UK couples sending embryo data to USA for PGT-P

Some UK patients are seeking preimplantation genetic testing involving polygenic scores (PGT-P), placing fertility clinics in an awkward position.

PGT-P – sometimes called polygenic embryo screening – is offered in the USA, and has recently been featured prominently in advertisements on the New York subway which say 'Have your best baby'. However, a UK clinic has reported that patients are requesting genetic data obtained from other embryo tests, sending this data to US firms for analysis, and then requesting that specific embryos be transferred.

In the UK, preimplantation genetic testing for monogenic conditions (PGT-M) or for structural chromosome rearrangements (PGT-SR) is permitted, in order to prevent the transmission of serious genetic conditions or chromosomal abnormalities that are known to be present in (or carried by) the prospective parents or their families.

Last week, at the annual conference of PET (the Progress Educational Trust) in London, Julia Chain – chair of the Human Fertilisation and Embryology Authority (HFEA) – said in her concluding presentation that that 'PGT-P is unlawful for use in the UK', because 'it does not meet a permitted purpose for testing set out in the Human Fertilisation and Embryology Act.'

PGT-P involves using polygenic scores to try to predict outcomes for partly heritable traits such as height or IQ, or to attribute risks of common medical conditions that are influenced by many small genetic effects (and that are also influenced by environmental factors).

Screening embryos for non-medical traits is not permissible in UK law. According to the HFEA, using PGT-P to screen for risk of conditions such as cancer, diabetes, or Alzheimer's disease is not permissible either. Chain explained at last week's PET conference that this is because 'PGT-P is not the search for the presence of a condition, but instead the assessment of its likelihood'. She added: 'Current evidence suggests that PGT-P is not sufficiently advanced for application in embryo testing, with scores giving information relevant to populations rather than individuals.'

Preimplantation testing for aneuploidy (PGT-A) is permitted in the UK, as an IVF 'add-on' intended to help select embryos for transfer that are more likely to lead to a successful pregnancy. The merits and demerits of PGT-A have long been the subject of lively debate, and evidence for the usefulness of PGT-A is mixed (see BioNews 1305 and 1312).

There are several different ways to perform PGT-A, but the latest versions of the test often involve sequencing the genome of each embryo. Patients may seek access to this genomic data, and it is reported that some patients have obtained the data and then sent it to US-based PGT-P providers for analysis.

'There is nothing to stop a UK-based couple seeking such testing, and indeed treatment, overseas, but a UK licensed clinic should not then make decisions on what embryo to put back using that information,' Peter Thompson, the HFEA's chief executive, told the Guardian. The challenge for clinics will be enforcing this stance, if patients express a preference for a particular embryo and do not disclose that their choice is based on PGT-P.

Dr Cristina Hickman – an embryologist and the founder of Avenues fertility clinic in London, who brought this quandary to the attention of the HFEA and the media – said: 'If a patient wants to have embryo number one transferred and the clinic says no, we want embryo number three, I cannot think that, if this were to go to a judge, they would say no, you have to transfer embryo number three.'