantation. It would be unethical to deny these children life

Imagine that there was a law which prevented 150 children a year suffering from a life threatening liver or kidney failure from receiving a transplant. This would be unethical. But this is precisely the current state of affairs for around 150 children every year in the UK suffering from mitochondrial disease, or mitochondrial failure.

From an ethical perspective, mitochondrial transfer is most accurately described as a form of transplantation, or “micro-organ” transplantation.

The human body is made up of microscopic building blocks called cells. There are around 100 trillion of them in the human body. There are around 200 different kinds of cells and they make up the tissues (like muscle) and organs (like heart, liver, lung).

Every cell has a two main parts: the nucleus and the cytoplasm (like the yolk and white of an egg). The nucleus contains the DNA or instructions for the cell. It determines how the cell functions and what it will be. The cytoplasm is the workshop where the instructions are carried out. It contains tiny “organelles” which do this work. One of these is the mitochondria. They provide the energy for the cell. But in mitochondrial disease, these energy packs don’t work properly. In extreme cases, infants die in the first year because no cell can work without energy.

Sadly, there is nothing that can be done for children already born with mitochondrial disease. They will suffer profound muscle weakness, dementia, learning disability, heart disease and early death. Transplantation has to occur, if it is to affect every one of the 100 trillion cells, just after conception. That is why IVF techniques need to be used.

Mitochondrial transfer is essentially the transplantation of healthy mitochondria to people with diseased mitochondria, just as we might transplant one kidney from a healthy person to a child with kidney failure. But this transplantation is at the microscopic scale: organelle transplantation.

Mitochondrial transfer essentially replaces the whole workshop of the cell at the very earliest stage of human development. The only way to do it at present is to take the egg from a healthy woman and remove its entire nuclear DNA. This leaves all the healthy organelles of that cell, including healthy mitochondria. Then the nuclear DNA, which contains all the instructions for life, is transferred from the sick woman’s egg. This combination is like a total organelle transplant. But the child will be genetically the child of the nuclear donor, except without mitochondrial disease.

All the ethically important characteristics of the child will be derived from the nuclear donor (the woman with the mitochondrial disease) – organ structure and function, personality, intellectual and emotional characteristics, appearance, etc.

Just as nothing of importance changes about a person when he receives a heart transplant, nothing of moral importance changes when a cell receives a mitochondrial transplant. These are processes which differ merely in scale.

The mitochondria carry tiny amounts of their own DNA, which follows the mother’s line but these code only for the energy metabolism of the cell. They serve no other important or morally relevant function. There are many kinds of foreign DNA in our bodies. Our cells contain DNA from viruses. There are 10 times as many bacteria (which have their own DNA) in our gut than there are cells in our bodies. It is DNA in the nucleus of our cells that has the important influence over who we are and how we develop. This is Nnot affected by mitochondrial transfer.

Mitochondrial transfer is sometimes misleadingly described as three person IVF. While IVF is necessary to transplant the organelles, this is more accurately described as transplantation. Three people are not having a child together with a mix of characteristics, any more than a person with a heart transplant becomes mixed with the donor in any important way. Solid organs like the liver or kidney also contain DNA from the donor, just as mitochondria do.

It would be absurd to say a child who receives a liver or kidney now has “three parents.” It is equally absurd to say a child who has been cured of mitochondrial disease has three parents.

Because the nucleus of the cell with the DNA instructions is not affected, this is not genetic engineering that could be used to create designer babies. If parents had two children, one who was normal and one who had had a mitochondrial transfer, you would not be able to tell which one had had the transplant. They would both be a mix of their parents’ characteristics, just as any other child is.

Importantly, by doing this transplant at the very early stage of embryo development, the disease is cured. The children of the offspring of this procedure will themselves be free of mitochondrial disease. It would be eradicated forever in this family.

There is no sound ethical basis to oppose this therapy. Opposition is based on misunderstanding, misrepresentation or personal values that should not influence public policy. It would be immoral to consign thousands to death over the next decades when we have a cost effective cure. It would be to be responsible for their deaths. The only ethical option is to legislate to support this form of transplantation. People often have difficulty with medical innovation and technology. Organ transplantation and brain death were controversial when first introduced. It is the same with mitochondrial transfer. But it is equally life saving. Transplantation has been one of the great success stories of medicine. Mitochondrial transfer is another step down that road.

There has been an extraordinarily scrupulous and exemplary seven year process of creating responsible legislation. There have been independent ethical reviews, three separate independent expert reviews of all the scientific evidence on the technique’s safety, and most importantly a widespread public consultation which has revealed broad support. Each day we delay, potentially another baby dies.

The House of Commons will debate legislation on Tuesday to allow mitochondrial diseases to be treated by micro-transplantation. It is time to pass this legislation and save 150 lives every year.

Professor Julian Savulescu is chair in Practical Ethics and director Oxford Uehiro Centre for Practical Ethics, and director for the Institute for Science and Ethics at the University of Oxford.

More on this story

More on this story

  • Mitochondria donation wins ethical approval for fertility treatments

  • Parliament should approve regulations for mitochondrial donation

  • The Church of England and the three-parent controversy

  • This isn’t about three-parent babies. It’s about saving families needless misery

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