A comprehensive genetic database research conducted by a research team at the Hokkaido University has revealed that there is no significant difference in seven genes responsible for assisting virus entry into human cells and recognition of virus RNA in human cells, across populations and ethnic groups. The research findings have revealed that in the United States, African Americans and Latinos, and in the United Kingdom, ethnic minorities are excessively affected by Covid-19, developing severe symptoms as well as showing profound proportion of mortalities relative to regional and ethnic groups. The research findings were published in the medical journal Infection, Genetics and Evolution, sponsored by the National Institutes of Health and by Grant-in-Aids for Scientific Research from the Japan Society for the Promotion of Science.
Variation in genes associated with viral entry of SARS-CoV-2 unlikely to influence COVID-19 morbidity and mortality, study finds https://t.co/mwYZsgsqGh
— Daily 2 Daily News (@Daily2DailyNews) September 25, 2020
Even morbidity and mortality rates are significantly disproportionate between ethnic groups and population worldwide. Therefore, it is presumed that genetic predisposition may have something to do with the disparities in diseases manifestation and infection severity. To investigate the genetic variation disparities, research team, including Assistant Professor Ji-Won Lee of Hokkaido University’s Graduate School of Dental Medicine, surveyed publicly available databases of genomic variants, including gnomAD, the Korean Reference Genome Database, TogoVar (a Japanese genetic variation database) and the 1000 Genomes Project. Scientist extensively studied genetic mutations and variants in seven genes, across multiple regional and ethnic groups in seven previously mentioned genes.
SARS-CoV-2 coronavirus has spiked protein (S protein) on its envelope, which encloses the virus. It helps the virus to bind the ACE2 receptor on the human cells. After entering the human cell, it breaks down into two pieces by the enzymes TMPRSS2 and cathepsin B and L, thereby the viral RNA binds with proteins such as TLR3, TLR7 and TLR8, triggering an innate (immediate) immune response. In the current study, researchers therefore investigated genetic changes in fundamental genes responsible for entering the host cells, ACE2 and TMPRSS2; and sensing of viral genomic RNAs (i.e., TLR3/7/8).
Results have revealed that proteins that reside in the active domains of these basic genes required for viral susceptibility are found highly conserved among population. From the data analyzed, no scientific evidence was found for genetic differences in ACE2, TMPRSS2, and TLR3/7/8 that predispose to ethnic differences. Moreover, the largest number of genetic changes in seven genes were in ACE2. However, this does not affect the function of these proteins. Since the difference was not that significant, overall variation frequency was less than 0.01 percent, the scientists determined there is no significant difference across populations or ethnic groups in the functions of the seven proteins involved in infection. Further, disproportionality in results indicate high incidence and mortality rates in African Americans in the US, it could be due to genetic and non-genetic factors.