Jacquemin, B.* ; Antoniades, C.* ; Nyberg, F.* ; Plana, E.* ; Müller, M. ; Greven, S. ; Salomaa, V.* ; Sunyer, J.* ; Bellander, T.* ; Chalamandaris, A.G.* ; Pistelli, R.* ; Koenig, W.* ; Peters, A.
Common genetic polymorphisms and haplotypes of fibrinogen alpha, beta, and gamma chains affect fibrinogen levels and the response to proinflammatory stimulation in myocardial infarction survivors: The AIRGENE study.
This study was designed to investigate whether single nucleotide polymorphisms (SNPs) and haplotypes of the fibrinogen gene-cluster (fibrinogen chains alpha [FGA], beta [FGB], and gamma [FGG]) could explain the inter- and intraindividual variability of fibrinogen levels in patients with atherosclerosis. We also searched for genetic determinants affecting the responses of fibrinogen genes to proinflammatory stimulation. BACKGROUND: The mechanisms regulating fibrinogen levels are not fully understood, and they are likely to be regulated by complex gene-environment interactions. METHODS: In the AIRGENE study, 895 survivors of myocardial infarction from 5 European cities were followed prospectively for 6 to 8 months, and plasma fibrinogen, interleukin (IL)-6, and C-reactive protein levels were determined monthly. We analyzed 21 SNPs and the corresponding haplotypes in the 3 fibrinogen genes. RESULTS: Eight SNPs in FGA and FGB were significantly associated with fibrinogen levels. Similarly, 2 different haplotypes in FGA and 3 in FGB were also associated with mean fibrinogen levels. The IL-6 levels had a significant impact on the associations between SNPs/haplotypes in FGA/FGB and fibrinogen levels. We also identified SNPs and haplotypes in FGA and FGB with strong impact on the intraindividual variability of fibrinogen during the follow-up period. CONCLUSIONS: We identified common SNPs and haplotypes on FGA/FGB genes, explaining the interindividual and intraindividual variability of fibrinogen levels, in patients with a history of myocardial infarction. We have also identified for the first time, SNPs/haplotypes on FGA/FGB whose effects on fibrinogen expression are modified by the underlying IL-6 levels. These findings may have an impact on risk stratification and the design of genetically guided therapeutic approaches in patients with advanced atherosclerosis.