No evidence for involvement of alleles of the 825-C/T polymorphism of the G-protein subunit β3 in body weight regulation

The 825-C/T polymorphism of the β3 subunit of the heterotrimeric G protein gene (GNB3) has been shown to be associated with essential hypertension in humans. Recently, it was also reported that the 825-T allele has a higher frequency in obese than non-obese hypertensives suggesting that the primary effect of this allele is on body weight. The association to hypertension might merely be a secondary effect of the higher weight of the respective allele carriers. - To investigate an involvement of the 825-Tallele in body weight regulation in young individuals, we evaluated allele frequencies in 440 extremely obese children and adolescents (82.9% had a body mass index [BMI] ≥99th percentile), 51 obese students (BMI ≥90^th percentile), 110 normal weight students (BMI between 40^th and 60^th percentile) and 144 underweight students (BMI≤15^th percentile). The study groups were genotyped by polymerase chain reaction with subsequent restriction fragment length polymorphism analysis (PCR-RFLP). The one-sided Yates- corrected x²-test and the Cochran-Armitage trend test for association were performed. Tests for association were negative. The 825-T allele frequencies were similar in the four study groups belonging to different weight ranges (extreme early onset obesity: 0.29; obesity: 0.28; normal weight: 0.35; underweight: 0.32). Similarly, genotype frequencies did not differ between the groups. We concluded that the 825-T allele of the GNB3 does not play a major role in weight regulation in German children, adolescents and young adults.