title: Association of an allelic variant of interleukin-6 with subclinical carotid atherosclerosis in an Australian community population.
abstract: OBJECTIVE
  Atherosclerosis can be viewed as a low grade inflammatory process, and genetic polymorphisms within cytokines are candidate risk factors for the development of atherosclerosis. We examined the association of a common functional variant in the IL-6 gene with carotid intimal-medial wall thickness (IMT) and the presence of plaques in a randomly selected, cross-sectional Australian population.
  
  
  METHODS
  B-mode carotid ultrasound was performed on 1109 subjects aged 27-77 years, who were genotyped for the IL-6 polymorphism (-174G>C) and assessed for conventional cardiovascular risk factors.
  
  
  RESULTS
  The frequency of the IL-6 -174C allele was 0.41. Initial univariate analysis showed no association of the IL-6 -174G>C polymorphism with carotid IMT. Multivariate analysis however showed an association of the IL-6 -174C allele with increased IMT in subjects older than the median age of 53 years (P=0.005). Initial univariate analysis of the IL-6 -174G>C polymorphism and carotid plaque showed no association in the whole sample. In multivariate analysis the -174C allele was independently associated with an increased risk of carotid plaque in the whole sample (CC vs GG, OR=2.22, 95% CI=1.32 to 3.73, P=0.003).
  
  
  CONCLUSIONS
  This study shows that the IL-6 -174G>C variant is independently associated with carotid plaque formation in the whole population and an increased carotid IMT in older subjects within a randomly selected, cross-sectional Australian population.
authors.affiliation: Clinical Biochemistry, Western Australian Centre for Pathology and Medical Research, Western Australia, Perth, Australia. caroline.chapman@health.wa.gov.au
authors.forename: Caroline M L
authors.initials: CM
authors.lastname: Chapman
authors.forename: John P
authors.initials: JP
authors.lastname: Beilby
authors.forename: Steve E
authors.initials: SE
authors.lastname: Humphries
authors.forename: Lyle J
authors.initials: LJ
authors.lastname: Palmer
authors.forename: Peter L
authors.initials: PL
authors.lastname: Thompson
authors.forename: Joseph
authors.initials: J
authors.lastname: Hung
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000235:genetics*; D003430:Cross-Sectional Studies; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D014463:Ultrasonography; D014904:Western Australia / Q000453:epidemiology
chemical_list: D015850:Interleukin-6