WASHINGTON (NEWSnet/AP) — Ancient DNA may help to explain why northern Europeans have a higher risk of multiple sclerosis than other ancestries.
It’s a genetic legacy of horseback-riding cattle-herders who swept into the region about 5,000 years ago.
The findings come from a project to compare modern DNA with that culled from ancient humans’ teeth and bones. It allows scientists to trace prehistoric migration and disease-linked genes.
When a Bronze Age people called Yamnaya moved from the steppes of what are now Ukraine and Russia into northwestern Europe, they carried gene variants that are known today to increase people’s risk of multiple sclerosis, researchers said Wednesday.
Yamnaya flourished, widely spreading those variants. Those genes probably also protected herders from infection carried by their cattle and sheep, concluded the research, published in the journal Nature.
It’s one of several findings from a gene bank with samples from early humans in Europe and western Asia, a project headed by Eske Willerslev of Cambridge and the University of Copenhagen.
Using the new gene bank to explore MS was a logical first step. MS can strike any population, it is most common among white descendants of northern Europeans and scientists have been unable to explain why.
The disease occurs when immune system cells mistakenly attack the protective coating on nerve fibers, gradually eroding them.
It’s not clear what causes MS, although a leading theory is that specific infections could trigger it in people who are genetically susceptible. More than 230 genetic variants have been found that can increase someone’s risk.
Researchers examined DNA from about 1,600 ancient Eurasians, mapping some major shifts in northern Europe’s population. The research team compared the ancient DNA to about 400,000 present-day people stored in a gene bank, to see the MS-linked genetic variations persist in the north, the direction Yamnaya moved, rather than in southern Europe.
In what is now Denmark, Yamnaya rapidly replaced ancient farmers, making them the closest ancestors of modern Danes, Willerslev said. MS rates are particularly high in Scandinavian countries.
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