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How should we use genomic data in assisted reproduction?

7 May 2019
By Sandy Starr
Deputy Director, Progress Educational Trust
Appeared in BioNews 997

Advances in genomics are having a growing impact on fertility treatment and assisted reproduction. Should we welcome the new possibilities that have emerged, or are there grounds for caution?

This is the question that the Progress Educational Trust (PET), the charity that publishes BioNews, will be grappling with at next week's public event 'Testing Times: How Should We Use Genomic Data in Assisted Reproduction?'.

Perhaps most striking is the impact of new technology on carrier screening - that is, testing prospective parents to see whether they carry gene variants that could lead to disease in their children. Even if a prospective parent has no symptoms of a disease, they might still be a carrier. If this is the case, then their child might be affected by the disease (with recessive diseases, this can happen if both parents are carriers). And even if the child of a carrier is not affected by the relevant disease, the child might in turn be a carrier themselves.

Traditionally, carrier screening was performed for one gene at a time, and was offered for genes strongly associated with severe conditions that are either present from birth or manifest during childhood. Such carrier screening has usually been offered to people either because there is a history of a particular disease in their family, or because their ethnic background suggests a higher-than-average risk that they carry a disease-related gene variant - for example, Tay-Sachs disease in people of Ashkenazi Jewish ancestry, or beta thalassemia in people of Mediterranean ancestry.

By contrast, 'expanded carrier screening' - first offered 10 years ago, but now growing rapidly in popularity and scope - can identify simultaneously the presence or absence of many gene variants (potentially thousands) associated with a vast number of different conditions. Rather than being offered to people on the basis of their family history or their ethnicity, expanded carrier screening is increasingly being made available - via the private sector - to any paying customer who wishes to use it, either for themselves (as prospective parents) or for sperm or egg donors (in cases of donor conception).

As the number of gene variants that can be screened for increases, so carrier screening encompasses a growing range of conditions of varying severity and predictability. Meanwhile, debate is ongoing about whether there could be a legitimate role for expanded carrier screening in public healthcare.

Besides carrier screening, genomics is also being used in new ways to make decisions about embryos. For example, a statistical approach called polygenic scores - which is different to a conventional genetic test - can be used to study the genome of a person or embryo, and ascribe to them a numerical likelihood of developing a given disease or characteristic.

The meaning and usefulness of these scores, both in healthcare and in other contexts, is a matter of heated debate. However, this has not deterred an American company from offering polygenic scores for IVF embryos, so that patients can avoid implanting embryos with very low scores for intelligence (see BioNews 976).

At our event on 16 May speakers including Dr Jess Buxton, César Díaz García, Karen Sage and Dr Véronique Berman, chaired by Jane Fisher, will explore questions including:

  • What is the cost to patients of these new technologies? Is there a case to be made for any routine and/or publicly-funded applications of these technologies?

  • How do these technologies fit into ongoing debate about the costs and merits of 'add-ons' to IVF? Are these technologies solely about avoiding illness in the future child, or do they have anything to do with improving the chances of establishing a pregnancy?

  • Will these technologies lead to parents being reassured, or made more anxious? How best to avoid false reassurance (assuming that a future child is guaranteed to be healthy, when this is not the case)? How best to avoid unnecessary anxiety (assuming that less-than-perfect results are a cause for concern, when they may not be)?

  • What is the role of genetic counselling, before and/or after results are sought and received? Is such counselling currently available? Is it adequate?

  • Is it advisable to provide people with results that are ambiguous, or that are of unknown significance? How might people respond to receiving such results?

  • Are results likely to be drastically different if they are provided by different companies or laboratories, or if they are generated using different approaches or algorithms? What standards and guidelines have been established in this area? Who should be responsible for developing them?

  • What gene variants and what conditions should - and conversely, should not - be screened for when establishing carrier status? Should there be any limit on how many gene variants, or how many conditions, are looked at? How can people consent meaningfully to being screened for large numbers of conditions?

  • What conditions is it reasonable to screen for in sperm or egg donors? Given that practically everyone is a carrier of at least some disease-related gene variants, is there a risk of excluding all prospective donors? Or of assessing donors in unhelpful or unrealistic ways?

  • Is the use of polygenic scores in assisted reproduction scientifically justified? And is it ethically defensible?

In the PET tradition, much of this event's running time will be devoted to letting the audience put questions and comments to the speakers.


'Testing Times: How Should We Use Genomic Data in Assisted Reproduction?' - an event produced by the Progress Educational Trust and supported by Igenomix - is taking place in London next week on the evening of Thursday 16 May.

Attendance is free, but advance registration is required. Register here.

If tweeting about this event, please use the hashtag #PETtestingtimes

SOURCES & REFERENCES
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