Association of Trp64Arg polymorphism of the beta3-adrenergic receptor gene and no association of Gln223Arg polymorphism of the leptin receptor gene in Japanese schoolchildren with obesity.

OBJECTIVE: To investigate whether Trp64Arg polymorphism of the beta3-adrenergic receptor (beta3-AR) gene and Gln223Arg polymorphism of the leptin receptor (Ob-R) gene are associated with obesity in Japanese schoolchildren. DESIGN: Population study of participants from a rural town located within 50 km northeast of Tokyo based on school medical examinations. SUBJECTS: 553 Japanese schoolchildren (291 boys and 262 girls) who were 9-15 y old with a mean age of 11.9 +/- 1.8 y. MEASUREMENTS: DNA was extracted from whole blood and genotyped by PCR-RFLP. Height, weight and blood pressure were measured in school medical examinations. Total cholesterol, triglyceride and HDL-cholesterol concentrations were measured by an autoanalyzer. Obesity index, body mass index (BMI) and LDL-cholesterol concentration were calculated by the respective formulae. RESULTS: In Trp64Arg polymorphism of the beta3-AR gene, the number of obese subjects with Trp/Arg or Arg/Arg genotypes was significantly higher than that of the non-obese subjects (chi2=5.79, P=0.02). The obesity index of subjects with the Arg/Arg or Arg/Trp genotype was significantly higher than that of those with the Trp/Trp genotype (8.2 +/- 18.7% vs 4.5 +/- 15.8%, P=0.04). Moreover, after adjustments for age and gender, BMI of subjects with the Trp/Arg or Arg/Arg genotype was significantly higher than that of those with the Trp/Trp genotype (19.4 +/- 3.6 kg/m2 vs 18.9 +/- 3.2 kg/m2, P= 0.02). However, no significant differences were observed in the clinical characteristics among the genotype groups of the Ob-R gene. CONCLUSIONS: Trp64Arg polymorphism of the beta3-AR gene appears to be a genetic risk factor for obesity in Japanese children, but Gln223Arg polymorphism of the Ob-R gene does not appear to be associated with obesity.