Effect of tumour necrosis factor-alpha and interleukin-6 promoter polymorphisms on course of Crimean-Congo hemorrhagic fever in Turkish patients

Objective: In this case-control study, we investigated whether IL-6 (-174G/C) and TNF-alpha (-308G/A) gene polymorphisms affect the clinical course and outcome of CCHF. Methods: Total 150 patients with CCHF and 170 controls were examined in this study. Genotyping of these polymorphisms were performed by PCR-RFLP methods. Results: We found no statistically significant differences in genotype and allele frequencies of these polymorphisms between patients and controls [(chi(2) = 1.31, p = 0.51 for TNF-alpha) and (chi(2)=2.61, p = 0.27 for IL-6)]. Either TNF-alpha AA or IL-6 CC genotypes in dead cases were not observed in this study. Frequency of heterozygous genotypes in both IL-6 (GC) and TNF-alpha (GA) was higher in dead patients than living patients. However, the difference was not statistically significant. A significant difference was found in AST levels and INR when compared to patients with CCHF who died and who survived [OR = 13.9 (95% CI = 1.79-107) for INR, p = 0.01] and [OR = 23.3 (95% CI = 3.62-149) for AST, p = 0.001], respectively. Conclusion: We did not find a significant association of IL-6 -174G/C and TNF-alpha -308G/A polymorphisms on the prognosis of CCHF and mortality in this study. We suggest that AST and INR may be important biomarkers for determining the risk of severity and death as a result of infection with Crimean-Congo hemorrhagic fever virus (CCHFV).