Recently I found myself at a presentation that included a fertility doctor at one of London’s leading hospitals. He was speaking about egg donation and concluded his talk by saying that new research was beginning to show that women carrying a child conceived this way did pass a very small amount of DNA to the embryo at the very early stage of development. He intended this information to be a comfort to women who felt they had had to give up all hope of a child inheriting anything from them and as a way to help them bond with their baby in utero. Such very good motives…so sad that, according to the geneticists I have consulted, it was incorrect information. So fascinating that a doctor…and I doubt he is the only one…usually so fixated on double-blind trials, gold standards and evidence based medicine…should choose to interpret findings this way from a scientific paper that came to no such conclusion.
In response to a question put at DCN’s conference about DNA being passed from mother to child, embryologist Victoria Ryder explained –
It’s not DNA. It’s a very similar molecule called RNA which does not code … so it is very similar to DNA in that it contains bases, but it’s a messenger service basically. What they have found is that there are microRNAs in the womb, and that we think that they can get into the cells of the embryo, but they don’t insert themselves into the DNA or replace any of the DNA; they are part of the signalling that goes into turning the genes on and off, so we have not got any evidence at all so far to say that there is actual DNA that is coding for genes and proteins moving between the mother and child. And I think it is unlikely that we will see something like that in the future.
Victoria’s answer was probably informed by a definitive article written by geneticist Dr Jess Buxton in Bio News back in November last year. I’ll give the link to the whole thing at the end but Dr. Buxton wrote about how epigenetic (environmental) factors present in the womb prior to implantation may alter embryonic gene activity. This does not mean that “Infertile Mums “pass on DNA,” as a misleading headline said at the time, but it does mean that women who conceive using donor eggs may affect the activity of their child’s genes from the earliest stages of pregnancy onwards. Dr. Buxton went on to say,
“The research team, based in Spain and the USA, studied molecules called microRNAs. As the name suggests microRNAs are short sections of RNA, a chemical relative of DNA. Their job is to fine-tune the activity levels of genes during development and throughout life. As such they are part of the epigenetic machinery.” Dr. Buxton’s interpretation of the findings in the original paper (named at the end) have since been confirmed by another geneticist.
You may be thinking, why does it matter that a fertility doctor slightly misinterpreted the findings. What’s one letter of the alphabet between patient and doctor? Isn’t this just nit picking?
I had a long phone conversation with the doctor concerned a few days after his talk and he continued to insist that it was DNA, in very small quantities, that was passed from mother to child. He emphasised that he always spoke about research being at an early stage and that only small amounts of DNA were absorbed by the early embryo. However, I hope he understood my concerns that what he was saying could be heard in a very different way by a woman who is probably still going through a process of mourning for her own lost fertility and therefore vulnerable to clinging on to, and potentially exaggerating, anything that might lead her to believe that her genes will play a role in the make-up of her child-to-be. At DC Network and on fertility forums we have come across several women who were clearly overjoyed by the misleading headlines. I don’t worry too much about DC Network members who will have lots of opportunities to be challenged, gently, in their belief that their DNA is being passed, but I do worry about women who, often typified by someone who thinks of egg donation as ‘just a cell’, will use the headlines to deny their donor and use the information as, yet another, excuse not to ‘tell’ their child.
One of the main tasks of couples and individuals using donor conception is to adjust to the ‘difference’ of having a child this way. All counsellors understand the need for potential parents by donation to grieve for the child they cannot have before moving on to have the one that is possible. If women (and their partners) believe that their DNA is likely to reach the child, then the grieving process may be interrupted with severe consequences for the future family. This is why it is so important that the information given to egg donation recipients is absolutely accurate. And why it is potentially so damaging that someone with the influence that fertility specialists have, should be mis-interpreting scientific findings in this way.
This is the original paper: Vilella F, Moreno-Moya JM, Balaguer N, et al. Hsa-miR-30d, Secreted by the human Endometrium, Is Taken up by the Pre-Implantation Embryo and Might Modify Its Transcriptome. Development. 2015.
Jess Buxton’s article can be found here http://www.bionews.org.uk/page_581621.asp
An edited transcription of Victoria Ryder’s talk at the DCN conference in April 2016 can be found in DCN’s Summer Journal, being distributed to members now.
Update at 29.8.16 Here is a link to Professor Marcus Pembrey’s article in Bio-News, supporting Dr Jess Buxton’s explanation of the Spanish paper. http://www.bionews.org.uk/page_686742.asp