Your genes and COVID-19: Gujaratis, Bangladeshis could be at higher risk than Northeast Indians

Last week, a Reuters report pointed out that, as the world marked 1 million COVID-19 deaths, Africa was doing much better than expected, with a lower percentage of deaths than other continents. "The continent’s case fatality count stands at 2.4 per cent, with roughly 35,000 deaths among the more than 1.4 million people reported infected with COVID-19. Hard-hit countries such as Italy and Britain have recorded fatality counts of 11.6 per cent and 9 per cent respectively, compared to 1.6 per cent for Ethiopia, 1.9 per cent for Nigeria and 2.4 per cent for South Africa, the continent’s worst affected country."

Why would that be the case? The report points out that scientists and public health experts have cited a number of possible factors, including the continent’s youthful population and lessons learned from previous disease outbreaks.

But, there could be more to it. A recent report published by European scientists in the journal Nature points out that genetics could play a big part—genes that some people have inherited from their Neanderthal ancestors may increase the likelihood of suffering severe forms of COVID-19. Modern humans and Neanderthals are known to have inter-bred at various points in history, resulting in an exchange of genes than can still be found today. The study identified a cluster of genes that are linked to a higher risk of hospitalisation and respiratory failure in patients who are infected with the new coronavirus.

Researchers Hugo Zeberg and Svante Paabo determined that the genes belong to a group, or haplotype, which likely came from Neanderthals. The haplotype is found in about 16 per cent of the population in Europe and half the population in South Asia, while in Africa and East Asia it is non-existent.  The genes are one of several risk factors for COVID-19, including age, sex and pre-existing conditions like obesity, diabetes and heart problems.

The researchers, who work at the Karolinska Institute in Sweden and the Max Planck Institute for Evolutionary Anthropology in Germany, say the prevalence of the particular Neanderthal gene group is highest in people from Bangladesh, where 63 per cent are estimated to carry a copy of the haplotype. THE WEEK had reported studies from the UK, showing that people of Bangladeshi descent have about two times higher risk of dying from COVID-19 than the general population.

"It is striking that the genetic heritage from the Neandertals has such tragic consequences during the current pandemic," Paabo said in a statement. "Why this is must now be investigated as quickly as possible."

How genetic variations in India might be affecting the death rates

Variation in a genetic mutation among Indians may be the main reason behind the difference in the death rates due to COVID-19 across various states of the country, says a study that could inform new policies for controlling the novel coronavirus pandemic. An international team, led by researchers at Banaras Hindu University (BHU) in Uttar Pradesh, analysed mutations in the gene responsible for the expression of the Angiotensin Converting Enzyme-2 (ACE2), a protein on the surface of cells which is believed to act as a gateway for the novel coronavirus into the human body.

Recent studies have effectively demonstrated that the ACE2 is encoded by a gene located on the X chromosome. In the journal Frontiers in Genetics, the researchers looked at the frequency of this mutation described as rs2285666 haplotype among various states of India. Their spatial analysis showed that in India, frequency of this haplotype, or a combination of mutations, varied between 33-100 per cent across different regions.

The rs2285666-associated haplotype increases the ACE2 expression—this means the mutation reduces the susceptibility against coronavirus. Gyaneshwer Chaubey, professor at the department of Zoology, BHU, said the variations identified reduce the susceptibility of a person against the novel coronavirus. "If in a region more people with this haplotype will be present, the infectiousness of the virus would likely be lesser," Gyaneshwer Chaubey, professor at the department of Zoology, BHU, who led the study, wrote.

He noted that, statewise, Maharashtra and Gujarat have the lowest frequency of the gene mutation of about 30-40 per cent, while the Northeastern region with a 75-100 per cent mutation in the gene has the highest frequency. "People in Western India are more susceptible to the disease than those in Central India or East India or South India or Northeast India," according to the study.

Considered on a global scale, the study researchers noted that the mutation among Indians is 60 per cent and 20 per cent in Europeans; this could imply that, as a whole, Indians are less susceptible to COVID-19 than Europeans and Americans.

The study adds important potential implications to understanding the transmission patterns of SARS-CoV-2 in various world populations. The researchers also observed that in India as well as in Bangladesh, the tribal populations have a higher frequency of this haplotype than the caste populations. "If we look at castes vs tribals, tribals have higher frequency than the caste groups," wrote Chaubey, adding it is likely that the tribal populations will be less susceptible than the caste populations to the viral disease.

Additionally, he noted that the virus strains present in India may also be responsible to contribute to the higher death rates, adding that the team is working on the infectiousness of various virus strains present in India in an ongoing study. Since the beginning, it has been hypothesised, and later observed that coronavirus is affecting people differently.

-Inputs from agencies