Women using donor eggs can pass on their DNA to baby

SCIENTISTS have discovered that infertile women who use donor eggs to have a baby pass on their own DNA to the child.

The findings could l ead to suggestions that a child has three genetic parents.

Until now it was always believed that the fertilised egg used to make the embryo held only DNA from the father.

But now, f or the f i rst ti me, researchers have proved that the baby’s mother makes her own genetic contribution.

Experts say the groundbreaking discovery will boost the self-esteem of mothers who have been unable to conceive a baby using their own eggs.

For a long time, fertility doctors and scientists had suspected that it was possible for a woman carrying an implanted embryo to pass on her characteristics, but this is the first scientific evidence.

Researchers based at a leading Spanish fertility clinic found that secretions from the mother’s womb penetrated pre-implanted embryos influencing their development.

The study – published i n the medical journal Development – was carried out by fertility specialist Dr Felipe Vilella and Dr Carlos Simón of the leading fertility clinic IVI in Valencia.

In the ten-patient investigation, t he doctors established t hat maternal genes were passing into the foetus by extracting fluid from the womb soon after the foetus had been placed in the mother.

But the researchers have been keen to point out that they are not a f ull set of genes and are only fragments, which by themselves could not create a child.

Dr Vilella and Dr Simón observed that f ragments of DNA, called Hsa-miR-30d, are secreted by the mother’s womb lining which are then absorbed by the embryo. Technically it could be argued that children born as a result of egg donation have three parents as the child will carry DNA from the father, the egg donor and the woman carrying the baby.

However the Spanish researchers claim that what is being transmitted by the mother to the foetus are only fragments of DNA and not full DNA.

Doctor Vilella said: ‘These findings have shown us that there is an exchange between the womb and the embryo which was previously not known.

‘It is something that we already suspected as a r esult of t he coincidence of certain physical characteristics between mothers and children born through egg donation.

‘It has been noted children of mothers who smoked during pregnancy or were obese in pregnancy were at greater risk of copying their mother but we didn’t know why.

‘ Now we believe we have the answer by the discovery that particl e s of DNA are being transmitted between the mother and the embryo.

‘By knowing that this transmission exists, in the future we should be able to detect how to interrupt it, putting an end to the trend of obese mothers having obese children.’

Professor Nick Macklon of the Complete Fertility Centre at Southampton Hospital, in the UK, said: ‘This is an amazing discovery. We have suspected this for as long as 20 years but we have never been able to prove it scientifically.

‘I tell a lot of our women who have egg donation that I believe they give something to the baby they are carrying. Now I can tell them I was right.

‘We know that women who have babies by egg donation are well adjusted to what is happening to them and that they bond with their babies as well as any other mother.

‘But there is something about knowing that you played a part, even small part, i n the genetics of inheritance. That you have passed something of yourself to the baby, even if it wasn’t your egg.’

Dr Vilella and Dr Simón have been observing the babies in the study for five years and have already discovered that mothers who were obese in pregnancy appear to have passed on obesity to their children.

Dr Vilella said: ‘We are only just beginning to look into what these fragments of DNA passed on by mothers can confer on t heir children. There are likely to be positives and negatives.

‘They might pass on the risk that a child might take up smoking or develop high blood pressure and heart disease.

‘On the positive side they might pass on artistic temperament or certain physical features that can be a bond between mother and child.’

‘A child might take up smoking’