A team of geneticists from Israel have calculated how accurately the growth and significance of the IQ can be predicted for an unborn child, based on genome sequencing prior to implantation. They tested their data on the theoretical model and on the genetic data of real families. The average “improvement” that parents can expect today by choosing from a dozen embryos “highest” or “smartest” is an additional two and a half centimetre and a point of the IQ.
Two weeks ago, the American company Genomic Prediction announced that it was going to take the first step towards “children to order” or custom-made children. It began offering a pre-implantation genetic diagnosis to people without hereditary diseases. The study should include an analysis on the risk of diabetes, cardiovascular disease and five types of cancer. In addition, the company promises to report if the embryo risks entering the two percent of the lowest people in the population or people with the lowest level of IQ. All this should give clients a chance to choose the most “successful” embryo from several, obtained during in vitro fertilization.
Ehud Karavani from The Hebrew University of Jerusalem, Jerusalem and his colleagues decided to find out how accurately growth and intelligence values (the two most popular) parameters of selection) of a person by his genome.
All modern research, which is devoted to the full-genome search of associations, works with large samples. And the models that scientists build on them are designed to predict the distribution of the values of a given parameter in a population. But when geneticists move from hundreds of thousands of people with different genomes to one particular embryo, instead of asking “Are these genes associated with this trait?” They begin to search for answers to the question “What value of a trait can be predicted based on these genes?”.
Karavani and co-authors have used previous studies on full-genome association searches to identify genes that may be associated with the growth of intelligence. Researchers tried to calculate how much the result of the “chosen” embryo would be better than the population average or than the average of any child of the same pair. To do this, scientists conducted three types of calculations. The first is theoretical, in which they proceeded from the probability distribution of traits in the population. The second is based on real samples: 102 Ashkenazi families and data on their growth, as well as 919 Greeks and data on their intelligence. The third is for “virtual families,” which scientists randomly compiled from their samples.
To begin with, the researchers calculated how much the gain in choosing an embryo depends on the strength of our predictions. Today, according to the search results for associations, approximately 24% of the distribution of growth and 4% of the distribution of IQ indicators can be predicted. In such a situation, you can count on the maximum gain of 3 centimeters or 3 points IQ. However, even if we find more genes associated with these traits, then, according to the authors, these numbers will not grow much: for example, if we can predict 50% of the distribution of growth, then the gain will grow only to 4.2 centimetres.
The scientists then tested how much the benefit depends on the number of embryos the parents choose. Previous calculations were made for 10 embryos, as this is the maximum achievable figure for today, although more often they are obtained after artificial insemination about 5. The authors of the work found that the winnings grow sharply from 0 to 10 embryos, and then the curve goes to the plateau and even when choosing from 50 embryos the gain will not be much more than 4 centimetres growth or 4 points of the IQ.
Finally, the researchers collected data on 28 real families with many children (up to 20 children) and suggested that this simulated a situation where parents could choose one of many Embryos. They collected the genomes of the children and tried to choose from them as potentially high, and then calculated the winnings as the difference between the growth of this child and the average growth of children in the family. In about a quarter of the cases, the gain was really significant – up to 10 centimetres, but in 5 out of 28 families it turned out to be negative, that is, selected on the basis of their genes the child was below the average height of his brothers and sisters.
Thus, the scientists gave their answer to the start-ups of genetic testing. No matter how much we try to predict the signs of an unborn child, right now we don’t have the tools to predict his growth or intelligence accurately enough, and also not enough space to choose – because even fifty embryos will win a maximum of 5 centimetres of growth or 5 points of the IQ, which at a total value of a hundred with a small point seems to be an insignificant gain compared to other costs and losses that will have to be incurred to get this gain.