Genetic and Blood group association with severity of COVID-19

One of the most confusing issues associated with COVID-19 is the considerable variation in disease behavior among patients who are diagnosed as infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)—otherwise known as the virus that causes the coronavirus disease 2019.

As of June 15, 2020, there were over 8 million cases confirmed worldwide and almost 440,000 total deaths. Unfortunately, the mortality rates are driven by the group of patients who have a severe respiratory failure (related to both pneumonia in the lungs and acute respiratory distress syndrome).

The purpose of this study, published in The New England Journal of Medicine, is to test the postulation that genomewide association analysis might allow for the identification of potential genetic factors involved in the development of COVID-19.

At the peak of the outbreak in Italy and Spain—earlier in 2020—this study intended to be a genome-wide associations study (GWAS) to help delineate host genetic factors that could contribute to patients with COVID-19 and respiratory failure.

The results? The study identifies a specific gene cluster that could act as a genetic susceptibility locus in patients with COVID-19 who experience respiratory failure.

The Study: Understanding the Methodology 

Scientists, researchers, and medical professionals conducted a study with 1980 patients with both COVID-19 and severe disease (respiratory failure) at seven different hospitals in the Spanish and Italian epicenters of the SARS-CoV-2 pandemic in Europe.

After excluding the outliers and ensuring quality control, the study used 835 patients and 1255 control participants from Italy alongside 775 patients and 950 control participants from Spain.

Over 8,580,000 single-nucleotide polymorphisms were analyzed.

What The Study Found: The Results 

The results of the study detected cross-replicating associations with rs11385942 at locus 3p21.31 and with rs657152 at locus 9q34.2, which were significant at the genome-wide level (P<5×10−8) in the meta-analysis of the two case-control panel. Further, at locus 3p21.31, the association signal spanned the genes SLC6A20, LZTFL1, CCR9, FYCO1, CXCR6, and XCR1.

In the cohort of ABO blood group locus, a blood-group specific analysis showed a higher risk in blood group A than in other blood groups as well as a protective effect in blood group O when compared to other blood groups.

So, what does this all mean?

Essentially, scientists, researchers, and medical professionals examined these patients and control participants and found through genomewide testing that a 3p21.31 gene cluster as a genetic susceptibility locus in patients with Covid-19 with respiratory failure and confirmed a potential involvement of the ABO blood-group system.