09 May 2016
ByAppeared in BioNews 850
Ewa Wybacz and Sergio Russu, the parents of the child, were enrolled in an ongoing clinical study to evaluate next-generation sequencing as a tool to help specialists better select which embryos to transfer during IVF treatment.
The technique was first used successfully in the USA in 2013, with the first baby born in June of that year in Pennsylvania (see BioNews 712). The same Oxford-based team were involved in both trials.
Next-generation sequencing is widely expected to replace other techniques used in preimplantation genetic screening (PGS) of embryos, with the goal being to select more reliably which embryos are most likely to implant and produce healthy babies.
For PGS, doctors remove a few cells from the tissue around the embryo at five days after conception. These cells are then analysed for signs that they have too few or too many chromosomes, a condition called aneuploidy, which increases the likelihood that they will fail to implant or be miscarried. Should aneuploid embryos be carried to term, the resulting baby would be born with one of a family of developmental disorders, of which Down's syndrome is the most common. There is currently debate over how likely it is for embryos containing some aneuploid and some normal cells – a state known as mosaicism – to develop into unaffected babies.
Next-generation sequencing is touted as being more reliable and sensitive than current PGS techniques at detecting aneuploidy. It should also be able to help spot embryos that have other DNA faults and identify mosaic aneuploid embryos.
Dr Tim Child, the medical director of Oxford Fertility, who carried out the treatment, told the Daily Telegraph that if the trial of next-generation sequencing was successful, fertility clinics could 'move away from putting back embryos, crossing our fingers and hoping that they are genetically normal. This way we can maximise the success of having a child'.
He added: 'It also stops couples spending a lot of money freezing eggs, which will never work.'
Next-generation sequencing currently costs between £2000 and £3500 on top of standard IVF fees, which is roughly half the price of PGS. It is not available on the NHS, but that may change if the trial shows it to be cost effective. 'I think this will become the standard way to do PGS,' Dr Child told The Guardian.
Wybacz and Russu put themselves forward for the trial as Wybacz had previously been told that she was unlikely to conceive naturally after a bout of appendicitis at age 12 damaged her ovaries.The couple's first IVF cycle produced ten embryos, but next-generation sequencing indicated that only three of them had a normal set of chromosomes. Of those three embryos, one was transferred while the other two have been cryopreserved for the couple to use in the future.