Explained: Here’s why some people who get COVID-19 don’t fall sick. It’s all in the genes!

CVOVID-19
Scientists and researchers have discovered a genetic link that offers some level of protection from severe COVID

Estimated reading time: 3 minutes

Coronavirus pandemic has shown us that not everyone who catches COVID-19 falls sick. Scientists and researchers have discovered a genetic link that offers some level of protection from severe COVID. The human leukocyte antigen gene identified as HLA-DRB1*04:01, discovered by the medical team of Newcastle University in the U.K., is found three times as often in asymptomatic people. Also Read: Explained: What is ECMO therapy and how is it useful for COVID-19 patients with lung damage

The presence of the gene suggests that people have genetic resistance from severe COVID. The study was funded by Innovate UK, the U.K.’s innovation agency. In the study,  asymptomatic people were compared to the patients from the same community who developed severe COVID but showed no underlying illnesses, said the study published in the HLA journal. The study compared severely affected people with asymptomatic COVID group and use next-generation sequencing to focus on the HLA genes which are packed together on Chromosome 6. Also Read: Moderna ‘TeenCOVE’ study: COVID-19 mRNA vaccine safe and 100% effective in adolescents

The study was more focused than the gnome wide studies and compared symptomatic to asymptomatic in the same population showcasing the “protective” qualities of the allele, which is one of two or more versions of a gene. Also Read: COVID-19 vaccine: Pfizer jab is 100% effective in trial of children between ages 12-15 years

 The HLA-DRB1 gene is part of a family of genes called the human leukocyte antigen (HLA) complex. The HLA complex helps the immune system distinguish the body’s proteins from proteins made by foreign invaders such as viruses and bacteria. Researchers have identified hundreds of different versions (alleles) of the HLA-DRB1 gene, each of which is given a particular number (such as HLA-DRB1*04:01). Also Read: COVID-19 vaccination: Pregnant women pass immunity against coronavirus to their babies

What we know: The gene HLA-DRB1*04:01 is more likely to be found in the North and West of Europe as it directly correlates to latitude and longitude. This means that the population of European descent will be more likely to remain asymptomatic but will still be able to transmit the disease to others. This finding explains why some people are more susceptible to Covid but don’t fall seriously ill.

Why are the findings important: The evidence of the genetic link may explain why some people get Covid but don’t fall sick and could lead us to a genetic test which may show who we need to prioritize for future vaccinations.

“At a population level, this is important for us to know because when we have lots of people who are resistant, so they catch COVID but don’t show symptoms, then they risk spreading the virus while asymptomatic,” said Dr Carlos Echevarria from the Translational and Clinical Research Institute, Newcastle University who also works as a Respiratory Consultant in the Newcastle Hospitals NHS Foundation Trust and is a co-author of the paper.

“Some of the most interesting findings were the relationships between longitude and latitude and HLA gene frequency. It has long been known that the incidence of multiple sclerosis increases with increasing latitude. This has been put down in part to reduced UV exposure and therefore lower vitamin D levels. We weren’t aware, however, that one of the main risk genes for MS, that is DRB1*15:01, directly correlates to latitude,” said study author, David Langton.

“This highlights the complex interaction between environment, genetics and disease. We know some HLA genes are vitamin D responsive, and that low vitamin D levels are a risk factor for severe COVID and we are doing further work in this area,” Langton added.

Reviewed By: Dr. Meenakshi Titoria Sahu

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