Leptin Responsiveness to Energy Restriction: Genetic Variation in the Leptin Receptor Gene

Genotype frequency analysis of rs2025804 LEPR genetic variant in Iranian population

Objectives

The LEPR gene is a key focus in obesity research, with studies linking its polymorphisms to various diseases like polycystic ovarian syndrome and energy intake disorders. This study aims to investigate the prevalence of the rs2025804 variant within LEPR and its distribution among healthy individuals across diverse ethnic groups in Iran.

Methods

The frequency of the rs2025804 genotype in the LEPR gene was analyzed in 1142 healthy adults representing different ethnicities in Iran. Saliva samples were randomly collected, and genomic DNA was extracted using a standard kit. Genotyping was performed using the Illumina Infinium Global Screening Array-24 BeadChip. Genotype and allele frequencies were calculated using SPSS software version 22, with a 95% confidence level.

Results

Among the 1142 individuals surveyed across 29 provinces, 683 (59.81%) had genotype AA, 408 (35.73%) had genotype AG, and 51 (4.47%) had genotype GG. The allele frequencies for A and G were found to be 1774 (77.67%) and 510 (22.32%), respectively. Our findings show a unique allele distribution compared to other ethnic groups, with genotype AA being the most prevalent (59.81%), followed by AG (35.73%) and GG (4.47%). Allele frequencies are A (77.67%) and G (22.32%).

Conclusions

This study documents the genotype and allele frequencies of rs2025804 in the LEPR gene among healthy Iranians for the first time. Routine LEPR genotyping could potentially serve as a screening tool for obesity-related disorders, given these results. This enhances our understanding of genetic diversity and holds promise for targeted healthcare interventions.

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.

Genetic Determination of Serum Levels of Diabetes-Associated Adipokines

Adipose tissue secretes an abundance of proteins. Some of these proteins are known as adipokines and adipose-derived hormones which have been linked with metabolic disorders, including type 2 diabetes, and even with cancer. Variance in serum adipokine concentration is often closely associated with an increase (obesity) or decrease (lipodystrophy) in fat tissue mass, and it is affected by age, gender, and localization of the adipose tissue. However, there may be genetic variants which, in consequence, influence the serum concentration of a certain adipokine, and thereby promote metabolic disturbances or, with regard to the "protective" allele, exert beneficial effects. This review focuses on the genetic determination of serum levels of the following adipokines: adiponectin, chemerin, leptin, progranulin, resistin, retinol binding protein 4, vaspin, adipsin, apelin, and omentin. The article reports on the latest findings from genome-wide association studies (GWAS) and candidate gene studies, showing variants located in/nearby the adipokine genes and other (non-receptor) genes. An extra chapter highlights adipokine-receptor variants. Epigenetic studies on adipokines are also addressed.

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.

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.:

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.

Leptin-receptor polymorphisms relate to obesity through blunted leptin-mediated sympathetic nerve activation in a Caucasian male population

Leptin plays a key role in the regulation of body weight through the sympathetic nervous system; however, the contributions of leptin-receptor polymorphisms to obesity and sympathetic nerve activity have not been fully clarified. In the present study, we examined the relationships between leptin-receptor polymorphisms, plasma leptin and whole-body norepinephrine (NE) spillover as an index of sympathetic nerve activity in a Caucasian male cohort. In 129 young healthy normotensive men with a wide range of body mass index (BMI) (19.4-39.5 kg/m(2)), we measured leptin-receptor polymorphisms (Gln223Arg, Lys656Asn, and Lys109Arg), plasma leptin levels, whole-body NE spillover, whole-body NE clearance, BMI and blood pressure (BP) levels in the supine position after overnight fasting. Overweight-obese (BMI>or=25 kg/m(2)) subjects had significantly greater BMI, BP levels, plasma leptin and whole-body NE spillover compared to lean (BMI<25 kg/m(2)) subjects, but the NE clearance was similar. Overweight-obese subjects had significantly higher frequencies of the Arg223 allele and the Arg223 homozygous allele of Gln223Arg and the Asn656 allele of Lys656Asn compared to lean subjects. Subjects carrying the Arg223 homozygous or the Asn656 allele had higher levels of plasma leptin, BMI, waist circumference, and waist-to-hip ratio, but significantly less whole-body NE spillover, especially when they were also overweight-obese. BP levels and whole-body NE clearance were similar between subjects with and without the Arg223 homozygous or Asn656 allele. No differences were found in the distributions of the Arg109 allele of Lys109Arg polymorphism between nonobese and overweight-obese subjects. In addition, BMI, BP, plasma leptin levels, whole-body NE spillover and whole-body NE clearance were similar between those with and without the Arg109 allele. Together, these findings demonstrate that leptin-receptor polymorphisms were related to the incidence of obesity in a Caucasian male population. These polymorphisms were accompanied by high plasma leptin levels (leptin resistance) and lower whole-body plasma NE spillover (blunted sympathetic nerve activity). We therefore hypothesize that leptin-receptor play a role in the development of obesity through leptin resistance and blunted leptin-mediated sympathetic nerve activity.

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.

Influence of Lys656Asn polymorphism of the leptin receptor gene on insulin resistance in nondiabetic obese patients

BACKGROUND

Alterations of the normal leptin receptor (LEPR) gene may be involved in the development of obesity. Leptin has been shown to be able to modulate insulin secretion. Different polymorphisms in the LEPR gene have been studied, albeit with unclear results. The polymorphism on codon 656 produces a change in charge, making this change possibly functional.

OBJECTIVE

The objective of this study was to investigate the influence of Lys656Asn polymorphism in the LEPR gene on serum insulin, glucose values, and insulin resistance in the fasted state among obese men and women without diabetes mellitus.

DESIGN

Two hundred thirty-three (body mass index, >30 kg/m(2)) nondiabetic obese patients were analyzed. Indirect calorimetry, tetrapolar electrical bioimpedance, blood pressure determination, serial assessment of nutritional intake with 3-day written food records, and biochemical analysis were performed. Statistical analysis was performed for Lys656/Asn656 and Asn656/Asn656 jointly as a mutant allelic group and for Lys656/Lys656 as a wild allelic group.

RESULTS

The subjects' (67 males and 166 females) mean age and mean body mass index were 43.6+/-16.6 years and 35.3+/-5.6 kg/m(2), respectively. One hundred forty-three patients (61.9%) had the genotype Lys656/Lys656 (wild group), whereas 88 (38.1%) had either the genotype Lys656/Asn656 (n=81; 30.7%) or the genotype Asn656/Asn656 (n=7; 7.4%) (mutant group). Age and sex distribution were similar in both groups. No difference was detected between the mutant and wild allelic groups in anthropometric parameters and dietary intakes. Homeostasis model assessment (HOMA; 2.8+/-1.7 vs. 5.6+/-4.8; P<.05) and insulin (18.1+/-10.7 vs. 32.1+/-25 mUI/ml; P<.05) levels were higher in males with the genotypes Lys656/Asn656 and Asn656/Asn656 than in males with the genotype Lys656/Lys656. Leptin levels were higher in males with a mutant genotype than in males with a wild genotype (39.3+/-23 vs. 63.5+/-28 ng/ml; P<.05).

CONCLUSION

The novel findings of our study are those of the association of the Lys656/Asn656 and Asn656/Asn656 genotypes with higher levels of insulin, HOMA, and leptin in males and the lack of such an association in females.

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

BACKGROUND

Human obesity is characterized by high levels of leptin, and it has been suggested that obese patients may be leptin resistant. The aim of our study was to investigate the influence of Lys656Asn polymorphism in the leptin receptor gene on leptin response and weight loss secondary to a lifestyle modification (Mediterranean hypocaloric diet and exercise) in obese patients.

METHODS

A population of 67 obese (body mass index >30) nondiabetic outpatients was analyzed in a prospective way. Before and after 3 months of lifestyle modification program, bipolar electrical bioimpedance, blood pressure, and a serial assessment of nutritional intake with 3 days written food records and biochemical analysis were performed. The lifestyle modification program consisted of a hypocaloric diet (1520 kcal, 52% carbohydrates, 25% lipids and 23% proteins). The exercise program consisted of aerobic exercise for at least three times per week (60 min each). Statistical analysis was performed for the combined Lys656/Asn656 and Asn656/Asn656 as mutant group and type Lys656/Lys 656 as wild-type second group.

RESULTS

Sixty seven patients gave informed consent and were enrolled in the study. The mean age was 45.7 +/- 16.6 years and the mean BMI 34.1 +/- 5.1, with 18 males (26.9%) and 49 females (73.1%). Thirty six patients (10 males/26 females) (46.8%) had the genotype Lys656/Lys 656 (wild-type group) and 31 patients (8 males/23 females) (46.3%) Lys656/Asn656 (n = 28, 41.8%) or Asn656/Asn656 (n = 3, 4.5%) (mutant group). The percentage of responders (weight loss) was similar in both groups (91.7 vs. 87.1%). In wild-type group (responders and nonresponders), BMI, weight, fat mass, systolic blood pressure and waist circumference decreased. In mutant group, BMI, weight and waist circumference decreased. No differences were detected between basal values in both groups. Only leptin levels decreased significantly in wild-type group (11.5%; p <0.05) (57.3 +/- 31.5 ng/mL vs. 45.8 +/- 29.3 ng/mL; p <0.05). In mutant group, leptin increased without statistical differences (0.44%; ns).

CONCLUSIONS

Patients with Asn656 allele of LEPR gene have a different response than wild-type patients, and Lys656Lys patients have a significant decrease in weight, BMI, fat mass, waist circumference, systolic blood pressure and leptin levels.

Genetics of leptin and obesity: a HuGE review

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