Variation analysis of beta3-adrenergic receptor and melanocortin-4 receptor genes in childhood obesity

β-3AR W64R Polymorphism and 30-Minute Post-Challenge Plasma Glucose Levels in Obese Children

OBJECTIVE

In this study, we aimed to investigate the association of W64R polymorphism of the β3-adrenergic receptor gene (β-3AR) with childhood obesity and related pathologies.

METHODS

β-3AR gene W64R genotyping was carried out in 251 children aged 6-18 years. Of these subjects, 130 were obese (62 boys) and 121 were normal-weight (53 boys). In the obese group, fasting lipids, glucose and insulin levels were measured. Oral glucose tolerance test (OGTT) was performed in 75 of the obese patients.

RESULTS

The frequency of W64R genotype was similar in obese and non-obese children. In obese children, relative body mass index, waist-to-hip ratio, serum lipid, glucose and insulin levels, as well as homeostasis model assessment of insulin resistance (HOMA-IR) scores were not different between Arg allele carriers (W64R and R64R) and noncarriers (W64W). In 75 obese children, OGTT results showed that Arg allele carriers had significantly higher 30-minute glucose levels (p=0.027).

CONCLUSION

W64R polymorphism of the β-3AR gene is not associated with obesity and waist-to-hip ratio in Turkish children. Although there were no relationships between the genotypes and lipid, glucose/insulin levels or HOMA-IR, the presence of W64R variant seemed to have an unfavorable influence on early glucose excursion after glucose loading.

Visceral fat accumulation and metabolic syndrome in children: the impact of Trp64Arg polymorphism of the beta3-adrenergic receptor gene

AIM

To investigate the association between Trp64Arg polymorphism of the beta3-adrenergic receptor (ADRB3) gene and total fat mass, abdominal fat distribution, other metabolic derangements and metabolic syndrome (MS) in Japanese children.

METHODS

Molecular screening of the ADRB3 gene polymorphism (Trp64Trp, Trp64Arg and Arg64Arg) was carried out in 132 children aged 6-12 years: 73 were obese (45 boys) and 59 were not obese (27 boys). Visceral fat (VF) and subcutaneous fat (SF) area were measured using magnetic resonance imaging, blood pressure, lipid and glucose profiles.

RESULTS

The frequencies of Arg carriers (Trp64Arg or Arg64Arg) were significantly higher in obese children with MS, compared to obese children without MS and nonobese children. In obese children, Arg carriers had significantly higher VF area, systolic and diastolic blood pressure, and low-density lipoprotein cholesterol and triglyceride than Arg noncarriers (Trp64Trp). However, there were no differences in total fat mass and SF area between the two groups. In nonobese children, none of these parameters differed significantly between Arg carriers and noncarriers.

CONCLUSION

Trp64Arg polymorphism of the ADRB3 gene may affect VF accumulation and be associated with MS, a cluster of conditions involving aggravated lipid metabolism and higher blood pressure, in Japanese children.

Association of adrenergic receptor gene polymorphisms with adolescent obesity in Taiwan

BACKGROUND

Polymorphisms of β2-adrenergic receptor (ADRB2) and β3-adrenergic receptor (ADRB3) have been reported to be associated with obesity in adults and adolescents, although study results have been controversial. The aim of the present study was to investigate the association of polymorphisms of ADRB2 (Arg16Gly, Gln27Glu) and ADRB3 (Trp64Arg) with adolescent obesity in Taiwan.

METHODS

A total of 559 adolescent volunteers with equal numbers female and male were enrolled. Participants were divided into two groups: obese (body mass index [BMI]≥ 95th percentile) and normal weight (BMI 15th-85th percentile). Genomic DNA was extracted from buccal mucosa cells and genotyped in TaqMan assays. Genotype results and clinical subject characteristics were analyzed.

RESULTS

Among the three ADRB polymorphisms, only Arg16Gly polymorphism was found to be significantly correlated with adolescent obesity, especially in girls. Girls with genotype Gly/Gly had a lower probability of obesity than those with genotypes Arg/Gly or Arg/Arg (P= 0.006; Arg/Gly: odds ratio [OR], 2.57, 95% confidence interval [95%CI]: 1.22-5.41; Arg/Arg: OR, 3.03, 95%CI: 1.50-6.12). Girls with genotype Gly/Gly had lower BMI than those with genotype Arg/Arg (P= 0.049). Obese adolescents with genotype Gly/Gly had a lower probability of hypertension than those with genotype Arg/Gly or Arg/Arg (P= 0.005).

CONCLUSIONS

Arg16Gly polymorphism of ADRB2 was significantly associated with obesity in female adolescents, and those with the Gly/Gly genotype were associated with a lower possibility of obesity and lower BMI. This polymorphism was also associated with a lower probability of hypertension in obese adolescents. The other two polymorphisms of ADRB (Gln27Glu and Trp64Arg) were not associated with adolescent obesity in Taiwan.