Does SARS-CoV-2 prefer carriers of the HLA B27 gene? This is what Jean-Marc Sabatier, PhD in Cellular Biology and Microbiology, has just discovered. Explanations.
Scientists are making progress in tracking down SARS-CoV-2, the coronavirus implicated in Covid-19 diseases whose wide variability in clinical profiles baffles physicians. This may be due to our genes, which form the basic unit of our heredity. Genes are responsible for our physical appearance, the functioning of our cells, but also for our vulnerability to certain diseases. In human cells, genes are located on loci, at specific places on the chromosomes, which are located in the heart of our cells, the nucleus.
We have mentioned the study according to which a DNA fragment inherited from Neanderthal multiplies the risk of a severe form of Covid-19. Today, Jean-Marc Sabatier, PhD in Cellular Biology and Microbiology, research director at the CNRS, affiliated to the Institute of Neuro-Physio-pathology (INP) of the University of Aix-Marseille, explains that the presence of the HLA B27 gene located on human chromosome 6, is associated with a certain number of autoimmune diseases.
“This means that an individual carrying this gene is more likely than others to develop these autoimmune diseases: chronic inflammatory bowel disease (Crohn’s disease), rheumatoid arthritis, psoriasis, multiple sclerosis… The gene has also been associated with heart disease (myocarditis) and lung disease (fibrosis), as well as various cardiovascular and inflammatory disorders. This HLA B27 gene will play a key role in the recognition mechanisms of the immune system, adds the scientist. If this gene predisposes to certain autoimmune diseases, it is also known to be protective against HIV and hepatitis C viruses.
The example of Japan
Autoimmune diseases are notably driven by the RAS (renin-angiotensin system, an essential hormonal/physiological system found throughout the human body that controls the innate immunity responsible for autoimmune diseases), which is also involved in Covid-19 symptomatology and diseases.
This HLA B27 gene is present in 6-8% of Caucasians/Europeans, 4-5% in North Africa, but only 1% in the rest of Africa, 2-9% in Chinese and 0.1-0.5% in Japanese. Japan has a population of about 126 million people, roughly twice that of France. It has had 14 times fewer cases of Covid-19 and 14 times fewer deaths. There are 116 deaths per million people in Japan compared to 1664 deaths per million people in France.
The HLA B27 gene thus seems to play a major role in the susceptibility to SARS-CoV-2 and the development of Covid-19 diseases in people who carry it.