11 January 2010
ByAppeared in BioNews 540
So-called epigenetic changes, which alter the pattern of activity of certain genes, as opposed to the DNA sequence, may help to explain the slightly increased risk of certain health problems among children conceived through assisted reproduction technologies, according to a study published in the journal Human Molecular Genetics. However, the origins of these changes are not well understood and it is not clear whether complications associated with the infertility of the parents might play a role, and not the IVF process itself.
As well as health problems, epigenetic errors could also have implications for susceptibility to cancer and other common diseases later in life, Professor Carmen Sapienza, a geneticist based at Temple University in Philadelphia and co-leader of the study, told the Sunday Times. 'These epigenetic differences have the potential to affect embryonic development and fetal growth, as well as influencing long-term patterns of gene expression associated with increased risk of many human diseases,' he said.
The researchers studied a phenomenon known as 'DNA methylation', the process by which genes not needed in certain tissues are 'switched off' by the attachment of molecules known as 'methyl groups' to the DNA sequence. By examining blood samples taken from the placenta and umbilical cord of 10 IVF children and 13 children who were conceived naturally, the researchers were able to identify differences in the methylation pattern between these two groups. They found that certain genes in babies conceived following IVF tended to have lower methylation levels in placental tissue and higher methylation levels among umbilical cord blood tissue, compared to babies among the group that had been conceived naturally.
It is unclear from the results what effect the epigenetic differences observed might have on gene expression and whether or not they are related to the IVF process. Another possible explanation is that the sperm and eggs of infertile couples may have a higher incidence of epigenetic changes, said Professor Sapienza. Further research is needed to establish the origins of these epigenetic differences and whether or not assisted reproductive technologies are to blame.