How protector genes turned culprits increasing risk of Multiple Sclerosis

In the past, when people changed the way they lived and the environment around them, it might have accidentally made it more likely for some people to get . Multiple sclerosis (MS) is a chronic and often disabling disease that affects the central nervous system. In MS, the immune system mistakenly attacks the protective covering of nerve fibers called myelin.

This leads to disruptions in the normal flow of electrical impulses along the nerves, causing a variety of symptoms. A new study says that the balance of special cells in our body that fight off different sicknesses has been thrown off by these changes in how we live, and that's playing a part in causing diseases like MS.

Why is it more common in some parts of Europe? The research also addresses the ongoing discussion about why is more common in Europe. Surprisingly, the chances of having MS depend on where you live and your background. In Europe, especially in the north, MS is more common, with about 142.81 cases for every 100,000 people.

Scientists are a bit puzzled about why this happens more in certain places. They think understanding these patterns could help them understand why MS has become more common in the last 50 years. After studying ancient DNA, specifically the Yamnaya, who migrated into northwestern Europe around 5,000 years ago, researchers discovered that the Yamnaya carried gene variants associated with an increased risk of MS.

Strikingly, these variants not only persisted but flourished, possibly offering protection against infections transmitted by their livestock. This means that the genes which gave us protection once, have now turned risky for our well being. The findings suggest that historical gene variations impacting immunity may be linked to the autoimmune disease.

The study, while significant, prompts further research to solidify the connection between ancient genetic factors and modern MS risk. The findings from the studies "astounded us all," said Dr. William Barrie, author of the papers and research associate at the University of Cambridge, in an interview with .

The material for this article has been gleaned from two studies published in the journal . Multiple sclerosis (MS) is a neuro inflammatory and neurodegenerative disease that is most prevalent in Northern Europe. Although it is known that inherited risk for MS is located within or in close proximity to immune related genes, it is unknown when, where and how this genetic risk originated .

Here, by using a large ancient genome dataset from the Mesolithic period to the Bronze Age , along with new Medieval and post Medieval genomes, we show that the genetic risk for MS rose among pastoralists from the Pontic steppe and was brought into Europe by the Yamnaya related migration approximately 5,000 years ago.

We further show that these MS associated immunogenetic variants underwent positive selection both within the steppe population and later in Europe, probably driven by pathogenic challenges coinciding with changes in diet, lifestyle and population density. This study highlights the critical importance of the Neolithic period and Bronze Age as determinants of modern immune responses and their subsequent effect on the risk of developing MS in a changing environment.

The Holocene (beginning around 12,000 years ago) encompassed some of the most significant changes in human evolution, with far reaching consequences for the dietary, physical and mental health of present day populations. Using a dataset of more than 1,600 imputed ancient genomeswe modelled the selection landscape during the transition from hunting and gathering, to farming and pastoralism across West Eurasia.

We identify key selection signals related to metabolism, including that selection at the FADS cluster began earlier than previously reported and that selection near the LCT locus predates the emergence of the lactase persistence allele by thousands of years. We also find strong selection in the HLA region, possibly due to increased exposure to pathogens during the Bronze Age.

Using ancient individuals to infer local ancestry tracts in over 400,000 samples from the UK Biobank, we identify widespread differences in the distribution of Mesolithic, Neolithic and Bronze Age ancestries across Eurasia. By calculating ancestry specific polygenic risk scores, we show that height differences between Northern and Southern Europe are associated with differential Steppe ancestry, rather than selection, and that risk alleles for mood related phenotypes are enriched for Neolithic farmer ancestry, whereas risk alleles for diabetes and Alzheimer’s disease are enriched for Western hunter gatherer ancestry.

Our results indicate that ancient selection and migration were large contributors to the distribution of phenotypic diversity in present day Europeans..