Impact of IL-6 rs1800795 and rs1800796 polymorphisms on clinical outcomes of COVID-19: a study on severity of disease in Turkish population

Abstract

Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is exacerbated by cytokine storms, leading to severe inflammation. Interleukin-6 (IL-6) plays a critical role in this process, and variations in its promoter may influence disease severity. This study aims to investigate the relationship between IL6 promoter polymorphisms rs1800795 (G > C) and rs1800796 (G > C) and the severity of COVID-19 in the Turkish population. A total of 332 participants were included: 84 control, 80 with mild COVID-19, and 168 with severe COVID-19. IL6 polymorphisms were genotyped using the restriction fragment length polymorphism (RFLP) method. The genotypes rs1800795 GC (OR = 3.00, 95% CI: 1.669–5.398, p < 0.000), CC (OR = 7.44, 95% CI: 2.899–19.131, p < 0.000), and rs1800796 GC (OR = 2.76, 95% CI: 1.603–4.761, p < 0.000), as well as the alleles rs1800795 C (OR = 3.01, p < 0.000) and rs1800796 C (OR = 1.97, p = 0.002), may be associated with the severity of COVID-19. According to the Jonckheere-Terpstra (J-T) test, the most significant trends that vary linearly with disease severity were observed for D-dimer [J-T = 15.896, Effect size = 0.68 (0.61 to 0.76), p < 0.000] and CRP [J-T = 15.389, Effect size = 0.66 (0.59 to 0.73), p < 0.000]. The distribution of clinical parameters across genotype combinations (rs1800796/rs1800795*) showed that GC/GC* and GC/CC* were linked to a higher risk of severe inflammation, clotting, and organ damage. Additionally, it has been determined that the G-C and C-C haplotypes may be associated with increased severity of COVID-19. The rs1800795 and rs1800796 polymorphisms are linked to COVID-19 severity and could help guide future treatment strategies.