Mitochondrial Gene Therapy

What are mitochondria?

Mitochondria are tiny rod-like structures in cells which act as power houses, generating the energy that allows our bodies to function. Unusually, they have their own DNA, distinct from the genetic material within the cell nucleus. Mitochondrial DNA (mtDNA) makes up about 0.1% of a cell’s total DNA and does not affect individual characteristics such as appearance and personality.

About MRT technique: MRT techniques essentially swap a woman’s defective mitochondrial DNA with that of a donor. The resulting embryo’s DNA will mostly come from the two parents who supplied the egg and sperm, but a tiny proportion – a fraction of a percentage – will come from the donor.

All cells have mitochondria, which are like power packs for the cells and create the energy that keeps cells alive. While a child’s DNA is a mixture from both the mother and father, mitochondria are separate “packages of genetics” that come solely from the mother.

Some people have a mitochondrial disease — a problem with the genetics in their mitochondria — which can lead to severe, life-threatening conditions, although this is rare. One treatment for a woman who might have one of these diseases is to replace the mitochondria in her eggs via IVF. This can be done via a process like the one used in Greece where the DNA is taken out of the woman’s egg and put into a donor woman’s egg once the DNA has been stripped from it, which is then fertilized with sperm to create an embryo.



Why is it so controversial?

Some people don’t like the idea of a baby having three biological parents, and argue that mitochondrial DNA goes some way to shaping important characteristics, such as personality. But the scientific consensus is that swapping mitochondria is similar to changing a battery – it’s unlikely to have much, if any, influence over a person’s behaviour.

Others have argued that the technique is unnecessary. After all, it won’t help those who have already been born with mitochondrial diseases. Parents often don’t find out they are carriers of these diseases until they give birth to sick children. And those who do know they could pass on a disease have other options, such as using a donor egg. The technique is specifically for people who carry genes for the disease, but want to have a child genetically related to them.

Another concern is that, by creating a new mix of genetic material, embryologists are creating lasting genetic changes that will be passed down through generations, before we have a chance to find out if they are dangerous. Some argue that this starts us on a slippery slope of germ-line editing – one that could eventually lead to “designer babies”.


Is it ethical?

With this, a woman’s inalienable right to become a mother with her own genetic material became a reality. However, some experts say the technique raises ethical questions and should be banned in cases not involving disease. The risks of the technique aren’t entirely known, though may be considered acceptable if being used to treat mitochondrial disease.