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‘Designer babies’ remain in sci-fi realm, say scientists

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According to a paper published in Cell, desirable traits in humans such as height and intelligence are the result of multiple genetic and non-genetic factors, making it difficult to select embryos with these traits in mind.

Ethicists have raised concerns that pre-implantation genetic screening (PGS) – screening embryos’ genomes before implantation in IVF – could lead to prospective parents-to-be selecting embryos for desirable traits.

While searching for some genetic defects which could severely impact quality of life is widely accepted, PGS has become associated with fears about eugenics and ‘designer babies’.  According to new research, however, there may be serious technical barriers standing in the way of designer babies, in addition to ethical and regulatory barriers.

Researchers at the Hebrew University of Jerusalem focused on genetic variations associated with intelligence (as indicated by IQ) and height. They collected genetic information from real people to generate genomic profiles for simulated embryos.

They used a model in which prospective parents undergoing IVF would have 10 embryos to choose from, and pick the tallest and highest-scoring embryo for implantation. They predicted the adult IQs and heights associated with each embryo, based on their genomes.

Their results showed that screening and selecting embryos makes little difference with regards to height and IQ: on average this process increased IQ by just three points and height by three centimetres. Even these results are not guaranteed as “there is much about these traits that is unpredictable.”

“If someone selected an embryo that was predicted to have an IQ that was two points higher than the average, this is no guarantee that it would actually result in that increase,” said Dr Shai Carmi. “There is a lot of variability that is not accounted for in the known gene variants.”

There are other barriers to using PGS to maximise height and IQ, such as the fact that the genes associated with these traits mainly apply to people with European heritage and would not be so relevant for other populations.

Carmi and his colleagues then analysed the genetic data of 28 families with adult children and confirmed that selecting embryos on the basis of PGS screening for height and IQ would not always result in the tallest and most ‘intelligent’ adult.

The University of Oxford’s Dr Liz Ormondroyd, who was not involved in the research, told the Press Association: “This computer simulation study shows that, for these complex characteristics, designer babies remain in the realm of science fiction.”

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