Neanderthal genes may explain Covid-19 severity in some people: Study

MILAN: People who suffered severe Covid-19 infections are more likely to have a set of genes, inherited from Neanderthals, according to an Italian study.

Italy was one of the severely affected countries during the early days of the pandemic.

Researchers from the country’s Mario Negri Institute for Pharmacological Research analysed the relationship between genetic factors and the severity of the Covid-19 disease in the province of Bergamo, the epicentre of the pandemic in the country.

Their study, published in the journal iScience, shows that a certain region of the human genome was significantly associated with the risk of getting Covid-19 and becoming seriously ill in residents in those areas most affected by the pandemic.

In the study of 1,200 people, the team found that the presence of three of the six genes of a region located on chromosome 3 makes people more susceptible to Covid severity.

These are the CCR9 and CXCR6 genes, responsible for recalling white blood cells and causing inflammation during infections, and the LZTFL1 gene, which regulates the development and function of epithelial cells in the respiratory tract, conditioning the different manifestations of the disease.

It's unclear which gene plays the most important role.

In addition, the study identified 17 other new genomic regions (loci) of which 10 were potentially associated with severe disease and 7 were potentially associated with risk of infection, the researchers said.

"The sensational thing is that three of the six genes associated with this risk have reached the modern population from Neanderthals, in particular from the Vindija genome that dates back to 50,000 years ago and was found in Croatia," said Giuseppe Remuzzi, Director of the Mario Blacks Institute, in a statement.

"It may once have protected Neanderthals from infection, but now it causes an excess of immune response that not only does not protect us but exposes us to a more severe disease.

The victims of the Neanderthal chromosome in the world are perhaps 1 million and could be precisely those who, in the absence of other causes, die from a genetic predisposition," he added.

In 2022, a study by a team from Karolinska Institutet in Sweden and Max Planck Institute in Germany showed modern humans have inherited a major genetic risk factor for severe Covid-19 from Neanderthals.

It showed that CCR5 gene, located on chromosome 3 can reduce a person’s risk of contracting HIV by 27 per cent.

In the latest study, the 1,200 people were divided into three homogeneous groups for characteristics and risk factors: 400 who had a severe form of the disease, 400 who contracted the virus in a mild form and 400 who did not contract it.

People who had severe Covid-19 more frequently had first-degree relatives who died from the virus than participants with mild Covid-19 or who had not become infected.

This finding highlights a contribution of genetics to the severity of the disease.

"The results show that those who have been exposed to the virus and are carriers of the Neanderthal haplotype had more than double the risk of developing severe Covid (pneumonia), Almost three times more risk of needing intensive care and an even greater risk of needing

mechanical ventilation than subjects who do not have this haplotype," said Marina Noris, Head of the Human Genomics Center of the Mario Blacks Institute.