Q&A with the Wellcome Trust on using IVF techniques to prevent mitochondrial disease

The Wellcome Trust invited your questions about the ethics of using a new IVF technique to prevent children inheriting incurable genetic conditions. 

Doug TurnbullThe new IVF technique, if approved, could stop children from inheriting severe diseases by replacing faulty DNA with genetic material from a donor. It's an amazing scientific breakthrough but also a controversial one - there have already been headlines about so-called 'three-parent babies'.

The new technique has been developed specifically to prevent mitochondrial disease, an umbrella term for a number of severe medical disorders caused by genetic mutations in mitochondria (the 'batteries' that power every cell in the body). These disorders include muscular dystrophy, ataxia - and Leigh's disease.

Scientists at Newcastle University are developing the new technique. It uses IVF technology to transfer genetic material between the mother's egg and a donor egg, to ensure the child won't develop the disease. Only a tiny proportion of the child's DNA - less than 1% - will come from the donor. But some people argue that it shouldn't be permitted because a child born this way would have 'three parents'.

Susan GolombokProfessor Doug Turnbull is developing the new IVF technique at Newcastle and Professor Susan Golombok, of Cambridge University, is an expert on the impact on families of using techniques such as IVF, and the Wellcome Trust invited them to answer Mumsnetters' questions.

Q. DuelingFanjo: I had IVF and was a bit scared about assisted hatching, but I had it and my son was born. In my opinion, the technique described in this Q&A will only be used very rarely and only as part of IVF for people who want to have a baby but can't.

I am interested in what Susan Golombok has to say on the 'impact on families of using techniques such as IVF' - in my experience the IVF can be quite hard but the overall outcome, if a live birth, is worth it. I imagine those objecting to this kind of treatment have never suffered from infertility or an inability to carry a child to full term.

A. Susan Golombok: When IVF first became possible, people expressed concerns about the potentially negative impact on families. It was thought that parents may be over-protective of their IVF children as a result of the years of infertility and the treatment that often preceded the birth of their IVF child. It was also suggested that parents may set themselves unattainably high standards of parenting and that they may expect too much of their long-awaited child.

In fact, these concerns turned out to be unfounded. Although some IVF mothers are more anxious about their babies than other mothers, by the time their children become toddlers they tend to have more positive relationships with their children than mothers of naturally conceived children.

When followed up to adolescence, IVF parents continue to have good relationships with their children characterised by high levels of warmth and affection accompanied by appropriate levels of discipline and control. With hindsight, it is not very surprising that IVF parents are highly committed to, and involved with, their much-wanted children.

Q. Asmywhimsytakesme: I would worry about unforeseen consequences. How do they know this is safe longer term? These babies would be the only humans ever to have DNA from three different people and we don't know the genetic consequences of that.

A. Doug Turnbull: This is an important question. There is an element of not knowing the risk in all new treatments. This was also true when IVF was originally introduced, for example, but we all know how important IVF is for infertile couples.

We are currently carrying out experiments looking very carefully at risk. Other groups have already shown that this technique is safe when used in animals. It has not affected the animals in any way and this is also true of the many generations born from these animals. The technique would only be allowed if a committee of experts felt it was sufficiently safe to go ahead.

Even then, this technique would only be used for families where there is a high risk of having offspring severely affected by mitochondrial diseases. Thus the risks without the technique are almost 100% of severe disease and any concern about the future risk has to be balanced against these.

Q. Asmywhimsytakesme:What happens when the children have children? Will their children inherit the original diseases or not?

A. Doug Turnbull: If the technique is successful, it should mean that the children of the offspring would also not have the disease. It is also important to remember any boys born using this technique would not transmit to their children anyway - the disease is passed down from mother to child.

Q. Trills: We already have the ability to screen for diseases before implanting embryos. We now have the ability to change the genetic makeup of the eggs/embryos. How can we realistically go about drawing the lines between:

  • Diseases/features/issues where this should be legal and free on the NHS
  • Diseases/features/issues where this should be legal but not free, and
  • Diseases/features/issues where this should not be permitted at all?

I'm not asking for your opinion on where the lines should be, I'm asking how we can go about making the decisions in a sensible and pragmatic manner.

A. Doug Turnbull: I believe that in the UK this is very carefully considered both by Parliament and the regulators. If we think about the technique currently being considered, there has been a very open debate about the issues in terms of benefits and concerns. The UK Government has commissioned a public consultation and all members of the public are then allowed to express a view. This will then be debated in Parliament.

The very openness of the debate allows society to make decisions and along the sort of lines you raise. This sort of debate is not possible in most countries where there is either a complete ban or no regulation at all.

"Mitochondria present in sperm are actively degraded in the egg after fertilisation. Any technique of taking mitochondria from other tissues will have major concerns about safety and are also likely to be rejected by the egg."

Q. Bedhogs: If the mitochondrial DNA only comes from the female parent, is there any way to extract it from the male parent (sperm, stem cells etc) so the embryo retains just two parents, or does it have to come from a donor egg?

A. Doug Turnbull: Unfortunately, this is not possible - mitochondria present in sperm are actively degraded in the egg after fertilisation. Any technique of taking mitochondria from other tissues will have major concerns about safety and are also likely to be rejected by the egg.

Q. DowagersHump: I would have no issue with this. If I was to have any more children, I would have IVF and the embryos screened for cystic fibrosis before implantation. Given the choice between passing on a life-limiting illness to my children or not, I'd choose the latter every time.

I would like to understand a bit more about the process and how it was developed.

A. Doug Turnbull: The technique was developed specifically because of the problems we see in so many families who carry these mutations and the major dilemmas and heartbreaks they suffer.

The techniques were originally developed using eggs from animals - using two different strains of mice. It was shown to be effective and several generations of mice were born after the technique with no adverse consequences. More recently our own group has used abnormally fertilised human eggs to show that the technique can also be applied to human eggs. We're now testing the research in normally-fertilised eggs.

I'd recommend taking a look at the Wellcome Trust video, which nicely explains how - and why - we do this research.

Q. MrsDen: I have no issues with this in principle, how can it be a bad thing to prevent such terrible diseases? The three-parent argument makes no sense to me. How close are we to offering this to couples? Is it still some way off? Are there any problems with compatibility between the donor mitochondria DNA and the other DNA? What research has there been into any long term effects.

Q. FundusCrispyPancake: DNA in the cell has come from a healthy donor, so there is no reason to think there will a problem with it. The third parent argument is crap. What about children conceived using egg/sperm donors? Are adoptive parents or step-parents not 'real' parents because their DNA isn't present?

"I agree about the three-parent argument - an adopted child, for example, will have four parents and a child born after egg or sperm donation will have three parents if we use this analogy."

A. Doug Turnbull: I agree about the three-parent argument - an adopted child, for example, will have four parents and a child born after egg or sperm donation will have three parents if we use this analogy.

Before this can be offered to couples we need to do some more research to find out if the technique is safe as we can make it. For this we are using normally fertilised human eggs and the supply of these is dependent upon women donating their eggs for research. Therefore we believe the technique will not be available for probably a couple of years, but this does depend on how the research progresses.

The incompatibility issue is an interesting question. It is important to remember that in an individual all the mitochondrial DNA comes from the mother - thus the mitochondrial DNA is always different from the father's genes. This does not create a problem and there is no obvious reason why it would under these circumstances. When these experiments have been carried out in animals there are no obvious ill effect, which suggests there are no problems with incompatibility.

As regards the risks, I have given a fairly full answer above.

Q. Mrsden: We are about to have our first ICSI cycle so I'd be interested in hearing more about Susan's work on the impact of using IVF.

Q. ClimbingKinder: I also don't have a problem with the three (or six that has been pointed out as a possibility!) parent thing and think being raised in a loving, stable environment is much more important.

My cousin was born with the help of IVF and doesn't have any issues with it as far as I'm aware. I remember her happily chatting around the age of eight about how she was made in a test tube.

I'd be really interested to know about the impact of IVF on families and other fertility procedures. Did you expect to find any problems when you started the research and have you found any? In the case of an egg / sperm donor, is the impact similar to that of adoption, and if it's different, how so?

Do you give any advice to people about how to when to tell their children?

A. Susan Golombok: I have answered this question above in relation to IVF using the parents' own egg and sperm. When an egg donor is used, the child lacks a genetic connection to the mother, and when donated sperm is used, it's the father to whom the child lacks a genetic link. Some people have expected that problems would arise for these families not just because of the absence of a genetic relationship with a parent but also because many parents keep egg or sperm donation secret from the child.

We know that adopted children benefit from information about their birth parents and it has been argued that donor-conceived children would similarly benefit from knowing that they are donor-conceived and also from information about their donor.

In our research at the Centre for Family Research in Cambridge, we have been following up children born through egg or sperm donation from infancy to age 10. These families generally function very well - again it's important to remember that these are much-wanted children and their parents often struggled against the odds to have them. Those parents who have told their children about their biological origins are pleased that they have done so and, in spite of parents' fears, the children seem to have taken this in their stride.

Other studies of those who found out about their donor conception in adolescence or adulthood, or by accident, have revealed more negative reactions, with some donor-conceived adults feeling that they have suffered emotionally as a result of this information being kept from them.

So it seems that the best time to begin to talk to children about being donor conceived is in the preschool years (just as adoptive parents do). Although children won't understand much, they will grow up feeling they have always known and parents won't have the worry hanging over them that their child might find out.

Contrary to parents' worries, openness about children's biological origins does not appear to have a harmful effect on the child's relationship with their non-genetic parent. 

FundusCrispyPancake: It is a fantastic breakthrough, I hope it goes ahead. I used to naively believe in leaving things 'to nature'. But after eight years trying to conceive, my daughter was finally conceived by ICSI.

Last updated: 7 months ago