Genetic mystery: Gene from the Ice Age makes COVID-19 worse — but protects against HIV

LEIPZIG, Germany — A common gene inherited from Neanderthals is making things worse for patients with COVID-19. However, a new study reveals that same gene also provides a shocking benefit — creating more protection against HIV.

Researchers from the Max Planck Institute for Evolutionary Anthropology say this genetic risk factor for COVID actually reduces the chances someone will contract HIV by 27 percent. The gene variant sits in a region on chromosome 3 that consists of many genes in a person’s DNA. Several genes in this area encode receptors in the human immune system. One of those receptors is CCR5, which the HIV virus uses to infect a patient’s white blood cells.

The new study reveals that people who carry this ancient gene variant have fewer CCR5 receptors. Using patient information from three major biobank databases (FinnGen, UK Biobank, and Michigan Genomic Initiative), study author Hugo Zeberg found that carriers of the variant had a significantly lower risk of HIV infection.

Bad news for COVID patients

The flip side of this discovery is that having the gene variant appears to make it more likely coronavirus patients suffer from severe symptoms. Along with pre-existing health conditions which determine whether someone has mild or severe COVID symptoms, a person’s genes can also play a role.

In 2020, Zeberg and fellow researcher Svante Pääbo showed that humans inherited a major genetic risk factor for severe COVID from Neandertals. In 2021, the same team discovered that this variant has become increasingly common in humans since the last Ice Age. The study authors say it’s surprising to see a Neandertal gene become so common in modern human DNA.

“This major genetic risk factor for COVID-19 is so common that I started wondering whether it might actually be good for something, such as providing protection against another infectious disease,” says Zeberg in a university release.

That investigation led to the researcher finding the gene variant’s connection to CCR5 receptors and their importance to HIV infection.

“This shows how a genetic variant can be both good and bad news: Bad news if a person contracts COVID-19, good news because it offers protection against getting infected with HIV,” Zeberg adds.

This gene variant may have stopped an ancient disease

Since HIV is a disease that emerged in the 20th century, Zeberg says this study can’t explain why the gene variant has become increasingly common over the last 10,000 years. Although it is a major risk factor for developing a severe case of COVID-19 today, the study author believes the gene may have developed as a defense against some other, unknown illness that emerged in prehistoric times.

“Now we know that this risk variant for COVID-19 provides protection against HIV. But it was probably protection against yet another disease that increased its frequency after the last ice age,” Zeberg concludes.

The study is published in the Proceedings of the National Academy of Sciences.

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