White Europeans are more likely to suffer from multiple sclerosis. Researchers studying ancient DNA may have figured out why. – DNyuz

Multiple sclerosis is more common among white Europeans. Researchers studying ancient DNA may have figured out why.

Genes that may have once helped ancient herders fight infectious parasites could contribute to autoimmune diseases today, like multiple sclerosis.

Multiple sclerosis is a progressive disease that affects the brain and spinal cord and can lead to a range of symptoms, including paralysis. While it’s not hereditary (environment also plays a role in its development), susceptibility is related to certain gene variants.

Researchers at the University of Copenhagen, University of Cambridge, and other institutions started searching for clues as to why certain diseases like MS are more common in some populations compared with others.

For instance, MS rates are two times higher in Scandinavia and the northwestern part of Europe than in southern Europe.

They analyzed teeth and bones from Europe and Western Asia, adding to an ancient DNA database of about 1,600 genomes. Then they compared the genetic information of over 400,000 modern people, mainly white Europeans, from the UK Biobank.

They published their results in a series of papers in the peer-reviewed journal Nature. One study connects UK populations with a higher genetic risk of MS with a group of Eurasian herders who may have benefited from an increased ability to ward off some infections.

“I think that this has trade-offs,” Rasmus Nilsen, University of California Berkeley professor and researcher who participated in the study, told a news conference.

Genes were likely passed on in a certain environment because they offered protection against some infectious diseases and carriers were more likely to survive.

Today, those genes can also make people susceptible to autoimmune diseases. Nielsen stated that as the environment changes so does the balance between advantages and disadvantages.

“It gives us sort of an insight into why these diseases exist today,” he said.

The legacy of herding ancestors

Around 5,000 years ago, the Yamnaya people, herders from the Eurasian steppe, arrived in Europe and moved north.

Yamnayan genes show up prominently in many Scandinavian populations, the BBC reported in 2015. The Yamnayan gene is more common in northern Europe than southern Europe.

The Yamnaya herders would have close contact with their sheep, goats, and cows — and the accompanying parasites. Zoonoses are diseases animals pass to humans, including parasitic infections.

Many of these parasitic infections have mostly disappeared in the Western world, coauthor and immunologist Dr. Astrid Iversen said during the press conference. Hygiene has improved, as have diets, distances from animals, and changes in the way people live.

But the immune system of humans hasn’t kept up. They’re still primed to create the pro-inflammatory responses, even without the parasites to fight.

As such, Iversen stated that “our immune systems are a little unbalanced.”

Iversen explained that for some, the inflammatory reaction can be excessive and attack their own body cells. This is what happens with MS.

Right now, doctors treat MS with steroids that suppress the immune system. Researchers hope to find more effective treatments by better understanding the origins of MS.

“Rather than just knocking it out, we should just try to find out in greater detail how it’s unbalanced, and then try to recalibrate it,” Lars Fugger, an expert on multiple sclerosis at the University of Oxford who was involved in the study, told The New York Times.

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