Israeli geneticists have calculated how accurately it is possible to predict the growth and IQ value for an unborn child, based on genome sequencing before implantation. They tested their data on a theoretical model and on the genetic data of real families. The average "improvement" that parents can count on today by choosing the "highest" or "smartest" from a dozen embryos is an additional two and a half centimeters and an IQ point. The work was published in the journal Cell.
Two weeks ago, the American company Genomic Prediction announced that it was going to take the first step towards “children to order”. She began offering preimplantation genetic diagnosis to people without inherited diseases. The study should include an analysis of the risk of diabetes, cardiovascular disease and five types of cancer. In addition, the company promises to report if the embryo is at risk of entering the two percent of the lowest people in the population or the people with the lowest IQ. All this should give clients a chance to choose the most "successful" embryo from several obtained in the course of in vitro fertilization.
We recently talked about how many scientists consider such manipulations with genetic diagnostics to be the harbingers of eugenics. And they mentioned that an article had already been published in the form of a preprint, the authors of which tried to evaluate how much one can approach eugenics with modern methods. This article has now been peer-reviewed and published in the journal Cell. Ehud Karavani of the Hebrew University of Jerusalem and his colleagues set out to find out how accurately one can predict the values of height and intelligence (two of the most popular selection parameters) of a person from their genome.
All modern studies that are devoted to genome-wide association search work with large samples. And the models that scientists build on their basis are designed to predict the distribution of values of a particular parameter in a population. But when genetics go from hundreds of thousands of people with different genomes to one particular embryo, they start instead asking, "Are these genes related to this trait?" look for answers to the question "What value of a trait can be predicted based on these genes?"
Caravani et al. Used previous genome-wide association studies to identify genes that may be associated with growth or intelligence. The researchers tried to calculate how much the result of the "chosen" embryo will be better than the average for the population or than the average for any child of the same couple. For this, scientists have carried out three types of calculations. The first is theoretical, in which they proceeded from the probabilistic distribution of trait values 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" that 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, a search for associations predicts about 24 percent of the distribution of height and 4 percent of the distribution of IQ scores. In such a situation, you can count on the maximum gain of 3 centimeters or 3 points of IQ. However, even if we find more genes associated with these traits, then, according to the calculations of the authors, these numbers will not grow much: for example, if we can predict 50 percent of the distribution of growth, then the gain will only grow to 4.2 centimeters.
Then the scientists checked how much the gain depends on the number of embryos, among which parents choose. They carried out previous calculations for 10 embryos, since this is the maximum achievable figure for today, although more often they are obtained after artificial insemination of about 5. The authors of the work found that the gain increases sharply from 0 to 10 embryos, and then the curve reaches a plateau and even when choosing out of 50 embryos, the gain will not be much more than 4 centimeters of growth or 4 points of IQ.
Finally, the researchers collected data from 28 real families with many children (up to 20 children) and suggested that this simulates a situation where parents could choose one of many embryos. They collected the genomes of the children and tried to choose the potentially taller one, and then calculated the gain as the difference between the height of this child and the average height of the children in the family. In about a quarter of cases, the gain was really significant - up to 10 centimeters, but in 5 out of 28 families it turned out to be negative, that is, the child selected based on his genes was below the average height of his brothers and sisters.
Promotional video:
Distribution of growth in families with many children. Gray is all children, red is the tallest (judging by genes), blue is parents.
So the scientists gave their answer to genetic testing startups. No matter how we tried to predict the signs of an unborn child, right now we do not have enough tools to predict his growth or intelligence accurately enough, and also there is not enough space for choice - since even fifty embryos will allow you to win a maximum of 5 centimeters of growth or 5 IQ points, which with a total value of a hundred and a half points, it seems an insignificant gain compared to other costs and losses that will have to be incurred in order to get this gain.
Polina Loseva
