Have an Autoimmune Disease? Blame the Black Death

TL;DR

The Black Death shaped gene variants that helped survivors fight the plague but are now linked to autoimmune diseases.

Transcript

So, the Black Death. Pretty exclusively a “back then” thing, right? But if you’re descended from  the European, Middle Eastern, and North African populations that experienced  the plague, and you’re dealing with an autoimmune disease, for you it  could be a “right now” kind of thing. That’s because evidence is emerging  that gene variants that were... Read More

Key Insights

• ❓ The Black Death was a natural selection event that favored gene variants associated with surviving the plague.
• 🍻 Specific variants of the ERAP2 gene provided a survival advantage during the Black Death but are now linked to autoimmune diseases.
• ❓ Antagonistic pleiotropy is a common phenomenon where genes have both beneficial and harmful effects.
• ❓ The relationship between infectious diseases and autoimmune diseases demonstrates a tradeoff between protective traits and vulnerability to chronic diseases.
• 💱 The evolution of genes and their effects can be influenced by changes in human lifestyles and exposure to pathogens.
• ✳️ Genetic adaptations to infectious diseases may result in an increased risk of autoimmune diseases.
• ⚖️ The study of genes impacted by antagonistic pleiotropy provides insights into the delicate balance between beneficial and harmful traits.

Questions & Answers

Q: How did the Black Death impact gene variants in the population?

The Black Death acted as a natural selection event, favoring gene variants that provided a survival advantage against the plague. The survivors had specific gene variants that became more common in the population.

Q: What is the significance of the ERAP2 gene in relation to the Black Death and autoimmune diseases?

The ERAP2 gene, specifically the type A variant, helped survivors of the Black Death by enhancing the immune system's ability to identify the plague bacteria and limit inflammation. However, this same gene variant is associated with autoimmune diseases like Crohn's disease.

Q: What is antagonistic pleiotropy?

Antagonistic pleiotropy refers to a phenomenon where a gene has multiple effects, some beneficial and some harmful. In the case of the Black Death survivors, gene variants that protected against the plague also increased the risk of autoimmune diseases.

Q: How has the relationship between infectious diseases and autoimmune diseases evolved over time?

A study suggests that as our genes evolved to better protect against infectious diseases, we became more susceptible to autoimmune diseases. Selective pressures favoring infectious disease protection traits, which arose during the Bronze Age, inadvertently increased vulnerability to chronic diseases.

Summary & Key Takeaways

• The Black Death, a massive plague outbreak in Europe during the 14th century, caused the death of over 25 million people and acted as a natural selection event.

• Researchers analyzed DNA samples from gravesites in London and Denmark to identify gene variants that were more common in the surviving population.

• Specific gene variants, such as the ERAP2 type A variant, helped survivors combat the plague but are also associated with autoimmune diseases like Crohn's disease.