G-2548A polymorphism of the leptin gene is correlated with extreme obesity in Taiwanese aborigines

Genetic Association of LEP Gene Polymorphisms with Obesity in Moroccan Individuals: Case-Control Study and Updated Meta-analysis

Obesity is a global epidemic disease representing the fifth leading cause of death in the world. It was shown that it is caused by the interaction between environmental factors and genes including leptin gene (LEP). This paper aimed to analyze the association between the LEP gene polymorphisms rs7799039 and rs11761556 with obesity in Moroccan individuals as well as to perform an update meta-analysis of this genetic association. Both polymorphisms were genotyped in 146 obesity patients and 104 controls using real-time PCR technique. The genetic association analysis and the comparison of quantitative parameters were carried out using the R language. Moreover, a meta-analysis including 20 genetic association studies was performed using Review Manager 5.3 software. No significant association was found between the polymorphisms rs7799039 and rs11761556 and the risk of obesity. The comparison of biochemical and clinical parameters between the genotypes of the rs7799039 polymorphism, showed a significant increased triglycerides levels in carriers of AA or GA genotypes (P value = 0.040). The meta-analysis showed no significant association between the rs7799039 polymorphism and obesity under all genetic models. In conclusion, the case-control study and meta-analysis demonstrated that the LEP gene polymorphisms rs7799039 and rs11761556 cannot be considered as genetic risk factors for obesity.

Impact of inflammatory cytokine and adipokine gene variations in the development of HIV-associated lipodystrophy

Cytokines affect lipid and glucose metabolism and also alter the body's habitus. They play a role in the development of lipodystrophy syndrome. Adipocytes secrete the pro-inflammatory cytokines IL-1, TNF-α and IL-6. The plasma cytokine concentration is associated with the percentage and distribution of fat tissue in the body. The metabolic disturbances are strongly associated with increased levels of pro-inflammatory cytokines (IL-1, IL-6 and TNF-α). Plasma levels of cytokines such as TNF-α, IL-6 and leptin were found to be increased while plasma resistin levels were found to be variable in patients suffering from obesity and type II diabetes mellitus. Until now, limited information has been available on the polymorphism of cytokine and adipokine genes in patients of HIV-associated lipodystrophy (HIVLD), which can contribute to individual variations in susceptibility to metabolic diseases, especially to HIVLD. Hence, we studied the association of cytokine and adipokine gene polymorphisms in various diseases and their impact on HIVLD. We carry out an extensive search using several databases, including PubMed, EMBASE and Google Scholar. The distribution of cytokine and adipokine gene polymorphisms and their expression levels varied among various populations. We examined the variants of cytokine and adipokine genes, which can contribute to individual variations in susceptibility to metabolic diseases, especially to HIVLD. In the current review, we present a brief account of the risk factors of HIVLD, the pathogenesis of HIVLD and the polymorphism of cytokine and adipokine genes in various diseases with special reference to their impact on HIVLD.

Association of Leptin and Leptin receptor Gene polymorphisms with Insulin resistance in pregnant women: A cross-sectional study

Introduction: Leptin is an adipokine hormone that regulates insulin sensitivity and lipid profile, which may contribute to complications like gestational diabetes.The goal of the study was to examine if there was a link between the leptin (LEP)/leptin receptor (LEPR) gene polymorphism and insulin resistance in pregnant women, and to determine the extent to which the leptin gene polymorphism could cause insulin resistance..

Methods: 208 pregnant women participated in this cross-sectional study of which 74 were insulin resistant cases and 134 were insulin sensitive controls. The study was carried out from December 2018 to December 2020 at a charitable hospital in Mangalore, Karnataka, India. Genotyping of leptin and its receptor gene were carried out using the Polymerase Chain Reaction- Restriction fragment Length Polymorphism (PCR-RFLP) method. Serum levels of leptin, insulin, and C peptide were assayed using Enzyme Linked Immuno Sorbent Assay (ELISA) and lipid profile by automated chemistry analyzer. Statistical analysis was carried out using SPSS 23.

Results: Insignificant association was observed between leptin receptor gene polymorphisms and insulin resistance, and leptin gene and insulin resistant women. There was no significant difference in the serum leptin levels among the cases and control (61.62±29.23 and 59.88±22.25). However, fasting blood sugar, insulin, C peptide, Triglycerides (TG), and very low-density Lipoprotein (VLDL) levels were significantly higher in cases as compared to controls (p=0.0068, p<0.0001, p<0.0001 and 0.01 respectively). Homeostatic Model Assessment for Insulin Resistance (HOMA IR) was greater in subjects with homozygous dominant, 'GG' of LEPR (p=0.0409) and hyperinsulinemia (p=0.023) as compared to other genotypes. However, hyperglycaemia was observed in subjects with homozygous dominant, ‘AA’ of leptin gene (p=0.0173).

Conclusion: No significant association was found between leptin and leptin receptor gene polymorphisms with insulin resistance in pregnancy. However, genotyping of these genes may be useful in predicting insulin resistance and gestational diabetes in pregnancy.

Association between Leptin (G2548A) and Leptin Receptor (Q223R) Polymorphisms with Plasma Leptin, BMI, Stress, Sleep and Eating Patterns among the Multiethnic Young Malaysian Adult Population from a Healthcare University

Relative leptin resistance in childhood to absolute leptin resistance in maturity suggests sleep, eating behaviour, and the psychological state as probable causes. The current body of research provides inconclusive evidence linking G2548A and Q223R to obesity. Furthermore, we could find very little data that have observed the association between the environment and gene polymorphism, especially in the multiethnic population that exists in Malaysia. This study searched for a possible link between sleeping habits, eating behaviour, and stress indicators with plasma leptin and its genetic variation in young adult Malaysian healthcare students. The study involved 185 first- and second-year medical and dental students from a healthcare university. Polymerase Chain Reaction−Restriction Fragment Length Polymorphism(PCR-RFLP) determined the genotype, Enzyme Linked Immunoabsorbant Assay (ELISA) tested the serum leptin, and a self-administered questionnaire evaluated sleep, eating behaviour, and psychological condition. Gender and ethnicity are linked to fasting plasma leptin levels (p < 0.001). Plasma leptin also affects stress, anxiety, and sadness. Leptin (LEP) and Leptin Receptor (LEPR) polymorphisms were not associated with BMI, plasma leptin, sleep, eating behaviour, or psychological state. Young adult Malaysian Indians were obese and overweight, while Chinese were underweight. These findings imply overweight and obese participants were in stage I of leptin resistance and lifestyle change or leptin therapy could prevent them from becoming cripplingly obese as they age.

-2548G>A LEP Polymorphism Is Positively Associated with Increased Leptin and Glucose Levels in Obese Saudi Patients Irrespective of Blood Pressure Status

Background and Objectives: In this study, we aimed to investigate the link between common -2548G>A (rs7799039) promoter variant of the human leptin gene (LEP) with leptin and serum glucose leptin levels in obese Saudi patients. Materials and Methods: A total of 206 Saudi adults (80 obese normotensive nondiabetics, 76 obese hypertensive with Type 2 Diabetes and 50 normotensive nondiabetic controls) were genotyped for -2548G>A LEP polymorphism using the polymerase chain reaction-restriction fragment-length polymorphism technique. Results: Participants with minor AA genotype had significantly higher blood glucose levels (6.8 ± 0.55 mmol/L vs. 5.8 ± 0.30 mmol/L; p < 0.04) and HOMA-IR (4.1 ± 0.84 vs. 2.6 ± 0.67; p = 0.03) against those carrying major GG genotype. Participants with heterozygous GA genotype had significantly higher serum leptin levels against those carrying major GG genotype (40.0 ± 2.6 ng/mL vs. 29.6 ± 2.6 ng/mL; p = 0.04). Further investigation showed that individuals with AA, GA, GA + AA genotypes are at greater risk of developing hyperglycemia compared to those with GG genotype [OR 3.7(1.6–8.4), p = 0.001; 3.2 (1.2–8.6), p = 0.03; 3.5 (1.6–7.7), p = 0.001, respectively]. Additionally, the -2548AA allele was shown to be a risk factor for hyperglycemia [OR 1.9 (1.2–3.0), p = 0.006]. Our data revealed no relationship between this variant of the LEP gene with systolic and diastolic BP, signifying that this genetic variant is not a significant marker of obesity and hypertension in the Saudi population. Conclusions: AA and GA genotypes and LEP gene -2548AA alleles may signify potent risk factors predisposing healthy individuals to develop T2DM regardless of blood-pressure profile.

-2548G>A LEP Polymorphism Is Positively Associated with Increased Leptin and Glucose Levels in Obese Saudi Patients Irrespective of Blood Pressure Status

Background and Objectives: In this study, we aimed to investigate the link between common -2548G>A (rs7799039) promoter variant of the human leptin gene (LEP) with leptin and serum glucose leptin levels in obese Saudi patients. Materials and Methods: A total of 206 Saudi adults (80 obese normotensive nondiabetics, 76 obese hypertensive with Type 2 Diabetes and 50 normotensive nondiabetic controls) were genotyped for -2548G>A LEP polymorphism using the polymerase chain reaction-restriction fragment-length polymorphism technique. Results: Participants with minor AA genotype had significantly higher blood glucose levels (6.8 ± 0.55 mmol/L vs. 5.8 ± 0.30 mmol/L; p < 0.04) and HOMA-IR (4.1 ± 0.84 vs. 2.6 ± 0.67; p = 0.03) against those carrying major GG genotype. Participants with heterozygous GA genotype had significantly higher serum leptin levels against those carrying major GG genotype (40.0 ± 2.6 ng/mL vs. 29.6 ± 2.6 ng/mL; p = 0.04). Further investigation showed that individuals with AA, GA, GA + AA genotypes are at greater risk of developing hyperglycemia compared to those with GG genotype [OR 3.7(1.6−8.4), p = 0.001; 3.2 (1.2−8.6), p = 0.03; 3.5 (1.6−7.7), p = 0.001, respectively]. Additionally, the -2548AA allele was shown to be a risk factor for hyperglycemia [OR 1.9 (1.2−3.0), p = 0.006]. Our data revealed no relationship between this variant of the LEP gene with systolic and diastolic BP, signifying that this genetic variant is not a significant marker of obesity and hypertension in the Saudi population. Conclusions: AA and GA genotypes and LEP gene -2548AA alleles may signify potent risk factors predisposing healthy individuals to develop T2DM regardless of blood-pressure profile.

Ethnic disparity in metabolic syndrome and related obesity and health behavior: a community study in Taiwan

BACKGROUND

As studies on ethnic disparities in metabolic syndrome and its risk factors in Taiwan are still rare, the aims of this study were: (1) to detect the differences in the rates of metabolic syndrome, obesity and health behaviors between two ethnic groups (indigenous Tsou and nonindigenous Han) living in the same area and with similar age and sex distributions; (2) to examine whether ethnicity per se plays a significant role in the occurrence of metabolic syndrome, while taking other risk factors including sociodemographic characteristics, obesity and health behaviors into consideration.

METHODS

This is a cross-sectional study using data from a community survey conducted in Chiayi County in southwestern Taiwan. A frequency matching strategy by age and sex with a ratio of 1 (Tsou) to 3 (Han) was applied to select a comparable sample between both ethnic groups (667 Tsou and 2001 Han) from among the survey participants. Furthermore, participants with cardiometabolic diseases diagnosed before the surveyed day were excluded to avoid confounding any associated risk factors for developing metabolic syndrome (MS). A final analytic sample of 1482 remained. The used information included sociodemographic characteristics, medical histories, health behaviors, and the concentrations of triglycerides, cholesterol, and glucose.

RESULTS

Indigenous Tsou had significantly higher rates of metabolic syndromes, obesity and unhealthy behaviors than their Han counterparts (MS: 54.0% vs. 29.1%, obesity: 54.0% vs. 23.2%, drinking alcohol: 17.5% vs. 13.6%, and higher intake of fried food: 6.4% vs. 4.4%), even though they were similar in age and sex distributions. The significant risk factors for subsequently developing MS included being indigenous Tsou (adjusted POR = 2.62, P < 0.001), older, single, and obese. Stratified analyses on the risk factors for developing MS by health behaviors and by obese problems also indicated increased risks of being indigenous Tsou.

CONCLUSIONS

There existed ethnic differences in the rates of metabolic syndrome, obesity, and health behaviors. Ethnicity per se did play a significant role in developing MS; in particular indigenous Tsou people had increased risks, suggesting possible biological reasons rooted in their origins that need further exploration. In addition, unhealthy behaviors may potentially have an indirect effect on developing MS via their effect on obesity.

Genetics of Obesity in East Asians

Obesity has become a public health problem worldwide. Compared with Europe, people in Asia tend to suffer from type 2 diabetes with a lower body mass index (BMI). Genome-wide association studies (GWASs) have identified over 750 loci associated with obesity. Although the majority of GWAS results were conducted in individuals of European ancestry, a recent GWAS in individuals of Asian ancestry has made a significant contribution to the identification of obesity susceptibility loci. Indeed, owing to the multifactorial character of obesity with a strong environmental component, the revealed loci may have distinct contributions in different ancestral genetic backgrounds and in different environments as presented through diet and exercise among other factors. Uncovering novel, yet unrevealed genes in non-European ancestries may further contribute to explaining the missing heritability for BMI. In this review, we aimed to summarize recent advances in obesity genetics in individuals of Asian ancestry. We therefore compared proposed mechanisms underlying susceptibility loci for obesity associated with individuals of European and Asian ancestries and discussed whether known genetic variants might explain ethnic differences in obesity risk. We further acknowledged that GWAS implemented in individuals of Asian ancestries have not only validated the potential role of previously specified obesity susceptibility loci but also exposed novel ones, which have been missed in the initial genetic studies in individuals of European ancestries. Thus, multi-ethnic studies have a great potential not only to contribute to a better understanding of the complex etiology of human obesity but also potentially of ethnic differences in the prevalence of obesity, which may ultimately pave new avenues in more targeted and personalized obesity treatments.

Modification effect of sex and obesity on the correlation of LEP polymorphisms with leptin levels in Taiwanese obese women

Background

Obesity has become the main health issue in developed countries as it impacts life expectancy and increases mortality of cerebrovascular or cardiovascular diseases. The leptin is one of the adipokines which presents in the serum in proportion to the amount of adipose tissue and is translated from LEP gene. It involves in energy homeostasis, lipid and glucose metabolisms, modulation of immune systems, and thermogenesis. Many previous studies have revealed controversial results between LEP polymorphisms and leptin levels in different ages and ethnicities. Herein, we investigated the impacts of LEP polymorphism against leptin levels in Taiwanese subjects.

Methods

In 599 Taiwanese subjects, excluding clinically overt systemic disease, age below 18 years old, and C‐reactive protein (CRP) level of above 10 mg/L, few of LEP polymorphisms were genotyped with TaqMan SNP genotyping assays, were further analyzed for association with leptin level in univariate and multivariate linear regression analyses with Bonferroni correction for multiple tests in stratified groups. The univariate and stepwise multivariate linear regression analyses were performed to determine the coefficient of determinant of LEP polymorphisms over leptin level.

Results

Significant associations were found between LEP polymorphisms and leptin levels in obese women. Circulating leptin level was positively correlated with inflammatory, insulin resistance markers, and visceral obesity markers in all subjects. Furthermore, stratified and interaction analyses revealed that LEP polymorphisms, rs7799039 and rs2167270, were significantly associated with leptin levels in obese women—8%–10% of which could be explained by LEP polymorphisms.

Conclusion

The LEP polymorphisms are independently associated with leptin levels in Taiwanese obese women. Further, the genetic determinants for leptin levels may be different between obese and nonobese, and in different sex individuals. The obesity status and female sex may exert modification effect on transcription of LEP, particularly in obese women.

Hair Trace Element Levels in Han and Indigenous Hualien Inhabitants in Taiwan

The objective of the present study was to assess the impact of ethnicity on hair trace element content in Han and aboriginal inhabitants of Hualien in Taiwan. Fifty Han (female/male = 35/15) and 50 aboriginal (female/male = 40/10) Hualien inhabitants aged 40-60 years were involved in the present study. Anthropometric data and dietary patterns were recorded. Hair mineral, essential, and toxic trace element levels were assessed using inductively coupled plasma mass spectrometry at NexION 300D (PerkinElmer Inc., USA) equipped with ESI SC-2 DX4 autosampler (Elemental Scientific Inc., USA). No group difference in gender, age, body weight, height, or physical activity was observed. Fish intake was more frequent in Han inhabitants, whereas aborigines consumed significantly more nuts. Indigenous people were characterized by higher hair Al (45%), Ca (threefold), Co (71%), Fe (twofold), I (74%), K (60%), Mg (2.5-fold), Na (62%), P (6%), Sn (78%), and V (46%) content. In turn, Han Hualien inhabitants had higher hair Be (twofold), Li, Se, Si levels as compared to indigenous counterparts. Multiple regression analysis demonstrated that ethnicity was significantly associated with hair Ca (β = 0.302), Mn (β = 0.284), P (β = 0.387), and Se (β = - 0.310) levels after adjustment for other confounders. At the same time, the overall models were significant for Ca, Mn, Se, and As. The obtained data may provide a background for monitoring and correction of trace element status in patients of different ethnic groups. However, further detailed studies are required to highlight the mechanisms underlying the observed associations.

Leptin Gene G2548A Polymorphism among Mongolians with Metabolic Syndrome

Metabolic syndrome (MetS) corresponds with multiple risk factors. Many studies have indicated that MetS significantly increases the risk of cardiovascular diseases and type 2 diabetes (T2D). The prevalence of MetS was estimated to be one third of the general Mongolian population in 2015. The purpose of our study was to determine polymorphisms of the LEP (Leptin) and LEPR (Leptin receptor) genes that show susceptibility to MetS and to predict the genetic risk of MetS. We selected 160 cases with MetS and 144 with healthy controls. The G2548A polymorphism of the LEP gene and the A668G (Q223R) polymorphism of the LEPR gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results of the regression analysis showed that the 2548 amino acids (AA) of LEP gene carriers had increased incidences of MetS (OR = 3.23; p = 0.035). Patients with MetS who were 2548A allele carriers had an increased concentration of serum leptin (p = 0.011). Moreover, G2548A of LEP polymorphism was associated with elevated body mass index (BMI) and fasting blood glucose (FBG) in the case group. Our results confirm that the LEP G2548A loci is the independent risk factor of MetS.

[Anthropometric measures and their relationship with the polymorphism G-2548A of the LEP gene in obese women from Mexico]

[No disponible]

Polymorphisms in Genes Involved in the Leptin-Melanocortin Pathway are Associated with Obesity-Related Cardiometabolic Alterations in a Southern Chilean Population

BACKGROUND

Polymorphisms in genes encoding proteins of the leptin-melanocortin pathway have been associated with obesity. The involvement of these polymorphisms with changes in body mass index (BMI) and anthropometric measures could also imply a contribution to the risk of metabolic syndrome (MetS) and metabolic alterations. We evaluated the relationship of leptin-melanocortin system polymorphisms with obesity, MetS, and other metabolic alterations in Southern Chilean individuals.

METHODS

Two-hundred individuals were grouped as normoweight (BMI 18.0-24.9 kg/m²), overweight (BMI 25.0-29.9 kg/m²), and obese (BMI ≥ 30 kg/m²) or according to MetS status. Anthropometric measures (BMI, abdominal circumference, waist-to-hip ratio [WHR]) and biochemical parameters (glycemia and lipid profile) were evaluated. Polymorphisms LEP rs7799039, LEPR rs1137101, MC3R rs3746619 and rs3827103, and MC4R rs17782313 were evaluated by real-time PCR using allelic discrimination assays.

RESULTS

LEPR rs1137101 GG genotype was related to reduced risk of obesity (odds ratio [OR] 0.26, 95% confidence interval [CI] 0.08-0.79; p = 0.018) and MetS (OR 0.36, 95% CI 0.15-0.88; p = 0.024), but it was not significant after Bonferroni correction for multiple tests as compared to the AA genotype (p > 0.01). Moreover, LEPR rs1137101 allele G (AG + GG) was related to lower BMI and WHR (p < 0.01). Further multiple linear regression analysis demonstrated that this genotype was also responsible for reduced BMI in 2.44 kg/m² and WHR in 0.033 units. MC4R rs17782313 allele C (TC + CC) was slightly associated with diminished risk of MetS (OR 0.48, 95% CI 0.23-0.98; p = 0.040) and reduced BMI values in 1.95 kg/m² (p < 0.05). Regarding lipid profile, LEPR rs1137101 allele G carriers had lower triglycerides and very-low-density lipoprotein (VLDL) cholesterol, whereas individuals carrying the MC4R rs17782313 allele C had higher high-density lipoprotein (HDL) cholesterol (p < 0.01). LEP rs7799039 allele A (GA + AA) was slightly associated with reduced total and low-density lipoprotein (LDL) cholesterol (p < 0.05).

CONCLUSIONS

These results suggest that polymorphisms at LEP, LEPR, and MC4R may be useful biomarkers of obesity-related cardiometabolic alterations in our population.

Genetics of Severe Obesity

PURPOSE OF REVIEW

This review aims to present current information on genes underlying severe obesity, with the main emphasis on the three genes LEP, LEPR and MC4R.

RECENT FINDINGS

There is a substantial amount of evidence that variants in at least ten different genes are the cause of severe monogenic obesity. The majority of these are involved in the leptin-melanocortin signalling pathway. Due to the frequency of some of the identified variants, it is clear that monogenic variants also make a significant contribution to common obesity. The artificial distinction between rare monogenic obesity and common polygenic obesity is now obsolete with the identification of MC4R variants of strong effect in the general population.

Association of ADIPOQ, leptin, LEPR, and resistin polymorphisms with obesity parameters in Hammam Sousse Sahloul Heart Study

BACKGROUND

Adipose tissue is an important endocrine organ that secretes a number of adipokines, such as adiponectin (ADIPOQ), leptin (LEP), leptin receptor (LEPR), and resistin (RETN) which may be implicated in obesity. Some adipokines' polymorphisms of genes might influence their concentrations and/or activities. Our aim was to study the relationship between seven SNPs in ADIPOQ (+45T<G (rs2241766); +276G<T (rs1501299); -4255C<T (rs822393); -395G<T (rs17366568)), LEP (2548G<A (rs7799039)), LEPR (223Q<R (rs1137101)), and RETN (-420C<G (rs1862513)) and obesity in Hammam Sousse Sahloul Heart Study (HSHS).

METHODS

The study, carried out between February and June 2009, is mainly focused on 1121 respondents in HSHS which is a population-based epidemiological study of type "community-based" on cardiovascular risk. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serum lipids and anthropometric parameters were measured. Statistic analysis was performed on SPSSv19.

RESULTS

The polymorphisms of ADIPOQ 4522C<T and 276G<T, LEP 2548G<A, and RETN 420C<G seem to contribute to obesity. In fact, adjusted odds ratios (ORs) of obesity associated with mutated genotypes of each polymorphism were respectively OR=1.38, P=.037; OR=0.608, P<.001; OR=2.23, P=.034; and OR=2.18, P<.001. The 276G<T, 4522C<T, and 420C<G were associated with increased BMI (P=.010, P=.028, and P<.001). A significant association was found between the 276G<T; 4522C<T, LEP 2548G<A and 420C<G, and the waist circumference and hip measurements.

CONCLUSION

ADIPOQ, LEP, and RETN gene polymorphisms were associated with obesity parameters in HSHS population.

Relationships between plasma leptin levels, leptin G2548A, leptin receptor Gln223Arg polymorphisms and gestational diabetes mellitus in Chinese population

The purposes of this study were to examine concentrations of leptin and biochemical parameters in gestational diabetes mellitus (GDM) patients and normal glucose tolerance (NGT) individuals, and also to explore the links of leptin (LEP) G2548A and leptin receptor (LEPR) Gln223Arg polymorphisms with leptin levels and GDM risk among Chinese. Our study included 357 GDM and 355 NGT individuals who were at 24~30 gestational weeks. Plasma leptin and insulin levels were analyzed by ELISA. Gene polymorphisms were genotyped using TaqMan real-time polymerase chain reaction assay. The results showed that plasma leptin levels were significantly higher in the impaired fasting glucose (IFG) group than NGT group (34.35 (26.54, 56.48) ng/mL vs 26.31 (17.99, 37.87) ng/mL, P < 0.05). Plasma leptin levels correlated with plasma fasting insulin levels, pre-pregnant body mass index, homeostasis model assessment-insulin resistance and quantitative insulin sensitivity check index both in GDM and NGT group (P < 0.05). However, neither LEP G2548A nor LEPR Gln223Arg polymorphisms were significantly associated with GDM risk and plasma leptin levels (P > 0.05). Our findings showed that high leptin level was associated with GDM. And larger and more rigorous researches were needed to further explore the association of LEP and LEPR gene polymorphisms and GDM among Chinese population.

Association of polymorphism in adiponectin (+45 T/G) and leptin (-2548 G/A) genes with type 2 diabetes mellitus in male Egyptians

INTRODUCTION

Adiponectin is an adipose tissue-specific protein with insulin-sensitizing properties. Many investigators have explored the association between adiponectin single nucleotide polymorphisms (SNPs) and type 2 diabetes mellitus (T2DM) in different ethnic populations from different regions. Leptin is a protein hormone constituting an important signal in the regulation of adipose tissue mass and body weight. The aim of this study was to explore potential associations between SNP +45 T>G of the adiponectin gene and SNP 2548G/A of leptin with T2DM and the effect of SNPs on serum adiponectin and leptin levels.

MATERIAL AND METHODS

From the Egyptian population, we enrolled 110 T2DM patients and 90 non-diabetic controls. Serum lipid profile, blood glucose, serum adiponectin, and leptin were measured. Genotyping for two common SNPs of the adiponectin and leptin genes was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The G allele and TG/GG genotype of SNP 45 occurred more frequently than the T allele and TT genotype in T2DM patients compares to the controls. Subjects with the GG + TG genotype of SNP 45 were at increased risk for T2DM (OR = 6.476; 95% CI: 3.401-12.33) and associated with a low serum adiponectin level compared with the TT genotype. The serum leptin concentration of GA + AA genotype carriers was not significantly different from that of the GG genotype in the diabetic group.

CONCLUSIONS

The G allele carriers who have reduced plasma concentrations of adiponectin may have an association with T2DM, while leptin SNP 2548 G/A is not associated with the risk of development of T2DM in the Egyptian population.

The Impact of LEP G-2548A and LEPR Gln223Arg Polymorphisms on Adiposity, Leptin, and Leptin-Receptor Serum Levels in a Mexican Mestizo Population

The polymorphisms in leptin (LEP G-2548A) and leptin-receptor (LEPR Gln223Arg) seem to influence obesity and lipid metabolism among others. The aim of this study was to investigate the effect of these polymorphisms on adiposity, leptin (sLeptin), and leptin-receptor (sLeptin-receptor) serum concentrations as well as inflammation markers. We included 382 adults originally from Western Mexico. They were genotyped by PCR-RFLP. Obese individuals showed higher sLeptin (58.2 ± 31.35 ng/mL) but lower sLeptin-receptor (12.6 ± 3.74 ng/mL) levels than normal weight ones (17.6 ± 14.62 ng/mL, 17.4 ± 4.62 ng/mL, resp.), P < 0.001. Obese subjects carriers of Arg/Arg genotype had more (P = 0.016) sLeptin-receptor (14.7 ± 4.96 ng/mL) and less (P = 0.004) sLeptin (44.0 ± 28.12 ng/mL) levels than Gln/Gln genotype (11.0 ± 2.92 ng/mL, 80.3 ± 33.24 ng/mL, resp.). Body fat mass was lower (P from 0.003 to 0.045) for A/A (36.5% ± 6.80) or Arg/Arg (36.8% ± 6.82) genotypes with respect to G/G (41.3% ± 5.52) and G/A (41.6% ± 5.61) or Gln/Gln (43.7% ± 4.74) and Gln/Arg (41.0% ± 5.52) genotypes carriers. Our results suggest that LEP -2548A and LEPR 223Arg could be genetic markers of less body fat mass accumulation in obese subjects from Western Mexico.

Genetic variants in leptin: Determinants of obesity and leptin levels in South Indian population

The revelation of leptin action mechanisms has led to various attempts to establish the association of polymorphisms in the leptin gene with obesity-related phenotypes. But, outcomes have been contradicting, which made the information on the role of the leptin gene in regulating the mechanism of pathophysiology of obesity inexplicable. Moreover, none of the studies are known to have similar implications on the Indian population. To address such contradictions, our study aims to evaluate the association of leptin gene polymorphism with obesity and leptin levels in a South Indian Population. A total of 304 cases (BMI≥27.5) and 309 controls (BMI≤23) from local inhabitants of Mysore, Karnataka were recruited for the study. The leptin gene variants rs7799039, rs2167270 and rs4731426 independently, as well as in 4 haplotype combinations, were found to be significantly associated with the risk of obesity. An increasing trend in BMI and leptin levels was observed with every addition of A and C minor alleles of exonic variant (rs2167270) and intronic variant (rs4731426) respectively. However, only AA genotype of SNP rs7799039 was positively associated with BMI. None of the SNPs were associated with fat percentage and waist to hip ratio. On a whole, this data suggests that the common polymorphisms in the leptin gene are strong predictors of obesity and leptin levels in South Indians.

Lack of association between leptin G-2548A polymorphisms and obesity risk: Evidence based on a meta-analysis

BACKGROUND

The prevalence of obesity is increasing in most industrialized and developing countries. We aimed to investigate the association between leptin (LEP) G-2548A polymorphisms and the risk of obesity.

METHODS

We searched the PubMed, Web of Science, and China National Knowledge Infrastructure databases for studies that evaluated the association between LEP G-2548A polymorphisms and obesity risk prior to March 2014. The odds ratio (OR) and its 95% confidence interval (95% CI) were calculated to estimate the risk of obesity. Meta-analysis of subgroup populations and different control sources was conducted using homozygote (AA vs. GG), allelic (A vs. G), dominant (AA+GA vs. GG), recessive (AA vs. GG+GA), and heterozygote (AG vs. GG) models. The heterogeneity of the studies was assessed using χ(2)-tests based on Q-statistics. The pooled ORs were calculated using a random-effects model if there was no heterogeneity; otherwise, a random-effects model was used. Two authors extracted the data independently. The funnel plots, Begg's and Egger's test were used to assess publication bias. All statistical analyses were performed using STATA 12.0 software.

RESULTS

Nine case-controlled publications that evaluated the association between LEP G-2548A polymorphisms and obesity risk, which included 2594 subjects (1235 obesity cases and 1359 controls), were included in our meta-analysis. No significant association between this polymorphism and obesity risk was observed (P>0.05). Significant heterogeneity was detected among the studies. The results of subgroup analysis according to ethnicity and different control groups suggested that LEP G-2548A polymorphisms might increase the obesity risk in African populations in the homozygote (AA vs. GG: OR=2.38, 95% CI=1.15-4.93, P=0.020) and recessive (AA vs. GG+GA: OR=2.03, 95% CI=1.34-3.06, P=0.001) models.

CONCLUSIONS

Overall, this meta-analysis indicated that LEP G-2548A polymorphisms are not associated with obesity risk, although significant associations were observed in the homozygote model (AA vs. GG) and the recessive model (AA vs. GG+GA) in Africa populations. Further studies are still needed to validate and confirm this association.

Gene polymorphisms and increased DNA damage in morbidly obese women

Obesity is characterized by increased adipose tissue mass resulting from a chronic imbalance between energy intake and expenditure. Furthermore, there is a clearly defined relationship among fat mass expansion, chronic low-grade systemic inflammation and reactive oxygen species (ROS) generation; leading to ROS-related pathological events. In the past years, genome-wide association studies have generated convincing evidence associating genetic variation at multiple regions of the genome with traits that reflect obesity. Therefore, the present study aimed to evaluate the relationships among the gene polymorphisms ghrelin (GHRL-rs26802), ghrelin receptor (GHSR-rs572169), leptin (LEP-rs7799039), leptin receptor (LEPR-rs1137101) and fat mass and obesity-associated (FTO-rs9939609) and obesity. The relationships among these gene variants and the amount of DNA damage were also investigated. Three hundred Caucasian morbidly obese and 300 eutrophic (controls) women were recruited. In summary, the results demonstrated that the frequencies of the GHRL, GHSR, LEP and LEPR polymorphisms were not different between Brazilian white morbidly obese and eutrophic women. Exceptions were the AA-FTO genotype and allele A, which were significantly more frequent in obese women than in the controls (0.23% vs. 0.10%; 0.46 vs. 0.36, respectively), and the TT-FTO genotype and the T allele, which were less frequent in morbidly obese women (p<0.01). Furthermore, significant differences in the amount of genetic lesions associated with FTO variants were observed only in obese women. In conclusion, this study demonstrated that the analyzed SNPs were not closely associated with morbid obesity, suggesting they are not the major contributors to obesity. Therefore, our data indicated that these gene variants are not good biomarkers for predicting risk susceptibility for obesity, whereas ROS generated by the inflammatory status might be one of the causes of DNA damage in obese women, favoring genetically related diseases as obesity comorbidities.

Association of leptin/receptor and TNF-α gene variants with adolescent obesity in Malaysia

BACKGROUND

Leptin (LEP) G-2548A (rs7799039), leptin receptor (LEPR) Q223R (rs1137101) and tumor necrosis factor (TNF)-α G-308A (rs1800629) gene variants have been reported to be associated with obesity, although results for subjects from different countries have been controversial. The aim of this study was to determine the prevalence of overweight and obesity in Malaysian adolescents and the association of these polymorphisms with overweight and obese or over-fat adolescents.

METHODS

A total of 613 adolescents (241 Malay, 219 Chinese, 153 Indian) were enrolled. Anthropometric measurements of body mass index (BMI) and body fat percentage were used to classify subjects as controls (non-overweight/obese or normal fat) or as cases (overweight/obese or over-fat). Genomic DNA was extracted from oral buccal mucosa cells for genotyping using polymerase chain reaction-restriction fragment length polymorphism and data obtained were statistically analyzed.

RESULTS

A total of 23.3% of subjects were overweight/obese whereas 11.4% were over-fat; there were significantly more overweight/obese and over-fat Indian and Malay adolescents compared to Chinese (P < 0.001). A allele was the minor one for LEPR Q223R and TNF-α G-308A in all ethnic groups, whereas G allele was minor for LEP G-2548A in Chinese and Malay adolescents, except for Indian adolescents. Indian male adolescents with AA genotype for LEP G-2548A were associated with overweight/obesity (P = 0.025; odds ratio, 3.64; 95% confidence interval: 1.15-11.54). Despite the lack of association observed for LEPR Q223R and TNF-α G-308A, Indian and Chinese subjects with AA risk genotype for LEPR Q223R/LEP G-2548A and TNF-α G-308A/LEP G-2548A, respectively, had increased mean BMI (P = 0.049, P = 0.016).

CONCLUSIONS

Genotype distribution and association of these polymorphisms with overweight/obesity vary between ethnic groups and genders. Nevertheless, the LEP G-2548A risk allele may be associated with overweight/obese Indian male adolescents in Malaysia.

Association of leptin gene -2548 G/A polymorphism with obesity: a meta-analysis

BACKGROUND

A common single-nucleotide polymorphism identified in the 5'-untranslated region of the leptin gene (LEP -2548 G/A polymorphism) may be associated with obesity, but the existing research findings are inconsistent, so we conducted this meta-analysis.

METHODS

Medline, Embase and ISI Web of Science databases were searched to identify relevant studies. Meta-analysis of the total and subgroup populations was conducted using allelic, additive, dominant and recessive models, and odds ratios and their 95% confidence intervals were calculated in a fixed-effect model if no heterogeneity (evaluated as I(2) statistic) existed. Otherwise, a random-effects model was adopted. Subgroup analysis was performed by ethnicity. Meta-regression and the HETRED analysis were used to explore the potential sources of between-study heterogeneity. Egger's test and influence analysis were conducted to evaluate the publication bias and study power, respectively.

RESULTS

The final selection enrolled 9 studies, including 2,988 subjects (1,372 obese subjects and 1,616 controls). No significant association was identified between the LEP -2548 G/A polymorphism and obesity for all genetic models in the overall population and Caucasians. We found a significant association with allelic, additive and dominant models for subjects of mixed race from South America. Notwithstanding, this significance should be treated cautiously for it is based on a rather small sample (788 involved subjects).

CONCLUSIONS

In total, the combined analysis of data from current and published studies suggested that the LEP -2548 G/A polymorphism does not contribute to the development of obesity, despite the fact that a significant association exists in a small subgroup from South America. Further studies are needed to elucidate the relationship. .

Leptin and leptin receptor gene polymorphisms and their association with plasma leptin levels and obesity in a multi-ethnic Malaysian suburban population

Background

This study was to investigate the prevalence of single nucleotide polymorphisms (SNPs) in leptin gene LEP (A19G and G2548A) and leptin receptor gene LEPR (K109R and Q223R) and their association with fasting plasma leptin level (PLL) and obesity in a Malaysian suburban population in Kampar, Perak.

Methods

Convenience sampling was performed with informed consents, and the study sample was drawn from patients who were patrons of the Kampar Health Clinic. A total of 408 subjects (mean age, 52.4 ± 13.7 years; 169 men, 239 women; 190 obese, 218 non-obese; 148 Malays, 177 ethnic Chinese, 83 ethnic Indians) participated. Socio-demographic data and anthropometric measurements were taken, and genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Results

The LEP A19G, G2548A and LEPR K109R, Q223R variant allele frequencies were 0.74, 0.67 and 0.61, 0.79, respectively. The genotype and allele distributions of these gene variants were significantly different among ethnic groups, but not among body mass index (BMI) classes. Subjects with LEPR K109 and Q223 allele had significantly higher systolic blood pressure and adiposity indices after adjustment for ethnicity (higher BMI, total body and subcutaneous fat; lower skeletal muscle percentage). Subjects with LEPR 109R allele had lower PLL than their wild-type allele counterparts. The influence of LEP A19G and G2548A SNPs on blood pressures, anthropometrics, and PLL was not evident. Interestingly, synergistic effect of the LEP and LEPR SNPs was observed as subjects homozygous for all four SNPs studied exhibited significantly higher subcutaneous fat and PLL than those with other genotype combinations.

Conclusions

The LEP and LEPR SNPs in this study may not be an obesity marker among Malaysians in this population, but were associated with ethnicity. Our findings suggest that each of these SNPs contributes to minor but significant variation in obesity-related traits and in combination they display synergistic effects on subcutaneous fat and PLL.

Hepatitis C treatment outcome in relation to alcohol consumption and racial differences in southeastern Taiwan

BACKGROUND/PURPOSE

Alcohol use may have negative impacts on hepatitis C virus (HCV) treatment due to low adherence, and racial differences can influence HCV sustained virological response (SVR) rate between East Asian and European ancestry. The objective of this study is to confirm the influence of alcohol consumption and racial differences on HCV treatment outcome in aboriginal and nonaboriginal people of southeastern Taiwan.

METHODS

In this retrospective cohort study, a total of 195 patients were treated with peginterferon-alpha once weekly plus ribavirin for 24 weeks. The efficacy analysis was performed based on the SVR rate for patients who received at least one dose of the study medication or who completed treatment. The endpoints were denoted by virological response rate including the influences of alcohol use, HCV genotype, serum level of HCV virological load, and racial differences.

RESULTS

No differences were observed in the baseline clinical characteristics between drinkers and nondrinkers, but a significant difference was noted in the body mass index between aboriginal and nonaboriginal populations (28.3 vs. 25.8; p < 0.01). With respect to the SVR rate, no difference was found between drinkers and nondrinkers, and between aboriginal and nonaboriginal people. The treatment efficacy of SVR in the whole group was significantly different between patients with HCV genotype 1 and nongenotype 1 (73.5% vs. 91.2%; p < 0.01). An analysis of the SVR rate in the aboriginal group showed no significant difference between patients with genotype 1 and nongenotype 1 (80.0% vs. 91.3%; p = 0.31).

CONCLUSION

In southeastern Taiwan, alcohol consumption did not influence the HCV treatment outcome, and the SVR rates were similar between patients with HCV genotype 1 and nongenotype 1 infections in the aboriginal group.

Advances in understanding the interrelations between leptin resistance and obesity

Obesity, which has developed into a global epidemic, is a risk factor in most chronic diseases and some forms of malignancy. The discovery of leptin in 1994 has opened a new field in obesity research. Currently, we know that leptin is the primary signal from energy stores and exerts negative feedback effects on energy intake. However, most individuals with diet-induced obesity (DIO) develop leptin resistance, which is characterized by elevated circulating leptin levels and decreased leptin sensitivity. To date, though various mechanisms have been proposed to explain leptin resistance, the exact mechanisms of leptin resistance in obesity are poorly understood. Consequently, it's an important issue worth discussing regarding what the exact interrelations between leptin resistance and obesity are. Here, we review the latest advancements in the molecular mechanisms of leptin resistance and the exact interrelations between leptin resistance, obesity, and obesity-related diseases, in order to supply new ideas for the study of obesity.

Analysis of the relationship between three coding polymorphisms in LEPR gene and obesity in northern Chinese

SUMMARY

To determine the effect of variants in LEPR gene on obesity in northern Chinese, three coding polymorphisms Arg109Lys (A/G), Asn656Lys (C/G) and Pro1019Pro (C/T) were investigated for association with overweight and obesity. By a case control design, 248 overweight or obese subjects and 351 lean normal controls were recruited in Harbin region in north China. All three polymorphisms were genotyped by Sequenom single nucleotide polymorphism (SNP) detection system in both cases and controls. Genotypes for all three polymorphisms were in Hardy-Weinberg equilibrium in control subjects. Both groups had similar distribution of alleles and genotypes created by the three coding polymorphisms of LEPR gene. No differences in frequencies of genotypes or alleles between cases and controls for any polymorphism individually were found by χ(2) analysis (p = 0.444, p = 0.507 and p = 0.662, respectively). Further, when the haplotypes of three polymorphisms were assessed, no association for any haplotype of three polymorphisms was revealed. In the present study, the three coding polymorphisms in LEPR gene were firstly investigated in a population of northern Chinese. It was suggested that the three coding polymorphisms in LEPR gene were unlikely to have major effects on susceptibility to obesity in northern Chinese.:

Association between Leptin gene polymorphisms and plasma leptin level in three consanguineous families with obesity

INTRODUCTION

Leptin (LEP) gene is one of the most promising candidate genes for obesity. Previous studies have tested the association of polymorphisms in LEP gene with obesity and obesity-related metabolic biomarkers (anthropometric variables, glucose, insulin level, leptin level and lipid profile). However, the results of these studies were still controversial. To determine whether LEP gene is associated with obesity in Tunisian population, we performed a family-based association study between LEP polymorphisms and obesity and obesity-related metabolic biomarkers.

METHODS

Seven single nucleotide polymorphisms (SNPs) in 5' region of LEP gene were genotyped in three consanguineous families including 33 individuals. The previously reported LEP SNPs (H1328084, H1328082, rs10487506, H1328081, H1328080, G-2548A and A19G) were evaluated by PCR-RFLP and direct sequencing methods. Single SNP association and haplotype association analyses were performed using the family-based association test (FBAT). To determine allele frequencies of these SNPs in general population, 52 unrelated individuals from the general Tunisian population were also analyzed.

RESULTS

Two SNPs showed significant associations with plasma leptin level (H1328084: A>G, Z=2.058, p=0.039; A19G: G>A, Z=2.058, p=0.039). When haplotypes were constructed with these two-markers, the risk AA haplotype (frequency 57.1%) was positively associated with plasma leptin level (Z=2.058, p=0.039). Moreover, SNPs H1328084 and A19G are predicted to modify transcription-factor binding sites.

CONCLUSIONS

Our study provided that two functional variants in 5' regulatory region of LEP gene are associated with plasma leptin level as a quantitative trait. It suggested that H1328084 and A19G have an important role in regulating plasma leptin level.

Aerobic fitness does not modify the effect of FTO variation on body composition traits

PURPOSE

Poor physical fitness and obesity are risk factors for all cause morbidity and mortality. We aimed to clarify whether common genetic variants of key energy intake determinants in leptin (LEP), leptin receptor (LEPR), and fat mass and obesity-associated (FTO) are associated with aerobic and neuromuscular performance, and whether aerobic fitness can alter the effect of these genotypes on body composition.

METHODS

846 healthy Finnish males of Caucasian origin were genotyped for FTO (rs8050136), LEP (rs7799039) and LEPR (rs8179183 and rs1137101) single nucleotide polymorphisms (SNPs), and studied for associations with maximal oxygen consumption, body fat percent, serum leptin levels, waist circumference and maximal force of leg extensor muscles.

RESULTS

Genotype AA of the FTO SNP rs8050136 associated with higher BMI and greater waist circumference compared to the genotype CC. In general linear model, no significant interaction for FTO genotype-relative VO(2)max (mL·kg(-1)·min(-1)) or FTO genotype-absolute VO(2)max (L·min(-1)) on BMI or waist circumference was found. Main effects of aerobic performance on body composition traits were significant (p<0.001). Logistic regression modelling found no significant interaction between aerobic fitness and FTO genotype. LEP SNP rs7799039, LEPR SNPs rs8179183 and rs1137101 did not associate with any of the measured variables, and no significant interactions of LEP or LEPR genotype with aerobic fitness were observed. In addition, none of the studied SNPs associated with aerobic or neuromuscular performance.

CONCLUSIONS

Aerobic fitness may not modify the effect of FTO variation on body composition traits. However, relative aerobic capacity associates with lower BMI and waist circumference regardless of the FTO genotype. FTO, LEP and LEPR genotypes unlikely associate with physical performance.

Study of the leptin levels and its gene polymorphisms in patients with idiopathic short stature and growth hormone deficiency

Leptin levels may regulate fat metabolism, skeletal growth, and puberty. Leptin gene variants affect risk of obesity, cancer, but their effect on onset of growth hormone deficiency (GHD) and idiopathic short stature (ISS) is unknown. We tested the hypothesis that the phenotype of GHD and ISS may be associated with polymorphism in the leptin gene. The prevalence of a single nucleotide polymorphism (SNP) in the leptin gene (LEP) promoter at -2548 and the leptin and insulin growth factor-1 (IGF-1) concentrations in GHD and ISS were compared to those of healthy controls. IGF-1 and leptin concentrations were significantly lower in both the GHD and ISS groups than in the control group. The ISS and GHD groups had a significantly different distribution of SNP alleles at the LEP -2548 (P = 0.010). Individuals with LEP -2548A/G or G/G genotype in ISS group (47.5%) showed a significantly lower weight and body mass index (BMI) (but not leptin levels) than individuals carrying the A/A genotype (52.5%). LEP -2548A/A in GHD patients (65.8%) was associated with lower weight, BMI, leptin concentrations than those of individuals carrying the A/G or G/G genotype (34.2%). These data suggest that the LEP -2548A polymorphism may associate with the weight and BMI of the children with ISS and GHD.

Relationship between leptin G2548A and leptin receptor Q223R gene polymorphisms and obesity and metabolic syndrome risk in Tunisian volunteers

Leptin is a key hormone of weight regulation that modulates food intake. Since the elaboration of the leptin action mechanism, several studies tried to establish the relationship between obesity and the common polymorphisms of leptin (LEP) and leptin receptor (LEPR) genes, but results were controversial. We studied the association of G2548A of the LEP gene and Q223R of LEPR gene polymorphisms with obesity and metabolic syndrome (MetS). We recruited 169 nonobese volunteers (body mass index [BMI] < 30 kg/m(2)) and 160 obese ones (BMI ≥ 30 kg/m(2)). Glucose, insulin, and lipids were measured. BMI, homeostasis model assessment-insulin resistance (HOMA-IR), and daily energy intake were calculated. After adjustment to confounders parameters, 2548AA was found to increase the MetS (p=0.043) and obesity risk (p=0.019) in the studied population. After stratification according to the degree of obesity, the odds ratio [OR] of 2548AA was associated with moderate obesity (p=0.048) and morbid obesity (p=0.048). The LEPR 223RR genotype was associated with obesity in the studied population (OR=1.74, p=0.037) and only in the overweight (OR=1.8, p=0.049). Subjects with 2548AA had significantly higher BMI, daily energy intake, total cholesterol (TC), waist circumference (WC), insulinemia, and low high-density lipoprotein-cholesterol (HDL-C) levels. With regard to 223RR, we noted a significantly higher daily energy intake, BMI, TC, glycemia, insulinemia, HOMA-IR index, and low HDL-C levels. Haplotype model AR (2548A+223R) and AQ (2548A+223Q) increased the risk of obesity (OR=3.36, p<0.001; OR=2.56, p=0.010, respectively). When we added daily energy intake in adjustment, these significant associations disappeared. In addition, the AR and AQ increased the MetS risk. This significant association persisted after we had added daily energy intake in adjustment. This study showed that LEP G2548A and LEPR Q223R polymorphisms and haplotype combination were associated with MetS and obesity risk in Tunisian volunteers.

Study of leptin levels and gene polymorphisms in patients with central precocious puberty

INTRODUCTION

Three single-nucleotide polymorphisms (SNPs) in the leptin (LEP) or leptin receptor (LEPR) genes were assessed for their association with central precocious puberty (CPP).

RESULTS

The control group with the A/G SNP at LEPR 223 or A/G SNP at LEPR 109 exhibited significantly higher peak luteinizing hormone (LH) levels. The leptin level in the CPP group was significantly higher than that in the control group, but SNPs in either LEP or LEPR gene could not explain this observation.

DISCUSSION

In conclusion, SNPs at LEPR 223 and LEPR 109 were significantly associated with higher levels of LH in girls without CPP, but none of the genotypes at these SNPs were significantly associated with CPP.

METHODS

The SNP genotypes of LEP (polymorphism at promoter at nt-2548) and LEPR (223A/G, 109A/G) of 219 healthy girls and 249 girls diagnosed with CPP were compared. Allele frequencies in SNPs were compared with anthropometric measures, circulating leptin, hormones (estradiol, follicle-stimulating hormone, and LH), and lipid concentrations for CPP risk.

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.

Appetite regulation genes are associated with body mass index in black South African adolescents: a genetic association study

BACKGROUND

Obesity is a complex trait with both environmental and genetic contributors. Genome-wide association studies have identified several variants that are robustly associated with obesity and body mass index (BMI), many of which are found within genes involved in appetite regulation. Currently, genetic association data for obesity are lacking in Africans-a single genome-wide association study and a few replication studies have been published in West Africa, but none have been performed in a South African population.

OBJECTIVE

To assess the association of candidate loci with BMI in black South Africans. The authors focused on single nucleotide polymorphisms (SNPs) in the FTO, LEP, LEPR, MC4R, NPY2R and POMC genes.

DESIGN

A genetic association study.

PARTICIPANTS

990 randomly selected individuals from the larger Birth to Twenty cohort (a longitudinal birth cohort study of health and development in Africans).

MEASURES

The authors genotyped 44 SNPs within the six candidate genes that included known BMI-associated SNPs and tagSNPs based on linkage disequilibrium in an African population for FTO, LEP and NPY2R. To assess population substructure, the authors included 18 ancestry informative markers. Weight, height, sex, sex-specific pubertal stage and exact age collected during adolescence (13 years) were used to identify loci that predispose to obesity early in life.

RESULTS

Sex, sex-specific pubertal stage and exact age together explain 14.3% of the variation in log(BMI) at age 13. After adjustment for these factors, four SNPs were individually significantly associated with BMI: FTO rs17817449 (p=0.022), LEP rs10954174 (p=0.0004), LEP rs6966536 (p=0.012) and MC4R rs17782313 (p=0.045). Together the four SNPs account for 2.1% of the variation in log(BMI). Each risk allele was associated with an estimated average increase of 2.5% in BMI.

CONCLUSIONS

The study highlighted SNPs in FTO and MC4R as potential genetic markers of obesity risk in South Africans. The association with two SNPs in the 3' untranslated region of the LEP gene is novel.

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.

Leptin and leptin receptor polymorphisms are associated with poor outcome (death) in patients with non-appendicular secondary peritonitis

Introduction

Leptin (LEP) and its receptor (LEPR) participate in the immunological response during infection. LEP serum levels rise during sepsis. In patients with peritonitis, an insufficient elevation in serum LEP is associated with an increased risk of death. As gene variants of LEP and LEPR have been associated with diverse pathologic conditions, we explored the association of genetic polymorphisms of LEP or LEPR with death in patients with secondary peritonitis.

Methods

A case control study was undertaken. LEP Gene -2548G > A and the LEPR Gene 223A > G polymorphism were determined in 74 patients. The odds ratio of genotype and allele distribution in survival (control) versus death (case) among patients was calculated. Serum LEP, interleukin (IL)-6, tumour necrosis factor alpha, C-reactive protein (C-RP), IL-10 and IL-13 levels were analyzed in 34 patients.

Results

There were significant differences in genotype and allele distribution between survivors and non-survivors for -2548G > A and 223A > G polymorphisms. The presence of the mutant allele A, in -2548, had an odds ratio of 4.64 (95% CI 1.22, 17.67) with significance (P = 0.017) in the risk of death. The presence of mutant allele G, in 223, had an odds ratio of 3.57 (95% CI 1.06, 12.01) with significance in the risk of death (P = 0.033). The presence of allele A in the -2548 polymorphism was associated with differences in serum LEP (P = 0.013), and IL-10 (P = 0.0001). The presence of allele G in 223 polymorphism was likewise correlated with differences in serum LEP (P < 0001), C-RP (P = 0.033), and IL-10 (P = 0.043).

Conclusions

The polymorphisms studied are associated with death in patients with peritonitis of non-appendicular origin. This association is stronger than many known risk-factors related to peritonitis severity, and is independent of body mass. The physiopathologic mechanism is possibly related to an insufficient increase in the elevation of serum LEP levels, and is unrelated to body mass.

Effect of three common SNPs in 5'-flanking region of LEP and ADIPOQ genes on their expression in Polish obese children and adolescents

Genes encoding adipokines are considered as candidates for human obesity. In this study we analyzed the expression of leptin (LEP) and adiponectin (ADIPOQ) genes in relation to common 5′-flanking or 5′UTR variants: -2548G>A (LEP), 19A>G (LEP) and -11377C>G (ADIPOQ) in Polish obese children and adolescents. Relative transcription levels in the subcutaneous adipose tissue (real time RT–PCR) and serum protein concentrations (RIA) were measured in 48 obese subjects with known genotypes at three polymorphic sites and in five non-obese controls. None of the studied polymorphisms altered significantly the expression. Significantly elevated relative transcription levels of the LEP gene (P < 0.05) and serum leptin concentrations (P < 0.01) were recorded in obese patients, when compared with the non-obese controls, but such differences were not found for the ADIPOQ gene. Interestingly, the leptin to adiponectin protein concentration ratio (L/A) was approximately sevenfold higher in obese children and adolescents when compared with the non-obese controls (P < 0.001). Taking into consideration the observed relationship between the genotypes and the gene expression level we suggest that these SNPs are not conclusive markers for predisposition to obesity in Polish children and adolescents. On the other hand, we confirmed that the leptin to adiponectin gene expression ratio (L/A) is an informative index characterizing obesity.

Leptin, leptin gene and leptin receptor gene polymorphism in heart failure with preserved ejection fraction

Heart failure with a normal ejection fraction (HFNEF) is common in obesity and coronary artery disease (CAD). Both ischemia and reperfusion induce leptin (LEP) and leptin receptor (LEPR) gene expression. We aimed to investigate the possible associations of serum leptin, leptin gene and leptin receptor gene polymorphism with HFNEF in patients with CAD. 100 Egyptian CAD patients with HFNEF and 100 healthy subjects (the control group) were genotyped for LEP and LEPR polymorphism. Leptin levels were measured. Serum leptin levels were significantly increased in patients compared to the control group. There was a significant increase in the leptin gene (AA genotype) and the leptin receptor gene (RR genotype) in HFNEF patients compared to the control group. Leptin levels, leptin gene (AA genotype) and LEPR (RR genotype) were more associated with NYHA III than with NYHA I and II. We thus concluded that HFNEF is associated with increased serum leptin levels, and the LEP AA genotype or LEPR RR genotype carries at least a threefold increased risk of developing HFNEF.

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.

Relationship between variants of the leptin gene and obesity and metabolic biomarkers in Brazilian individuals

OBJECTIVE

The relationship between variants of the leptin gene (LEP) and obesity and metabolic biomarkers was investigated in Brazilian individuals.

SUBJECTS AND METHODS

One-hundred-ten obese (BMI > 30 kg/m(2)) and 100 non-obese individuals (145 women and 65 men, aged 49 +/- 14 years) were randomly selected. Plasma leptin, glycemia, serum lipid measurements and LEP -2548G>A and 3'HVR polymorphisms were analyzed.

RESULTS

The LEP -2548GG genotype was associated with a 2.2% and 2.0% increase in BMI (p = 0.009) and plasma leptin (p = 0.031), respectively. 3'HVR I/II (classes I/I+I/II) genotypes contributed with 1.8% of BMI values (p = 0.046). LEP I/G combined genotypes (I/IGG, I/IGA and I/IIGG) were associated with obesity, and increased BMI, waist circumference, leptin and triglycerides (p < 0.05). These relationships were found in women (p < 0.05) but not in men. LEP I/G combined genotypes were not associated with hypertension, hyperglycemia, dyslipidemia and coronary artery disease.

CONCLUSIONS

LEP I/G combined genotypes are associated with obesity-related metabolic biomarkers and phenotype in a gender-dependent manner.

Genetic variations of leptin and leptin receptor are associated with body composition changes in response to physical training

Leptin regulates body weight, metabolism, and tissue adaptations to environmental stressors. We examined the association of single nucleotide polymorphism (SNP) of leptin promoter G-2548A (rs7799039) and leptin receptor Gln223Arg (rs1137101) with body composition, plasma leptin levels, and peak oxygen uptake (VO(2)peak) in response to 8 weeks of physical training in 48 male military conscripts. AA homozygotes of leptin promoter SNP-2548 showed higher body fat and BMI values than G allele carriers. Acute exercise decreased leptin levels in G allele carriers, but increased in AA homozygotes. Physical training significantly decreased BMI values and also a tendency for decreased plasma leptin levels was observed in all subjects. In G allele carriers, BMI loss was mainly due to decreased fat mass, whereas in AA homozygotes due to loss of fat-free mass. Training increased VO(2)peak in all subjects with most prominent effects in G allele carriers. Regarding leptin receptor SNP, there were no statistically significant differences in BMI values between the genotype groups at baseline or after physical training. Our results suggest that physical training-induced alterations in body composition and plasma leptin may be influenced by a genetic variation of leptin promoter but not of leptin receptor.

Adiponectin gene SNP276 variants and central obesity confer risks for hyperglycemia in indigenous Taiwanese

This cross-sectional study analyzed the effects of two single nucleotide polymorphisms (SNP) of the adiponectin gene, SNP45 and SNP276, on hyperglycemia in indigenous Taiwanese, and whether central obesity modulates the effects of these SNPs. Overall, 550 indigenous Taiwanese were recruited for this cross-sectional study. The subjects were categorized into a hyperglycemic group if fasting plasma glucose was > 126 mg/dL (n = 88) or the control group if fasting plasma glucose was < 100 mg/dL (n = 462). The SNP276 TT homozygote carried greater hyperglycemia risk than SNP276 GG [odds ratio (OR) = 2.67, 95% confidence interval (CI) = 1.05-6.78], but not heterozygote (OR = 1.54, 95% CI = 0.95-2.50). SNP45 T > G was not associated with hyperglycemia risk. In multivariate-adjusted modeling, we found a significant relationship between SNP276 T carriers (GT + TT) (OR = 2.06, 95% CI = 1.10-3.88) and central obesity (OR = 4.50, 95% CI = 1.91-10.61) with hyperglycemia. Compared with non-central-obese carriers of SNP276 GG, non-central-obese SNP276 T carriers, and central obese subjects with SNP276 GG and SNP276 T carriers had 5.50, 8.31 and 13.76-fold, respectively, higher risks for hyperglycemia; obese carriers of the T-containing variants experienced a combined risk for hyperglycemia. Furthermore, the hyperglycemic risks were more pronounced in leaner (non-central-obese) individuals carrying the T variant than the central-obese individuals. The adiponectin SNP276 T variant and central obesity had independent and additive effects on hyperglycemia risks. These findings may provide valuable information regarding preventive strategies that might be useful to prevent or treat diabetes and its related complications.