The long battle to prevent the birth of babies with genetic abnormalities has recently taken an enormous step forward. Next generation screening (NGS) has now been successfully applied in centres in China and the UK enabling the detection during in-vitro fertilization (IVF) of embryos with genetic abnormalities.
In order to perform this technique of pre-implantation screening, 7-12 cells are removed from normal looking embryos 5 days after eggs obtained by IVF have been fertilized. The embryos are then frozen while the sampled cells are examined for genetic abnormalities using the very latest DNA technology. Once embryos have been proven to be genetically normal, they can be thawed and transferred to the uterus with appropriate timing in the following cycle. So far, the birth of 18 healthy babies has been reported. The removal of the cells for examination from the embryos has not had any detrimental effect on pregnancy rates.
Genome sequencing is the most accurate method for the detection of genetic abnormalities. It allows the selection of the best embryos for transfer. In so doing, it will increase the pregnancy rate as many of the embryos selected by conventional methods that are transferred today may well be genetically abnormal and do not subsequently implant or are ‘rejected’ by the uterus. In addition and importantly, it can prevent the birth of genetically abnormal babies.
Although the cost of such a procedure may still be prohibitive for many couples, this will undoubtedly fall as the procedure is adopted by more centres. As for every scientific step taken in this direction, there will be sensationalist media attention talking about ‘designer babies’ which of course is absolute nonsense, as was the media outcry when IVF was first described by the sadly missed Robert Edwards and Patrick Steptoe…..and look where we are today!