Ancient DNA From Eurasian Herders Sheds Light on the Origins of Multiple Sclerosis

 January 14, 2014

Genetic variants linked to the risk of MS were brought to Europe during a migration around 5,000 years ago, a new study finds—and they might have helped herders survive

Genes that significantly increase risk of developing multiple sclerosis were introduced to northwestern Europe by herders who migrated from the east around 5,000 years ago. SayoStudio

More than 1.8 million people around the world have the autoimmune disease multiple sclerosis (MS). The condition, in which a person’s immune system attacks their brain and spinal cord, is most common in northern Europe, but researchers haven’t been entirely sure why.

A new study of ancient DNA, published Wednesday in the journal Nature, sheds light on this trend, suggesting herders who migrated to Europe from western Eurasia around 5,000 years ago carried genetic variants linked to MS. These variants grew in prevalence at the time and contribute to an increased risk for the disease today, the paper authors write.

“This is a tour de force,” Lluís Quintana-Murci, a population geneticist at the Pasteur Institute in Paris who did not contribute to the findings, tells Nature News’ Sara Reardon.

The study accompanies three other new papers in Nature investigating ancient DNA in Europe and Asia. One of those found that genes linked to an increased risk for diabetes and Alzheimer’s disease were carried by hunter-gatherers.

“Processes that were occurring many thousands of years ago are having these really pronounced and profound effects on the health and longevity of people in the present,” Evan Irving-Pease, an author of all four of the studies and a population geneticist at the University of Copenhagen in Denmark, tells the Washington Post’s Carolyn Y. Johnson.

Researchers explored this history by sequencing ancient genomes and comparing them to modern DNA. The team examined ancient DNA from bones and teeth dating to the Mesolithic period and Bronze Age, as well as new genomes collected from Medieval times. They studied this data against DNA from 410,000 white British people included in the modern U.K. Biobank.

Major migrations had a strong impact on genetic diversity in western Eurasia, the authors write. Hunter-gatherers entered the picture around 45,000 years ago, farmers came from the Middle East around 11,000 years ago and herders migrated from the Pontic Steppe, a grassland region in the Balkans and western Asia, around 5,000 years ago.

These herders, known as the Yamnaya, rode horses and drove ox-drawn carts, writes Science News’ Bruce Bower. And they buried their dead with gold and jewelry, per the New York Times’ Carl Zimmer. Most people in northern Europe today can trace their ancestry to this group.

Major migrations had a strong impact on genetic diversity in western Eurasia, the authors write. Hunter-gatherers entered the picture around 45,000 years ago, farmers came from the Middle East around 11,000 years ago and herders migrated from the Pontic Steppe, a grassland region in the Balkans and western Asia, around 5,000 years ago.

These herders, known as the Yamnaya, rode horses and drove ox-drawn carts, writes Science News’ Bruce Bower. And they buried their dead with gold and jewelry, per the New York Times’ Carl Zimmer. Most people in northern Europe today can trace their ancestry to this group.

The researchers found that variants linked to MS arose around 5,000 years ago in the Yamnaya, who spread their genes when they got to northern Europe. These variants increased in prevalence for the steppe population, and later, in the European population, which signaled to the scientists that that they might have provided an evolutionary advantage.

“These variants that are causing the high risk of multiple sclerosis today must in the past have had a benefit,” Eske Willerslev, a geneticist at the University of Copenhagen and a leader of the research, tells the New York Times.

Continue reading this interesting story from The Smithsonian

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