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

Leptin and the GA genotype of rs2167270 of the LEP gene increase the risk of prediabetes

Prediabetes is a precursor stage that frequently develops to definitive type 2 diabetes mellitus (T2DM). Therefore, identifying individuals with prediabetes can allow for early intervention measures that delay or prevent disease progression to T2DM. Several biochemical changes appear to be associated with prediabetes, including an increase in the serum levels of leptin. In Jordan, this association has not been previously investigated. In the present study, the serum levels of leptin were measured in 122 prediabetes subjects and 122 controls. Furthermore, the genotypes of three single nucleotide polymorphisms in the LEP gene (rs7799039, rs2167270 and rs791620) were investigated for their association with prediabetes using PCR-restriction fragment length polymorphism. The results revealed a significant increase in serum leptin levels in the prediabetes group. It was also shown that the GA genotype and the A allele of rs2167270 were significantly associated with an increased risk of prediabetes (P<0.05). These findings were shown to be independent of body mass index, waist circumference and serum glucose levels. To the best of our knowledge, the present study is the first in Jordan to have reported an association between serum leptin levels and the GA genotype of rs2167270 with an increased risk of prediabetes, identified both in the univariate and multivariate models.

Polymorphic Analysis of Leptin Promoter in Obese/diabetic Subjects in Kashmiri Population

BACKGROUND

The role of common variants in leptin promoter has already been established to play a major role in obesity and diabetes in humans. The study was accordingly focused on leptin promoter variants and their potential association with diabetes and obesity in ethnic population from Kashmir, India.

METHODS

Allele frequencies of 620 Kashmiri subjects with diabetes (200), obese subjects (200), and ethnically matched healthy controls (200) were tested for the Hardy-Weinberg disequilibrium. Among 200 obese subjects, a total of 50 persons were with diabetes. The genotype and allele frequencies were evaluated using the Chi-square or Fisher's exact tests.

RESULTS

Sequence analysis revealed two reported variations i.e., rs72563764C>T and rs7799039G>A in promoter region. Both variants show homozygous as well as heterozygous genotypes. These variations indicated significant difference with respect to allelic and genotypic frequencies in all groups i.e., persons with diabetes, obese, and obese persons with diabetes (P < 0.05). We also analyzed the association of these variations with biochemical characteristics and found significant association of rs72563764C>T with triglycerides (TG) in obese patients and fasting plasma glucose (FPG) and random blood sugar (RBS) in obese/persons with diabetes. Also rs7799039G>A showed association with postprandial plasma sugar (PPPS) in obese patients and FPG and resting plasma glucose (RPG) in obese persons with diabetes.

CONCLUSIONS

Our results are suggestive of the association of leptin promoter gene variations i.e., rs72563764C>T and rs7799039G>A with both diabetes and obesity.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

The association of insertions/deletions (INDELs) and variable number tandem repeats (VNTRs) with obesity and its related traits and complications

BACKGROUND

Despite the fact that insertions/deletions (INDELs) are the second most common type of genetic variations and variable number tandem repeats (VNTRs) represent a large portion of the human genome, they have received far less attention than single nucleotide polymorphisms (SNPs) and larger forms of structural variation like copy number variations (CNVs), especially in genome-wide association studies (GWAS) of complex diseases like polygenic obesity. This is exemplified by the vast amount of review papers on the role of SNPs and CNVs in obesity, its related traits (like anthropometric measurements, biochemical variables, and eating behavior), and its related complications (like hypertension, hypertriglyceridemia, hypercholesterolemia, and insulin resistance-collectively known as metabolic syndrome). Hence, this paper reviews the types of INDELs and VNTRs that have been studied for association with obesity and its related traits and complications. These INDELs and VNTRs could be found in the obesity loci or genes from the earliest GWAS and candidate gene association studies, like FTO, genes in the leptin-proopiomelanocortin pathway, and UCP2/3. Given the important role of the brain serotonergic and dopaminergic reward system in obesity susceptibility, the association of INDELs and VNTRs in these neurotransmitters' metabolism and transport genes with obesity is also reviewed. Next, the role of INS VNTR in obesity and its related traits is questionable, since recent large-scale studies failed to replicate the earlier positive associations. As obesity results in chronic low-grade inflammation of the adipose tissue, the proinflammatory cytokine gene IL1RA and anti-inflammatory cytokine gene IL4 have VNTRs that are implicated in obesity. A systemic proinflammatory state in combination with activation of the renin-angiotensin system and decreased nitric oxide bioavailability as found in obesity leads to endothelial dysfunction. This explains why VNTR and INDEL in eNOS and ACE, respectively, could be predisposing factors of obesity. Finally, two novel genes, DOCK5 and PER3, which are involved in the regulation of the Akt/MAPK pathway and circadian rhythm, respectively, have VNTRs and INDEL that might be associated with obesity.

SHORT CONCLUSION

In conclusion, INDELs and VNTRs could have important functional consequences in the pathophysiology of obesity, and research on them should be continued to facilitate obesity prediction, prevention, and treatment.

The association of vaspin rs2236242 and leptin rs7799039 polymorphism with metabolic syndrome in Egyptian women

BACKGROUND/AIM

Genetic predisposition is implicated in the etiology of metabolic syndrome. This study aimed to investigate the1397645907association of vaspin rs2236242 and leptin rs7799039 polymorphisms with their serum levels and with the risk of developing metabolic syndrome in Egyptian women.

MATERIALS AND METHODS

This case control study included 100 Egyptian women with metabolic syndrome and 100 without metabolic syndrome. The genotypes of vaspin rs2236242 and leptin rs7799039 were detected by a methodology based on PCR-RFLP. Serum vaspin and leptin levels were determined by ELISA.

RESULTS

The metabolic syndrome group was associated with higher serum vaspin and leptin levels when compared to the nonmetabolic syndrome group. The AA genotype of leptin rs7799039 was associated with metabolic syndrome and with higher serum leptin levels, while the different genotypes of vaspin rs2236242 were not associated with metabolic syndrome or different serum vaspin levels.

CONCLUSION

The AA genotype of leptin rs7799039 was associated with metabolic syndrome and higher serum leptin levels. Serum leptin and vaspin can be used as diagnostic markers of metabolic syndrome.

LEP -2548G>A Polymorphism of the Leptin Gene and Its Influence on the Lipid Profile in Obese Individuals

BACKGROUND/AIM

We studied the molecular pathogenesis of obesity, involving complex interactions between environmental and genetic factors, with a focus on the leptin gene. It was our aim to characterize the LEP -2548G>A leptin polymorphism and lipid profile in obese and normal-weight individuals.

METHODS

A total of 212 individuals were divided into the study group including 136 obese patients (body mass index, BMI≥30) and the control group with 76 normal-weight individuals (BMI>18.5 and ≤24.9). DNA was amplified by polymerase chain reaction and restriction fragment length polymorphism. The lipid profile was analyzed by enzymatic colorimetric methods. The level of significance was set at p<0.05.

RESULTS

There was a prevalence of the GA genotype in both groups. However, comparative group analysis showed an association of the recessive model (AA+GA) with increased triglycerides (TG) and decreased high-density lipoprotein cholesterol (HDL-C) levels in the study group.

CONCLUSION

This study did not confirm an association between obesity and the LEP -2548G>A polymorphism. However, AA+GA genotypes, in the presence of obesity, seem to contribute to a reduction in HDL-C and an increase in TG compared with normal-weight individuals. This should be confirmed in further studies.

The effect of leptin promoter and leptin receptor gene polymorphisms on lipid profile among the diabetic population: modulations by atorvastatin treatment and environmental factors

PURPOSE

This study investigated the effect of leptin (LEP) 2548A/G and leptin receptor (LEPR) Q223R polymorphisms on the levels of HDL, LDL, TG, and total cholesterol (t-chol). In addition, the interactions between examined polymorphisms, statin therapy and environmental factors on lipid profile were examined.

METHODS

Adult diabetic patients (n-418) were recruited from diabetes/endocrine clinics in north of Jordan. Lipid profile was measured using standard protocols. Genotyping of LEP 2548A/G and LEPR Q223R polymorphisms was carried out using polymerase chain reaction-restriction fragment length polymorphisms.

RESULTS

No significant association between LEP 2548A/G and LEPR genotypes and levels of HDL (P = 0.83), LDL (P = 0.40), TG (P = 0.23) and t-chol (P = 0.91). However, in patient on atorvastatin, those with GG or GA genotypes of LEP 2548 experienced significantly higher levels of LDL compared with AA genotype of LEP 2548 (P < 0.002). Patients with dyslipidemia had higher TG in comparison with those without (P < 0.03). Smokers had lower HDL and higher TG levels compared with none smokers or previous smokers (P < 0.002 and P < 0.02, respectively). Female patients tend to have a higher HDL in comparison with male patients (P < 0.05). Patients with HbA1c value greater than or equal to 7 had higher LDL and t-chol compared with patients who had an HbA1c levels of <7 (P < 0.02 and < 0.005, respectively). Patients with disease duration of 5 or more years had a lower HDL compared with those patients with duration of <5 years (P < 0.03).

CONCLUSION

In conclusion, and although lipid profile regulation is a multifactorial process, -2548G/A LEP polymorphism seems to affect statins treatment response among diabetic patients. More studies are required to specifically define factors that influence lipid profiles interaction with statin treatment response especially among patients with diabetes.

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 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.

Investigation of associations between obesity and LEP G2548A and LEPR 668A/G polymorphisms in a Turkish population

Objective. Obesity is a complex heterogeneous disease that is caused by genes, environmental factors, and the interaction between the two. The leptin (LEP) and leptin receptor (LEPR) genes have been evaluated for polymorphisms that could potentially be related to the pathophysiology of obesity and its complications. The aim of this study was to investigate the role of LEP G2548A and LEPR 668A/G polymorphisms in the pathogenesis of obesity. Subjects. The study included 127 patients with obesity and 105 healthy controls. Polymerase chain reaction and restriction fragment length analysis for LEP G2548A and LEPR 668A/G polymorphisms were applied. Results. There was no statistically significant difference in the genotype frequencies of the LEP gene polymorphism between patients and control groups (P > 0.05). We found a difference in the LEPR genotypes between patients and controls, but this was not statistically significant (P = 0.05). Additionally, we found an increased risk of obesity in the LEP/LEPR GG/GG combined genotype (P < 0.05). Conclusion. Our findings indicate that the LEP G2548A polymorphism is not a relevant obesity marker and that the LEPR 668A/G polymorphism may be related to obesity in a Turkish population. Further researches with larger patient population are necessary to ascertain the implications of LEP and LEPR polymorphisms in obesity.

The impact of obesity-related SNP on appetite and energy intake

An increasing number of studies have reported a heritable component for the regulation of energy intake and eating behaviour, although the individual polymorphisms and their ‘effect size’ are not fully elucidated. The aim of the present study was to examine the relationship between specific SNP and appetite responses and energy intake in overweight men. In a randomised cross-over trial, forty overweight men (age 32 (sd 09) years; BMI 27 (sd 2) kg/m2) attended four sessions 1 week apart and received three isoenergetic and isovolumetric servings of dairy snacks or water (control) in random order. Appetite ratings were determined using visual analogue scales and energy intake at an ad libitum lunch was assessed 90 min after the dairy snacks. Individuals were genotyped for SNP in the fat mass and obesity-associated (FTO), leptin (LEP), leptin receptor (LEPR) genes and a variant near the melanocortin-4 receptor (MC4R) locus. The postprandial fullness rating over the full experiment following intake of the different snacks was 17·2 % (P= 0·026) lower in A carriers compared with TT homozygotes for rs9939609 (FTO, dominant) and 18·6 % (P= 0·020) lower in G carriers compared with AA homozygotes for rs7799039 (LEP, dominant). These observations indicate that FTO and LEP polymorphisms are related to the variation in the feeling of fullness and may play a role in the regulation of food intake. Further studies are required to confirm these initial observations and investigate the ‘penetrance’ of these genotypes in additional population subgroups.

Influence of fresh forage-based diets and αs₁-casein (CSN1S1) genotype on nutrient intake and productive, metabolic, and hormonal responses in milking goats

Polymorphism at the αS1-casein locus (CSN1S1) in goats influences several milk production traits. Milk from goats carrying strong alleles, which are associated with high αS1-casein (αS1-CN) synthesis, has higher fat and casein contents, longer coagulation time and higher curd firmness than milk from goats with weak alleles linked to low αS1-CN content. Nutrition also affects these milk properties; therefore, it is important to better understand the interaction between dietary characteristics and the CSN1S1 genotype in goats. This study aimed to investigate the effect of fresh forage based diet or energy supplement on feeding behavior, milk production, and metabolic and hormonal parameters of Girgentana goats with different genotypes at CSN1S1 loci. From a group of goats genotyped by PCR at the DNA level, 12 were selected because they had the same genotype for αS2-CN, β-CN, and κ-CN but a different genotype for αS1-CN: 6 were homozygous for strong alleles at the CSN1S1 loci (AA) and 6 were heterozygous for a weak allele (AF). Goats of each genotype were allocated to 3 subgroups and fed 3 diets ad libitum in a 3×3 Latin square design. The diets were sulla (Hedysarum coronarium L.) fresh forage, sulla fresh forage plus 800 g/d of barley meal (SFB), and mixed hay plus 800 g/d of barley meal (MHB). Diet had a stronger effect than CSN1S1 genotype. The SFB diet led to the highest energy intake, dry matter (DM) digestibility, and milk yield. The fresh forage diets (SFF and SFB) increased DM and crude protein (CP) intake, CP digestibility, and milk CN compared with the MHB diet. The diets supplemented with energy (SFB, MHB) reduced milk fat and urea, improved CP utilization for casein synthesis, and limited body fat mobilization, in accordance with a lower level of nonesterified fatty acids and higher levels of glucose and IGF-1. With regard to CSN1S1 genotype, AA goats showed higher CP digestibility and lower free thyroxine hormone and cholesterol levels than AF goats. Significant diet × genotype interactions indicated how AA goats, compared with AF goats, showed higher DM digestibility and milk yield when fed the SFB diet, which had more energy. A reduction in free triiodothyronine hormone occurred in AF goats fed the MHB diet, whereas no differences were observed in AA goats. These results demonstrate how goats with a higher capacity for αS1-CN synthesis exhibit more efficient energy and protein utilization, evident at the digestive level, and better productive responses to high-nutrition diets.

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.

Common variants of IL6, LEPR, and PBEF1 are associated with obesity in Indian children

The increasing prevalence of obesity in urban Indian children is indicative of an impending crisis of metabolic disorders. Although perturbations in the secretion of adipokines and inflammatory molecules in childhood obesity are well documented, the contribution of common variants of genes encoding them is not well investigated. We assessed the association of 125 common variants from 21 genes, encoding adipocytokines and inflammatory markers in 1,325 urban Indian children (862 normal weight [NW group] and 463 overweight/obese [OW/OB group]) and replicated top loci in 1,843 Indian children (1,399 NW children and 444 OW/OB children). Variants of four genes (PBEF1 [rs3801266] [P = 4.5 × 10(-4)], IL6 [rs2069845] [P = 8.7 × 10(-4)], LEPR [rs1137100] [P = 1.8 × 10(-3)], and IL6R [rs7514452] [P = 2.1 × 10(-3)]) were top signals in the discovery sample. Associations of rs2069845, rs1137100, and rs3801266 were replicated (P = 7.9 × 10(-4), 8.3 × 10(-3), and 0.036, respectively) and corroborated in meta-analysis (P = 2.3 × 10(-6), 3.9 × 10(-5), and 4.3 × 10(-4), respectively) that remained significant after multiple testing corrections. These variants also were associated with quantitative measures of adiposity (weight, BMI, and waist and hip circumferences). Allele dosage analysis of rs2069845, rs1137100, and rs3801266 revealed that children with five to six risk alleles had an approximately four times increased risk of obesity than children with less than two risk alleles (P = 1.2 × 10(-7)). In conclusion, our results demonstrate the association of the common variants of IL6, LEPR, and PBEF1 with obesity in Indian children.

Relationship of short tandem repeats flanking leptin-melanocortin pathway genes with anthropometric profile and leptinemia in Brazilian individuals

OBJECTIVE

To investigate the relationship of short tandem repeats (STR) near genes involved in the leptin-melanocortin pathway with body mass index (BMI) and leptinemia.

SUBJECTS AND METHODS

Anthropometric variables and leptinemia were measured in 100 obese and 110 nonobese individuals. D1S200, D2S1788, DS11912, and D18S858 loci were analyzed by PCR and high-resolution electrophoresis.

RESULTS

Overall STR allele frequencies were similar between the obese and non-obese group (p > 0.05). Individual alleles D1S200 (17), D11S912 (43), D18S858 (11/12) were associated with obesity (p < 0.05). Individuals carrying these alleles showed higher BMI than non-carriers (p < 0.05). Moreover, a relationship between D18S858 11/12 alleles and increased waist circumference was found (p = 0.040). On the other hand, leptinemia was not influenced by the studied STRs (p > 0.05).

CONCLUSIONS

D1S200, D11S912, and D18S858 loci are associated with increased BMI and risk for obesity in this sample.

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

BACKGROUND

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

OBJECTIVE

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

DESIGN

A genetic association study.

PARTICIPANTS

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

MEASURES

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

RESULTS

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

CONCLUSIONS

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

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.