Leptin promoter variant G2548A is associated with serum leptin and HDL-C levels in a case control observational study in association with obesity in a Pakistani cohort

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.

Risk variants of obesity associated genes demonstrate BMI raising effect in a large cohort

Obesity is highly polygenic disease where several genetic variants have been reportedly associated with obesity in different ethnicities of the world. In the current study, we identified the obesity risk or protective association and BMI raising effect of the minor allele of adiponectin, C1Q and collagen domain containing (ADIPOQ), cholesteryl ester transfer protein (CEPT), FTO alpha-ketoglutarate dependent dioxygenase (FTO), leptin (LEP), and leptin receptor (LEPR) genes in a large cohort stratified into four BMI-based body weight categories i.e., normal weight, lean, over-weight, and obese. Based on selected candidate genetic markers, the genotyping of all study subjects was performed by PCR assays, and genotypes and allele frequencies were calculated. The minor allele frequencies (MAFs) of all genetic markers were computed for total and BMI-based body weight categories and compared with MAFs of global and South Asian (SAS) populations. Genetic associations of variants with obesity risk were calculated and BMI raising effect per copy of the minor allele were estimated. The genetic variants with higher MAFs in obese BMI group were; rs2241766 (G = 0.43), rs17817449 (G = 0.54), rs9939609 (A = 0.51), rs1421085 (C = 0.53), rs1558902 (A = 0.63), and rs1137101 (G = 0.64) respectively. All these variants were significantly associated with obesity (OR = 1.03–4.42) and showed a high BMI raising effect (β = 0.239–0.31 Kg/m²) per copy of the risk allele. In contrast, the MAFs of three variants were higher in lean-normal BMI groups; rs3764261 A = 0.38, rs9941349 T = 0.43, and rs7799039 G = 0.40–0.43). These variants showed obesity protective associations (OR = 0.68–0.76), and a BMI lowering effect per copy of the protective allele (β = -0.103–0.155 Kg/m²). The rs3764261 variant also showed significant and positive association with lean body mass (OR = 2.38, CI = 1.30–4.34). Overall, we report six genetic variants of ADIPOQ, FTO and LEPR genes as obesity-risk markers and a CETP gene variant as lean mass/obesity protective marker in studied Pakistani cohort.

Isotretinoin Induced Hyperlipidemia and Impact of Leptin Gene rs 7799039 Polymorphism in Safety of Acne Patients

Background

Acne vulgaris (AV) is a chronic inflammatory disease that affects the pilosebaceous unit. Leptin (LEP) gene polymorphisms is associated with higher risk of multiple disorders. Insulin-like growth factor-1 (IGF-1) exerts comedogenic effect by stimulating the sebaceous glands. Isotretinoin is an effective oral therapy for AV with many side effects including hyperlipidemia and increased serum levels of liver enzymes.

Purpose

To evaluate the impact of LEP gene rs7799039 polymorphism in acne patients' clinical response lipid profile and liver enzymes following 6 months oral isotretinoin therapy in Egyptian AV patients.

Methods

One hundred eligible AV patients received 0.5 mg/kg oral isotretinoin for 6 months. Patients' demographics and clinical data were obtained. Body mass index (BMI), lipid profile, liver enzymes and IGF-1 were measured at baseline and after 6 months of therapy. Genotyping was done for LEP gene rs 7799039.

Results

Six month administration of oral isotretinoin in Egyptian AV patients is associated with significantly elevated aspartate transaminase (AST) in CC and AC genotypes (P<0.001). Significant alanine aminotransferase (ALT) elevation was observed in CC, AC and AA genotypes (P <0.001, 0.004, 0.002, respectively). Total cholesterol (TC), triglycerides (TG) and low density lipoprotein (LDL) were elevated significantly P<0.001) in the three genotypes. IGF-1 was decreased significantly in CC and AC genotypes (P<0.001). CC genotype is associated with highest response (P<0.001).

Conclusion

LEP rs7799039 gene had an impact on the clinical response, lipid profile and liver enzymes in AV patients treated with oral isotretinoin. LEP rs7799039 CC genotype is predicted to be the treatment candidate for 6 month oral isotretinoin.

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.

Leptin Protein Expression and Promoter Methylation in Ovarian Cancer: A Strong Prognostic Value with Theranostic Promises

Ovarian cancer (OC) is the deadliest among all gynecological cancers. Epidemiological studies showed that obesity might influence many cancers including OC. One of the key factors that may link obesity and OC is leptin (LEP), known as an adipokine with pleiotropic effects on body homeostasis. This study aims to investigate the expression pattern of LEP, assess the methylation profiles of LEP and their associations with clinicopathological features including survival outcomes of OC patients. The protein expression of LEP was evaluated in 208 samples using both tissue microarray and immunohistochemistry techniques. The methylation profiles of LEP were measured in 63 formalin-fixed, paraffin-embedded tumor tissues by quantitative polymerase chain reaction using a MethyLight assay. Our results showed a significant association of LEP protein overexpression with several clinicopathological variables, mainly tumor subtype, LVI, age of menarche, tumor size and stage (p < 0.04). Kaplan-Meier analysis (using low expression versus high expression as a discriminator) indicated that LEP protein overexpression is a powerful positive prognosticator of both OC recurrence (DFS) and disease-specific survival (DSS) in our OC cohort (log-rank p = 0.01 and p = 0.002, respectively). This implies that patients with high LEP expression profiles live longer with less recurrence rates. Methylation analysis results demonstrated a clear association between no/low LEP protein expression pattern (38%) and LEP promoter CpG island hypermethylation (43%). Results of this study suggest that LEP is a powerful prognosticator of OC recurrence and DSS. LEP expression in OC seems to be regulated by its promoter hypermethylation through gene partial/total silencing. Further multi-institutional studies using larger cohorts are required to demystify the intricate molecular functions of this leptin-driven effects in OC pathophysiology and to accurately assess its theranostic potential and validate its prognostic/predictive power in OC onset, progression towards more effective and personalized management of OC patients.

Associations of MC4R, LEP, and LEPR Polymorphisms with Obesity-Related Parameters in Childhood and Adulthood

MC4R, LEP, and LEPR genes are involved in the hypothalamic leptin-melanocortin regulation pathway, which is important for energy homeostasis. Our study aimed to evaluate the associations between the MC4R rs17782313, LEP rs7799039, and LEPR rs1137101 polymorphisms with obesity-related parameters in childhood and adulthood. The data were obtained from the Kaunas Cardiovascular Risk Cohort study, which started in 1977 with 1082 participants aged 12-13 years. In 2012-2014, the follow-up survey was carried out. Genotype analysis of all respondents (n = 509) aged 48-49 years was performed for the gene polymorphisms using Real-Time Polymerase Chain Reaction. Anthropometric measurements were performed in childhood and adulthood. In childhood, only skinfold thicknesses were associated with gene variants being the lowest in children with MC4R TT genotype and LEP AG genotype. In adulthood, odds of obesity and metabolic syndrome was higher in MC4R CT/CC genotype than TT genotype carriers (OR 1.8; 95% CI 1.2-2.8 and OR 1.6; 95% CI 1.1-2.4, respectively). In men, physical activity attenuated the effect of the MC4R rs17782313 on obesity. The LEP GG genotype was associated with higher BMI, waist circumference, and visceral fat level only in men. No associations of the LEPR rs1137101 polymorphisms with anthropometric measurements and leptin level were found. In conclusion, the associations of the MC4R and LEP gene polymorphisms with obesity-related parameters strengthened with age.

Leptin gene polymorphism (rs 7799039;G2548A) is associated with changes in lipid profile during a partial meal-replacement hypocaloric diet

BACKGROUND

Some studies have demonstrated a positive association of the rs7799039 genetic variant of the LEP gene with energy intake and metabolic parameters. The present study aimed to analyse the effects of the rs7799039 genetic variant of the LEP gene on metabolic parameters after weight loss secondary to a partial meal-replacement (pMR) hypocaloric diet.

METHODS

We conducted a non-randomised, single-treatment study in 122 obese subjects with body mass index (BMI) > 35 kg m^-2 . The subjects were treated with two intakes of a normocaloric hyperproteic formula during 12 weeks. Anthropometric parameters and biochemical profile were measured at basal time and after 12 weeks. The variant genetic variant (rs7799039) of the LEP gene was assessed by a real-time polymerase chain reaction.

RESULTS

We recruited 122 subjects [26 GG (21.3%), 59 GA (29.5%) and 37 AA (30.3%)]. The mean (SD) age of the all group was 59.4 (6.3) years (range 45-63 years) and the mean (SD) BMI was 39.3 (2.8) kg m^-2 (range 36.2-45.1 kg m^-2 ). After the pMR hypocaloric diet, body weight, BMI, fat mass, waist circumference, fasting insulin, homeostasis model assessment for insulin resistance and blood pressure decreased in both genotypes. All of these improvements were similar in both genotypes. Moreover, after dietary intervention, only subjects without an A allele showed a significant improvement in triglycerides (GG versus GA + AA) [mean (SD) -15.3 (6.4) mg dL^-1 versus -3.7 (4.3) mg dL^-1 : P = 0.02], total cholesterol [-25.0 (5.3) mg dL^-1 versus -8.1 (3.5) mg dL^-1 : P = 0.02] and low-density lipoprotein-cholesterol [-20.7 (4.2) mg dL^-1 versus -5.4 (2.3) mg dL^-1 : P = 0.01].

CONCLUSIONS

Subjects with an A allele of the rs7799039 variant in the LEPR gene showed a significant improvement in low-density lipoprotein-cholesterol and triglycerides levels after weight loss secondary to a pMR hypocaloric diet.

Adiponectin and leptin gene variants and their effects on body weight trajectories in children from birth to 6 years of age: the PREDI Study

Excess body weight confers a high risk to human health. Body weight variation between subjects can be partially explained by genetic differences. The aim of the present study was to investigate the association of genetic variants in the ADIPOQ (rs2241766) and LEP (rs7799039) genes with body weight trajectories in children from birth to 6 years of age. This was a prospective cohort (PREDI Study). Socio-economic, biological and anthropometric data were collected at four time points: at birth in the maternity unit; 1-2, 4-5 and 6 years old at the participants' homes. Genotyping was performed by PCR-restriction fragment length polymorphism. Poisson regression and linear mixed-effect regression models were used to address the association of ADIPOQ and LEP genotypes with BMI. Excessive body weight at pre-pregnancy (β = 0·339, P = 0·01) and excessive gestational weight gain (β = 0·51, P < 0·001) were associated with children's BMI trajectory from birth to 6 years. The ADIPOQ-rs2241766 TG or GG genotype was associated with a higher risk of excess body weight in the first 6 years of life (both sexes relative risk 1·25, 95 % CI 1·01, 1·56; female relative risk 1·67, 95 % CI 1·20, 2·31). BMI increased over the years according to the presence of the TG or GG genotype (β = 0·01, 95 % CI 0·01, 0·02), particularly in females (β = 0·02, 95 % CI 0·01, 0·04). The ADIPOQ-rs2241766 TG and GG genotypes increased the risk of excess body weight in children from birth to 6 years of age and had a positive effect on body weight trajectories in girls. The LEP-rs7799039 genetic variant was not associated with body weight trajectory in children.

Leptin in Tumor Microenvironment

Leptin is a hormone that plays a major role as mediator of long-term regulation of energy balance, suppressing food intake, and stimulating weight loss. More recently, important physiological roles other than controlling appetite and energy expenditure have been suggested for leptin, including neuroendocrine, reparative, reproductive, and immune functions. These emerging peripheral roles let hypothesize that leptin can modulate also cancer progression. Indeed, many studies have demonstrated that elevated chronic serum concentrations of leptin, frequently seen in obese subjects, represent a stimulatory signal for tumor growth. Current knowledge indicates that also different non-tumoral cells resident in tumor microenvironment may respond to leptin creating a favorable soil for cancer cells. In addition, leptin is produced also within the tumor microenvironment creating the possibility for paracrine and autocrine action. In this review, we describe the main mechanisms that regulate peripheral leptin availability and how leptin can shape tumor microenvironment.

Leptin gene polymorphism (rs7799039; G2548A) is associated with changes in serum lipid concentrations during pregnancy: a prospective cohort study

PURPOSE

Little is known about the effects of leptin and leptin receptor polymorphisms on lipid changes during pregnancy. The aims of this study were to evaluate the associations between the single nucleotide polymorphisms (SNPs) of leptin and leptin receptor genes and the lipid concentrations during pregnancy; and to test whether dietary intake is a mediator in these associations.

METHODS

A prospective cohort of 154 pregnant women was followed up in Rio de Janeiro, Brazil during the following gestational periods: 5-13th, 20-26th and 30-36th weeks. HDL-C, total cholesterol (TC) and triglyceride (TG) were measured by the enzymatic colorimetric method, and LDL-C was calculated. DNA was extracted by the phenol-chloroform method, and leptin (G2548A, rs7799039) and leptin receptor SNPs (Q223R; rs1137101 and K109R; rs1137100) were genotyped using real-time PCR. Statistical analyses included linear mixed-effect models.

RESULTS

Women with the AA genotype of G2548A polymorphism reported a higher fat and total energy intake and had a higher increase in TG concentration during pregnancy than women with AG or GG genotype. The association between G2548A SNP and TG concentrations was not attenuated by adjusting for total lipid (g) and energy (kcal) intake. We did not observe significant associations between the Q223R and K109R SNPs and the lipid concentrations.

CONCLUSIONS

Women homozygous for the A allele of the leptin SNP (G2548A) had a higher increase in TG concentrations per gestational week compared with women with the AG or GG genotype. This is an exploratory and hypothesis-generating study, and the results need confirmation in studies with larger sample sizes.'

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.

Identification of genetic basis of obesity and mechanistic link of genes and lipids in Pakistani population

We aimed to identify the genetic causes of common forms of obesity in the Pakistani people and find out the mechanistic link by observing the relationship of genes and serum lipid traits. Four hundred and seventy-five subjects were genotyped for two mutations in (leptin:N103K and proopiomelanocortin:R236G) and ten common variants in different genes. Serum lipids were also measured. The prevalence of mutations was very low (one heterozygous subject each for both mutations), but fairly high minor/risk allele frequency (M/RAF) was observed for all SNPs. MAF of G2548A was 42.8% in obese and 30.1% in controls (P=5.7 × 10⁻⁵), it showed association with weight, body mass index (BMI), waist circumference (WC), high density lipoprotein cholesterol (HDL-c) and leptin, Gln223Arg had MAF 32% in obese and 18.7% in controls (P=5.4 × 10⁻⁶), it showed association with fasting plasma glucose (FPG) and all lipid traits, Ala54Thr had MAF 42.4% in obese and 33.1% (P=0.002), it showed association with none of the tested parameters. rs9939609 MAF was 26.6%, and showed association with none of the tested parameters. rs1802295 (P=0.002); rs7178572 (P=0.007); rs2028299 (P=0.04); rs4812829 (P=0.02) showed significant while rs3923113 and rs16861329 did not show a significant association (P=0.20 and P=0.3, respectively) with obesity. Major genetic contribution to common forms of obesity in Pakistan is from low/modest effect size common variants that act additively to affect body weight quantitatively and mechanism may involve modulating serum lipids.

Association between leptin gene rs7799039 polymorphism and lipid profile changes induced by isotretinoin treatment in acne patients

Introduction

Isotretinoin, a vitamin A-derived medication, is one of the effective treatments for severe acne. However, in a fraction of patients, this treatment causes significant adverse effects. Leptin is a pro-inflammatory cytokine that plays a role in apoptosis of adipose cells and sebaceous lipid metabolism. Thus, genetic polymorphisms in the leptin (LEP) gene may modulate the response to isotretinoin therapy. Here, we explore the contribution of rs7799039 polymorphism of the LEP gene in the adverse effects of the oral isotretinoin therapy among acne patients.

Materials and methods

Clinical parameters were obtained from 200 patients before and after isotretinoin treatment for acne. In addition, circulatory lipid profile and aspartate transaminase (AST) and alanine aminotransferase (ALT) enzymes from acne subjects before and 1 month after oral isotretinoin treatment were also measured.

Results

An association between the rs7799039 polymorphism and the following lipid parameters: high-density lipoprotein (HDL) at baseline and after treatment, HDL % change, low-density lipoprotein % change and total cholesterol % change (P < 0.05). In addition, there was an association between the LEP polymorphism and higher AST and ALT at baseline and after treatment (P < 0.05).

Conclusion

In conclusion, rs7799039 LEP polymorphism might modulate lipid parameters and liver enzymes, but not other major side effects of oral isotretinoin therapy.

Genetic polymorphisms in leptin, adiponectin and their receptors affect risk and aggressiveness of prostate cancer: evidence from a meta-analysis and pooled-review

Leptin and adiponectin signaling was associated with development and progression of various cancers. The present study aimed to clarify the role of genetic variants in leptin, adiponectin and their receptors in prostate cancer. After comprehensive search and manuscript scanning, a total of 49 genetic variants were enrolled and examined for their relations to cancer risk and aggressiveness. In the meta-analysis, LEP rs7799039 (allele contrast: OR 1.133, 95%CI 1.024-1.254), ADIPOQ rs2241766 (allele contrast: OR 1.201, 95%CI 1.015-1.422) and ADIPOR1 rs10920531 (allele contrast: OR 1.184, 95%CI 1.075-1.305) variants were identified to be correlated with increased risk of prostate cancer. On the contrary, LEPR rs1137101 (allele contrast: OR 0.843, 95%CI 0.730-0.973) and ADIPOR1 rs2232853 (allele contrast: OR 0.638, 95%CI 0.535-0.760) variants were associated with decreased risk of prostate cancer. From the pooled-review, we additionally recognized eight variants associated with cancer risk and another eight variants associated with cancer aggressiveness, respectively. These observations indicated important roles of leptin, adiponectin and their receptors in the development and progression of prostate cancer. The identified polymorphisms might assist in developing better risk-assessment tools, as well as generating novel targeted therapies, especially for obese cancer patients with impaired leptin and adiponectin signaling.