Leptin G-2548A promoter polymorphism is associated with increased plasma leptin and BMI in Brazilian women

The role of adiposity, adipokines and polymorphisms of leptin and adiponectin in myelodysplastic syndromes

The aim of the present study was to investigate the relationship between leptin and adiponectin gene polymorphisms, circulating levels of leptin and adiponectin, adiposity and clinical markers in patients with myelodysplastic syndrome (MDS). This cross-sectional study was conducted with 102 adults and elderly MDS patients and 102 age- and sex-matched controls. Clinical characteristics, co-morbidities, anthropometric data, laboratory evaluation and genetic analysis (polymorphisms -2548G > A/rs7799039 of the LEP gene and +276G > T/rs1501299 of the ADIPOQ gene) were investigated. Serum leptin was higher and adiponectin lower in MDS when compared with controls. There was a significant positive correlation between serum leptin levels and BMI (r = 0·264, P = 0·025), waist circumference (r = 0·235, P = 0·047), body fat percentage (BF %) (r = 0·373, P = 0·001) and the fat mass index (FMI) (r = 0·371, P < 0·001). A lower mean adiponectin was found among patients with high BF %, higher visceral adiposity index and metabolic syndrome. A significant association was found between the AA genotype (mutant) of the LEP polymorphism rs7799039 and male sex and blast excess (≥ 5 %). In addition, a significant association was observed between the TT genotype (mutant) of the ADIPOQ rs1501299 polymorphism and Fe overload. These results demonstrate the importance of a comprehensive and systematic evaluation in patients with MDS in order to identify and control negative factors not related to the disease at an early stage.

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.

Gene polymorphism of leptin and risk for heart disease, obesity, and high BMI: a systematic review and pooled analysis in adult obese subjects

Objectives

Leptin polymorphism (LEP) has been associated with coronary heart disease (CAD), obesity, and high body mass index (BMI). However, we performed a systematic review and meta-analysis to discover the association because previous studies reached different conclusions.

Methods

Review Manager, version 5.3.5, and Stata, version 15.0, were used for statistical analysis. We calculated the effect size of the studies using the OR with the corresponding 95% CI, and two-sided (bilateral) p-values of 0.05 were considered significant. To determine heterogeneity among the selected studies, the Q test and I2 statistics were used. Meta-regression was used to examine the disease (heart disease, obesity, and high BMI) and heterogeneity between these subgroups.

Results

Eleven studies with 18,984 subjects were included in this study. The G-2548A (rs12112075), rs7799039, and A19G (rs2167270) polymorphisms of the leptin gene (but not the Lys656Asn (rs1805094) polymorphism) are associated with an increased risk of cardiovascular disease. Our pooled analysis revealed an association between the G-2548A (rs12112075) polymorphism and heart disease, high BMI, and obesity. This indicates that individuals carrying the AA allele are at an increased risk for heart disease, high BMI, and obesity. People with heart failure and coronary artery disease did not have the rs7799039 polymorphism or its alleles linked to them.

Conclusions

Combined analysis of data from current and published research suggests that the leptin gene polymorphisms G-2548A (rs12112075), rs7799039, and A19G (rs2167270) (but not the Lys656Asn (rs1805094) polymorphism) are associated with an increased risk of cardiovascular disease. Further research is needed to understand this association.

Leptin in Human Milk-One of the Key Regulators of Nutritional Programming

Breast milk is the optimal food for infants and toddlers, providing basic nutrients. It is also a source of many biologically active substances. Among them are hormones responsible for metabolic balance. One of the hormones taken in with breast milk by a breastfed baby is leptin. This hormone is involved in the regulation of appetite, informing the brain about the body’s energy resources. Having the correct mechanisms related to the action of leptin is a factor reducing the risk of obesity. The natural presence of leptin in the composition of breast milk suggests that it has a specific role in shaping the health of a breastfed child. Obesity as a disease of civilization affects more and more people, including children. The development of this disease is multifaceted and determined by many factors, including genetic and environmental factors such as eating habits and low physical activity. Behind obesity, there are complex mechanisms in which many elements of the human body are involved. Understanding the effects of breastfeeding as a natural source of leptin can help prevent childhood obesity and development of this disease in future life.

Leptin Signaling in Obesity and Colorectal Cancer

Obesity and colorectal cancer (CRC) are among the leading diseases causing deaths in the world, showing a complex multifactorial pathology. Obesity is considered a risk factor in CRC development through inflammation, metabolic, and signaling processes. Leptin is one of the most important adipokines related to obesity and an important proinflammatory marker, mainly expressed in adipose tissue, with many genetic variation profiles, many related influencing factors, and various functions that have been ascribed but not yet fully understood and elucidated, the most important ones being related to energy metabolism, as well as endocrine and immune systems. Aberrant signaling and genetic variations of leptin are correlated with obesity and CRC, with the genetic causality showing both inherited and acquired events, in addition to lifestyle and environmental risk factors; these might also be related to specific pathogenic pathways at different time points. Moreover, mutation gain is a crucial factor enabling the genetic process of CRC. Currently, the inconsistent and insufficient data related to leptin's relationship with obesity and CRC indicate the necessity of further related studies. This review summarizes the current knowledge on leptin genetics and its potential relationship with the main pathogenic pathways of obesity and CRC, in an attempt to understand the molecular mechanisms of these associations, in the context of inconsistent and contradictory data. The understanding of these mechanisms linking obesity and CRC could help to develop novel therapeutic targets and prevention strategies, resulting in a better prognosis and management of these diseases.

-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.

A Case-Control Study of the Association of Leptin Gene Polymorphisms with Plasma Leptin Levels and Obesity in the Kerala Population

BACKGROUND

Over the last few years, the importance of leptin in energy metabolism has been extensively studied in both animal models and in humans. Very few results are available on the association between human leptin gene (LEP) variants and obesity traits in India. We designed this study to analyse the polymorphisms in human leptin gene and the association of sequence variants with obesity among the population in Kerala, South India.

METHODS

In this case-control design of 148 study participants, data were collected on socioeconomic aspects and anthropometric measurements. Plasma glucose, insulin, leptin, and lipid profile were measured. Genotyping was done by automated DNA sequencing.

RESULTS

The common Single Nucleotide Polymorphism (SNP) of 5'-UTR of LEP - 2548G/A was found to be present in the study population with "A" variant as dominant allele. A novel synonymous mutation Thr5Thr of exon 2 of LEP was identified in heterozygous form in one subject with morbid obesity with hyperleptinemia. A novel missense mutation Phe17Leu was observed in two subjects with obesity in heterozygous condition. A novel missense mutation Lys36Arg in exon 2 of LEP was observed in one subject with abdominal obesity and decreased serum leptin level.

CONCLUSION

LEP - 2548G/A at 5'-untranslated region was found to be common with the mutant "A" variant in the study population. SNPs of exons in LEP were found to be rare but associated with morbid obesity and altered levels of serum leptin in the study population in Kerala, India.

The role of ghrelin and leptin in feeding behavior: Genetic and molecular evidence

Feeding behavior is integrated within a wide variety of eating behaviors, which depend on psychosocial, biological and environmental factors. These types of behavior can cause nutrition-related diseases such as obesity, which affects more than 650 million people worldwide. Ghrelin and leptin are key hormones that regulate appetite, food intake and energy metabolism. Research in genetics suggests that genetic variants of both hormones are associated with complex forms of eating behavior, such as a preference for palatable food, making individuals susceptible to the modern obesogenic environment. This review analyses the scientific evidence around polymorphisms in the ghrelin and leptin genes and their association with eating behavior. The understanding of these mechanisms is relevant since it could impact on the objectives of pharmacological or behavioral interventions for their treatment.

Lifestyle Genetics-Based Reports in the Treatment of Obesity

Obesity becomes a chronic disease due to the increasing number of mortality and morbidity cases around the world. In most regions, chronic illnesses, such as obesity, are important sources of morbidity and mortality. Due to a lack of effective strategies for prevention and management, the adverse effects of obesity and related diseases on health continue to be a serious problem. Relevant information was searched from Google Scholar, Scopus, and PubMed using such different terms as "Obesity", "Obesity Management", "Obesity AND Physical activity", "Obesity AND Genetics", "Obesity AND Diet", and "Obesity AND Nutrigenomics". Obesity is characterized by a complex interaction of hereditary and lifestyle factors, which includes food. Diet is an environmental element that plays an important and considerable role in the management of health and reduces the risk of obesity and its comorbidities. Changes in lifestyle patterns not only help burn extra calories but also prevent the development of obesity via its modulating effect on genetic factors. Different people respond differently to an obesogenic environment. The notion of nutrigenetics emerged as a result of various genetic variations that may explain this heterogeneity. Nutritional genomics, also known as nutrigenetics, is the study that investigates and analyses gene variations linked to varied responses to certain foods; moreover, it links this variation to diseases, such as obesity. As a result, tailored nutrition advice based on a person's genetic profile may improve the outcomes of a specific dietary strategy and offer a novel dietary strategy to improve life quality and preventing obesity. This study concluded that physical activity and dietary interventions play an effective role in the management of obesity. Moreover, understanding of the function of the most prominent obesity-related genes, as well as the interaction between nutrition and gene expression, will help researchers design personalized treatment strategies for humans.

Impaired Leptin Signalling in Obesity: Is Leptin a New Thermolipokine?

Leptin is a principal adipose-derived hormone mostly implicated in the regulation of energy balance through the activation of anorexigenic neuronal pathways. Comprehensive studies have established that the maintenance of certain concentrations of circulating leptin is essential to avoid an imbalance in nutrient intake. Indeed, genetic modifications of the leptin/leptin receptor axis and the obesogenic environment may induce changes in leptin levels or action in a manner that accelerates metabolic dysfunctions, resulting in a hyperphagic status and adipose tissue expansion. As a result, a vicious cycle begins wherein hyperleptinaemia and leptin resistance occur, in turn leading to increased food intake and fat enlargement, which is followed by leptin overproduction. In addition, in the context of obesity, a defective thermoregulatory response is associated with impaired leptin signalling overall within the ventromedial nucleus of the hypothalamus. These recent findings highlight the role of leptin in the regulation of adaptive thermogenesis, thus suggesting leptin to be potentially considered as a new thermolipokine. This review provides new insight into the link between obesity, hyperleptinaemia, leptin resistance and leptin deficiency, focusing on the ability to restore leptin sensitiveness by way of enhanced thermogenic responses and highlighting novel anti-obesity therapeutic strategies.

The role of ghrelin and leptin in feeding behavior: Genetic and molecular evidence

Feeding behavior is integrated within a wide variety of eating behaviors, which depend on psychosocial, biological and environmental factors. These types of behavior can cause nutrition-related diseases such as obesity, which affects more than 650 million people worldwide. Ghrelin and leptin are key hormones that regulate appetite, food intake and energy metabolism. Research in genetics suggests that genetic variants of both hormones are associated with complex forms of eating behavior, such as a preference for palatable food, making individuals susceptible to the modern obesogenic environment. This review analyses the scientific evidence around polymorphisms in the ghrelin and leptin genes and their association with eating behavior. The understanding of these mechanisms is relevant since it could impact on the objectives of pharmacological or behavioral interventions for their treatment.

Associations of ADIPOQ and LEP Gene Variants with Energy Intake: A Systematic Review

This systematic review aims to evaluate the association of adiponectin (ADIPOQ) and leptin (LEP) gene variants with energy intake. Cross-sectional, cohort, and case–control studies that reported an association of leptin and/or adiponectin gene variants with energy intake were included in this review. Human studies without any age restrictions were considered eligible. Detailed individual search strategies were developed for each of the following bibliographic databases: Cochrane, Latin American and Caribbean Center on Health Sciences Information (LILACS), PubMed/MEDLINE, Scopus, and Web of Science. Risk of bias assessment was adapted from the Downs and Black scale and was used to evaluate the methodology of the included studies. Seven studies with a pooled population of 2343 subjects were included. The LEP and ADIPOQ gene variants studied were LEP-rs2167270 (k = 1), LEP-rs7799039 (k = 5), ADIPOQ-rs2241766 (k = 2), ADIPOQ-rs17300539 (k = 1), and ADIPOQ marker D3S1262 (k = 1). Two of the seven studies reviewed demonstrated a positive association between the LEP-rs7799039 polymorphism and energy intake. Two other studies—one involving a marker of the ADIPOQ gene and one examining the ADIPOQ-rs17300539 polymorphism—also reported associations with energy intake. More research is needed to further elucidate the contributions of genetic variants to energy metabolism.

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]

Genetic Variants in Preeclampsia: Lessons From Studies in Latin-American Populations

Placental vascularization is a tightly regulated physiological process in which the maternal immune system plays a fundamental role. Vascularization of the maternal-placental interface involves a wide range of mechanisms primarily orchestrated by the fetal extravillous trophoblast and maternal immune cells. In a healthy pregnancy, an immune cross-talk between the mother and fetal cells results in the secretion of immunomodulatory mediators, apoptosis of specific cells, cellular differentiation/proliferation, angiogenesis, and vasculogenesis, altogether favoring a suitable microenvironment for the developing embryo. In the context of vasculopathy underlying common pregnancy disorders, it is believed that inefficient invasion of extravillous trophoblast cells in the endometrium leads to a poor placental blood supply, which, in turn, leads to decreased secretion of angiogenic factors, hypoxia, and inflammation commonly associated with preterm delivery, intrauterine growth restriction, and preeclampsia. In this review, we will focus on studies published by Latin American research groups, providing an extensive review of the role of genetic variants from candidate genes involved in a broad spectrum of biological processes underlying the pathophysiology of preeclampsia. In addition, we will discuss how these studies contribute to fill gaps in the current understanding of preeclampsia. Finally, we discuss some trending topics from important fields associated with pregnancy vascular disorders (e.g., epigenetics, transplantation biology, and non-coding RNAs) and underscore their possible implications in the pathophysiology of preeclampsia. As a result, these efforts are expected to give an overview of the extent of scientific research produced in Latin America and encourage multicentric collaborations by highlighted regional research groups involved in preeclampsia investigation.

Association of polymorphisms of leptin, leptin receptor and apelin receptor genes with susceptibility to coronary artery disease and hypertension

AIMS

Apelin and leptin are factors which have a potential physiological and pathological role in cardiovascular homoeostasis. Apelin receptor (APLNR), leptin receptor (LEPR) and leptin variants may affect the vascular tone in heart or peripheral circulation, thereby predisposing patients to hypertension and coronary artery disease (CAD). The aim of the present study was to evaluate four single nucleotide polymorphisms (SNPs) of APLNR genes (rs11544374 and rs948847), LEPR (rs1137101) and leptin (rs7799039) gene in patients with CAD and hypertension.

MATERIALS AND METHODS

This case-control study was carried out on 286 CAD-suspected patients. The participants were divided into four subgroups including: CAD patients with no hypertension (H^-CAD⁺), hypertensive patients with no CAD (H⁺CAD^-), CAD patients with hypertension (H⁺CAD⁺) and non-hypertensive non-CAD subjects as control group (H^-CAD^-). Genomic DNA from whole blood was extracted and four SNPs were assessed using PCR-RFLP.

KEY FINDINGS

A significant difference was found in the genotype frequency of APLNR rs11544374 gene in H⁺CAD⁺ and H^-CAD⁺ groups compared to control subjects (P < 0.001 for both comparisons). Regarding the rs1137101, the prevalence of A allele compared to G allele was significantly different among the four groups (P = 0.02). Results of multinomial regression analysis indicated that G allele carriers in the recessive genetic model (AA vs. AG + GG) of rs11544374 had a significantly protective effect compared to H^-CAD⁺ and H⁺CAD⁺after adjustment (OR = 0.12; 95% CI = 0.02-0.61; P = 0.01 and OR = 0.40; 95% CI = 0.17-0.98; P = 0.04, respectively).

SIGNIFICANCE

The findings of present study revealed that the APLNR rs11544374 gene polymorphism might serve as predisposing factor in CAD.

The rs2167270 polymorphism of leptin gene is associated with atopic dermatitis

Atopic dermatitis is a chronic inflammatory skin disease that arises because of complex environmental, immunological, and genetic interactions. Adipokines are bioactive mediators secreted from adipocytes of white adipose tissue and are known to have a role in body metabolism and regulation of immune responses. Leptin is a proinflammatory adipokine that functions mainly to regulate food intake and energy expenditure. Few studies have implicated adipokines in the pathogenesis of atopic dermatitis. In this study, we investigated the association of three leptin gene polymorphisms: -2548G>A (rs7799039), -188 C/A (rs791620), and A19G (rs2167270), with the incidence of atopic dermatitis. One hundred and sixty-four patients and one hundred and sixty-seven age- and gender-matched controls were genotyped using the polymerase chain reaction-restriction fragment length polymorphism procedure. A significant association was found between rs2167270 and the incidence of atopic dermatitis (P < 0.05). The GG allele was more prevalent in the patients' group with genotype frequency of 38.7%, compared to 26.1% for the control group. No significant differences were found in the genotype distribution or allelic frequency of the other two examined polymorphisms, rs7799039 and rs791620, between atopic dermatitis patients and controls (P > 0.05). The results suggest that rs2167270 might play a role in the pathogenesis of atopic dermatitis.

Effects of maternal and fetal LEP common variants on maternal glycemic traits in pregnancy

Previous studies suggest that leptin (LEP) has an important role in glucose metabolism in the nonpregnant state. During pregnancy, circulating maternal concentrations of leptin rise significantly, mainly due to increased secretion of leptin from maternal adipose tissue and placenta. This study aimed to analyze the impact of maternal and fetal common LEP variants on glucose homeostasis in the pregnant state. Several glycemic traits, including fasting plasma glucose, fasting plasma insulin (FPI), and plasma glucose 1 hour after a 50-g oral glucose load, were measured in 1,112 unrelated Chinese Han pregnant women at 24–28 weeks gestation. Homeostatic model assessment (HOMA) was used to assess beta cell function (HOMA1-β and HOMA2-β) and insulin resistance (HOMA1-IR and HOMA2-IR).The relationships between glycemic traits and 12 LEP variants were determined. After applying the Bonferroni correction, we detected that (1) maternal rs10954173 and fetal rs10244329 were associated with maternal FPI although the effect of fetal rs10244329 may be not independent of maternal rs10244329, and (2) maternal rs12537573 was associated with maternal FPI and HOMA2-IR. This study provides genetic evidence that both maternal and fetal LEP polymorphisms may affect maternal glucose metabolism in pregnancy.

Genetic polymorphisms of IL-23R (rs7517847) and LEP (rs7799039) among Egyptian patients with hepatocellular carcinoma

BACKGROUND

Genetic polymorphisms of IL-23 R (rs7517847) and LEP (rs7799039) have been stated to be associated with various types of human cancers. The purpose of this work is to test the association of these genetic polymorphisms with hepatocellular carcinoma (HCC) among Egyptian patients.

SUBJECTS AND METHODS

This study involved 150 unrelated Egyptian HCC patients in addition to 100 healthy controls from the same locality. DNA was genotyped for these genetic polymorphisms using the PCR-RFLP technique.

RESULTS

The frequency of the IL-23 R (rs7517847) G and LEP (rs7799039) G alleles were significantly higher among HCC patients compared to controls (p = .004 and .02). However, HCC patients with the IL-23 R GG and LEP GG genotypes showed no significant difference compared to others regarding their clinical and laboratory markers.

CONCLUSIONS

IL-23 R (rs7517847) and LEP (rs7799039) polymorphisms were associated with an increased risk but not affecting the clinical presentation of HCC among Egyptian patients.

Polymorphisms in the leptin (rs7799039) gene are associated with an increased risk of excessive gestational weight gain but not with leptin concentration during pregnancy

Single nucleotide polymorphisms (SNPs) in leptin (LEP) and leptin receptor (LEPR) have been shown to be linked to obesity-related metabolic markers and phenotype. Therefore, we hypothesized that the LEP-rs7799039 and LEPR-rs1137101 SNPs are related to the risk of pre-pregnancy overweight/obesity (body mass index ≥25 kg/m²) as well as to excessive gestational weight gain (GWG) and high concentrations of leptin throughout pregnancy. We investigated a prospective cohort of 147 Brazilian pregnant women through weeks 5-13, 20-26, and 30-36 of gestation. Genetic variants of LEP and LEPR were analyzed by real-time polymerase chain reaction and leptin by enzyme-linked immunosorbent assay. Statistical analyses included multiple linear regression, linear mixed effects, and Poisson regression models. Genotype AA carriers for the LEP-rs7799039 gene maintained a lower body weight throughout pregnancy compared with those with genotypes GG or GA + GG (β_AAvsGG = -7.91 kg; 95% confidence interval [CI], -14.21 to -1.61; P = .01; and β_{AAvsGA + GG} = -7.66 kg; 95% CI, -14.07 to -1.25; P = .02). The A allele was significantly associated with an increased risk for excessive GWG (relative risk_LEP-GAvsGG, 2.16; 95% CI, 1.23-3.80; and relative risk_LEP-AAvsGG, 2.37; 95% CI, 1.04-5.39). Neither the LEP-rs7799039 nor LEPR-rs1137101 SNP was significantly associated with pre-pregnancy overweight/obesity risk and leptin concentrations during pregnancy. In conclusion, our results indicate that women who had the AA genotype for LEP-rs7799039 displayed a lower body weight throughout pregnancy compared with GG or GA + GG carriers. LEP-rs7799039 was significantly associated with an increased risk for excessive GWG, but the results do not support significant associations of the LEP-rs7799039 and LEPR-rs1137101 polymorphisms with pre-pregnancy overweight/obesity risk and leptin concentrations throughout pregnancy.

Polymorphisms in Lep and Lepr Genes in Infants: Correlation with Serum Leptin Values in the First 6 Months of Life

OBJECTIVE

Because several studies indicate that polymorphisms in leptin (Lep) and leptin receptor (Lepr) genes play a central role in determining obesity, we analyzed 2 single nucleotide polymorphisms (SNPs) in the Lep gene (Lep G2548A and A19G) and one in the Lepr gene (Lepr A668G) to verify the effect of the 3 SNPs on leptin concentrations in infancy.

METHODS

We enrolled 80 healthy Caucasian infants under 6 months of age, who were genotyped for the 3 SNPs with amplification refractory mutation system-mismatch amplification mutation assay (ARMS-MAMA) real-time polymerase chain reaction (PCR). Serum leptin values were measured with a radioimmunoassay method. Statistical significance was set at p < 0.05.

RESULTS

There were no significant differences between individually analyzed leptin polymorphisms Lep G2548A and A19G and serum leptin levels (p > 0.05). Because we found that Lep G2548A and A19G are in linkage disequilibrium on chromosome 7, we performed the haplotype analysis for Lep G2548A and Lep A19G. We obtained higher serum leptin levels in infants with the GG/GG haplotype (p < 0.05). Regarding receptor, we found higher leptin levels in GG-genotype infants for Lepr A668G (p < 0.001). Considering the 3 SNPs together, we found higher serum leptin values in GG/GG-GG infants (LepG2548A/A19G-Lepr A668G; p < 0.001).

CONCLUSION

We obtained higher serum leptin levels in infants with the GG genotype for Lepr A668G, with haplotype GG/GG for Lep G2548A/A19G, and with GG/GG-GG (LepG2548A/A19G-Lepr A668G); thus, it seems that the genotype GG could be a protector against obesity development in infancy and adulthood. Moreover, these data confirm that not variations in the Lep gene as well as in the Lepr gene could play a role in weight gain. Further studies are needed to evaluate the role of genetics and the environment in a predisposition toward obesity later in life.

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.

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.

Leptin receptor gene polymorphisms are associated with adiposity and metabolic alterations in Brazilian individuals

OBJECTIVE

The aim of the study was to investigate whether adiposity and metabolic markers, such as leptin, glucose, and lipids, are influenced by leptin (LEP) and leptin receptor (LEPR) gene polymorphisms in a sample of our population.

SUBJECTS AND METHODS

A group of 326 individuals of Caucasian-European descent, aged 30 to 80 years, 87 men and 239 women, 148 obese and 178 non-obese, was randomly selected at two clinical hospitals in the city of Sao Paulo, Brazil. All individuals declared their ethnic group as white during the initial interview. Anthropometric measurements, body mass index (BMI), and fat mass were evaluated. Blood samples were drawn for DNA extraction and measurements of leptin, soluble leptin receptor, glucose, and lipids. LEP -2548G>A and LEPR Lys109Arg (c.326A>G), Gln233Arg (c.668A>G) and Lys656Asn (c.1968G>C) polymorphisms were detected by PCR-RFLP.

RESULTS

Increased leptin and serum lipids, and LEPR Arg223Arg (GG genotype) were associated with higher risk for obesity (p < 0.05), while reduced risk was found in LEPR Arg109Arg (GG genotype) carriers (OR: 0.38, 95%CI: 0.19-0.77, p = 0.007). Multiple linear regression analysis showed a relationship between LEPR 223Arg, increased waist circumference, and leptinemia (p < 0.05), while LEPR 109Arg was associated with high total cholesterol and triglycerides (p < 0.05). LEPR haplotype 3 (AGG: 109Lys/233Arg/656Lys) carriers have increased risk for obesity (OR: 2.56, 95% CI: 1.19-5.49, p = 0.017). Moreover, this haplotype was associated with increased BMI, waist circumference, and leptinemia (p < 0.05).

CONCLUSIONS

LEPR polymorphisms are associated with obesity, hyperleptinemia, and atherogenic lipid profile, suggesting their potential role for leptin resistance and cardiovascular risk. Moreover, LEPR haplotype 3 confers susceptibility to adiposity and hyperleptinemia in our population.

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.

Polymorphisms in LEPR, PPARG and APM1 genes: associations with energy intake and metabolic traits in young children

OBJECTIVE: To assess the association of single nucleotide polymorphisms (SNPs) in five genes - leptin, leptin receptor (LEPR), adiponectin (APM1), peroxisome proliferator-activated receptor gamma (PPARG) and uncoupling protein 1 - with anthropometric, metabolic, and dietary parameters in a Southern Brazilian cohort of 325 children followed up from birth to 4 years old. MATERIALS AND METHODS: SNPs were analyzed using polymerase chain reaction-based procedures, and their association with phenotypes was evaluated by t-test, analysis of variance, and general linear models. RESULTS: LEPR223Arg allele (rs1137101) was associated with higher daily energy intake at 4 years of age (P = 0.002; Pcorrected = 0.024). PPARG 12Ala-carriers (rs1801282) presented higher glucose levels than Pro/Pro homozygotes (P = 0.007; Pcorrected = 0.042). CONCLUSIONS: Two of the six studied SNPs presented consistent associations, showing that it is already possible to detect the influences of genetic variants on susceptibility to overweight in 4-year-old children.

Association with leptin gene C.-2548 G>A polymorphism, serum leptin levels, and body mass index in Turkish obese patients

Leptin is a protein hormone which plays a critical role in the regulation of both body-weight through reducing food intake and stimulating energy expenditure. Several polymorphisms in leptin gene (LEP), which encodes for leptin, have been described. However, its association with obesity is still controversial. Therefore, in the present study, we aimed to investigate whether LEP c.-2548 G>A polymorphism was associated with serum leptin levels, lipid parameters, and body mass index in Turkish obese patients. Forty-seven obese patients and 48 healthy individuals were included in the study. Blood samples were collected for DNA extraction. LEP c.-2548 G>A polymorphism were detected using polymerase chain reaction-restriction fragment length polymorphism technique. Serum leptin levels and lipid parameters were measured by ELISA and enzyme colorimetric assay techniques, respectively. GA or AA genotypes and A allele carrier frequencies of the c.-2548 G>A polymorphism in the LEP were higher in obese (38.3, 34.0 and 72.3 %) when compared with controls (14.6, 12.5, and 27.1 %; p = 0.011, 0.016, and 0.002, respectively). On the other hand, AA or AG genotypes were also related to increased serum leptin levels (p < 0.001) and body mass index (p < 0.0001). All these consequences showed that LEP -2548 AA or AG genotypes are important predictors for increased levels of leptin and BMI in Turkish obese patients and it may be a useful marker for obesity risk in our population.

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.

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.

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.

Leptin promoter G-2548A genotypes and associated serum leptin levels in childhood acute leukemia at diagnosis and under high-dose steroid therapy

Genotype/allele distributions of leptin promoter G-2548A polymorphism, serum leptin and insulin levels and body weight were not significantly different between 72 children (39 male/33 female; age range 1.08-16, median 6 years) with acute leukemia (56 acute lymphoblastic leukemia [ALL]/16 acute non-lymphoblastic leukemia [ANLL]) at diagnosis and 70 age- and sex-matched controls (p > 0.05). The - 2548GG genotype was associated with the highest leptin levels in controls and patients with acute leukemia after 7-day high-dose methylprednisolone (HDMP) therapy (p < 0.05), while no significant association of genotype with leptin levels was detected in patients at diagnosis (p > 0.05). One-week HDMP therapy in patients carrying the - 2548G allele caused a significant increase in leptin levels and body weight (p < 0.001), whereas increases in those carrying the - 2548AA genotype were insignificant (p > 0.05). Decreases in white blood cell counts of patients after therapy were insignificant in - 2548GG (p > 0.05) yet significant in - 2548GA and - 2548AA (p < 0.05) genotypes. These results revealed no association of leptin genotype with the etiology of childhood acute leukemia but a possible association with leptin levels and effects of HDMP therapy.

Congenital leptin deficiency: diagnosis and effects of leptin replacement therapy

To describe our 10-year experience in treating leptin-deficient humans. Three adults and one boy presented with childhood-onset morbid obesity, hypogonadism and family history of obesity and early death. Serum leptin was inappropriately low. A recessive C105T leptin gene mutation was identified. Metabolic and endocrine assessments were conducted, before and while on and off leptin. The adults' body mass index decreased from 51.2 ± 2.5 to 29.5 ± 2.8 kg/m(2). Serum lipids normalized, insulin resistance decreased, and one of the initially diabetic females became normoglycemic. Hypogonadotropic hypogonadism was reversed, and other changes were observed in the adrenal, sympathetic, somatotropic and thyroid functions. Leptin replacement therapy reverses endocrine and metabolic alterations associated with leptin deficiency. Some of these results may be extrapolated to other diseases.

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.

Association between the leptin gene 2548G/A polymorphism, the plasma leptin and the metabolic syndrome with psoriasis

BACKGROUND

Psoriasis is a disorder with genetic and immunologic background. Leptin can regulate the T-helper response.

OBJECTIVE

Our primary goal is to study the functional polymorphism (G-2548A) of the leptin (LEP) gene in the genetic predisposition of psoriasis, and our secondary goal is to examine factors affecting plasma leptin levels in psoriasis and to compare patients with and without metabolic syndrome (MS).

METHODS

The study involved 94 patients with psoriasis and 100 healthy controls. Analysis of G-2548A polymorphism of the LEP gene was made by the PCR and restriction fragment length polymorphism technique. The relationship between LEP gene polymorphism and the clinical features of the patients was analysed. Plasma leptin levels and proportions of comorbidities in patients vs controls were compared.

RESULTS

In controls, the GA, AA and GG frequencies were 50%, 30% and 20%, respectively, while in patients, the distribution of genotypes was 42.5%, 20.2% and 38.3%, respectively, with significant difference (P = 0.014) between patients and controls. In patients with MS, the GG, GA and AA frequencies were 61.5%, 23.1% and 15.4%, respectively, while in patients without MS, the distribution of genotypes was 29.4%, 50% and 20.6%, respectively, with significant difference (P = 0.014) between both groups. Plasma leptin showed a significant higher levels in the patients versus the controls (P < 0.001), and among the different LEP genotypes (P < 0.001) in the patients' group.

CONCLUSION

LEP G-2548A polymorphism could be a predictor for higher plasma leptin and increased risk of psoriasis and could be used as a marker for psoriasis-related comorbidity risk.

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.

Metabolic and infectious pathologies in Brazilian medical literature: a review

OBJECTIVE

This review of original reports on metabolic and infectious diseases that were recently published in Brazilian journals is designed to inform the readership of CLINICS about their content.

METHODS

I conducted a search in PubMed for original research articles (clinical or basic research) recently published (2008-2009) by Brazilian medical and biological periodicals. Papers on metabolic pathologies were retrieved by searching for appropriate keywords such as metabolic syndrome and obesity. Papers on infectious disease were obtained by entering 15 different keywords for the most commonly occurring pathologies. Review articles, editorials, letters to the editor, and case reports were manually excluded. Selected titles were then categorized into appropriate sub-categories.

RESULTS

This search produced a total of 123 articles, which filtered down to 72 articles after eliminating editorials, review articles, letters to the Editor and case reports. Reviewed periodicals were Arquivos Brasileiros de Cardiologia, Arquivos Brasileiros de Endocrinologia e Metabologia, Brazilian Journal of Biological and Medical Research, Brazilian Journal of Infectious Diseases, Jornal de Pediatria, Jornal de Pneumologia, Revista da Associação Médica Brasileira, Revista da Escola de Enfermagem da Universidade de São Paulo, and São Paulo Medical Journal. The articles were then briefly summarized.

Association of G-2548A LEP polymorphism with plasma leptin levels in Tunisian obese patients

OBJECTIVES

The aim of this study was to examine the association of the G-2548A polymorphism of the human leptin gene (LEP) with body mass index (BMI), plasma leptin, insulin, and lipid parameters in a sample of Tunisian population.

DESIGN AND METHODS

Two hundred and twenty nine obese patients (BMI>or=30 kg/m(2)) were screened and compared to 251 normal weight subjects (BMI<25 kg/m(2)). The human leptin gene promoter G-2548A genotype was determined by polymerase chain reaction followed by a digestion with the restriction of endonuclease CfoI.

RESULTS

In the entire study sample, carriers of -2548A allele had significantly lower leptin levels than homozygous for -2548G allele (14.28+/-9.10 ng/mL vs. 18.27+/-12 ng/mL, p<0.001 respectively) adjusted for BMI and gender. In obese patients but not control, subjects carrying the -2548A allele exhibited lower leptin levels than those with GG genotype (16.96+/-8.27 ng/mL vs. 21.37+/-11.72 ng/mL, p=0.001 respectively) adjusted for BMI and gender. In this group, carriership of the -2548A allele was identified, by multiple linear regression models, as significant independent predictor for leptin levels variability. Separate analyses by gender revealed that only in obese women, the -2548A allele was found to be associated with lower leptin levels independently of BMI (p=0.004).

CONCLUSIONS

The present study showed that G-2548A LEP polymorphism is associated with lower leptin levels in Tunisian obese women.