Effect of interleukin-6 promoter polymorphisms in survivors of myocardial infarction and matched controls in the North and South of Europe

Elevated plasma IL-6 levels have been implicated in the pathogenesis of coronary heart disease. We have investigated the association of two polymorphisms in the promoter of IL-6 (-572G>C and -174G>C) with levels of inflammatory markers and risk of myocardial infarction (MI) in a European study of MI survivors and age-matched controls from two high-risk centres in the North of Europe, and two low risk centres in the South. IL-6 and CRP levels were similar in controls in both regions, but were higher in cases. For the -174G>C polymorphism the rare -174C allele showed a regional difference in allele frequency, being more common in the North European group (0.43 vs 0.28; p<0.0005), where-174C allele carriers showed an apparent reduced risk of MI compared to -174GG homozygotes (OR 0.53, 95%CI 0.32, 0.86). No such effect was observed in the South or with the -572G>C in either group. Neither genotype was associated with a significant effect on plasma IL-6 levels in either cases or controls. Furthermore, no regional difference was observed in the frequency of the -572G>C SNP, suggesting that these polymorphisms are unlikely to be contributing to the observed increased risk of cardiovascular disease in Northern Europe.