麻豆传媒

THE prospect of creating intelligent designer babies has been the subject of ethical debate for decades, but we have lacked the ability to actually do it. That may now change, thanks to a new method of testing an embryo鈥檚 genes that could soon be available in some IVF clinics in the US, 麻豆传媒 can reveal.

The firm Genomic Prediction says it has developed genetic screening tests that can assess complex traits, such as the risk of some diseases and low intelligence, in IVF embryos. The tests haven鈥檛 been used yet, but the firm began talks last month with several IVF clinics to provide them to customers.

For intelligence, Genomic Prediction says that it will only offer the option of screening out embryos deemed likely to have 鈥渕ental disability鈥�. However, the same approach could in future be used to identify embryos with genes that make them more likely to have a high IQ. 鈥淚 think people are going to demand that. If we don鈥檛 do it, some other company will,鈥� says the firm鈥檚 co-founder Stephen Hsu.

For many years, it has been possible to do simpler genetic tests on embryos as part of IVF. For example, parents at risk of having a child with cystic fibrosis have the option to undergo IVF and select an embryo that doesn鈥檛 carry the gene behind the condition. It is also possible to screen for several other conditions caused by a single gene, as well as those caused by chromosomal abnormalities, such as Down鈥檚 syndrome.

However, most medical conditions are influenced by hundreds of genes, which has made it impossible to screen out embryos with a high risk of heart disease, for example, or select embryos with a low likelihood of experiencing depression. This is true for traits like intelligence too.

In recent years, it has become possible to work out a person鈥檚 likelihood for having certain conditions or traits by analysing many DNA regions at once to calculate something called a polygenic risk score (see 鈥�Predicting an embryo鈥檚 future traits鈥�).

Predicting potential

Genomic Prediction is the first company to offer polygenic risk scores for embryos rather than adults. The firm is mainly promoting its tests as a way of screening out embryos at high risk of certain medical conditions. But the company鈥檚 polygenic test for 鈥渕ental disability鈥� is more controversial. It isn鈥檛 accurate enough to predict IQ for each embryo, but it can indicate which ones are genetic outliers, giving prospective parents the option of avoiding embryos with a high chance of an IQ 25 points below average, says Hsu.

鈥淚f we consider inclusion and diversity to be a measure of societal progress, then IQ screening proposals are unethical,鈥� says Lynn Murray of Don鈥檛 Screen Us Out, a group that campaigns against prenatal testing for Down鈥檚 syndrome. 鈥淭here must be wide consultation.鈥�

Information from the same test could be used to go one step further and select whichever embryo is most likely to have a high IQ. 鈥淲hat that corresponds to is way-above-average intellectual potential,鈥� says Hsu.

For ethical reasons, Genomic Prediction won鈥檛 help parents select high-IQ embryos in this way. Nevertheless, it seems likely that other firms will do so in future. 鈥淚f it doesn鈥檛 happen in the US, it will happen in another country,鈥� says Kevin Mitchell of Trinity College Dublin, Ireland.

The idea of using such tests to select embryos predicted to have high intelligence is 鈥渞epugnant, but technologically feasible鈥�, says geneticist Peter Visscher at the University of Queensland, Australia.

Intelligence is only one trait the firm can give a polygenic risk score for. Others on offer include heart disease, breast cancer, type 1 and type 2 diabetes, and inflammatory bowel disease.

All the geneticists 麻豆传媒 spoke to agree that the principles behind polygenic testing are valid, but Mitchell says the service may be of limited use in practice, because many people using IVF have just a few embryos to choose from.

鈥淲e don鈥檛 yet fully understand what other effects genes involved in intelligence may have鈥�

What鈥檚 more, if these embryos all share the same biological parents, they are unlikely to show much variation in their polygenic scores for various traits. Also, we don鈥檛 yet fully understand what other effects the many genes involved in traits like a higher intelligence or lower risk of heart disease might have. For example, some studies have suggested that people with higher polygenic scores for academic ability are also more likely to be autistic.

鈥淵ou don鈥檛 know what you鈥檙e selecting for and what comes with it,鈥� says Visscher. 鈥淏ut there are people who pay hundreds of thousands of dollars to have their dead pet cloned. I鈥檓 sure there are people who would do this.鈥�

In the UK, screening embryos for polygenic conditions isn鈥檛 currently allowed 鈥� they can only be screened for simpler genetic conditions.

But some IVF doctors want that to change. 鈥淚 take my hat off to what they鈥檙e doing, it鈥檚 a potential revolution,鈥� says Simon Fishel, president of the Care Fertility Group clinics in the UK.

This article appeared in print under the headline 鈥淐hoose your child鈥檚 intelligence鈥�