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New findings from ancient human DNA provide insights into why there is a high prevalence of Multiple Sclerosis among Northern Europeans today.
Science & Health

New findings from ancient human DNA provide insights into why there is a high prevalence of Multiple Sclerosis among Northern Europeans today.

Ancient genetic material provides insight into the reason for the increased prevalence of multiple sclerosis among individuals of northern European descent: It is due to inherited genes from pastoralists who arrived in the area approximately 5,000 years ago and relied on horseback riding and cattle herding.

The discoveries are a result of a large-scale study that compared present-day DNA with DNA extracted from the teeth and bones of ancient humans. This has enabled researchers to track the movement of prehistoric populations and identify genetic markers for diseases.

On Wednesday, researchers reported that when the Yamnaya, a group of people from the Bronze Age, migrated from the steppes of present-day Ukraine and Russia to northwestern Europe, they brought with them gene variations that are currently associated with a higher likelihood of developing multiple sclerosis.

However, the Yamnaya people thrived and spread these variations widely. According to a study published in the journal Nature, these genes likely also provided protection against infections carried by their livestock such as cattle and sheep.

“The results of our study were unexpected,” stated William Barrie, a genetics researcher at the University of Cambridge and co-author of the study. “These genetic variations were providing some sort of benefit to these individuals.”

This is a discovery made by a unique genetic repository containing numerous samples from ancient human populations in Europe and western Asia. The project was led by Eske Willerslev from Cambridge and the University of Copenhagen, who is a pioneer in the field of studying ancient DNA. Previous studies have also identified prehistoric human ancestors, including Neanderthals.

The logical initial approach was to utilize the recently established gene repository in studying MS. This is due to the fact that although MS can affect any demographic, it is most prevalent in individuals of white European descent, particularly those from northern regions. Despite efforts, scientists have been unable to determine the cause behind this disparity.

This condition, which can lead to disability, arises when the body’s immune cells mistakenly target the protective layer of nerve fibers, gradually wearing them down. It can result in different symptoms, such as numbness and tingling for one person or difficulty walking and vision impairment for another, which may come and go over time.

The root cause of MS is still uncertain, but one prominent idea suggests that specific infections may activate the condition in individuals with a genetic predisposition. Research has identified over 230 genetic variations that can heighten the likelihood of developing MS.

The initial focus of the study was the DNA of approximately 1,600 ancient individuals from Eurasia. This allowed for the identification of significant changes in the population of northern Europe. The first change observed was the replacement of hunter-gatherers by farmers from the Middle East. Later, approximately 5,000 years ago, the Yamnaya people migrated into the area, bringing with them horses and wagons as they engaged in herding practices with cattle and sheep.

The researchers examined ancient DNA and compared it to the genetic information of approximately 400,000 individuals currently stored in a gene bank in the UK. They specifically looked for genetic variations linked to multiple sclerosis (MS) and found that these variations were more prevalent in populations that migrated north with the Yamnaya people, rather than in southern Europe.

According to Willerslev, the Yamnaya people quickly took over from traditional farmers in what is currently Denmark, making them the most closely related ancestors of present-day Danes. Scandinavian nations have notably high rates of multiple sclerosis.

How could genetic mutations that were initially thought to enhance immunity in the past contribute to an autoimmune disorder? According to co-author Dr. Astrid Iversen from Oxford University, changes in modern human exposure to animal pathogens may disrupt the balance of the immune system and play a role.

Dr. Samira Asgari, a genetic expert from Mount Sinai School of Medicine in New York, who was not involved in the research, cautioned that while the results provide an explanation for the north-south divide of MS in Europe, further investigation is necessary to confirm the connection.

Maria Van Kerkhove, the head of COVID-19 at WHO, mentioned a rise in respiratory illnesses worldwide caused by the coronavirus as well as influenza, rhinovirus, and pneumonia.

She mentioned that we anticipate those patterns to persist throughout January and the winter season in the northern hemisphere. However, she also pointed out a rise in COVID-19 cases in the southern hemisphere, where it is currently summer.

According to Van Kerkhove, while experiencing coughing, sniffles, a fever, and fatigue during the winter is not uncommon, this year in particular, there is a simultaneous spread of various types of pathogens.

It is advised by officials from the World Health Organization that individuals should receive vaccinations when available, wear masks, and ensure proper ventilation in indoor spaces.

Dr. Michael Ryan, head of emergencies at the World Health Organization, stated that while the vaccines may not guarantee protection against infection, they do greatly decrease the likelihood of hospitalization or death.