Researchers from UCLA dropped a bombshell at the recent European Society of Human Reproduction and Embryology conference, declaring that the conditions in which embryos are cultured in the lab during IVF could be causing genetic errors that are associated with certain developmental syndromes and other abnormalities in growth and development, such as low birth weight.
The research, using mouse embryos, showed that certain laboratory culture media used in IVF and concentrations of oxygen altered the expression of several imprinted genes (imprinting is the process by which some genes are activated or inactivated depending on whether they have been inherited in chromosomes from the mother or the father).
"We found that the culture of mouse embryos in the laboratory is sufficient to alter the expression of several imprinted genes and that this effect can be modified by the composition of the culture medium and oxygen concentration," explained Professor Paolo F Rinaudo, from UCLA. "Interestingly, the expression of one gene, H19, was reduced regardless of the culture conditions, and as H19 is associated with Beckwith-Wiedeman syndrome, this finding needs to be investigated further."
But Rinaudo cautioned against reading too much into the results at this stage. "These studies are important for better directing future resources and studies in humans. But we must remember that these are preliminary results in a mouse model, and they need to be repeated and confirmed in other strains of mice before translating to studies in humans."
This is not the first study to suggest that culturing embryos in the laboratory during IVF could be affecting embryos adversely. "Emerging new evidence shows that some neurological and behavioral abnormalities are associated with assisted reproductive techniques. Cases of Angelman and Beckwith-Wiedeman syndromes in humans, which are due to aberrant genomic imprinting, and other abnormalities in growth and development in mice have been described after culture in vitro," said Rinaudo.
Angelman syndrome is characterised by severe mental retardation, speech impairment, balance disorder and a happy, excitable demeanour; it occurs in about one in 10,000 to 30,000 of the population. Beckwith-Wiedeman syndrome is characterised by overgrowth, with an abnormally large tongue, umbilical hernia, neonatal hypoglycaemia and a predisposition to certain tumours.
Other possibly IVF related anomalies were identified in the genes responsible for T cell development (part of the immune system), tumor suppression, amino acid transport, Silver-Russell syndrome (a growth disorder) and McCune-Albright syndrome (involves bone, hormone and skin abnormalities).
Rinaudo plans to continue his investigations into how IVF procedures could be causing these abnormalities. "We want to understand why these techniques appear to be affecting the imprinting of these genes. We hope this understanding will enable the scientific community to make better culture media for IVF in humans," he said in conclusion.
Source: European Society for Human Reproduction and Embryology