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

Meta-analysis investigating the impact of the LEPR rs1137101 (A>G) polymorphism on obesity risk in Asian and Caucasian ethnicities

Obesity is a chronic condition which is identified by the buildup of excess body fat caused by a combination of various factors, including genetic predisposition and lifestyle choices. rs1137101 (A > G) polymorphism in the CHR1 domain of LEPR protein linked to different diseases including obesity. Nevertheless, the connection between this polymorphism and the likelihood of developing obesity has not been determined definitively. Therefore, a meta-analysis was conducted to assess the relationship between rs1137101 and the risk of obesity. The meta-analysis included all studies meeting pre-defined criteria, found through searching databases up until February 2023. A combined odds ratio with a 95% confidence interval was estimated as overall and in continent subgroups for homozygous, heterozygous, recessive, dominant and allelic models using the fixed or the random-effects model. The meta-analysis identified 39 eligible studies with cases and controls (6099 cases/6711 controls) in 38 articles under different ethnic backgrounds. The results indicated a significant relationship between rs1137101 and the likelihood of developing obesity in each of the genetic models [the homozygous model (GG vs. AA: 95% Confidence Interval = 1.12-1.73, Odds Ratio = 1.39, P value = 0.003); the heterozygous model (AG vs. AA: 95% Confidence Interval = 1.07-1.42, Odds Ratio = 1.23, P value = 0.005); the dominant model (AG/GG vs AA: 95% Confidence Interval = 1.10-1.49, Odds Ratio = 1.28, P value = 0.001); the recessive model (GG vs AA/AG: 95% Confidence Interval = 1.02-1.45, Odds Ratio = 1.21, P value = 0.03); and the allelic model (G vs A; 95% Confidence Interval = 1.07-1.33, Odds Ratio = 1.19, P value = 0.002)] tested. Additionally, with an FDR <0.05, all genotypic models demonstrated statistical significance. The association remained significant among subgroups of Asian and Caucasian populations, although analysis in some genetic models did not show a significant association. Begg's and Egger's tests did not show publication biases. In sensitivity analysis, one particular study was found to have an impact on the Recessive model's significance, but other models remained unaffected. The current meta-analysis found significant indications supporting the association between rs1137101 and obesity. To avail a deeper understanding of this association, future research should include large-scale studies conducted in diverse ethnic populations.

The Relationship of Leptin (+19) AG, Leptin (2548) GA, and Leptin Receptor Gln223Arg Gene Polymorphisms with Obesity and Metabolic Syndrome in Obese Children and Adolescents

PURPOSE

Obesity is defined as the abnormal or excessive accumulation of fat over acceptable limits. Leptin is a metabolic hormone present in the circulation in amounts proportional to fat mass. Leptin reduces food intake and increases energy expenditure, thus regulating body weight and homeostasis. Various polymorphisms are present in the leptin gene and its receptor. These polymorphisms may be associated with obesity. This study aimed to show the association of leptin (+19) AG, leptin (2548) GA, and Gln223Arg leptin receptor polymorphisms with obesity and metabolic syndrome in Turkish children aged 6-17 years, and to conduct further investigations regarding the genetic etiology of obesity.

METHODS

A total of 174 patients diagnosed with obesity and 150 healthy children who were treated at Tokat Gaziosmanpaşa Medical School Hospital between September 2014 and March 2015 were included in this study. The ages of the children were between 6 and 17 years, and anthropometric and laboratory results were recorded. Genotyping of leptin (+19) AG, leptin (2548) GA, and leptin receptor Gln223Arg polymorphisms was performed by polymerase chain reaction.

RESULTS

An association between leptin receptor Gln223Arg gene polymorphism and obesity was detected.

CONCLUSION

Further studies are needed to determine the role of genetic etiologies and to indicate the role of leptin signal transmission impairment in the pathogenesis of obesity. We hope that gene therapy can soon provide a solution for obesity.

The ADRB3 rs4994 polymorphism increases risk of childhood and adolescent overweight/obesity for East Asia's population: an evidence-based meta-analysis

Whether the Adrenoceptor Beta 3 (ADRB3) gene rs4994 polymorphism could affect the individual risk of childhood and adolescent overweight/obesity remains controversial. This meta-analysis was performed to estimate the prevalence of this polymorphism in overweight/obesity, and test the potential association by summarizing existing evidence. Comprehensive literature search in PubMed, Web of Science, Cochrane Library, Wanfang, and CNKI databases was performed to identify eligible data sets. Finally, 16 studies involving 5,147 overweight/obese cases and 7,350 non-obese controls were included for further synthetic analyses. Odds ratio (OR) and its corresponding 95% confidence intervals (CIs) were statistically calculated. Totally, 69.9% of the included subjects came from East Asia. In the meta-analysis for overall population, statistically significant associations with increased risk of childhood and adolescent overweight/obesity were identified in allele model (OR 1.23, 95% CI 1.10–1.38), heterozygote model (OR 1.39, 95% CI 1.16–1.68), and dominant model (OR 1.31, 95% CI 1.12–1.54). Further stratified analysis according to geographical regions revealed that the statistical significance could only be detected in the East Asia subgroup in allele model, homozygote model, heterozygote model, and dominant model. In summary, our meta-analysis indicated that the ADRB3 rs4994 polymorphism could significantly increase the risk of childhood and adolescent overweight/obesity, especially for the East Asia’s population.

Association Between Trp64arg Polymorphism of the β3 adrenoreceptor Gene and Female Sex in Obese Turkish Children and Adolescents

PURPOSE

The β3-adrenergic receptor (ADRB3) is expressed in visceral adipose tissue and has been speculated to contribute to lipolysis, energy metabolism, and regulation of the metabolic rate. In this study, we aimed to investigate the association of polymorphism of the ADRB3 gene with the sex of children with obesity and related pathologies.

METHODS

ADRB3 gene trp64arg genotyping was conducted in 441 children aged 6-18 years. Among these subjects, 264 were obese (103 boys; 161 girls) and 179 were of normal weight (81 boys; 98 girls). In the obese group, fasting lipids, glucose and insulin levels, and blood pressure were measured. Metabolic syndrome (MS) was defined according to the modified World Health Organization criteria adapted for children.

RESULTS

The frequency of trp64arg genotype was similar in obese and normal weight children. In obese children, serum lipid, glucose, and insulin levels; homeostasis model assessment of insulin resistance (HOMA-IR) scores; and MS were not different between arg allele carriers (trp64arg) and noncarriers (trp64trp). In 264 obese children, genetic analysis results revealed that the arg allele carriers were significantly higher in girls than in boys (p=0.001). In the normal weight group, no statistically significant difference was found between genotypes of boys and girls (p=0.771).

CONCLUSION

Trp64arg polymorphism of the ADRB3 gene was not associated with obesity and MS in Turkish children and adolescents. Although no relationships were observed between the genotypes and lipids, glucose/insulin levels, or HOMA-IR, the presence of trp64arg variant was frequent in obese girls, which can lead to weight gain as well as difficulty in losing weight in women.

Influence of K656N Polymorphism of the Leptin Receptor Gene on Obesity-Related Traits in Nondiabetic Afro-Caribbean Individuals

Background: Ethnic variations have been reported in allelic frequencies of the leptin receptor gene (LEPR) with population-specific effects. We aimed to explore the association of LEPR polymorphisms with obesity, metabolic syndrome (MetS), and leptin levels in Afro-Caribbean nondiabetic subjects. Methods: Genotypic analysis of three LEPR polymorphisms (K109R, Q223R, and K656N) was performed using TaqMan allelic discrimination assays. Associations were measured with phenotypic variables, including body mass index (BMI), waist circumference (WC), and leptin levels. Linear and logistic regressions were performed to evaluate the effects of single-nucleotide polymorphisms (SNPs). Results: Mean age was 46 ± 12 years. Among the 375 participants, 29.3% were obese, 36.3% had abdominal obesity, and 18.1% had MetS. Significant association between BMI (P < 0.002) and WC (P < 0.005) was observed for K656N, whereas the associations were not statistically significant for the other two SNPs. No association was found with leptin levels for the three SNPs. The variant allele frequencies for LEPR 109R, 223R, and 656N were 0.16, 0.46, and 0.20, respectively. In dominant models, the variant allele 656N (GC/CC vs. GG) was associated with prevalence of obesity [odds ratio (OR) 1.82; P = 0.012] and abdominal obesity (OR 2.00; P = 0.007), but not significantly with prevalence of MetS (OR 1.72; P = 0.029). Individuals carrying four variant alleles of the three SNPs had a significantly higher risk of obesity (OR 2.86; P = 0.032) than those carrying none variant allele. Conclusion: Our results suggest an influence of K656N polymorphism in the LEPR gene on obesity and abdominal obesity in this Afro-Caribbean population.

Food Consumption as a Modifier of the Association between LEPR Gene Variants and Excess Body Weight in Children and Adolescents: A Study of the SCAALA Cohort

No studies showing that food consumption is a modifier of the association of variants of the leptin receptor gene (LEPR) with body weight have involved a Brazilian population. The aim of this study was to evaluate the modifying effect of dietary intake on the association between the LEPR gene and excess weight. In this study, 1211 children and adolescents aged 4⁻11 years were assessed. Participants were genotyped for 112 single-nucleotide variants of the LEPR gene. Anthropometric measurements were performed, and dietary data were obtained. Logistic regressions were used to study the associations of interest. Of the participants, 13.4% were overweight/obese. The risk allele (G) of the rs1137100 variant was associated with excess weight in individuals with fat consumption below the median (odds ratio OR = 1.92; 95% confidence interval CI = 1.18⁻3.14), with daily frequency of consumption of drink/artificial juice (OR = 2.15; 95% CI = 1.26⁻3.68) and refined cereals (OR = 2.17; 95% CI = 1.31⁻3.62) above the median. The risk allele (G) of variant rs1177681 was also associated with excess weight (OR = 2.74; 95% CI = 1.65⁻4.57) in subjects with a daily frequency of refined cereal consumption above the median. The association between LEPR and excess weight can be modulated by the type and distribution of dietary fatty acids, sugary drinks, and refined cereals.

Association between LEPR, FTO, MC4R, and PPARG-2 polymorphisms with obesity traits and metabolic phenotypes in school-aged children

PURPOSE

Evaluate the relationship of leptin receptor (LEPR) rs1137101, fat mass obesity-associated (FTO) receptors 9939609, melanocortin-4 receptors (MC4R) rs2229616 and rs17782313, and proliferator-activated receptor-gamma (PPARG) rs1801282 with clinical and metabolic phenotypes in prepubertal children.

RESEARCH QUESTION

What is the effect of polymorphisms on clinical and metabolic phenotypes in prepubertal children?

METHODS

A cross-sectional descriptive study was performed to evaluate anthropometric features, percentage body fat (%BF), biochemical parameters, and genotype in 773 prepubertal children.

RESULTS

FTO rs9939609 was associated with an increase in body mass index (BMI) and BMI z-score (zBMI). MC4R rs17782313 was associated with a decrease in BMI and +0.06 units in zBMI. LEPR, and PPARG-2 polymorphisms were associated with decreases in BMI and an increase and decrease units in zBMI, respectively. The homozygous SNPs demonstrated increases (FTO rs993609 and MC4R rs17782313) and decreases (LEPR rs1137101, PPARG rs1801282) in zBMI than the homozygous form of the major allele. In the overweight/obese group, the MC4R rs17782313 CC genotype showed higher average weight, zBMI, waist circumference, waist-circumference-to-height ratio, and waist-hip ratio, and lower BMI, mid-upper arm circumference, calf circumference, and %BF (P< 0.05). FTO rs9939609 AT and AA genotypes were associated with lower triglycerides (P < 0.05).

CONCLUSIONS

We showed that MC4R rs17782313 and FTO rs9939609 were positively associated with zBMI, with weak and very weak effects, respectively, suggesting a very scarce contribution to childhood obesity. LEPR rs1137101 and PPARG-2 rs1801282 had weak and medium negative effects on zBMI, respectively, and may slightly protect against childhood obesity.

ADRB3 polymorphism rs4994 (Trp64Arg) associates significantly with bodyweight elevation and dyslipidaemias in Saudis but not rs1801253 (Arg389Gly) polymorphism in ARDB1

Background

In some populations, obesity and body weight related disorders show a correlation with polymorphisms in three subtypes of beta-adrenoceptor (β1, β2, and β3) [ADRB1, ADRB2 and ADRB3] genes. We scanned for the polymorphism of Arg389Gly (rs1801253) in ADRB1 and Trp64Arg (rs4994) in ADRB3 genes in Saudi population to determine association, if any, of these polymorphisms with obesity and related disorders.

Methods

We studied 329 non-related adults (33.1% men and 66.9% women), aged 18–36 years. Anthropometric measurements were recorded, and Body mass index (BMI) and waist/hip ratio were calculated; leptin, insulin, lipidogram, and glucose concentrations were determined. ADRB1 and ADRB3 polymorphisms (Arg389Gly and Trp64Arg, respectively) were screened by DNA sequencing. The subjects were divided into three groups according to BMI: normal weight (BMI < 25 kg/m²), overweight (BMI ≥25.1–29.9 kg/m²) subjects, and obese (≥30 kg/m²).

Results

In the age-matched groups of the normal weight, overweight and obese male and female subjects, all anthropometric parameters were found to be significantly higher, and in the obese group, all biochemical parameters were significantly elevated compared to the normal weight controls. The allelic frequency of Gly389 ADRB1 did not differ amongst the three groups, whereas the frequency of Arg64 of ADRB3 gene was significantly higher in the overweight and obese subjects, compared with the normal weight subjects. In addition, subjects carrying Arg64 allele regardless of their BMI had a greater waist and hip circumference, W/H ratio, plasma cholesterol, triglyceride, LDL, leptin, insulin, and glucose level compared to those with the wild-type Trp allele.

Conclusion

The results of this study have shown a significant association between the Trp64Arg polymorphism in ADRB3 gene and the development of overweight and obesity in Saudi populations. It also has an influence on the levels of lipid, insulin, leptin, and glucose, whereas, Arg389Gly polymorphism in ADRB1 is not associated with overweight, obesity or dyslipidaemias in Saudis.

High-Carbohydrate/Low-Fat Diet-Induced Gender-Specific Serum Lipid Profile Changes Are Associated with LEPR Polymorphisms in Chinese Youth

BACKGROUND/AIMS

The study aimed to investigate the interactions of genetic variants in the leptin receptor (LEPR) gene with lipid profile changes following a high-carbohydrate/low-fat (HC/LF) diet in a Chinese Han population.

METHODS

Fifty-six healthy young subjects were given washout diets, followed by HC/LF diets consisting of 15% fat and 70% carbohydrate for 6 days. Serum lipid profiles and insulin levels before and after HC/LF diets were analyzed.

RESULTS

Statistically elevated high-density lipoprotein cholesterol (HDL-C), apolipoprotein A-1 (apoA-I), and insulin levels were only observed in the GG genotype of LEPR Lys109Arg but not in the A carriers after HC/LF diet. When gender was taken into account, significantly increased HDL-C, apoA-I, and insulin levels were found in women with the GG genotype. Moreover, lower low-density lipoprotein cholesterol (LDL-C) and higher insulin levels were only observed in subjects with the GG genotype of LEPR Gln223Arg, while higher HDL-C and apoA-I were only found in the A allele carriers. Additionally, the lower LDL-C and body mass index (BMI), and higher HDL-C and insulin levels were only observed in subjects with the GG genotype of LEPR Lys656Asn.

CONCLUSIONS

LEPR polymorphisms contribute to the heterogeneities in BMI, LDL-C, and HDL-C responsiveness that are induced by a HC/LF diet in healthy young Chinese adults.

Genetic Determinants of Prepubertal and Pubertal Growth and Development

This article surveys the current general understanding of genetic influences on within- and between-population variation in growth and development in the context of establishing an International Growth Standard for Preadolescent and Adolescent Children. Traditional genetic epidemiologic analysis methods are reviewed, and evidence from family studies for genetic effects on different measures of growth and development is then presented. Findings from linkage and association studies seeking to identify specific genomic locations and allelic variants of genes influencing variation in growth and maturation are then summarized. Special mention is made of the need to study the interactions between genes and environments. At present, specific genes and polymorphisms contributing to variation in growth and maturation are only beginning to be identified. Larger genetic epidemiologic studies are needed in different parts of the world to better explore population differences in gene frequencies and gene—environment interactions. As advances continue to be made in molecular and statistical genetic methods, the genetic architecture of complex processes, including those of growth and development, will become better elucidated. For now, it can only be concluded that although the fundamental genetic underpinnings of the growth and development of children worldwide are likely to be essentially the same, there are also likely to be differences between populations in the frequencies of allelic gene variants that influence growth and maturation and in the nature of gene–environment interactions. This does not necessarily preclude an international growth reference, but it does have important implications for the form that such a reference might ultimately take.

Effects of LEP G2548A and LEPR Q223R Polymorphisms on Serum Lipids and Response to Simvastatin Treatment in Chinese Patients With Primary Hyperlipidemia

Objectives:

To investigate whether LEP G2548A and LEPR Q223R polymorphisms influence serum lipid levels and whether the 2 polymorphisms affect the efficacy of simvastatin treatment in Chinese patients with primary hyperlipidemia.

Methods:

We used an extreme sampling approach by selecting 212 individuals from the top and bottom 15% of adjusted lipid-lowering response residuals to simvastatin (n = 106 in each group of good or bad response) from a total of 734 samples with primary hyperlipidemia. They were treated with simvastatin orally 20 mg/d. Fasting serum lipids were measured at baseline and after 4 and 8 weeks of treatment. Genotyping was carried out using polymerase chain reaction-restriction fragment length polymorphism.

Results:

More patients in the good response group (27%) had LEPR Q223R than in the bad response group (16%, P = .046). Secondary stratified analyses showed that patients carrying the RR genotype of the LEPR Q223R gene had significantly higher high-density lipoprotein cholesterol levels than those with the QR genotype at baseline ( P = .034) among good responders. After 29 consecutive days of treatment with simvastatin, patients carrying the RR genotype had a significantly larger decrease in triglycerides (change: −0.74 ± 0.92, P = .036) and total cholesterol levels (change: −1.77 ± 0.68, P = .023) compared with those carrying QR genotype among bad responders. After Bonferroni correction, the results were not statistically significant.

Conclusion:

LEPR Q223R polymorphism, but not LEP G2548A, could modulate the efficacy of simvastatin in Chinese patients with primary hyperlipidemia.

Correlations Between Leptin Gene Polymorphisms 223 A/G, 1019 G/A, 492 G/C, 976 C/A, and Anthropometrical and Biochemical Parameters in Children With Obesity: A Prospective Case-Control Study in a Romanian Population-The Nutrichild Study

The aim of this study was to establish the manner in which the LEPR 223, 1019, 492, and 976 gene polymorphisms influence child obesity.We performed a prospective case-control study on 264 hospitalized children from Romania (Nutrichild study) whom we divided into 2 groups: Group I -143 controls and Group II-121 obese children.The 2 groups were evaluated regarding the anthropometry (MUAC, TST, H/L, hip, and abdominal circumference), paraclinical results (protein, leptin, adiponectin, TNF alfa, IL 6, IL 8, VEGF, protein, albumin) and LEPR 223, 1019, 492, and 976 gene polymorphisms. We noticed that the most frequent genotypes in obese children were AG+GG for LEPR 223 gene (P = 0.0001) and GA+AA for LEPR 1019 gene (P = 0.0001), whereas LEPR 492 and LEPR 976 gene polymorphisms did not correlate with obesity. MUAC, TST, H/L, leptin, and adiponectin were correlated with the GG genotype of the LEPR 223 gene, whereas the AG genotype correlated with TNF alpha and serum IL 8. Hip and abdominal perimeters were higher in LEPR 1019 AA genotype carriers, whereas TNF alpha and IL 6 correlated with the GG genotype of the same gene. Obesity did not correlate with protein serum levels.We observed that obesity is more frequent in children with LEPR 223 AG+GG and LEPR 1019 GA+AA genotypes. In obese children LEPR 223/492/1019 AG/GG/GA, GG/GG/GA and AA/GG/GA combined genotypes are more frequent.

Association of Leptin Receptor Gene Polymorphisms with Genetic Susceptibility to Ischemic Stroke

BACKGROUND

Ischemic stroke is a multifactorial disease that is influenced by both genetic and environmental factors. Identification of the genetic factors that are underlining this disease is important. Leptin receptor (LEPR) mediates the leptin-regulated human energy homeostasis, and mutations of LEPR can increase cardiovascular risks and may predispose an individual to ischemic stroke.

METHODS

We analyzed distribution of 3 single nucleotide polymorphisms (SNPs) of LEPR gene (Lys109Arg, Gln223Arg, and Lys656Asn) in 101 patients with ischemic stroke and 105 controls by polymerase chain reaction-restriction fragment length polymorphism strategy.

RESULTS

Our results showed that there were significant differences in the genotype and allele distribution of Lys109Arg and Gln223Arg polymorphisms of the LEPR gene between case and control. The 109GG and 223GG genotype were associated with a significantly increased risk of ischemic stroke (odds ratio [OR], 3.23; P = .001 and OR, 2.87; P = .008, respectively). The 109G and 223G alleles carriers were correlated with an increased incidence of ischemic stroke (OR, 2.72; P = .001; OR, 2.94; P = .004). By haplotype analyses, we found that 109A/223G/656G haplotype was associated with an increased risk of ischemic stroke although this was not observed in the control group (OR, 3.86; P = .029).

CONCLUSIONS

LEPR 109GG and 223GG genotypes and the 109G and 223G alleles are associated with the risk of ischemic stroke. Our data suggest that LEPR Lys109Arg and Gln223Arg polymorphisms could be used as genetic predictive factor for ischemic stroke.

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.

β3Adrenergic Receptor Polymorphism and Obesity-Related Phenotypes in Hypertensive Patients

OBJECTIVES

Obesity is a complex trait that is affected by both environmental and genetic risk factors. The beta(3) adrenergic receptor (ADRB3) is expressed in adipose tissue and plays a role in energy metabolism. A missense mutation on codon 64 of this gene (W64R) is associated with receptor malfunction. Previous studies examining the relation between this polymorphism and obesity produced inconsistent findings. The current study assessed the association between the W64R genotype and obesity-related phenotypes, including body weight, BMI, and serum triglycerides, cholesterol, and glucose.

RESEARCH METHODS AND PROCEDURES

We determined the ADRB3 W64R genotypes and fasting serum lipid and glucose concentrations for 695 hypertensive adults (336 men,359 women) from a rural county in Anhui Province, China. Multivariate linear regression models were fit to detect associations between the genetic polymorphism and obesity-related phenotypes.

RESULTS

The ADRB3 W64R polymorphism was significantly associated with body weight and BMI in men but not in women. After controlling for potential confounding variables, men who were homozygous for the R64 allele were 11.8 kg heavier (p < 0.001) and had a BMI that was 3.7 kg/m(2) greater (p = 0.001) than men who were homozygous for the W64 allele. Serum concentrations of lipids and glucose were found not associated with the genetic polymorphism.

DISCUSSION

The ADRB3 R64 allele was associated with increased body weight and BMI in men but not in women. The genetic association was not modified by triglyceride, cholesterol, blood glucose, or blood pressure levels of the subjects.

The Human Obesity Gene Map: The 2003 Update

This is the tenth update of the human obesity gene map, incorporating published results up to the end of October 2003 and continuing the previous format. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) from human genome-wide scans and animal crossbreeding experiments, and association and linkage studies with candidate genes and other markers is reviewed. Transgenic and knockout murine models relevant to obesity are also incorporated (N = 55). As of October 2003, 41 Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. QTLs reported from animal models currently number 183. There are 208 human QTLs for obesity phenotypes from genome-wide scans and candidate regions in targeted studies. A total of 35 genomic regions harbor QTLs replicated among two to five studies. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 272 studies reporting positive associations with 90 candidate genes. Fifteen such candidate genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, more than 430 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful sites can be found at http://obesitygene.pbrc.edu.

The Human Obesity Gene Map: The 2004 Update

This paper presents the eleventh update of the human obesity gene map, which incorporates published results up to the end of October 2004. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTLs) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2004, 173 human obesity cases due to single-gene mutations in 10 different genes have been reported, and 49 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 166 genes which, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 221. The number of human obesity QTLs derived from genome scans continues to grow, and we have now 204 QTLs for obesity-related phenotypes from 50 genome-wide scans. A total of 38 genomic regions harbor QTLs replicated among two to four studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably with 358 findings of positive associations with 113 candidate genes. Among them, 18 genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, >600 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful publications and genomic and other relevant sites can be found at http://obesitygene.pbrc.edu.

Obesity and eating behaviour in children and adolescents: contribution of common gene polymorphisms

The prevalence of childhood obesity is increasing in many countries and confers risks for early type 2 diabetes, cardiovascular disease and metabolic syndrome. In the presence of potent 'obesogenic' environments not all children become obese, indicating the presence of susceptibility and resistance. Taking an energy balance approach, susceptibility could be mediated through a failure of appetite regulation leading to increased energy intake or via diminished energy expenditure. Evidence shows that heritability estimates for BMI and body fat are paralleled by similar coefficients for energy intake and preferences for dietary fat. Twin studies implicate weak satiety and enhanced food responsiveness as factors determining an increase in BMI. Single gene mutations, for example in the leptin receptor gene, that lead to extreme obesity appear to operate through appetite regulating mechanisms and the phenotypic response involves overconsumption and a failure to inhibit eating. Investigations of robustly characterized common gene variants of fat mass and obesity associated (FTO), peroxisome proliferator-activated receptor (PPARG) and melanocortin 4 receptor (MC4R) which contribute to variance in BMI also influence the variance in appetite factors such as measured energy intake, satiety responsiveness and the intake of palatable energy-dense food. A review of the evidence suggests that susceptibility to childhood obesity involving specific allelic variants of certain genes is mediated primarily through food consumption (appetite regulation) rather than through a decrease in activity-related energy expenditure. This conclusion has implications for early detection of susceptibility, and for prevention and management of childhood obesity.

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.

Genetic polymorphisms in adipokine genes and the risk of obesity: a systematic review and meta-analysis

Polymorphisms in adipokine genes, such as leptin (LEP), leptin receptor (LEPR), resistin (RETN), adiponectin (ADIPOQ), interleukin-1β (IL-1β), IL-6 (IL-6), and tumor necrosis factor-α (TNF-α) may be involved in the development of obesity. We conducted a systematic review of published evidence on the association between different adipokine genes and the risk of obesity. Librarian-designed searches of PubMed and HuGeNet, review of reference lists from published reviews and content expert advice identified potentially eligible studies. The genotyping information and polymorphisms of different adipokine genes, numbers of genotyped cases and controls and frequencies of genotypes were extracted from 48 eligible studies included in this review. Twenty-one polymorphisms each associated with obesity in at least one study were identified. Polymorphisms in the adipokine genes, LEP, LEPR, and RETN were not associated with obesity susceptibility, whereas ADIPOQ G276T (T vs. G: odds ratio (OR), 1.59; 95% confidence interval (CI), 1.39-1.81), IL-1β C3953T (CC vs. CT+TT: OR, 1.61; 95% CI, 1.18-2.20), and TNF-α G308A (GG vs. GA+AA: OR, 1.19; 95% CI, 1.02-1.39) polymorphisms were associated with an increased risk of obesity. The IL-6 G174C polymorphism was also associated obesity when using allelic comparisons, the recessive genetic model and the dominant genetic model with OR (95% CI) of 1.95 (1.37-2.77), 1.44 (1.15-1.80), and 1.36 (1.16-1.59), respectively. No significant evidence of publication bias was present. However, these "null" results were underpowered due to a small pooled sample size, and analysis of additional case-control studies with larger sample sizes should provide further clarifications.

Association between variants of the leptin receptor gene (LEPR) and overweight: a systematic review and an analysis of the CoLaus study

BACKGROUND

Three non-synonymous single nucleotide polymorphisms (Q223R, K109R and K656N) of the leptin receptor gene (LEPR) have been tested for association with obesity-related outcomes in multiple studies, showing inconclusive results. We performed a systematic review and meta-analysis on the association of the three LEPR variants with BMI. In addition, we analysed 15 SNPs within the LEPR gene in the CoLaus study, assessing the interaction of the variants with sex.

METHODOLOGY/PRINCIPAL FINDINGS

We searched electronic databases, including population-based studies that investigated the association between LEPR variants Q223R, K109R and K656N and obesity- related phenotypes in healthy, unrelated subjects. We furthermore performed meta-analyses of the genotype and allele frequencies in case-control studies. Results were stratified by SNP and by potential effect modifiers. CoLaus data were analysed by logistic and linear regressions and tested for interaction with sex. The meta-analysis of published data did not show an overall association between any of the tested LEPR variants and overweight. However, the choice of a BMI cut-off value to distinguish cases from controls was crucial to explain heterogeneity in Q223R. Differences in allele frequencies across ethnic groups are compatible with natural selection of derived alleles in Q223R and K109R and of the ancient allele in K656N in Asians. In CoLaus, the rs10128072, rs3790438 and rs3790437 variants showed interaction with sex for their association with overweight, waist circumference and fat mass in linear regressions.

CONCLUSIONS

Our systematic review and analysis of primary data from the CoLaus study did not show an overall association between LEPR SNPs and overweight. Most studies were underpowered to detect small effect sizes. A potential effect modification by sex, population stratification, as well as the role of natural selection should be addressed in future genetic association studies.

The effect of ponderal index at birth on the relationships between common LEP and LEPR polymorphisms and adiposity in adolescents

This study examined the effect of ponderal index (PI) at birth on the relationships between eight common polymorphisms of the leptin (LEP) and leptin receptor (LEPR) genes and adiposity in adolescents. A total of 823 European adolescents (45.4% girls) aged 14.8 ± 1.4 years were genotyped for the LEP (rs2167270, rs12706832, rs10244329, rs2071045, and rs3828942) and LEPR (rs1137100, rs1137101, and rs8179183) polymorphisms. The PI was calculated from parental reports of birth weight and length. Fat mass index (FMI) was calculated. Analyses were adjusted for relevant confounders. An "adiposity-risk-allele score" based on genotypes at the three single-nucleotide polymorphisms (SNPs) associated with adolescents' FMI in adolescents within the lower tertile of PI was calculated. The LEP rs10244329 and rs3828942 polymorphisms were associated with higher FMI only in adolescents within the lower PI tertile (+0.55 kg/m(2) per minor T allele, P = 0.040, and +0.58 kg/m(2) per major G allele, P = 0.028, respectively). The LEPR rs8179183 polymorphism was significantly associated with higher FMI in adolescents within the lower PI tertile (+0.87 kg/m(2) per minor C allele, P = 0.006). After correction for multiple comparisons, only the association between the LEPR rs8179183 and FMI persisted. However, each additional risk allele conferred 0.53 kg/m(2) greater FMI in adolescents within the lower tertile of PI (P = 0.008). In conclusion, our results suggest that those adolescents born with lower PI could be more vulnerable to the influence of the LEP rs10244329 and rs3828942 polymorphisms and LEPR rs8179183 polymorphism on total adiposity content. Due to the relatively small sample size, these findings should be replicated in further larger population samples.

Relationships of adrenoceptor polymorphisms with obesity

Obesity, hypertension, and type 2 diabetes are rapidly growing public health problems. Heightened sympathetic nerve activity is a well-established observation in obesity, hypertension, and type 2 diabetes. Human obesity, hypertension, and diabetes have strong genetic as well as environmental determinants. Reduced energy expenditure and resting metabolic rate are predictive of weight gain, and the sympathetic nervous system participates in regulating energy balance through thermogenesis. The thermogenic effects of catecholamines in obesity are mainly mediated via the β2, and β3-adrenergic receptors in humans. Further, β2-adrenoceptors importantly influence vascular reactivity and may regulate blood pressure. β-adrenoceptor polymorphisms have also been associated with adrenoceptor desensitization, increased adiposity, insulin resistance, and enhanced sympathetic nervous activity. Many epidemiological studies have shown strong relationships between adrenoceptor polymorphisms and obesity, but the observations have been discordant. This paper will discuss the current topics involving the influence of the sympathetic nervous system and β2- and β3-adrenoceptor polymorphisms in obesity.

The serum leptin level and body mass index in Melanesian and Micronesian Solomon Islanders: focus on genetic factors and urbanization

OBJECTIVES

This study examined the association between the serum leptin level and body mass index (BMI) and the effects of urbanization and polymorphisms of leptin (LEP) or leptin receptor (LEPR) genes on the leptin level in three Solomon Islands populations.

METHODS

A Melanesian population living in a remote area (participants: 106 males and 106 females, ages: 18-74 years), a Melanesian population in an urban area (89 and 94, 18-79 years), and a Micronesian population who migrated to a peri-urban area in the 1960s (84 and 69, 18-71 years) were studied. Anthropometric and serum leptin measurements and genotyping for LEP G-2548A and LEPR K109R and Q223R were performed.

RESULTS

The prevalence of obesity (BMI ≥ 30 kg/m(2)) was the highest in the Micronesian population (30.1%), followed by the urban (18.6%) and the rural (2.4%) Melanesian population. The serum leptin concentration was the highest in the urban Melanesian, followed by the Micronesian and the rural Melanesian populations (P < 0.05). Interestingly, the parameter coefficients of the leptin concentrations on the BMIs were nearly identical in the urban and rural Melanesians after adjusting for age and gender. The LEPR 223Q/Q genotype was associated with an increased leptin level only in the Micronesian population after adjusting for BMI (P = 0.0008 and 0.0016 referenced to the Q/R and the R/R types, respectively).

CONCLUSIONS

These observations suggest that the increase in obesity in the Micronesians had a genetic component while that in Melanesians might have been related with the urbanization.

Weight gain, schizophrenia and antipsychotics: new findings from animal model and pharmacogenomic studies

Excess body weight is one of the most common physical health problems among patients with schizophrenia that increases the risk for many medical problems, including type 2 diabetes mellitus, coronary heart disease, osteoarthritis, and hypertension, and accounts in part for 20% shorter life expectancy than in general population. Among patients with severe mental illness, obesity can be attributed to an unhealthy lifestyle, personal genetic profile, as well as the effects of psychotropic medications, above all antipsychotic drugs. Novel "atypical" antipsychotic drugs represent a substantial improvement on older "typical" drugs. However, clinical experience has shown that some, but not all, of these drugs can induce substantial weight gain. Animal models of antipsychotic-related weight gain and animal transgenic models of knockout or overexpressed genes of antipsychotic receptors have been largely evaluated by scientific community for changes in obesity-related gene expression or phenotypes. Moreover, pharmacogenomic approaches have allowed to detect more than 300 possible candidate genes for antipsychotics-induced body weight gain. In this paper, we summarize current thinking on: (1) the role of polymorphisms in several candidate genes, (2) the possible roles of various neurotransmitters and neuropeptides in this adverse drug reaction, and (3) the state of development of animal models in this matter. We also outline major areas for future research.

No association of LEPR Gln223Arg polymorphism with leptin, obesity or metabolic disturbances in children

Objective

The aim of the study was to investigate whether the Gln223Arg in the leptin receptor may influence body weight, leptin concentration, and metabolic parameters in children.

Materials and methods

The examined group included 101 obese children (58 girls and 43 boys) with BMI 31.41 ± 5.03 kg/m² (BMI ≥ 2 SDS) and the control group consisted of 41 children with BMI 20.0 ± 0.80 kg/m² (BMI < 1.0 SDS). Polymorphism identification was performed in total genomic DNA using PCRRFLP method.

Results

The distribution of genotypes LEPR was the following: in the obese group: AA - 20.8%, AG-55.4%, GG-23.8%; in the control group AA-31.7%, AG-53.65%, GG-14.65%. Comparative analyses between AA homozygous children and carriers of G alleles did not confirm any relation between the analyzed polymorphism and BMI, leptin concentrations, and metabolic disturbances in children with obesity.

Conclusion

In children with obesity we did not observe association of the LEPR Gln223Arg gene polymorphism with obesity, leptin, insulin resistance, and metabolic abnormalities.

Impact of leptin and leptin-receptor gene polymorphisms on serum lipids in Japanese obese children

AIM

Leptin is one of the factors affecting serum lipid profile. We investigated the association between serum lipids and leptin/leptin receptor (LEPR) gene polymorphisms in obese Japanese children.

METHODS

One hundred and thirty-six obese children (99 males and 37 females, relative weight over than 20%) from 5 to 17 years of age were recruited from 10 institutes. Four known polymorphisms in leptin gene [(+19)A G, (-2548)G A, (-188)C A, (-633)C T] and four known polymorphisms in LEPR gene [Lys109Arg, Gln223Arg, Pro(G)1019Pro(A), Ser(T)343Ser(C)] were determined using polymerase chain reaction-restriction fragment length polymorphism-based analyses.

RESULTS

No associations were found between leptin gene polymorphisms and serum lipid profile. On the other hand, Lys109Arg and Ser343Ser polymorphism in LEPR gene, but not Gln223Arg or Pro1019Pro, had significant relationships with serum lipid profile; lower total and low-density lipoprotein cholesterol levels in Arg109Arg homozygotes, and lower TG levels in Ser343Ser(C/C) homozygotes. In addition, LEPR gene also associated with relative weight; Arg109Arg homozygotes had higher relative weight and Ser343Ser(C/C) homozygotes had lower one.

CONCLUSION

These results suggest that LEPR gene polymorphisms may partly contribute to serum lipid profile in obese children.

Polymorphisms of the LEP- and LEPR gene and obesity in patients using antipsychotic medication

Weight gain is one of the most serious adverse effects of atypical antipsychotic agents. Genetic factors influence the risk of an individual to gain weight. The objective of our study was to determine whether the LEPR Q223R polymorphism and the LEP promoter 2548G/A polymorphism are associated with obesity in a group of male and female patients using atypical antipsychotic drugs. A cross-sectional study design was used. The study population consisted of 200 patients aged between 18 and 65 years, diagnosed with a psychotic disorder, all of whom had been using an atypical antipsychotic for at least 3 months. The primary outcome measure was the presence of obesity. Determinants were the LEPR Q223R (rs1137101) polymorphism and the LEP promoter 2548G/A single nucleotide polymorphism ([SNP] rs7799039). Of the 200 included patients, 61 (31%) were obese. In females, the LEPR 223QR (adjusted odds ratio, 0.11; 95% confidence interval [CI], 0.02-0.54) and LEPR 223RR (adjusted odds ratio, 0.07; 95% CI, 0.01-0.63) genotypes were associated with a lower risk of obesity. In males, this association was not found. In females, the average body weight was 13.6 kg more (95% CI, 1.11-26.1) in the LEPR 223QQ group compared with the LEPR 223RR group. No significant association was found between the LEP promoter 2548G/A polymorphism and obesity. Taken together, the results of our study show that the LEPR Q223R polymorphism may be associated with obesity in women with a psychotic disorder treated with atypical antipsychotic drugs and stress the importance of stratification for gender when investigating the role of variations of the LEP- and LEPR genes on the metabolic side effects of antipsychotic medications.

Association of leptin -2548G/A and leptin receptor Q223R polymorphisms with increased risk for oral cancer

PURPOSE

We investigated the possible association of DNA polymorphisms -2548G/A and Q223R in the leptin (LEP) and leptin receptor (LEPR) genes, respectively, which both affect the amount of circulating cytokine-type hormone leptin, with risk for development of oral cancer.

METHODS

Polymerase chain reaction-based restriction analysis was performed in DNA samples of 150 patients with oral squamous cell carcinoma (OSCC) and 152 healthy control subjects of equivalent gender, age, and ethnicity (Greeks and Germans).

RESULTS

Compared to controls, the homozygous high gene expression genotype A/A of the LEP -2548G/A polymorphism was significantly increased in the subgroups of patients with advanced cancer stages (P = 0.0001; OR 9.0, 95% CI 2.62-30.89), with a positive family history of cancer (P = 0.0346; OR 3.55, 95% CI 1.15-11.01), without tobacco abuse (P = 0.0051; OR 9.69, 95% CI 1.03-91.24), and without alcohol abuse (P = 0.0472; OR 2.16, 95% CI 0.87-5.37). The homozygous low-leptin-binding genotype G/G of the LEPR Q223R polymorphism was strongly associated with an increased risk for OSCC for all patients (P = 0.0028; OR 4.11, 95% CI 1.30-12.97) as well for most of the patient subgroups.

CONCLUSIONS

The above findings are consistent with the growth-promoting role of leptin in cancer and its induction effect on angiogenesis and metastasis. This is the first study indicating the association of these LEP and LEPR gene polymorphisms with increased risk for OSCC.

beta(3)-adrenergic receptor polymorphism and metabolic syndrome in postmenopausal women

OBJECTIVES

Some studies indicate that the Trp64Arg polymorphism in the gene encoding the beta(3)-adrenergic receptor (ADRB3) is associated with obesity, insulin resistance and earlier onset of type 2 diabetes mellitus. The aim of the present study was to evaluate the frequency of ADRB3 polymorphism and its association with metabolic syndrome in postmenopausal women.

METHODS

We performed the study on 284 randomly chosen postmenopausal women, aged 50-60 years, who were then selected to the study. Measurements of anthropometric parameters and biochemical estimations such as lipid profile, glucose and insulin level in serum were carried out using commercial kits. ADRB3 genotyping was performed by polymerase chain reaction and mini-sequencing.

RESULTS

The frequency of the Trp64/Arg64 genotype in the investigated population was 13%, and of the Trp64/Trp64 genotype, 85%. The Arg64/Arg64 genotype was present in only 2% of women. Metabolic syndrome was recognized in 22% of women bearing Trp64/Arg64 genotype and in 14% of women bearing Trp64/Trp64 genotype, without a statistically significant difference between the two groups (p > 0.05 in the chi(2) test). Women bearing the Trp64/Arg64 genotype had lower serum levels of high-density lipoprotein cholesterol (HDL-C) than Trp64/Trp64 genotype women (63.2 +/- 13.0 vs. 71.4 +/- 17.4 mg/dl). Both groups did not differ in any other investigated parameter.

CONCLUSION

Trp64Arg polymorphism of the beta(3)-adrenergic receptor gene is not related to metabolic syndrome in postmenopausal Polish women; however, it seems to be associated with decreased HDL-C levels.

Association of Trp64Arg polymorphism of beta3-adrenergic receptor with insulin resistance in Polish children with obesity

AIM

To establish the influence of the Trp64Arg variant of the beta3-adrenergic receptor (Trp64Arg- beta3AR) on body mass index (BMI) and insulin resistance (IR) in obese children.

METHODS

BMI, presence of the Trp64Arg mutation, plasma glucose and insulin concentrations during an oral glucose tolerance test (OGTT) and IR were determined in 60 obese and 33 normal weight children.

RESULTS

The frequency of Trp64Arg was similar in normal weight and obese children. BMI, glucose and insulin concentrations during an OGTT in children with Trp64Argbeta3AR were not different from those with Trp64Trpbeta3AR. IR was confirmed in 42.8% of children with Trp64Argbeta3AR and in 45.6% of children with Trp64Trpbeta3AR (NS).

CONCLUSIONS

1. The similar frequency of the Trp64Argbeta3AR variant in normal weight and obese children suggests that it is not a susceptibility gene for obesity in Polish children. 2. The presence of the Trp64Argbeta3AR variant does not have an unfavourable influence on BMI, glucose or insulin concentrations during OGTT or on IR frequency in Polish obese children.

Arg64 variant of the beta3-adrenergic receptor is associated with gallstone formation

OBJECTIVES

The beta3-adrenergic receptor (ADRB3) is a transmembrane receptor highly expressed in adipose tissue and thought to be involved in the regulation of lipolysis. ADRB3 is also highly expressed in gallbladder tissue where it may be involved in gallbladder contraction. Because polymorphisms of ADRB3 are present in populations with a high prevalence of gallstones (e.g., Pima-Indians, obese subjects), we hypothesized that known polymorphisms for ADRB3 (Trp64Arg) may represent an independent risk factor for gallstone disease.

METHODS

The EMIL cross-sectional study investigated the health behavior and prevalence of chronic diseases in a small Southwestern German town of 12,475 inhabitants. From 3,893 randomly selected citizens 2,147 subjects were enrolled and screened for gallstones employing ultrasonography. Blood samples were drawn for biochemical analysis and isolation of genomic DNA. ADBR3 genotypes were determined by TaqMan SNP Assay.

RESULTS

We identified 171 (8%) gallstone carriers of whom 143 participated (46 male, 97 female), with a mean age of 51.4, and mean BMI of 29.3 kg/m2. For these subjects an age, gender and BMI matched partner without gallstones was recruited from the study population. Genotyping for ADRB3 revealed an Arg64 allele frequency of 5.9 versus 0.7% (HR = 11.9, P < 0.05) compared with controls.

CONCLUSIONS

Our results indicate that the ADRB3 Trp64Arg polymorphism is associated with gallstone disease thereby representing a genetic marker that identifies subjects at higher risk for gallstone formation.

Post-exercise oxidative stress and obesity in postmenopausal women: the role of beta3-adrenergic receptor polymorphism

AIM

Some studies indicate that the Trp64Arg polymorphism in the gene encoding the beta3-adrenergic receptor (ADRB3) is associated with obesity, insulin resistance and earlier onset of type 2 diabetes mellitus. The aim of the present study was to evaluate the frequency of this polymorphism and its relationship with obesity and oxidative stress in postmenopausal women.

MATERIAL AND METHODS

We performed the study on 200 women, aged 50-60 years. Estimation of anthropometric parameters and total body fat, android and gynoid fat deposits was carried out using dual-energy X-ray absorptiometry. Oxidative stress was estimated by measurement of thiobarbituric acid-reactive substances (TBARS) in serum. Blood for analysis was collected before, directly after and 6 h after a 30-min physical test on a cycle ergometer. ADRB3 genotyping was performed by polymerase chain reaction.

RESULTS

The frequency of Trp64/Arg64 genotype in the investigated population was 12%, and of Trp64/Trp64 was 87%. The Arg64/Arg64 genotype was present in only 1% of women. Women bearing the Trp64/Arg64 genotype did not differ in any measured anthropometric parameters from women bearing the Trp64/Trp64 genotype. Moreover, genotype had no influence on oxidative stress parameters. Likewise, in both groups, mean plasma level of TBARS was increased significantly (p < 0.05) directly after the endurance test and remained elevated 6 h after the test.

CONCLUSIONS

The Trp64Arg polymorphism of ADRB3 seems to not be related to obesity in postmenopausal women. Moreover, the Trp64Arg polymorphism has no influence on oxidative stress intensification after standardized physical effort in postmenopausal women.

Gene-diet interactions in childhood obesity: paucity of evidence as the epidemic of childhood obesity continues to rise

Childhood obesity is growing rapidly worldwide. Although there have been enormous advances in the genetic underpinnings of obesity in recent years, the pathways that lead to obesity are still not completely understood. One of the ongoing challenges is the lack of a comprehensive definition of the obese phenotype that encompasses intermediary phenotypic expressions of biological and behavioral nature. Interactions between genetic and environmental factors, including nutrient exposures and dietary behaviors, can influence the development of the obese phenotype. Specifically, genes play a decisive role in the etiology of childhood obesity under the permissive circumstances of an obesogenic environment (increase in energy intake with a decrease in physical activity). Like many diseases, the causes of obesity are complex and their investigation requires novel approaches. Given the many contributors to obesity (weight gain, weight loss, weight maintenance, variability in body composition), as well as the dynamic nature of this issue, genomic tools must continue to be employed to evaluate all dimensions of the obesity phenotype, such as biochemical characteristics, susceptibility markers, nutrient intake, feeding practices and gene-environment interactions. Fundamental knowledge of the types of genes involved and available gene-diet interaction studies in children's obesity are reviewed. Although there is a paucity of existing literature in this specific domain of childhood obesity, ongoing investigations utilizing large cohorts have potential for providing the knowledge needed for targeted interventions in the future.

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

BACKGROUND

Decreased energy expenditure and increased food intake are principal causes for obesity. In the present study, genotypes of beta(3)-adrenergic receptor (beta(3)AR) and of melanocortin-4 receptor (MC4R), both of which are believed to have a close link to the cause of obesity, were analyzed and compared with phenotypes of childhood obesity.

METHODS

Thirty-five obese children with moderate to severe obesity were enrolled. Direct sequencing of the MC4R coding region and pinpoint-polymerase chain reaction were used to detect genomic variation in the beta(3)AR gene using peripheral blood-derived DNA.

RESULTS

Allele frequency of Trp64Arg variation in the beta(3)AR gene in the obese subjects was 0.16, which is comparable with that in the healthy general population in eastern Asia. Comparison of phenotypical characteristics did not show a significant difference between Trp/Trp and Trp/Arg subjects. It was notable that body height SD was significantly higher in the Trp/Trp than the Trp/Arg subjects (0.93 +/- 1.0 SD vs 0.07 +/- 1.3 SD, P= 0.03). Annual weight gains were far beyond a hypothetical fat gain in an Arg64 heterozygote with decreased energy consumption, suggesting increased food intake in childhood obesity. There was, however, no variation in the MC4R gene despite thorough sequencing of the entire coding region.

CONCLUSIONS

The Trp64Arg variation in the beta(3)AR gene has no relationship to the degree or the incidence of childhood obesity. The majority of childhood obesity can be characterized as tall stature, more rapid weight gain than that expected by decreased energy expenditure. Further investigation is necessary in regard to the increased food intake as a major cause of childhood obesity.

The human obesity gene map: the 2005 update

This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.

Comparison of Body Fat Distribution and Blood Lipid Profiles according to Trp64Arg Polymorphism for the .BETA.3-Adrenergic Receptor Gene in Korean Middle-Aged Women

The aim of this study was to determine whether there was an association between body fat distribution, blood lipid profiles, and beta 3-adrenergic receptor gene polymorphism in Korean middle-aged women. Subjects were grouped according to BMI as obese (> or = 5 BMI, n = 95) or non-obese (BMI<25, n = 93). The Trp64Arg mutation of the beta 3-adrenergic receptor gene was detected by PCR-RFLP. Skinfold thickness, body circumference, intra-abdominal fat area by CT, and blood lipid profiles were also measured. Data were compared using ANOVA, Bonferroni t-test, and Chi-square. Significance for statistical analyses were set at p<0.05. In the obese group, 63.16% were Trp64Trp homozygotes and 36.84% were Trp64Arg heterozygotes, compared to 80.65% who were Trp64Trp homozygotes and 19.35% who were Trp64Arg heterozygotes in the non-obese group. These results indicated a significant (chi-square = 4.943, p<0.05) difference between the two groups. Frequency of the Arg64 allele in the obese group (16.84%) showed a significant (chi-square = 4.185, p<0.05) difference as compared to the non-obese group (9.68%). Skinfold thickness and body circumference of the Trp64Arg heterozygote group showed a consistent increase as compared to the Trp64Trp homozygote group. Visceral fat area and VSR of Trp64Arg heterozygote group showed a higher tendency than Trp64Trp homozygotes in the obese group, but these differences were not statistically significant. In conclusion, the Trp64Arg polymorphism of the beta 3-adrenergic receptor gene is associated with obesity in middle-aged Korean women, but it is difficult to suggest the prominent association of the Trp64Arg polymorphism of the beta 3-adrenergic receptor gene with prevalence of abdominal obesity or dyslipidemia in Korean middle-aged women.

Increased risk of obesity resulting from the interaction between high energy intake and the Trp64Arg polymorphism of the beta3-adrenergic receptor gene in healthy Japanese men

BACKGROUND: Few studies have investigated the interaction between the Trp64Arg polymorphism of the β₃-adrenergic receptor gene (ADRB3) and environmental factors. This study aimed to investigate whether energy intake affects the relationship between this polymorphism and obesity.

METHODS: Healthy Japanese men (n=295; age 46.1±11.5 years (mean ± standard deviation); waist circumference 83.9±9.3 cm; body mass index (BMI) 23.3±3.3 kg/m²) recruited in a Japanese chemical industry firm were eligible for analysis. Daily energy intake, protein, fat, and carbohydrate (PFC) ratio and daily physical activity were assessed by self-reported questionnaires. Genotyping for the polymorphism was performed with written informed consent.

RESULTS: When the subjects were classified into two groups according to presence of the polymorphism, the groups were not significantly different in waist circumference or BMI. Quartile classification of energy intake, however, demonstrated a significantly larger ratio of obese subjects to non-obese subjects in the group with the polymorphism in the highest 4th quartile alone. Multiple logistic regression analysis also revealed that the presence of the polymorphism increased the risk of obesity significantly in the 4th quartile alone (adjusted odds ratio=3.37, 95% confidence interval=1.12-10.2).

CONCLUSION: Presence of the polymorphism alone does not significantly increase the risk of obesity. However, high energy intake interacts with the polymorphism and leads to a significant increase in risk of obesity. The Trp64Arg polymorphism of ADRB3 warrants consideration, along with other polymorphisms involved in the development of obesity, for tailor-made prevention of obesity.

Genetics of leptin and obesity: a HuGE review

Leptin is an important regulator of the mass of adipose tissue and of body weight; it operates by inhibiting food intake and stimulating energy expenditure. Some polymorphic genes involved in the regulation of leptin-the leptin gene (LEP A19G), the leptin receptor gene (LEPR Q223R, K109R, and K656N), and the peroxisome proliferator-activated receptor-gamma gene (PPARG P12A and C161T)--have been investigated as possible factors associated with obesity. Allelic frequencies of these polymorphisms show ethnic variation. The authors performed a meta-analysis of the available data on the association between these polymorphisms and obesity based on case-control studies. Odds ratios and 95% confidence intervals for obesity associated with leptin polymorphisms were calculated by using both fixed- and random-effects models. Results suggest no evidence of association between the genes under study and obesity. The lack of association could be due to the complex pathogenesis of obesity, which involves a number of genetic and environmental factors. Large studies including testing of multiple genes in both obese and lean subjects, with epidemiologic data on dietary habits in different ethnic groups, are necessary to better understand the role of leptin in regulating weight in human populations.

Single nucleotide variants in the beta2-adrenergic and beta3-adrenergic receptor genes explained 18.3% of adolescent obesity variation

Associations of obesity with its candidate genes, beta-adrenergic receptor genes (ADRBs), peroxisome proliferator-activated receptor-gamma (PPARgamma), and uncoupling proteins (UCPs) were studied in Korean adolescents. We analyzed the obesity-related phenotypes body mass index (BMI), percentage of body fat, plasma leptin and insulin levels, fasting glucose concentration, and plasma lipid profile in 329 teenagers to investigate the effects of seven single nucleotide variants 252G/A, 523C/A and 1053G/C in ADRB2; Trp64Arg in ADRB3; 161C/T in PPARgamma; Ala55Val in UCP2; and 210C/T in UCP3. The 1053G/C polymorphism (P < 0.05) in the ADRB2 gene and the Trp64Arg polymorphism (P < 0.01) in the ADRB3 gene were associated with BMI after adjustment for dietary energy intake. Trp64Arg polymorphism also influenced percentage of body fat (P < 0.01) and plasma leptin level (P < 0.05). Furthermore, significant interaction effects between the 1053G/C and Trp64Arg polymorphisms were observed on BMI (P < 0.01). The polymorphisms of the ADRB2 and ADRB3 genes explained 4.3% and 10.1% of the variation on BMI, and the two loci effect, including their epistasis, explained 18.3%. We concluded that 1053G/C and Trp64Arg polymorphisms of the ADRB genes additively and interactively contributed to the variation of complex adolescent obesity.

The frequency of Trp64Arg polymorphism of the β3-adrenergic receptor gene in healthy and obese Hungarian children and its association with cardiovascular risk factors

OBJECTIVE

To estimate the frequency of Arg64 allele of the beta(3)-adrenergic receptor (3-BAR) gene in healthy (H) and obese (O) Hungarian children, and to look for possible associations between this polymorphism and some clinical and metabolic characteristics of obese children.

PATIENTS/METHODS

In all, 147 healthy (male: 68) and 295 obese (male: 168) children were examined. The average age of the children in the two groups was 12.4+/-1.7 vs 12.6+/-3.2, respectively. Exon 1 of 3-BAR was amplified by polymerase chain reaction and the fragments were digested with BstN1. In obese children, oral glucose tolerance test was carried out and blood pressure (BP) was checked.

RESULTS

The frequency of Trp64Arg polymorphism in normal and obese Hungarian children was similar (H vs O: n=14/9.5% vs n=35/11.8%). Obese children carrying the Arg64 allele (n=35, male: 23) were compared to randomly chosen, obese children without the Arg64 allele (n=35, male: 20). A significant difference was found between the body weight (81.2+/-23.2 vs 75.6+/-17.7 kg; mean+/-s.d.; P<0.01), body fat (38.8+/-3.9 vs 36.5+/-2.3%; mean+/-s.d.; P<0.05), mean fasting insulin levels (31.4+/-16.7 vs 16.9+/-7.6 microIU/ml; P<0.001) and mean systolic BP values (125.2+/-10.1 vs 114.5+/-8.3 mmHg; P<0.001) of the two obese groups.

CONCLUSIONS

The frequency of Trp64Arg polymorphism was similar in Hungary as compared to other European countries. Although the prevalence of this polymorphism was similar in H and O children, the presence of Arg64 allele seems to be associated with increased adiposity, elevated systolic BP and higher fasting insulin levels.

Pharmacogenetics of antipsychotic-induced weight gain

RATIONALE

Antipsychotic medications have been associated with considerable weight gain. The degree of inter-individual variability and known genetic contributions to obesity suggest a combination of genetic and environmental factors. In the absence of established mechanisms and valid predictors for this relevant adverse effect, pharmacogenetic studies may provide the basis for the development of individualized treatment and preventive interventions.

OBJECTIVE

The aim of the present review is to analyze the theoretical and empirical knowledge base for the selection of the most promising target genes that may contribute to antipsychotic-induced weight gain.

METHODS

Examination of the preclinical and clinical literature that can inform the rational choice of target genes that may play a role in the development of adverse changes in body composition associated with antipsychotic treatment.

RESULTS

Theoretically, candidate gene selection can be guided by knowledge about molecular pathways associated with obesity, receptors modulated by antipsychotic drugs, and enzymes implicated in their metabolism and bioavailability. While most available data relate to the general mechanisms of obesity and few studies have directly examined the genetic contributions to antipsychotic-induced weight gain, several genes warrant further investigation. These include the 5-HT(2C), pro-opiomelanocortin, leptin, ghrelin, tumor necrosis factor alpha, adiponectin, dopamine D(2) receptor, histamine-H(1) receptor, and alpha(1), beta(2) and beta(3) adrenergic receptor genes.

CONCLUSIONS

Pharmacogenetic studies can provide powerful tools for the pre-treatment identification of individuals at high risk for antipsychotic-induced weight gain, to uncover biological mechanisms that may even generalize to non-drug-induced weight gain, and to isolate novel targets for treatments of weight gain and obesity. To enhance power, future studies should pay close attention to population selection and avoidance/control of confounds, particularly past treatment exposure.

Effect of Trp64Arg mutation of the beta3-adrenergic receptor gene and C161T substitution of the peroxisome proliferator activated receptor gamma gene on obesity in Japanese children

OBJECTIVE

Obesity is a multifactorial syndrome influenced by both genetic and behavioral factors. Trp64Arg mutation of the beta3-adrenergic receptor (AR) gene and C161T substitution of the peroxisome proliferator-activated receptor (PPAR) gamma gene have been reported to be associated with obesity or lipid metabolism in adults. However, the effects of these mutations on children have not yet been clarified. For this reason, we studied the effects of Trp64Arg mutation of the beta3-AR gene and C161T substitution of the PPARgamma gene on obesity in Japanese children.

SUBJECTS AND METHODS

In order to determine the effects of Trp64Arg mutation of the beta3-AR gene and C161T substitution of the PPARgamma gene on obesity in children, 105 obese Japanese children were screened by the polymerase chain reaction and restriction fragment-length polymorphism analysis. Plasma lipid, apolipo-protein (apo), glucose, insulin and leptin levels were also determined.

RESULTS

Obese boys with Trp64Arg showed a higher obesity index and lower plasma levels of high-density lipoprotein cholesterol (HDL-C), apoA-I and apoA-II than those of them without the mutation. Obese boys with both mutations showed a higher plasma leptin level than those with only the beta3-AR gene mutation or PPARgamma gene mutation. No significant effect of these mutations was found in obese girls.

CONCLUSION

All of these data suggest that Trp64Arg mutation of the beta3-AR gene might affect obesity and HDL metabolism in obese boys. In contrast, C161T mutation of the PPARgamma gene, by itself, is unlikely to influence obesity, lipid metabolism or plasma leptin levels.

The human obesity gene map: the 2002 update

This is the ninth update of the human obesity gene map, incorporating published results through October 2002 and continuing the previous format. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) from human genome-wide scans and various animal crossbreeding experiments, and association and linkage studies with candidate genes and other markers is reviewed. For the first time, transgenic and knockout murine models exhibiting obesity as a phenotype are incorporated (N = 38). As of October 2002, 33 Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and the causal genes or strong candidates have been identified for 23 of these syndromes. QTLs reported from animal models currently number 168; there are 68 human QTLs for obesity phenotypes from genome-wide scans. Additionally, significant linkage peaks with candidate genes have been identified in targeted studies. Seven genomic regions harbor QTLs replicated among two to five studies. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 222 studies reporting positive associations with 71 candidate genes. Fifteen such candidate genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. More than 300 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful sites can be found at http://obesitygene.pbrc.edu.

Relationship between the .BETA.3-Adrenoceptor Gene Variant and Body Fat in Japanese Children

In this study, we investigated whether the variant of the beta3-adrenoceptor gene is associated with accumulation of body fat in Japanese junior high school students. A total of 87 junior high school students, 50 boys and 37 girls, participated in this survey. The beta3-adrenoceptor gene variant was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Accumulation of body fat was assessed by skinfold thickness at the triceps and subscapular with a skinfold caliper. There was no difference between boys and girls in the frequency of the beta3-adrenoceptor gene allele. There were no significant differences in body mass index and percent body fat between the Arg carriers (Trp/Arg or Arg/Arg) and the Arg noncarriers (Trp/Trp) for either sex. The Trp64Arg variant of the beta3-adrenoceptor gene does not seem to have a strong effect on the accumulation of body fat in this group of Japanese junior high school students.