There is no need to choose
Study: selecting embryos by height and IQ is pointless
Sergey Kolenov, Hi-tech+
Israeli scientists have proved that these signs are too complex for existing polygenic assessment methods. And even in the ideal case, they give only a small advantage.
This idea is of concern to bioethicists. However, it may not come to life – at least in the near future. According to a study by geneticists from the Hebrew University in Jerusalem, which tells Science Magazine, polygenic assessment is not yet accurate enough to predict the growth or IQ level of an unborn child.
This assessment is based on comparing the effects of thousands of genetic markers, each of which has little effect on the likelihood of a certain trait or the risk of disease. This technique is already used for adults, but its effectiveness for embryos remained poorly understood.
To test how well this technology works, Israeli scientists have created virtual genomes of embryos based on DNA data from real people – 102 couples of Jewish origin and 919 men from Greece. For Jewish "parents" the height was known, and for Greek – the level of intelligence.
Then polygenic estimates of growth and cognitive abilities were calculated for potential embryos.
It turned out that if you choose the best of the five embryos that are usually produced in the IVF cycle, then this will give an increase in height by only 2.5 cm and an increase in IQ by only 2.5 points.
An additional analysis of the genomes of adult children from 28 large families confirmed that growth is most strongly influenced by factors not taken into account in polygenic estimates. Among them are the diet and genes not included in the analysis. In only seven families, the tallest child was the one with the highest polygenic growth rates.
In five families, the child with the best growth score had a height below the average for siblings.
The authors did not have similar IQ data, however, apparently, polygenic estimates are even less accurate for this indicator.
Thus, at the moment, the methods of polygenic assessment do not allow us to accurately select embryos by height, intelligence level and, probably, other complex characteristics. Even with an accurate assessment, the benefits of embryo selection will be negligible. Mistakes can also lead to the rejection of potentially the tallest and smartest children. In the future, the predictive power of polygenic tests may grow significantly. However, so far their use for embryos looks completely unjustified.
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