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- Diseases from the past: how ancient DNA explains modern genetic mutations
Diseases from the past: how ancient DNA explains modern genetic mutations
Analysis of the skeletons of a mother and daughter from the Paleolithic era has shown that genetic diseases existed long before the advent of modern medicine. The remains of two women, buried about 12,000 years ago in the Grotta del Romito cave, remained a mystery to archaeologists because of the unusual structure of the bones. But recently, an ancient DNA study revealed that the young woman suffered from a rare hereditary growth disorder caused by a genetic mutation. Her mother turned out to have the same diagnosis, but with less pronounced manifestations. This means that rare hereditary pathologies have accompanied humanity throughout its history. Izvestia investigated how this helps scientists better understand their modern nature.
How did genetics solve the mystery of glacial burial?
Scientists from the University of Vienna, together with colleagues from the University Hospital of Liege, have discovered genetic variants associated with a rare hereditary growth disorder in two women who lived about 12 thousand years ago. The results of their work are published in the New England Journal of Medicine.
The object of the study was a double burial of the Upper Paleolithic era, found back in 1963 in the Grotta del Romito cave in southern Italy. The skeletons were lying in each other's arms. The height of one of the women, who received the symbol Romito-2, was only about 110 cm, significantly below the norm for that time. The second, Romito-1, was 145 cm tall, which was only slightly lower than the average of the era.
To establish a possible relationship and the cause of the pronounced short stature, the researchers extracted DNA from the stony part of the temporal bone and applied an integrated approach combining paleogenetics, clinical genetics and physical anthropology. The analysis showed that the women were related in the first degree — most likely, they were mother and daughter.
Romito-2 was found to have a homozygous mutation in the NPR2 gene, which plays a key role in bone growth. This was how the diagnosis of acromezomelic dysplasia of the Maroto type was confirmed. This is a rare disease accompanied by marked shortening of limbs and stunted growth. Romito-1 was found to have one altered copy of the same gene, which explains its slightly reduced growth.
Of particular interest is the fact that Romito-2 survived to adolescence or even adulthood. In the harsh conditions of the Late Paleolithic, this would have been almost impossible without constant help from the community.
How does ancient DNA help fight diseases today?
Studying ancient DNA opens a unique window into the lives of our ancestors and at the same time helps modern medicine. Today, the analysis of the genetic data of ancient people makes it possible to predict the course of diseases in patients with similar mutations.
This allows you to understand in advance what symptoms may occur, which body functions will remain stable, and which aspects of health you should pay special attention to. For example, if a certain mutation in an ancient person did not lead to severe complications, a modern patient with the same mutation may receive more accurate recommendations for prevention and treatment.
Experts note that understanding how the ancient human body coped with genetic disorders opens up opportunities for developing personalized approaches to therapy. This approach helps not only to slow down the development of the disease, but also to improve the patient's quality of life.
Why is illness not necessarily a problem?
The discovery of a genetic disease in a person who lived about 12,000 years ago makes us take a broader look at the role of mutations in human history. They are usually perceived solely as a cause of illness. However, from the point of view of evolution, changes create biological diversity, thanks to which living organisms can adapt to changing environmental conditions.
According to general practitioner and geneticist, Candidate of Medical Sciences Yuri Sharets, mutations are considered the most striking mechanism of evolutionary genetics. What is perceived as pathology today may turn out to be an adaptation to a changing environment under certain conditions. There is an illustrative example in medicine — congenital heart defects.
— They can be divided into two groups. The first one includes anomalies that actually repeat the stages of the evolutionary development of animals — from fish to mammals. Such features can be considered as a kind of "return" to earlier forms of the body structure. The second group is the so-called futuristic vices. They have no analogues in the animal world and have not been encountered before in evolution," the expert explains.
A similar situation is observed in acromesomelic dysplasia of the Maroto type.
— In this disease, the mutation allows the body to maintain its functional capabilities in the struggle for survival. Therefore, such people are viable and theoretically may be better adapted to changing environmental conditions," explains Sharets.
At the same time, the concept of norm in biology is much more conventional than is commonly thought.
— A comparative study of developmental stigmata shows that the complete absence of any features occurs only in about 4% of people. That is, the absolute norm is a rather rare phenomenon," the expert notes.
Therefore, the line between norm and pathology is often blurred. Many of the body's features are simply variants of a person's natural biological diversity. Today, science has learned to study matter very precisely, from the structure of cells to DNA molecules. But, as Sharets emphasizes, an understanding of the more complex processes of life is still only being formed.
What is the power of paleogenetics?
Modern DNA analysis methods allow scientists not only to diagnose diseases in people who lived thousands of years ago, but also to reconstruct the history of entire nations. Paleogenetics is increasingly becoming a tool with which to test historical hypotheses about the origin of ancient cultures and population migrations. One such example is a large—scale study of the genetics of the Scythians, nomadic peoples who inhabited the steppes of the Black Sea region more than 2 thousand years ago.
The Scythians appeared in this region around the 8th–7th centuries BC. Their origin has long been the subject of scientific debate. According to one hypothesis, the Scythians could be descendants of the population of the steppe cultures of the Bronze Age, primarily the Srubnaya culture, which mixed with local tribes. Another version suggested that their ancestors came to the Black Sea region from Central Asia.
To test these assumptions, an international team of scientists conducted a major genetic study led by geneticist Evgeny Rogaev, director of the Center for Genetics and Life Sciences at Sirius University and a professor at the University of Massachusetts Medical School. As the scientist said in an interview with Izvestia, the researchers conducted a genome-wide analysis of ancient DNA samples.
— We have analyzed the genomes of more than 150 people from the burials of the Bronze and Iron Ages in the territory of Great Scythia, described by Herodotus. Samples with well-preserved genetic material were also taken. The final sample included 131 genomes obtained from 289 genomic libraries,— said Evgeny Rogaev.
Scientists compared these data with the genetic material of representatives of neighboring cultures, in particular people from the Semiluksky settlement on the Middle Don, as well as from monuments of the Pyanobor and Koban cultures. In addition, samples from the foothills of the Caucasus were included in the analysis.
In this regard, the Scythian population was genetically very heterogeneous both geographically and temporally. At the same time, the data did not confirm the hypothesis of the Central Asian origin of these peoples.
— Genetic analysis has shown that the groups that lived at different times in the Black Sea region are most closely related to the steppe cultures of the Bronze Age. The contribution of the East Asian and Siberian components turned out to be minimal," Rogaev noted.
According to the researchers, this means that the Scythian culture could spread primarily through cultural contacts between different groups of the population, and not solely through large-scale migrations.
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