C allele of rs479200 of the host EGLN1 gene - a risk factor for severe COVID-19 (pilot study)

Abstract

Background Coronavirus disease-2019 (COVID-19) symptoms can range from asymptomatic, moderate to severe manifestations that result in an overall global case fatality rate of 2-7 %. While each variant has had it challenges, and some variants are more severe than others, risk factors of severe COVID-19 are still under investigation. In this context, the host genetic predisposition is also a crucial factor to investigate. In the present study, we investigated host genotypes of the SNP rs479200 of the host EGLN1 gene, previously implicated in high altitude pulmonary edema (HAPE), some of whose symptoms such as hypoxia profoundly overlap with severe COVID-19. Methods After informed consent, 158 RT-PCR confirmed COVID-19 patients (March 2020 to June 2021) were enrolled in the study. Based on their clinical manifestations, disease severity was categorized by the clinical team. Blood samples were drawn and DNA was extracted from the clot to infer different genotypes of the SNP rs479200 of the host EGLN1 gene. PCR-RFLP analysis of the SNP rs479200 (C > T) was performed with an amplicon size of 367 bp. Various genotypes (TT, TC and CC) were assigned based on the presence/absence of a restriction site (T/GTACA) for restriction enzyme BsrGI. Allele frequencies, Hardy-Weinberg Equilibrium (HWE) and multinomial logistic regression were performed using statistical tool SPSS version 23 (IBM). Findings We observed that the severe COVID-19 category was composed of comparatively younger patients with mean age (34.9), compared to asymptomatic and moderate categories whose mean age was 49.7 and 54.3, respectively. Preponderance of males and high heterozygosity (TC) was observed across the clinical categories. Notably, the frequency of C allele (0.664) was 2-fold higher than the T allele (0.336) in severe COVID-19 patients, whereas the allele frequencies were similar in asymptomatic and moderate category of COVID-19 patients. Multinomial logistic regression showed an association of genotypes with increasing clinical severity; odds ratio (adjusted OR- 11.414 (2.564-50.812)) and (unadjusted OR- 6.214 (1.84-20.99)) for the genotype CC in severe category of COVID-19. Interestingly, the TC genotype was also found to be positively associated with severe outcome (unadjusted OR-5.816 (1.489-22.709)), indicating association of C allele in imparting the risk of severe outcome. Interpretation The study provides strong evidence that the presence of C allele of SNP (rs479200) of the EGLN1 gene associates with severity in COVID-19 patients. Thus, the presence of C allele may be a risk factor for COVID-19 severity. This study opens new avenues towards risk assessment that include EGLN1 (rs479200) genotype testing and identifying patients with C allele who might be prioritized for critical care.