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.

Association of the LEP gene with immune infiltration as a diagnostic biomarker in preeclampsia

Objective: Preeclampsia (PE) is a serious condition in pregnant women and hence an important topic in obstetrics. The current research aimed to recognize the potential and significant immune-related diagnostic biomarkers for PE. Methods: From the Gene Expression Omnibus (GEO) data sets, three public gene expression profiles (GSE24129, GSE54618, and GSE60438) from the placental samples of PE and normotensive pregnancy were downloaded. Differentially expressed genes (DEGs) were selected and determined among 73 PE and 85 normotensive control pregnancy samples. The DEGs were used for Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Disease Ontology (DO) enrichment analysis, and Gene Set Enrichment Analysis (GSEA). The candidate biomarkers were identified by the least absolute shrinkage and selection operator (LASSO) and support vector machine recursive feature elimination (SVM-RFE) analysis. The receiver operating characteristic curve (ROC) was applied to evaluate diagnostic ability. For further confirmation, the expression levels and diagnostic value of biomarkers in PE were verified in the GSE75010 data set (80 PE and 77 controls) and validated by qRT-RCR, Western blot, and immunohistochemistry (IHC). The CIBERSORT algorithm was used to calculate the compositional patterns of 22 types of immune cells in PE. Results: In total, 15 DEGs were recognized. The GO and KEGG analyses revealed that the DEGs were enriched in the steroid metabolic process, receptor ligand activity, GnRH secretion, and neuroactive ligand-receptor interaction. The recognized DEGs were primarily implicated in cell-type benign neoplasm, kidney failure, infertility, and PE. Gene sets related to hormone activity, glycosylation, multicellular organism process, and response to BMP were activated in PE. The LEP gene was distinguished as a diagnostic biomarker of PE (AUC = 0.712) and further certified in the GSE75010 data set (AUC = 0.850). The high expression of LEP was associated with PE in clinical samples. In addition, the analysis of the immune microenvironment showed that gamma delta T cells, memory B cells, M0 macrophages, and regulatory T cells were positively correlated with LEP expression (P < 0.05). Conclusion: LEP expression can be considered to be a diagnostic biomarker of PE and can offer a novel perspective for future studies regarding the occurrence and molecular mechanisms of PE.

Early-onset severe obesity due to homozygous p.R105W (c313C> T) mutation in leptin gene in Turkish siblings: Two cases reports

Congenital leptin deficiency (CLD) is a rare cause of monogenic form obesity due to homozygous or compound heterozygous mutations in the LEP gene. To date, nine pathogenic mutations have been reported. In this study, we present are; an 18-year-old morbidly obese girl and a 14-year-old obese brother, both with homozygous mutation in the LEP gene [p.R105W (c313C> T)] and their data after three years of recombinant leptin treatment. To date, few cases of CLD have been reported in the literature. The cases reported here were siblings who were not diagnosed despite presentation at the clinic due to obesity in childhood, and diagnosis was delayed until adolescence. Clinicians need to consider CLD, a monogenic form of obesity in children with early severe obesity onset, especially if they are the child of a consanguineous marriage.

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.

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.

Congenital Leptin Deficiency and Leptin Gene Missense Mutation Found in Two Colombian Sisters with Severe Obesity

Background: Congenital leptin deficiency is a recessive genetic disorder associated with severe early-onset obesity. It is caused by mutations in the leptin (LEP) gene, which encodes the protein product leptin. These mutations may cause nonsense-mediated mRNA decay, defective secretion or the phenomenon of biologically inactive leptin, but typically lead to an absence of circulating leptin, resulting in a rare type of monogenic extreme obesity with intense hyperphagia, and serious metabolic abnormalities. Methods: We present two severely obese sisters from Colombia, members of the same lineal consanguinity. Their serum leptin was measured by MicroELISA. DNA sequencing was performed on MiSeq equipment (Illumina) of a next-generation sequencing (NGS) panel involving genes related to severe obesity, including LEP. Results: Direct sequencing of the coding region of LEP gene in the sisters revealed a novel homozygous missense mutation in exon 3 [NM_002303.3], C350G>T [p.C117F]. Detailed information and clinical measurements of these sisters were also collected. Their serum leptin levels were undetectable despite their markedly elevated fat mass. Conclusions: The mutation of LEP, absence of detectable leptin, and the severe obesity found in these sisters provide the first evidence of monogenic leptin deficiency reported in the continents of North and South America.

Association between Leptin gene polymorphisms and plasma leptin level in three consanguineous families with obesity

INTRODUCTION

Leptin (LEP) gene is one of the most promising candidate genes for obesity. Previous studies have tested the association of polymorphisms in LEP gene with obesity and obesity-related metabolic biomarkers (anthropometric variables, glucose, insulin level, leptin level and lipid profile). However, the results of these studies were still controversial. To determine whether LEP gene is associated with obesity in Tunisian population, we performed a family-based association study between LEP polymorphisms and obesity and obesity-related metabolic biomarkers.

METHODS

Seven single nucleotide polymorphisms (SNPs) in 5' region of LEP gene were genotyped in three consanguineous families including 33 individuals. The previously reported LEP SNPs (H1328084, H1328082, rs10487506, H1328081, H1328080, G-2548A and A19G) were evaluated by PCR-RFLP and direct sequencing methods. Single SNP association and haplotype association analyses were performed using the family-based association test (FBAT). To determine allele frequencies of these SNPs in general population, 52 unrelated individuals from the general Tunisian population were also analyzed.

RESULTS

Two SNPs showed significant associations with plasma leptin level (H1328084: A>G, Z=2.058, p=0.039; A19G: G>A, Z=2.058, p=0.039). When haplotypes were constructed with these two-markers, the risk AA haplotype (frequency 57.1%) was positively associated with plasma leptin level (Z=2.058, p=0.039). Moreover, SNPs H1328084 and A19G are predicted to modify transcription-factor binding sites.

CONCLUSIONS

Our study provided that two functional variants in 5' regulatory region of LEP gene are associated with plasma leptin level as a quantitative trait. It suggested that H1328084 and A19G have an important role in regulating plasma leptin level.