Leptin Receptor Lys656Asn Polymorphism Is Associated with Decreased Leptin Response and Weight Loss Secondary to a Lifestyle Modification in Obese Patients

Genome-wide association study for growth traits in Blanco Orejinegro and Romosinuano cattle

Growth traits are economically important characteristics for the genetic improvement of local cattle breeds. Genome-wide association studies (GWAS) provide valuable information to enhance the understanding on the genetics of complex traits. The aim of this study was to perform a GWAS to identify genomic regions and genes associated to birth weight, weaning weight adjusted for 240 days, 16 months, and 24 months weight in Romosinuano (ROMO) and Blanco Orejinegro (BON) cattle. A single-step genomic-BLUP was implemented using 596 BON and 569 ROMO individuals that were genotyped with an Illumina BovineSNP50 BeadChip. There were 25 regions of interest identified on different chromosomes, with few of them simultaneously associated with two or more growth traits and some were common to both breeds. The gene mapping allowed to find 173 annotations on these regions, from which 49 represent potential candidate genes with known growth-related functions in cattle and other species. Among the regions that were associated with several growth traits, that at 24 - 27 MB of BTA14, has important candidate genes such as LYPLA1, XKR4, TMEM68 and PLAG1. Another region of interest at 0.40-0.77 Mb of BTA23 was identified in both breeds, containing KHDRBS2 as a potential candidate gene influencing body weight. Future studies targeting these regions could provide more knowledge to uncover the genetic architecture underlying growth traits in BON and ROMO cattle. The genomic regions and genes identified in this study could be used to improve the prediction of genetic merit for growth traits in these creole cattle breeds.

The Genetic Basis of Childhood Obesity: A Systematic Review

Overweight and obesity in childhood and adolescence represents one of the most challenging public health problems of our century owing to its epidemic proportions and the associated significant morbidity, mortality, and increase in public health costs. The pathogenesis of polygenic obesity is multifactorial and is due to the interaction among genetic, epigenetic, and environmental factors. More than 1100 independent genetic loci associated with obesity traits have been currently identified, and there is great interest in the decoding of their biological functions and the gene-environment interaction. The present study aimed to systematically review the scientific evidence and to explore the relation of single-nucleotide polymorphisms (SNPs) and copy number variants (CNVs) with changes in body mass index (BMI) and other measures of body composition in children and adolescents with obesity, as well as their response to lifestyle interventions. Twenty-seven studies were included in the qualitative synthesis, which consisted of 7928 overweight/obese children and adolescents at different stages of pubertal development who underwent multidisciplinary management. The effect of polymorphisms in 92 different genes was assessed and revealed SNPs in 24 genetic loci significantly associated with BMI and/or body composition change, which contribute to the complex metabolic imbalance of obesity, including the regulation of appetite and energy balance, the homeostasis of glucose, lipid, and adipose tissue, as well as their interactions. The decoding of the genetic and molecular/cellular pathophysiology of obesity and the gene-environment interactions, alongside with the individual genotype, will enable us to design targeted and personalized preventive and management interventions for obesity early in life.

Genetic test for the prescription of diets in support of physical activity

Owing to the fields of nutrigenetics and nutrigenomics today we can think of devising approaches to optimize health, delay onset of diseases and reduce its severity according to our genetic blue print. However this requires a deep understanding of nutritional impact on expression of genes that may result in a specific phenotype. The extensive research and observational studies during last two decades reporting interactions between genes, diet and physical activity suggest a cross talk between various genetic and environmental factors and lifestyle interventions. Although considerable efforts have been made in unraveling the mechanisms of gene-diet interactions the scientific evidences behind developing commercial genetic tests for providing personalized nutrition recommendations are still scarce. In this scenario the current mini-review aims to provide useful insights into salient feature of nutrition based genetic research and its commercial application and the ethical issue and concerns related to its outcome.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Complementary Effects of Genetic Variations in LEPR on Body Composition and Soluble Leptin Receptor Concentration after 3-Month Lifestyle Intervention in Prepubertal Obese Children

In obese individuals, weight loss might be affected by variants of the adipokine-encoding genes. We verified whether selected functional single nucleotide polymorphisms in LEP, LEPR and ADIPOQ are associated with changes in serum levels of the respective adipokines and weight loss in 100 prepubertal obese (SDS-BMI > 2) Caucasian children undergoing lifestyle intervention. Frequencies of the -2548G > A LEP, Q223R LEPR, K656N LEPR, -11377C > G and -11426A > G ADIPOQ polymorphisms were analyzed by restriction fragment length polymorphism. Serum adipokine and soluble leptin receptor (sOB-R) concentrations were measured using the ELISA method. Among the analyzed polymorphisms, only LEPR polymorphisms were associated with changes of SDS-BMI or sOB-R concentrations in children after therapy. Carriers of the wild-type K665N and at least one minor Q223R allele had the greatest likelihood of losing weight (OR = 5.09, p = 0.006), an increase in sOB-R (ptrend = 0.022) and decrease in SDS-BMI correlated with the decrease of fat mass (p < 0.001). In contrast, carrying of the wild-type Q223R and at least one minor K665N allele were associated with a decrease in sOB-R concentrations and a decrease in SDS-BMI correlated with a decrease in fat-free mass (p = 0.002). We suggest that the combination of different LEPR variants, not a single variant, might determine predisposition to weight loss in the prepubertal period.

Effect of Lys656Asn Polymorphism of Leptin Receptor Gene on Cardiovascular Risk Factors and Serum Adipokine Levels after a High Polyunsaturated Fat Diet in Obese Patients

BACKGROUND

Human obesity is characterized by high levels of leptin, and leptin levels may change with weight loss and dietary restriction. The aim of our study was to investigate the influence of Lys656Asn polymorphism in the leptin receptor gene on cardiovascular risk factors, weight loss, and serum leptin levels to a high polyunsaturated fatty acid (PUFA) hypocaloric diet in obese patients.

DESIGN

A sample of 132 obese patients was analyzed in a prospective way with a dietary intervention. The enriched PUFAs hypocaloric intervention consisted in a diet of 1,459 kcal, 45.7% of carbohydrates, 34.4% of lipids, and 19.9% of proteins.

RESULTS

In wild-type group, BMI (-1.9 ± 1.4 kg/m(2) ), weight (-4.4 ± 3.2 kg), fat mass (-4.2 ± 3.8 kg), waist circumference (-4.1 ± 3.1 cm), systolic blood pressure (-7.0 ± 12.1 mmHg), diastolic blood pressure (-3.9 ± 6.8 mmHg), insulin (-1.8 ± 5.6 MUI/l) and HOMA-IR (-0.5 ± 1.5 Units) decreased. In mutant genotype group, BMI (-2.0 ± 2.1 kg/m(2) ), weight (-3.6 ± 4.1 kg), waist circumference (-3.1 ± 4.1 cm), total cholesterol (-25.2 ± 19.6 mg/dl), LDL cholesterol (-16.6 ± 25.6 mg/dl), and tryglicerides (-26.6 ± 39.1 mg/dl) decreased. Only leptin levels have a significant decrease in wild genotype group (-6.6 ± 10.2 ng/ml) (25.1%).

CONCLUSION

Carriers of ASn656 allele have a different response than wild-type obese, with a lack of decrease in insulin levels, leptin levels, and HOMA-IR. However, obese patients with this mutant allele have a better lipid profile after weight loss.

Role of leptin receptor gene polymorphisms in susceptibility to the development of essential hypertension: a case-control association study in a Northern Han Chinese population

In order to explore the potential association between the leptin receptor (LEPR) gene polymorphisms and essential hypertension (EH) risk in the Northern Han Chinese population, we recruited 823 hypertensive subjects and 491 healthy control subjects from the Northern Han Chinese. Genotyping was performed to identify the Lys109Arg, Gln223Arg and Lys656Asn polymorphisms of the LEPR gene. Significant associations were found in a dominant genetic model ([GG+AG] vs AA), P=0.007, odds ratio (OR)=3.697, 95% confidence interval (CI) 1.442–9.482), and in homozygote comparison (GG vs AA, P=0.005, OR=3.890, 95% CI 1.501–10.077) for the Gln223Arg polymorphism. No significant association could be found between Lys109Arg or Lys656Asn polymorphism and EH risk. Linkage disequilibrium was detected between the Lys109Arg and Gln223Arg polymorphisms, and haplotype analyses identified that the G-A haplotype was a protective haplotype for EH. Our studies demonstrated that the LEPR Gln223Arg polymorphism had an important role in a patient's susceptibility to EH in the Northern Han Chinese population.

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.:

Lack of mutations in the leptin receptor gene in severely obese children

OBJECTIVE

To analyze the LEPR gene in obese children and to investigate the associations between molecular findings and anthropometric and metabolic features.

SUBJECTS AND METHODS

Thirty-two patients were evaluated regarding anthropometric characteristics, blood pressure, heart rate, serum glucose, insulin, leptin levels, and lipid profile. The molecular study consisted of the amplification and automatic sequencing of the coding region of LEPR in order to investigate new mutations.

RESULTS

We identified a high prevalence of metabolic disorders: impaired fasting glucose in 12.5% of the patients, elevated HOMA-IR in 85.7%, low HDL-cholesterol levels in 46.9%, high triglyceride levels in 40.6%, and hypertension in 58.6% of the patients. The molecular study identified 6 already described allelic variants: rs1137100 (exon-2), rs1137101 (exon-4), rs1805134 (exon-7), rs8179183 (exon-12), rs1805096 (exon-18), and the deletion/insertion of the pentanucleotide CTTTA at 3'untranslated region.

CONCLUSIONS

The frequency of alleles observed in this cohort is similar to that described in the literature, and was not correlated with any clinical feature. The molecular findings in the analysis of the LEPR did not seem to be implicated in the etiology of obesity in these patients.

Leptin receptor gene K656N polymorphism is associated with low body fat levels and elevated high-density cholesterol levels in Mexican children and adolescents

INTRODUCTION

This study evaluated the association between obesity and the K109R, Q223R, and K656N polymorphisms of the leptin receptor (LEPR) locus. Such polymorphisms cause changes in the extracellular extreme of the LEPR gene product and appear to be related to signal transduction toward the cell.

SUBJECTS AND METHODS

A total of 128 participants between 6 and 17 years of age from a Mexican Mestizo population were included in the study. Individuals were classified as overweight-obese (n = 76) and normal (n = 52), based on anthropomorphic measurements. The K109R, Q223R, and K656N polymorphisms of the LEPR were determined by the size of restriction fragments obtained from polymorphic fragment amplification (polymerase chain reaction-restriction fragment length polymorphism) obtained from genomic DNA. Allele frequency was compared using the chi-square test. Odds ratio was calculated to determine allele obesity risk factor.

RESULTS

Variant allele frequency was 109R = 0.35, 223R = 0.49, and 656N = 0.11 for the K109R, Q223R, and K656N polymorphisms, respectively. No statistically significant association with obesity was found in any of the alleles. The N allele of the K656N polymorphism was associated with nonobesity markers, such as high concentrations of high-density lipoproteins, normal body mass index, less thickness of skinfolds, and body perimeters. None of the alleles studied were shown to be obesity risk factors.

CONCLUSIONS

Our results suggest that there is no association between the K109R, Q223R, and K656N polymorphisms of the LEPR gene with obesity, and none of the alleles of the LEPR gene K109R, Q223R, and K656N polymorphisms are an obesity risk factor.

Clock genes and body composition in patients with schizophrenia under treatment with antipsychotic drugs

CONTEXT

In the healthy population, several pathways are known to exert an effect on basal metabolic factors. Previous studies have found associations between single nucleotide polymorphisms in clock genes or downstream hormone receptors such as the leptin receptor (LEPR) or glucocorticoid receptor (NR3C1) and obesity in the healthy population, but this association remains to be examined in patients with schizophrenia treated with antipsychotics.

OBJECTIVE

To assess anthropomorphic parameters in patients taking second-generation antipsychotics (SGA) as a function of nine polymorphisms in three core genes of the clock pathway, and two genes of downstream hormone receptors.

METHODS

Clinical parameters were evaluated in 261 patients with schizophrenia spectrum disorder. Polymorphisms in LEPR, MC3R, NR3C1, PER2 and SDC3 were genotyped. In order to control for multiple testing, permutation tests were used to generate corrected empirical p-values using the Max(T) procedure in PLINK.

RESULTS

A significant effect of the rs6196 polymorphism in the NR3C1 on weight (β=-4.18; SE=2.02; p=0.018), BMI (β=-1.88; SE=0.64; p=0.004), waist (β=-5.77; SE=1.75; p=0.001) and waist/hip ratio (β=-0.03; SE=0.012; p=0.009) was found. Permutation tests confirmed the findings for BMI (p=0.037) and waist (p=0.024). Carriers of the G allele consistently displayed better parameters than patients with the wild type allele. A weak effect of rs4949184 in SDC3 on BMI was found, but this did not sustain permutation testing (β=-1.27; SE=0.58; p=0.030, p=0.270 after permutations).

CONCLUSION

Variations in genes implicated in circadian regulation or its related downstream pathways may be important in the regulation of antropomorphic parameters in patients with schizophrenia during long-term treatment with SGA.

Leptin receptor (Lepr) is a negative modulator of bone mechanosensitivity and genetic variations in Lepr may contribute to the differential osteogenic response to mechanical stimulation in the C57BL/6J and C3H/HeJ pair of mouse strains

This study investigated the role of leptin receptor (Lepr) signaling in determining the bone mechanosensitivity and also evaluated whether differences in the Lepr signaling may contribute to the differential osteogenic response of the C57BL/6J (B6) and C3H/HeJ (C3H) pair of mouse strains to mechanical stimuli. This study shows that a loading strain of ∼2,500 με, which was insufficient to produce a bone formation response in B6 mice, significantly increased bone formation parameters in leptin-deficient ob(-)/ob(-) mice and that a loading strain of ∼3,000 με also yielded greater osteogenic responses in Lepr-deficient db(-)/db(-) mice than in wild-type littermates. In vitro, a 30-min steady shear stress increased [(3)H]thymidine incorporation and Erk1/2 phosphorylation in ob(-)/ob(-) osteoblasts and db(-)/db(-) osteoblasts much greater than those in corresponding wild-type osteoblasts. The siRNA-mediated suppression of Lepr expression in B6 osteoblasts enhanced (but in osteoblasts of C3H (the mouse strain with poor bone mechanosensitivity) restored) their anabolic responses to shear stress. The Lepr signaling (leptin-induced Jak2/Stat3 phosphorylation) in C3H osteoblasts was higher than that in B6 osteoblasts. One of the three single nucleotide polymorphisms in the C3H Lepr coding region yielded an I359V substitution near the leptin binding region, suggesting that genetic variation of Lepr may contribute to a dysfunctional Lepr signaling in C3H osteoblasts. In conclusion, Lepr signaling is a negative modulator of bone mechanosensitivity. Genetic variations in Lepr, which result in a dysfunctional Lepr signaling in C3H mice, may contribute to the poor osteogenic response to loading in C3H mice.

Influence of lys656asn polymorphism of leptin receptor gene on surgical results of biliopancreatic diversion

BACKGROUND

Bariatric surgery is the most effective long-term treatment for morbid obesity, reducing obesity-associated comorbidities. The purpose of the present study was to evaluate Lys656Asn polymorphism of leptin receptor gene on outcomes 1 year after biliopancreatic diversion.

METHODS

A sample of 41 morbidly obese patients (body mass index (BMI) > 40 kg/m(2)) were operated on. Biochemical and anthropometric evaluation were realized at basal visit and at each visit. The frequency of patients with diabetes mellitus, hypertension, and hyperlipidemia was recorded at each visit.

RESULTS

Thirty-two patients (78%) had genotype Lys656/Lys656, eight patients (19.5%) Lys656/Asn656 genotype, and one patient (2.4%) Asn656/Asn656 genotype. In the wild-type group, body mass index, weight, glucose, total cholesterol, LDL cholesterol, triacylglycerol, and systolic blood pressure decreased. In the mutant group, the same parameters improved. Initial weight percent loss at 1 year of follow-up was higher in mutant group than in wild-type group (38.9% vs 29.9%; p < 0.05). Total weight loss was higher in mutant group than wild-type group (50.7 vs 37.2 kg; p < 0.05). Basal weight and BMI were higher in mutant group than wild type.

CONCLUSION

Weight loss was higher in mutant group (Lys656Asn and Asn656Asn) than wild-type group (Lys656Lys) after bariatric surgery. Carriers of the allelic variant (Asn) had higher basal weight.

Genetic variants influencing effectiveness of weight loss strategies

Body weight excess has an increasingly high prevalence in the world. Obesity is a complex disease of multifactorial origin with a polygenic condition affected by environmental factors. Weight loss is a primary strategy to treat obesity and its morbidities. Weight changes through life depend on the interaction of environmental, behavioral and genetic factors. Interindividual variation of weight loss in response to different types of interventions (behavioral, caloric restriction, exercise, drug or surgery) has been observed. In this article, currently available data on the role of candidate gene polymorphisms in weight loss are reviewed. Even though control of weight loss by genotype was described in twin and family studies, it is premature to recommend use of genotyping in the design of therapeutic diets or drug treatment. Future studies will have to be large in order to assess the effects of multiple polymorphisms, and will have to control factors other than diet.

Leptin receptor polymorphisms interact with polyunsaturated fatty acids to augment risk of insulin resistance and metabolic syndrome in adults

The leptin receptor (LEPR) is associated with insulin resistance, a key feature of metabolic syndrome (MetS). Gene-fatty acid interactions may affect MetS risk. The objective was to investigate the relationship among LEPR polymorphisms, insulin resistance, and MetS risk and whether plasma fatty acids, a biomarker of dietary fatty acids, modulate this. LEPR polymorphisms (rs10493380, rs1137100, rs1137101, rs12067936, rs1805096, rs2025805, rs3790419, rs3790433, rs6673324, and rs8179183), biochemical measurements, and plasma fatty acid profiles were determined in the LIPGENE-SU.VI.MAX study of MetS cases and matched controls (n = 1754). LEPR rs3790433 GG homozygotes had increased MetS risk compared with the minor A allele carriers [odds ratio (OR) = 1.65; 95% CI: 1.05-2.57; P = 0.028], which may be accounted for by their increased risk of elevated insulin concentrations (OR 2.40; 95% CI: 1.28-4.50; P = 0.006) and insulin resistance (OR = 2.15; 95% CI: 1.18-3.90; P = 0.012). Low (less than median) plasma (n-3) and high (n-6) PUFA status exacerbated the genetic risk conferred by GG homozygosity to hyperinsulinemia (OR 2.92-2.94) and insulin resistance (OR 3.40-3.47). Interestingly, these associations were abolished against a high (n-3) or low (n-6) PUFA background. Importantly, we replicated some of these findings in an independent cohort. Homozygosity for the LEPR rs3790433 G allele was associated with insulin resistance, which may predispose to increased MetS risk. Novel gene-nutrient interactions between LEPR rs3790433 and PUFA suggest that these genetic influences were more evident in individuals with low plasma (n-3) or high plasma (n-6) PUFA.

Interação entre gene e nutriente e sua associação à obesidade e ao diabetes melito

A genômica nutricional avalia o efeito da variação genética na interação entre dieta e doenças crônicas. O objetivo deste manuscrito foi revisar os principais polimorfismos associados à obesidade, ao diabetes melito e também aos fatores da dieta. As principais interações entre polimorfismos genéticos e dieta foram: para obesidade: interleucina-6 (IL-6) com consumo energético; receptor ativado por proliferador de peroxissoma gama 2 (PPAR-gama2) e fat mass and obesity associated (FTO) com consumo de gorduras; receptor β-adrenérgico 2 (ADRB2) e receptor da melanocortina-4 (MCR4) com consumo de carboidratos; para perda de peso: proteínas desacopladoras (UCPs) com restrição calórica; para leptinemia: receptor da leptina (LEPR) com restrição calórica; para diabetes melito: PPAR-gama2 com consumo de gordura; para hipertrigliceridemia: proteína transportadora de ácidos graxos 2 (FABP2) com consumo de gordura. Os dados apresentados sugerem que a genômica nutricional é importante ao desenvolvimento da obesidade e do diabetes melito.

The human gene map for performance and health-related fitness phenotypes: the 2006-2007 update

This update of the human gene map for physical performance and health-related fitness phenotypes covers the research advances reported in 2006 and 2007. The genes and markers with evidence of association or linkage with a performance or a fitness phenotype in sedentary or active people, in responses to acute exercise, or for training-induced adaptations are positioned on the map of all autosomes and sex chromosomes. Negative studies are reviewed, but a gene or a locus must be supported by at least one positive study before being inserted on the map. A brief discussion on the nature of the evidence and on what to look for in assessing human genetic studies of relevance to fitness and performance is offered in the introduction, followed by a review of all studies published in 2006 and 2007. The findings from these new studies are added to the appropriate tables that are designed to serve as the cumulative summary of all publications with positive genetic associations available to date for a given phenotype and study design. The fitness and performance map now includes 214 autosomal gene entries and quantitative trait loci plus seven others on the X chromosome. Moreover, there are 18 mitochondrial genes that have been shown to influence fitness and performance phenotypes. Thus,the map is growing in complexity. Although the map is exhaustive for currently published accounts of genes and exercise associations and linkages, there are undoubtedly many more gene-exercise interaction effects that have not even been considered thus far. Finally, it should be appreciated that most studies reported to date are based on small sample sizes and cannot therefore provide definitive evidence that DNA sequence variants in a given gene are reliably associated with human variation in fitness and performance traits.

Atorvastatin and BMD in coronary syndrome. Role of Lys656Asn polymorphism of leptin receptor gene

OBJECTIVES

To evaluate the effect of atorvastatin on bone mass and markers of bone remodeling in patients with acute coronary syndrome according to the Lys656Asn leptin receptor gene polymorphism.

METHODS

Sixty-two patients with acute coronary syndrome were included. Patients were allocated to low and high doses of atorvastatin according to baseline levels of cholesterol and triglycerides and the index of vascular risk and were studied at hospital admission and at 12 months. Cholesterol, triglycerides, total calcium, phosphorus, magnesium, osteocalcin and urinary deoxypyridinoline were determined in all patients at baseline and at 12 months of follow up. Densitometric studies were conducted in the lumbar spine and hip. Patients with a T-score<-2.5 were considered osteoporotic. The Lys656Asn leptin receptor gene polymorphism was determined by PCR.

RESULTS

Forty-two patients were Lys/Lys homozygotic and 20 Lys/Asn heterozygotic. The prevalence of osteoporosis was 31% for the Lys/Lys genotype and 27% for the Lys/Asn genotype with no significant differences between groups. There was a significant increase in bone mineral density in the lumbar spine (1.117 +/- 0.24 versus 1.135 +/- 0.24, P = 0.008) in patients with the Lys/Lys genotype.

CONCLUSION

Atorvastatin increases lumbar spine bone mineral density only in patients with the Lys/Lys genotype of the Lys656Asn polymorphism.

Implications of gene-behavior interactions: prevention and intervention for obesity

A vast body of research exists to demonstrate that obesity is a complex disorder with a strong genetic basis and a multifactorial etiology. Yet despite the overwhelming evidence that genes play an important role in the development of obesity, many people argue that the increasing prevalence of obesity is simply due to an abundance of palatable food and a dearth of opportunities for physical exercise. While activity and eating behaviors contribute substantially to the development of obesity, considering these to be the only etiologic factors is directly contradictory to what is now known about how eating and energy balance are regulated. Our understanding of the molecular processes controlling eating behavior, in particular, has accelerated exponentially in the last 10 years, and this is one area in which obesity genetics has made great progress. Our challenge is to understand more fully how genetic variation may interact with behavioral factors to influence the regulation of body weight and adiposity. Although exercise and diet strategies are used routinely for obesity treatment, there is a huge variability in how individuals respond to these interventions. There is also a substantial amount of evidence that such responses may also be regulated by genes. Understanding gene-response relationships is the key to developing more efficacious intervention and prevention programs for obesity.

Implications of gene-behavior interactions: prevention and intervention for obesity

A vast body of research exists to demonstrate that obesity is a complex disorder with a strong genetic basis and a multifactorial etiology. Yet despite the overwhelming evidence that genes play an important role in the development of obesity, many people argue that the increasing prevalence of obesity is simply due to an abundance of palatable food and a dearth of opportunities for physical exercise. While activity and eating behaviors contribute substantially to the development of obesity, considering these to be the only etiologic factors is directly contradictory to what is now known about how eating and energy balance are regulated. Our understanding of the molecular processes controlling eating behavior, in particular, has accelerated exponentially in the last 10 years, and this is one area in which obesity genetics has made great progress. Our challenge is to understand more fully how genetic variation may interact with behavioral factors to influence the regulation of body weight and adiposity. Although exercise and diet strategies are used routinely for obesity treatment, there is a huge variability in how individuals respond to these interventions. There is also a substantial amount of evidence that such responses may also be regulated by genes. Understanding gene-response relationships is the key to developing more efficacious intervention and prevention programs for obesity.

The haplotype identified in LEPR gene is associated with type 2 diabetes mellitus in Northern Chinese

Leptin receptor (LEPR) plays an important physiological role in energy metabolism. The study addressed the relationship between leptin receptor gene variations and type 2 diabetes mellitus (T2DM). Three single nucleotide polymorphisms (SNPs) of LEPR gene, Arg109Lys (A/G), Asn656Lys (C/G) and Pro1019Pro (C/T) were detected in a northern population in China. Totally, 317 patients with T2DM and 282 healthy controls were recruited randomly from urban communities in Harbin area in the Northeast of China. All polymorphisms were genotyped by Sequenom SNP detection system in both case and control groups. Linkage disequilibria analysis showed moderate linkage disequilibria between the pair-wise SNPs for all three SNPs. Then, we identified the haplotype covering the three SNPs (AGC) with higher risk of T2DM (OR=1.69 (1.09-2.61)), and showed that there existed significant difference between cases and controls (9.8% vs. 6.0%, P=0.02). We also observed significant difference in frequencies of the heterozygous haplotype combination (GGT/AGC), that is 17.0% vs. 8.2% in cases and controls, respectively (P=0.001). It further supported the evidence that the haplotype (AGC) was associated with T2DM. So, AGC haplotype in LEPR gene could be a risk factor associated with T2DM in Northern Chinese.

Influence of Lys656Asn polymorphism of leptin receptor gene on leptin response secondary to two hypocaloric diets: a randomized clinical trial

BACKGROUND

Human obesity is characterized by high levels of leptin, and it has been suggested that obese patients may be leptin-resistant.

OBJECTIVE

The aim of our study was to investigate the influence of Lys656Asn polymorphism in the LEPR gene on leptin response secondary to a low fat versus a low carbohydrate diet in obese patients.

DESIGN

A population of 78 obesity patients was enrolled. Before and after 2 months of two diets, a nutritional evaluation was performed.

RESULTS

52 patients had genotype Lys656/Lys656 (wild group) and 26 patients Lys656/Asn656 or Asn656/Asn656 (mutant group). In the low fat and wild groups, BMI, weight, fat mass, glucose, total cholesterol, triglyceride, insulin, and blood pressure decreased. In mutant type (MT), BMI, weight and fat mass decreased. In wild type (WT) with low carbohydrate diet, BMI, weight, fat mass, waist circumference, waist-to-hip ratio, total cholesterol, and blood pressures decreased. In MT, BMI, weight and fat mass decreased. Only leptin concentrations have a significant decrease in WT with both diets (diet I: 30.3%; p < 0.05) and (diet II: 15.5%; p < 0.05).

CONCLUSION

In WT patients, the changes in serum leptin concentration due to 2 months' intervention with low fat are higher than with a low carbohydrate diet.

Interaction of single nucleotide polymorphisms in ADRB2, ADRB3, TNF, IL6, IGF1R, LIPC, LEPR, and GHRL with physical activity on the risk of type 2 diabetes mellitus and changes in characteristics of the metabolic syndrome: The Finnish Diabetes Prevention Study

Single nucleotide polymorphisms (SNPs) in the ADRB2, ADRB3, TNF, IL6, IGF1R, LIPC, LEPR, and GHRL genes were associated with the conversion from impaired glucose tolerance (IGT) to type 2 diabetes mellitus (T2D) in the Finnish Diabetes Prevention Study (DPS). In this study, we determined whether polymorphisms in these genes modified the effect of changes in physical activity (PA) on the risk of T2D in the DPS. Moreover, we assessed whether the polymorphisms modified the effect of changes in PA on changes in measures of body fat, serum lipids, and blood pressure during the first year of the follow-up of the DPS. Overweight subjects with IGT (n = 487) were followed for an average of 4.1 years, and PA was assessed annually with a questionnaire. The interactions of the polymorphisms with changes in total and moderate-to-vigorous PA on the conversion to T2D during the 4.1-year follow-up were assessed using Cox regression with adjustments for the other components of the intervention (dietary changes, weight reduction). Univariate analysis of variance was used to assess interactions on changes in continuous variables during the first year of the follow-up. No interaction between the polymorphisms and PA on the conversion to T2D was found. The Leu72Met (rs696217) polymorphism in GHRL modified the effect of moderate-to-vigorous PA on changes in weight and waist circumference, the -501A/C (rs26802) polymorphism in GHRL modified the effect of total and moderate-to-vigorous PA on change in high-density lipoprotein cholesterol, and the Lys109Arg (rs1137100) polymorphism in LEPR modified the effect of total PA on change in blood pressure. In conclusion, genetic variation may modify the magnitude of the beneficial effects of PA on characteristics of the metabolic syndrome in persons with IGT.

Resistance to obesity and resistance to atherosclerosis: is there a metabolic link?

AIM

This review deals with the question whether resistance to obesity affects resistance to atherosclerosis.

DATA SYNTHESIS

Resistance to diet-induced obesity in inbred mouse strains involves an adequate response to Leptin, the main regulator of the energy balance cycle. Leptin, an adipokine with both central and peripheral targets, regulates food intake and energy expenditure. Adequate response to leptin involves repression of stearoyl-CoA desaturase, activation of Amp-activated protein-kinase and uncoupling proteins, resulting in fatty acid oxidation and energy expenditure. Most of the obesity-resistant strains are also resistant to atherosclerosis, but so far no information concerning the response to the leptin cycle is available in these strains when bred onto a LDLR(-/-) or apoE(-/-) background. Recent studies in mouse strains on an atherosclerosis permissive background have identified genetic links between obesity and atherosclerosis. Moreover, information derived from studies on mice was applied in order to learn about the metabolic effectors in humans and is included in this review.

CONCLUSIONS

The data presented in this review provide recent information concerning metabolic pathways that play an important role in the regulation of energy balance, a prerequisite for resistance to obesity. Hopefully they will provide a background for future genetic studies involved in resistance to atherosclerosis.