Scientists have discovered how to predict life expectancy
People have always dreamed of knowing how long they have left to live. Fortune tellers and other psychics all over the world take advantage of a person’s desire to look into the future. Although the credibility of their predictions is zero, people continue to give the “fortune tellers” money.
It seems that for fans of predicting the future from coffee grounds, a much more reliable source of information has appeared – researchers have managed to find a way to predict the approximate life expectancy of a person from his DNA.
Unlike “magicians” and “fortune tellers”, scientists do not name the exact date of death. Their assessment on this matter is primarily probabilistic – researchers from the University of Edinburgh, Scotland, noticed that the less a person’s DNA is modified, the greater the probability that he will die earlier.
The scientists focused their research on a specific modification with the complex name called DNA methylation.
It was this modification that cost the life of Dolly the sheep – more precisely, it was because of it that the cloned animal died 7 years after its birth, much earlier than the normal lifespan of sheep.
Methylation is the addition to the DNA strands of a small group of 4 atoms, one carbon and 3 hydrogen /chemists call it a methyl group, and its chemical formula is CH3/.
This “appendage” that attaches to DNA specific proteins that signal to cellular enzymes that the corresponding DNA is specific. Most often, the addition of a methyl group “turns off” the DNA, “forbidding” the enzymes to “read” the information embedded in them.
Methyl groups do not change the DNA sequence itself, but influence how exactly the information embedded in it is reproduced. The impact is so serious that a special term “epigenetics”, that is, supragenomic regulation of the genome, was created for such changes.
If we imagine that the human organism with all its physiological features and personality traits is one country, then genetics and epigenetics are its president and prime minister. And until now it is not clear which of them is of greater importance.
Different epigenetic marks affect DNA in different ways, but the CH3 group is almost always the “choking” appendage. For a long time, scientists believed that as living things age, the amount of methyl groups in their DNA increases.
However, scientists recently proved that this is not the case. In general, genome methylation decreases during aging processes. The key point is that over the years the methyl appendages “move” to other parts of the DNA.
The human genome is full of so-called mobile elements – fragments that can jump from one place to another and disrupt the function of genes.
In young people, such elements are “blocked” by the CHZ-groups, and in those in old age, the “lock” is released and the genome becomes unstable.
The biological clock
Although all the mechanisms by which methylation regulates gene function are currently unknown, the total amount of CH3 groups in the genome can be used to predict lifespan.
Scientists from the University of Edinburgh analyzed data from 4 long-term studies, the authors of which followed a total of 5,000 elderly people over many years.
At the beginning of the observations, blood samples were taken from the participants, from which it was possible to separate DNA.
Preliminarily, the scientists determined the average amount of methyl groups in the genome of each of the participants, and it turned out that excessively rapid demethylation of the genome is a harbinger of early death.
However, the risk for people with undermethylated DNA /relative to the norm for their age/ to die too early did not depend on how healthy a lifestyle they lead, whether they have diabetes or heart problems, and other factors, which are relevant to life expectancy.
