Interleukin-6 Gene Polymorphisms (rs1800796, rs1800797, and rs2069845) and Susceptibility to Severe COVID-19 in Southern Brazil

Infection with SARS-CoV-2, the virus responsible for COVID-19, is associated with cytokine storm, an excessive immune response. Interleukin-6, a multifunctional cytokine, is involved in the COVID-19 immune response. Functional polymorphisms in the interleukin-6 gene promoter, namely rs1800796, rs1800797, and rs2069845, may contribute to individual susceptibility to or severity of COVID-19. In this study, 106 healthy SARS-CoV-2-negative individuals (controls) and 106 patients with severe COVID-19 (COVID-19 group), confirmed by qPCR or rapid antigen tests, were genotyped using fluorescent probes for polymorphisms. All participants were from southern Brazil. Groups were matched for sex and body mass index, with a median age of 56–57 years. The COVID-19 group exhibited blood biomarker concentrations consistent with severe disease. No significant differences were detected in genotypic or allelic frequencies between groups, and all polymorphisms conformed to the Hardy–Weinberg equilibrium. The control group minor allelic frequencies for rs1800796 (allele C, 11.3%; 95% CI, 7–16), rs1800797 (allele A, 28.3%; 95% CI, 22–34), and rs2069845 (allele G, 36.8%; 95% CI, 30–50) were similar to those of African, American, and European populations. The polymorphisms investigated were not associated with severe COVID-19 in this cohort.