Scientists have found a new way to determine – very accurately – the number of chromosomes in very old genomes. And that immediately leads to a striking discovery: a 2,500-year-old case of Turner Syndrome.
This can be read in the magazine Communications Biology. For the study, scientists used their new method of ‘counting’ chromosomes on a large number of genomes previously within the Thousand Ancient British Genomes-project have been collected. This concerns the genomes of people who lived between 2,500 and 250 years ago.
Turner syndrome
Ultimately, the researchers came across five people with abnormal sex chromosomes (see box). And one of them could be diagnosed – about 2,500 years after death – with Turner Syndrome: a condition in which women do not have two X chromosomes, but must be completely (or partially) missing one X chromosome. This is the first time that this condition has been diagnosed in someone who lived in prehistoric times, the researchers write in their study.
Sex chromosomes
Most cells in the human body have 23 chromosomes. However, sometimes cells have more or fewer chromosomes. In that case there is aneuploidy. This can also occur in the sex chromosomes. Women generally have two X chromosomes, while men have an X and a Y chromosome. When women are missing (partially) an X chromosome, they have Turner Syndrome. The most common symptoms include: heart defects, short stature and delayed puberty. The condition has now also been diagnosed in a woman who lived in the Iron Age, about 2,500 years ago. The individual suffered from the so-called ‘mosaic form’ of Turner Syndrome. That means some of the cells had one copy of the X chromosome and others had two. An analysis of her remains indicates that she would have been between 18 and 22 years old at the time of death, but it is unlikely that she had gone through puberty and menstruated; a further indication of Turner Syndrome.
Extra Y-chromosoom
In addition to Turner Syndrome, researchers have made other remarkable discoveries by examining the ancient genomes in the aforementioned dataset. For example, they diagnosed XYY syndrome in someone who lived in the early Middle Ages. This syndrome is characterized by an extra Y chromosome. This diagnosis is also special; This condition has never been diagnosed in anyone who lived so long ago.
Extra X-chromosoom
In addition, the researchers also diagnosed Klinefelter Syndrome in three people. This syndrome is characterized by an extra X chromosome. The three individuals lived at different times in the period between 2,500 and 250 years ago. Although they were not contemporaries, there were certainly similarities; they were all taller than average due to the syndrome.
Down syndrome
In addition to these five individuals with abnormal sex chromosomes, the researchers also made another discovery in the dataset. They also discovered that a child who lived in the Iron Age possessed the hereditary material of chromosome 21 in triplicate. It means that the child had Down Syndrome, the researchers write.
As mentioned, the findings are all made possible by a new method that allows scientists to better count the number of chromosomes in very outdated DNA. “By measuring exactly six chromosomes, we were able to determine that this was prehistoric evidence of someone who had Turner Syndrome 2,500 years ago,” researcher Kakia Anastasiadou explains the findings. “At the same time, we were able to identify XYY syndrome in the other individual, who lived about 1,200 years ago. It is quite difficult to get a good picture of how these individuals lived and interacted with society, as they were found without any possessions.”
Nevertheless, the researchers are hopeful that their new method will lead to new insights in the future. “By combining this type of data (about chromosomes, ed.) with the context of the cemetery, we can develop new historical insights. This way we can find out how sex, gender and diversity were seen in the past,” expects researcher Pontus Skoglund. Colleague Rick Schulting agrees. “The results of this study offer new possibilities in gender studies. In the past, scientists have mainly thought in binary terms, but we hope this new method can help to take steps in this direction.”
2024-01-17 15:40:40
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