Evaluation of the relationship between IL-6 gene single nucleotide polymorphisms and the severity of COVID-19 in an Iranian population.

Background: Emerged coronavirus disease 2019 (COVID-19) is a pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2). Disease severity is associated with elevated levels of proinflammatory cytokines, such as interleukin-6 (IL-6). Genetic polymorphisms in the regulatory regions of cytokine genes may be associated with differential cytokine production in COVID-19 patients. This study aimed to investigate the association between three potentially functional single-nucleotide polymorphisms (SNPs) in the promoter region of IL-6 and the severity of susceptibility to COVID-19 in an Iranian population.

Methods: In total, 346 individuals (175 patients with severe COVID-19 and 171 patients with mild COVID-19) were recruited for this cohort study. Genomic DNA was extracted from peripheral blood leukocytes of patients to determine the genotypes of three selected SNPs (rs1800795 (-174 G > C), rs1800796 (-572 G > C), and rs1800797 (-597 G > A)) in the promoter region of the IL-6 gene using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results: There were no significant differences in the genotype or allele distribution of selected SNPs (rs1800795 (-174 G > C), rs1800796 (-572 G > C), and rs1800797 (-597 G > A)) in the promoter region of the IL-6 gene in patients with severe COVID-19 and patients with mild COVID-19.

Discussion: Our study indicated that these SNPs are not associated with COVID-19 severity in the Kurdish population from Kermanshah, Iran.