Researchers determine genetic variants offered protection during Black Death, associated with current autoimmune disorders

 

https://www.eurekalert.org/news-releases/973919

 

 News Release 8-Dec-2022
Peer-Reviewed Publication
Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign

 

Infectious diseases are some of the strongest selective pressures in human evolution, selecting for genetic variants that increase resistance to infection. In the face of a pandemic, resistance to the disease undergoes strong positive selection that likely affects the genetic makeup of the population afterward. The Black Death, otherwise known as the Bubonic Plague, remains the most devastating pandemic in recorded history, reducing the European population by 30-50% within a 4-year span (1346-1350) and affecting nearly all of Afro-Eurasia. The Black Death was caused by Yersinia pestis, a highly contagious and deadly bacterium that quickly spread across the eastern continents.

How did this plague alter the population’s genetic composition, and did any alleles confer protection in those that survived?

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 “It was exciting once we delved into to the variants, to see that our variants of interest show this signal of balancing selection,” Klunk said. “We were able to say one of the variants we're looking at clearly shows a signal of selective pressure over the course of Black Death, and we showed that it’s definitely involved in the immune response to Y. pestis, as well as other pathogens. But today that variant is also associated with a higher risk of autoimmune and inflammatory disorders. So being able to make that link was like, wow, that's something special.”

“I think studies like this help us understand why we're at risk for certain diseases, and how past pandemics have shaped current disease risks,” Vilgalys said. “Why does 50% of the population have these ERAP2 variants that put you at increased risk for chronic disease? Part of the reason is that our genomes have been shaped by past infectious disease, like the Black Death. Across the board, if we were to look at a lot of risk alleles for modern disorders, you're probably going to see that those are protective against some disease that we've had in the past.”

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