IL1B genetic variation and plasma C-reactive protein level among young adults: the CARDIA study.
OBJECTIVE
Interleukin-1B (IL1B) modulates C-reactive protein (CRP) expression. However, whether IL1B genetic variation is associated with CRP level is unknown. Further, obesity, a state of low-grade inflammation that influences cellular IL-1 functions may modify this association.


RESULTS
Study participants (N=3289), 48% blacks and 52% whites, had CRP level measurements at year 7 and year 15 examinations as part of the CARDIA study. Ten tag single nucleotide polymorphisms (SNPs) that characterize common IL1B gene variation were genotyped. In SNP analysis, no significant associations with either level or change in time CRP were observed after multiple testing adjustments. However, global ILIB gene variation was associated with year 7 to year 15 change in CRP (global nominal p=0.004, multiple testing corrected p=0.048) among obese blacks. Compared to the commonest haplotype, a common haplotype that includes the SNP rs1143642 was associated with greater increases in CRP from year 7 to year 15 among obese blacks and whites while another common haplotype that includes the SNP rs3917356 was associated with decreased change in CRP from year 7 to year 15 among obese blacks. The rare alleles of ILIB SNPs, SNP 7114 (rs1143642) and SNP 3298 (rs3917356), were associated with greater increases and decreases in CRP from year 7 to year 15 among blacks, respectively, compared to their common variants.


CONCLUSIONS
IL1B genetic variation may have a role in CRP level regulation and this association may be modified by obesity.
Cardiovascular Health Research Unit, Department of Epidemiology, University of Washington, Seattle, WA, USA. denquoba@hsph.harvard.edu
Daniel A
DA
Enquobahrie
Kenneth
K
Rice
O Dale
OD
Williams
Michelle A
MA
Williams
Myron D
MD
Gross
Cora E
CE
Lewis
Stephen M
SM
Schwartz
David S
DS
Siscovick
D000293:Adolescent; D044383:Black People / Q000235:genetics; D002097:C-Reactive Protein / Q000378:metabolism*; D005260:Female; D014644:Genetic Variation; D006239:Haplotypes; D006801:Humans; D053583:Interleukin-1beta / Q000235:genetics*; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000208:ethnology / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D044465:White People / Q000235:genetics; D055815:Young Adult
D053583:Interleukin-1beta; D008055:Lipids; D002097:C-Reactive Protein