Ewan Bolton, writing for the Telegraph, covered how a US fertility clinic was offering a type of embryo selection called preimplantation genetic testing for polygenic risk (PGT-P). PGT-P is a method of genetic screening which is illegal in the UK.
The US clinic claimed among other things that PGT-P can be used to rank embryos to detect whether the person born from them will go on to develop a condition such as schizophrenia in later life.
An analysis published in Nature, found that use of PGT-P today is premature and that it 'is not sufficiently effective or robust for embryo selection.'
PET Director Sarah Norcross told the Telegraph:
'Many ethical debates can be had about whether it's right to select embryos with or without certain characteristics. But before you even get to those debates, you have to start by asking whether PGT-P could successfully select for such characteristics in the first place. If the answer is no, then offering PGT-P to patients is a con.
'PGT-P uses a type of data – polygenic scores – that's very different from the results of traditional genetic test. These scores don't tell you anything concrete or reliable about the presence or absence of a specific gene variant. Instead, they're a statistical construct that involves taking the genome of a person or an embryo, and then trying to say how someone with that genome is likely to compare – in terms of some specified characteristic – to people in a particular population and at a particular moment in time, whose genomes have also been sequenced.
'The resulting data just doesn't give you the kind of certainty that you need, in order to meaningfully select embryos. The problem is made even worse by the fact that the embryos you have to choose from in IVF are usually created from the same genetic parents (so the genomes of the embryos are unlikely to differ substantially enough to result in drastically different polygenic scores), and these embryos are usually very limited in number (which makes it still less likely that any two embryos will have drastically different polygenic scores).
'These are just some of the reasons why PET – along with many other organisations and professional bodies including the European Society of Human Genetics, the American College of Medical Genetics and Genomics, the International Society of Psychiatric Genetics and the International Common Disease Alliance – thinks that it is wrong to offer PGT-P to patients.'
You can read Dr Francesca Forzano's article 'PGT-P? Why using polygenic risk scores to select embryos is bad science' on BioNews for more information.
