Associations between serum C-reactive protein (CRP) levels and polymorphisms of CRP, interleukin 1B, and tumor necrosis factor genes among Japanese health checkup examinees.

C-reactive protein (CRP) is a sensitive marker of acute inflammation, which is associated with risk of cardiovascular and other chronic diseases. Some CRP polymorphisms are reported to affect the basal and stimulated CRP levels. Thus we conducted a population-based cross-sectional study to examine the associations of CRP levels with CRP C1444T polymorphism and two cytokine polymorphisms (IL-1B C-31T and TNF-A T-1031C), according to sex, age, smoking, alcohol, and BMI, in a total of 489 Japanese health checkup examinees (156 males and 333 females). Serum CRP levels were measured by high sensitivity latex-enhanced nephelometry. CRP C1444T, IL-1B C-31T and TNF-A T-1031C genotypes were genotyped by PCR-CTPP (polymerase chain reaction with confronting two-pair primers). Males, aged, smokers, and those with high BMI had a higher CRP on average. All genotype frequencies among the 489 subjects were in Hardy-Weinberg equilibrium. No significant associations of serum CRP levels with the genotypes of CRP C1444T and IL-1B C-31T were observed. TNF-A -1031CC polymorphism was significantly associated with high CRP values. For the females, those aged 61-69 years, never smokers, non-drinkers, or those with body mass index 24 or less, the association was remarkable. Since the biological mechanism is not clear, further investigations are required to confirm the association.