Association of an allelic variant of interleukin-6 with subclinical carotid atherosclerosis in an Australian community population.
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.
Chapman
Caroline M L
CM
Clinical Biochemistry, Western Australian Centre for Pathology and Medical Research, Western Australia, Perth, Australia. caroline.chapman@health.wa.gov.au
Beilby
John P
JP
Humphries
Steve E
SE
Palmer
Lyle J
LJ
Thompson
Peter L
PL
Hung
Joseph
J
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
D015850:Interleukin-6