Genetic polymorphism of interleukin-6 gene and susceptibility to acute myocardial infarction

Objectives: Inflammatory processes play a pivotal role in the pathogenesis of atherosclerosis. Genes coding for cytokines such as interleukin-6 (IL-6) are candidates for predisposing to the risk of coronary artery disease. The aim of this study was to investigate whether molecular polymorphism of the IL-6 gene is involved in the predisposition to acute myocardial infarction (AMI). Methods: Genomic DNA and peripheral blood mononuclear cells of patients with AMI and controls were extracted. IL-6 gene variations were evaluated by polymerase chain reaction followed by restriction enzyme analysis. The mRNA expression of IL-6 gene and plasma levels of IL-6 and C-reactive protein (CRP) were analyzed. Results: The prevalence of 'C'allele in -174 G/C variation was higher in patients with AMI than in controls. The IL-6 -174 'C'allele is associated with high levels of IL-6 in the patients, of which the patients with CC and GC genotypes significantly have higher IL-6 concentrations, respectively. Increased CRP concentrations were associated with -174 G/C variation in the patients compared with controls. The mRNA expression levels of IL-6 were significantly higher in the patient compared with controls (P<0.001). Conclusion: The findings of this study indicate the relationship between IL-6 gene polymorphism and the risk of AMI, which suggests that genetic polymorphism in IL-6 gene, might be helpful for determining susceptibility to AMI in Iranian patients. In addition, susceptibility to AMI might be related to IL-6 gene expression, which affects its plasma levels. CRP plasma levels also were associated with IL-6 gene variation in the patients.