The Arg/Arg genotype of leptin receptor gene Gln223Arg polymorphism may be an independent risk factor for nonalcoholic fatty liver disease

BACKGROUND

Given that obesity and insulin resistance play key roles in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and the connection between leptin and these metabolic diseases, the association between NAFLD and a leptin receptor gene (LEPR) polymorphism was examined.

METHODS

In this genetic case-control association study, 144 biopsy-proven NAFLD patients and 144 controls were genotyped for the LEPR gene Gln223Arg (rs1137101) polymorphism using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The distributions of genotypes and alleles of Gln223Arg variant were in accordance with the Hardy-Weinberg equilibrium in the study groups (P > .05). Multivariate logistic regression analysis showed that the LEPR Gln223Arg Arg/Arg genotype was an independent risk factor for NAFLD; the Arg/Arg genotype, compared with the Gln/Gln genotype, was associated with a 2.09-fold increased risk for NAFLD (P = .036, odds ratio = 2.09 [95% CI = 1.31-5.95]).

CONCLUSIONS

We found that the LEPR Gln223Arg Arg/Arg genotype was independently associated with a more than 2-fold rise in biopsy-proven NAFLD risk. Our findings, however, need to be corroborated by further studies.

Association of the Human Leptin Receptor Gene (rs1137101; Gln223Arg) Polymorphism and Circulating Leptin in Patients with Metabolic Syndrome in the Indian Population

Phenotypic expression of metabolic syndrome is precipitated by environmental variables along with the individual genetic susceptibility to the obesogenic environment and growing body of evidence suggest a paramount role of adipocytokines. Therefore, identifying the genetic influence on circulation leptin levels and clarifying genotype-phenotype correlation of rs1137101 {Leptin receptor gene (LEPR) Gln223Arg (Q223R; A668G)} in metabolic syndrome were the primary objective of this study. A total of 447 adult participants, including 214 metabolic syndrome patients and 233 healthy controls, were genotyped using polymerase chain reaction-restriction fragment length polymorphism method to unravel the effects of genetic risk loci {Leptin receptor gene; Gln223Arg (Q223R; A668G); rs1137101} on the occurrence of metabolic syndrome in consort with circulation leptin levels. Suitable descriptive statistics was used for different variables. The genotype frequencies were found to be in Hardy-Weinberg equilibrium for both cases (p > 0.2722) as well as in controls (p > 0.2331). However, genotype (x2: 11.26, 2 d.f. p = 0.0036) and allele distribution (x2: 10.51, 2 d.f. p: 0.0012) of the LEPR Gln223Arg (Q223R; A668G) differed significantly between cases and controls. Gln/Arg genotype (OR = 1.6099; 95% CI = 1.0847-2.3893; p value = 0.0181), Arg/Arg genotype (OR = 2.8121; 95% CI = 1.4103-5.6074; p value = 0.0033) and R allele (OR = 1.5875; 95% CI = 1.1996-2.1008; p value = 0.0012) were significantly associated with increased risk of metabolic syndrome in univariate analysis. Further a multivariate logistic regression adjusted for potential confounders showed that Arg/Arg genotype (OR = 1.9; 95% CI = 1.271-2.639; p-value < 0.05) and Gln/Arg (OR: 1.3; 95% CI = 0.873-2.034; p value < 0.05) have a significant risk for the occurrence of the metabolic syndrome. A progressive increase in the serum leptin levels from major homozygous alleles to minor homozygous alleles were observed indicating that rs1137101 modify the serum leptin concentrations in patients with metabolic syndrome. These findings provide enough evidence of a significant association of LEPR Gln223Arg (Q223R; A668G) polymorphism in the LepR gene in Indian patients with increased risk of metabolic syndrome for R allele and Arg/Arg homozygote. Thus, rs1137101 might be a pleiotropic locus for metabolic syndrome and its components in studied population.

LEPR gene Gln223Arg polymorphism and type 2 diabetes mellitus: a meta-analysis of 3,367 subjects

Background

The Leptin receptor (LEPR) Gln223Arg gene polymorphism has been associated with an increased susceptibility to Type 2 diabetes mellitus (T2DM). Results from various studies, however, are inconsistent.

Objective and methods

To better elucidate the association of LEPR Gln223Arg gene polymorphism with T2DM in the Chinese population, a meta-analysis of 3,367 subjects from seven independent studies was performed. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (95% CI) were evaluated by the fixed-effects model.

Results

A significant relationship between LEPR Gln223Arg gene polymorphism and T2DM in the Chinese population was found under allele (OR: 1.432, 95% CI: 1.211-1.694, P=2.67×10^-5), dominant (OR: 1.466, 95% CI: 1.215-1.769, P=6.33×10^-5), recessive (OR: 0.539, 95% CI: 0.303-0.960, P=0.036), heterozygous (OR: 0.700, 95% CI: 0.577-0.849, P=3.06×10^-4), and homozygous (OR: 0.472, 95% CI: 0.265-0.839, P=0.011) genetic models.

Conclusions

LEPR Gln223Arg gene polymorphism was associated with an increased risk of T2DM in the Chinese population. Therefore, Chinese carriers of the G allele of LEPR Gln223Arg gene polymorphism may be more susceptible to T2DM than the general population.

Association of rs1137101 polymorphism in LEPR and susceptibility to knee osteoarthritis in a Northwest Chinese Han population

Background

Osteoarthritis (OA) is a complex arthritic condition in which the genetic factor plays a crucial role. A single nucleotide polymorphism (SNP), rs1137101 (Gln223Arg) of leptin receptor (LEPR) gene has been demonstrated to be associated with susceptibility to knee OA. However, this association in Chinese Han population has never been examined. The present study aimed to investigate whether Gln223Arg was related to knee OA susceptibility in a Northwest Chinese population with Han ethnicity.

Methods

Gln223Arg polymorphisms were genotyped in 587 patients with confirmed knee OA and in 628 age- and sex-matched healthy controls using polymerase chain reaction-restriction fragment length polymorphism analysis. Besides, LEPR genotypes were verified by direct DNA sequencing analysis on PCR products.

Results

The genotype and allele frequencies in LEPR SNP rs1137101 were significantly different between cases and control groups (chi-square = 6.52, P = 0.038 for genotype and chi-square = 5.06, P = 0.024 for allele frequencies; respectively). Rs1137101 was correlated with knee OA in the dominant genetic model (GG + GA versus AA) (P = 0.016) and a higher G allele frequency existed (P = 0.024) among all patients with knee OA and controls. On stratification analysis, the genotype GG and G allele were associated with susceptibility to knee OA in females, both young (≤65 years) and old groups (>65 years) and patients with mild knee OA.

Conclusions

Our finding suggested that the genetic variant of LEPR gene rs1137101 is independently related to knee OA susceptibility in Northwest Chinese population with Han ethnicity and may serve as a potential biomarker to determine risk of knee OA.

Association of LEPR Gln223Arg polymorphism with T2DM: A meta-analysis

A meta-analysis was conducted to evaluate the association of LEPR Gln223Arg polymorphism with type 2diabetes (T2DM). Sixteen individual studies with 7827 subjects were included into the meta-analysis. Current studies suggest that LEPR Gln223Arg polymorphism may not affect the susceptibility with type 2diabetes (T2DM).

Effect of leptin receptor mutation on the development of chronic bronchitis

To investigate the effect of serum leptin level and leptin receptor (Lepr) genetic mutation on chronic bronchitis, we measured the serum leptin levels of 236 patients with chronic bronchitis and 107 healthy controls by ELISA, the genotype distribution of Lepr gene containing Gln223Arg polymorphic sites by the polymerase chain reaction-restriction fragment length polymorphism (RFLP) method, the levels of inflammatory markers in serum, and the concentration of neutrophils. We found that the GG genotype distribution and G gene frequency of Lepr gene Gln223Arg site of the patient group were higher than that in the control group. The serum high-sensitivity C-reactive protein and neutrophil granulocyte levels of the patient group were higher than those of the control group. But the leptin concentrations of those with GG genotype were lower than those with AA+AG genotype (P < .05). The mutation of Lepr gene Gln223Arg site may not directly influence the leptin level but could possibly advance the disease through inhibiting the biological effect of leptin.