Scientists solve the mystery of how autoimmune diseases spread

Why are diseases more common in some parts of Europe than others, and why are northern Europeans taller than southern Europeans?

An international team of scientists say they have discovered the answer in DNA they found in ancient teeth and bones.

Genes that protected our ancestors from animal-borne diseases now increase the risk of developing multiple sclerosis (MS).

The researchers describe their discovery as a “quantum leap” in understanding the development of the disease.

They say the ad could change opinions about the causes of MS and could have an impact on the way it is treated.

Why look at MS?

There are almost twice as many cases of multiple sclerosis per 100,000 people in north-western Europe, including the UK and Scandinavia, than in southern Europe.

Researchers from the universities of Cambridge, Copenhagen and Oxford spent more than 10 years delving into archaeology to find out why.

MS is a disease in which the body's immune cells attack the brain and spinal cord, causing symptoms such as muscle stiffness and problems walking and speaking.

They discovered that genes that increase the risk of MS were introduced through northwestern Europe about 5,000 years ago through a mass migration of cattle herders called Yamna.

Yemen came from the west Russia, Ukraine and KazakhstanIt moved west toward Europe, says one of four Nature articles published on the subject.

Dr. William Barry, study author and expert in computational analysis of ancient DNA at the University of Cambridge, said the results “surprised us all.”

At the time, genetic variants carried by herders were an advantage, helping them protect against diseases in their sheep and cattle.

However, today, with modern lifestyles and better diets and hygiene, these genetic variants have played a different role.

Today, these same traits pose a greater risk of developing certain diseases, such as MS.

The research project was a massive undertaking: genetic information was extracted from ancient human remains found in Europe and western Asia and compared with the genes of hundreds of thousands of people living in the UK today.

In the process, a DNA bank of 5,000 ancient humans, preserved in museum collections in several countries, was created to aid future research.

“Find the sweet spot”

Professor Lars Fugger, author of the study and an MS doctor at John Radcliffe Hospital in Oxford, says this discovery helps “demystify” the disease.

“MS is not caused by mutations, but is driven by normal genes to protect us from pathogens,” he explains.

Vaccines, antibiotics and higher hygiene standards have completely changed the disease landscape: many diseases have disappeared and people are living decades longer.

Researchers say modern immune systems may now be more vulnerable to autoimmune diseases, such as MS, in which the immune system attacks the body rather than protecting it.

The medications currently used to treat MS target the body's immune system. The downside is the risk of it being suppressed to the point that patients have difficulty fighting the infection.

“In dealing with it, we are dealing with evolutionary forces,” says Professor Fugger.

“We need to find the sweet spot where there is balance with the immune system, rather than eliminating it.”

The team now plans to search ancient DNA for other diseases and follow them over time.

Their research could reveal more about the origins of autism, attention deficit hyperactivity disorder (ADHD), bipolar disorder, and depression.

Another article in Nature revealed more clues about our genetic past: that Yamna herders could also be responsible for northwestern Europeans being taller than those to the south.

While Northern Europeans have a higher genetic risk of developing MS, Southern Europeans are more likely to develop bipolar disorder, and Eastern Europeans are more likely to develop Alzheimer's disease and type 2 diabetes.

The research shows that the DNA of prehistoric hunter-gatherers increases the risk of Alzheimer's disease, but that the genes of ancient farmers are linked to mood disorders.

He also discovered that the ability of humans to digest milk and other dairy products and survive on a plant-rich diet only emerged about 6,000 years ago. Before that, they ate meat.

The research compared the DNA of thousands of ancient skeletons found in Eurasia with genetic samples from modern Europeans.

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