Polymorphism of interleukin-1 receptor antagonist gene and obesity

Background: Cytokines appear to be major regulators of adipose tissue metabolism. Interleukin-1 receptor antagonist (IL-1ra) serum concentrations are increased in human obesity, and are under strong genetic control. We tested the hypothesis that the IL-1ra gene might be a candidate for obesity. Methods: We investigated the frequency of a penta-allelic 86-bp tandem repeat (VNTR) in the intron 2 of IL-1ra gene in 52 lean (body mass index (BMI) <25 kg/m ²), 133 overweight (BMI 25-29.9 kg/m²) and 76 obese (BMI ≥30.0 kg/m²) otherwise healthy Korean women. Total fat mass and percent body fat were determined by dual-energy X-ray absorptiometry. Genomic DNA was extracted and used for polymerase chain reaction-based genotyping of IL-1ra. Results: Carriers of the allele 2 did not show a significant difference in physical and clinical characteristics. The genotypic, or allelic distribution did not differ markedly between the three groups. The relative risk of being obese in comparison with lean group tended to be higher in allele 2 carriers, but not significantly. Conclusions: We found no relationship between the IL-1ra polymorphism and BMI in Korean women.