Possible Origin of Multiple Sclerosis Gene: Protection Against Infection in Animals

The largest genetic database of ancient humans to date is shedding new light on why people vary in modern conditions such as multiple sclerosis (MS) and other genetic traits such as height.

One of the findings is that the genes behind MS may have become more common because they helped people resist infections transmitted from animals.

Other findings include why Alzheimer’s disease is more common in some groups than others and why people in northern Europe tend to be taller than people in the southern part of the continent. Includes description.

“What happened thousands of years ago can have a very serious impact on the health and longevity of people living today,” he says. Evan Irving Pease at the University of Copenhagen, Denmark.

The genes of people of European and Western Asian ancestry have been shaped by three major waves of migration. Modern hunter-gatherer humans first arrived in these areas about 45,000 years ago. Then, about 11,000 years ago, a wave of farmers arrived from the Middle East, followed by a further influx of pastoralists, now called the Yamnaya, from the Eurasian steppe.

To understand how these popular movements shaped the modern medical landscape, Irving Pease's team collected bone and tooth samples from approximately 5,000 ancient sites found in museum collections across Europe and Western Asia. The oldest one is 34,000 years old.

The latest study reports on the first batch of samples analyzed based on approximately 1600 individuals. The researchers compared these people to the genetic data of 410,000 people in a huge medical dataset called the UK Biobank, and analyzed only white participants to select participants with European ancestry. did.

The research team started by focusing on MS, an autoimmune disease that occurs when the immune system begins to attack nerves, often leading to progressive disability.What previous research has found 233 genetic variants associated with increased risk of MS.

Among modern people in the UK, those at high genetic risk of multiple sclerosis are more likely to have Yamnaya ancestry, a study has shown. The research team also found that some of these MS-predisposing genetic mutations first arose in the Yamnaya tribe and became more frequent among their descendants as they spread westward through Europe.

Given that some of the 233 variants associated with MS also affect the immune system, and that the Yamnaya people have lived among animals, researchers believe that the genes behind MS are probably The researchers concluded that the species may help protect against bacteria and viruses that can be transmitted to humans. animal.The team has previously shown that Some MS risk variants are associated with partial resistance to tuberculosis.

In another paper, researchers have revealed how our ancestry influences our genetic risk for Alzheimer's disease. Modern humans are more likely to have a gene called . Apo E4If you have more ancestors from Europe's first hunter-gatherers, you have a higher risk of developing Alzheimer's disease.

Another variant of this gene is Apo E2The result is a lower risk of Alzheimer's disease, which likely occurred in the incoming Yamnaya people because it provided protection against malaria and unknown viral infections, the researchers wrote in their paper.

Variants that protect against Alzheimer's disease do not confer a reproductive advantage, so they may not have been selected by evolution to have an effect on dementia, given that dementia typically develops long after people have had children. Yes, researchers say. benjamin trumbull from Arizona State University and was not involved in any research.

“The great thing about this paper is that they go further back in time and say what was advantageous or disadvantageous at that time,” Trumbull said. “Too often we look at our modern environment and say: [a certain gene] Purely harmful. We have to consider what the selection pressures were at different points in time. ”

A further finding from the analysis is that among people living in Europe, those with more Yamnaya ancestry tend to be taller, which explains why Northern Europeans are, on average, taller than Southern Europeans. This may explain why it is so expensive.