08 July 2013
ByAppeared in BioNews 712
The technique, known as next generation sequencing (NGS), analyses the genome of embryos, allowing doctors to choose an embryo without known genetic defects in the hope that this will lead to more successful pregnancies.
NGS can detect genetic abnormalities, such as an incorrect number of chromosomes, gene defects and mitochondrial DNA mutations. The researchers, from the University of Oxford's NIHR Biomedical Research Centre, tested the accuracy of NGS in blastocysts and then implanted chromosomally normal embryos into two women. The first baby, a healthy boy, was born in June in Pennsylvania, in the USA.
Only around 30 percent of embryos that are transferred into the womb for IVF implant successfully. Dr Dagan Wells, who led the study, suggests that this is due to genetic abnormalities in the embryo. 'Many of the embryos produced during infertility treatments have no chance of becoming a baby because they carry lethal genetic abnormalities', he says. 'Aneuploidy is probably the single biggest factor in embryos not implanting'.
'NGS improves our ability to detect these abnormalities and helps us identify the embryos with the best chances of producing a viable pregnancy. Potentially, this should lead to improved IVF success rates and a lower risk of miscarriage', he added.
Genetic analysis of embryos is currently possible using techniques such as preimplantation genetic screening, but the team hope that their method could provide a cheaper alternative. 'NGS is a way which could make chromosome testing more widely available to a greater number of patients, improving access by cutting the costs', said Dr Wells, estimating that around £200 could be saved per patient.
The technique may raise ethical issues, such as whether parents would be able to select embryos based on their genetic make-up. However, Dr Wells stressed that 'trivial' information, such as eye colour, would not be a factor in embryo selection.
Dr Wells also emphasised that NGS would only be useful in cases where at least one viable embryo is produced, so could be less useful for women over 38 years of age.
More research is needed to confirm the results. 'Our next step is a randomised clinical trial to reveal the true efficacy of this approach - and this will begin later this year', said Dr Wells.
The study was presented at the annual meeting of the European Society of Human Reproduction and Embryology.