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INTRODUCTION: The Q223R polymorphism of the leptin receptor (LEPR) gene is one of the most common polymorphisms and it is believed to be associated with a damaged capacity of LEPR signaling and with high circulating leptin levels. METHODS: An observational, cross-sectional, analytical study was carried out in the Autonomous University of Ciudad Juarez, Mexico, where a sample of young adult participants (ranging from 18 to 30 years of age) was obtained. They were classified based on the results of body mass index: non-obese, and overweight/obese. The polymorphic variant was determined by Polymerase Chain Reaction (PCR) from the DNA sample and serum leptin levels were measured by Enzyme-Linked Immuno Sorbent Assay. RESULTS: A total of 159 participants were included (non-obese, n=103; overweight/obese, n=56). Leptin levels were 15.14±12.3 ng/mL in the non-obese group and 26.13±19.0 ng/mL in the overweight/obese group (p≤0.001). The allelic frequencies of the Q and R alleles of the LEPR gene in the studied subjects were as follows: non-obese, Q=0.56, R=0.44; overweight/obese, Q=0.62, R=0.38. The relative risk for the Q/Q genotype was 1.18 (Cl 0.53-2.34), for Q/R was 1.14 (Cl 0.59-2.18) and for R/R was 0.59 (Cl 0.23-1.50). CONCLUSIONS: This study shows that leptin levels are associated with overweight/obesity in Mexican young adults, but this is not related to the presence of the Q223R polymorphism in the LEPR gene, so the underlying mechanisms for a possible disturbance in leptin signaling in obese Mexican young adults await further studies.
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OBJECTIVE: The aim of the present study was to evaluate the possible association between the Q223R Leptin receptor (LEPR) polymorphism (A>G; rs1137101) and leptin levels in patients with rheumatoid arthritis (RA) from Western Mexico. METHODS: A cross-sectional study was performed with 70 RA patients and 74 controls subject (CS). Disease activity was evaluated using DAS28 score, the Q223R LEPR polymorphism was determined by the Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and serum leptin levels, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and rheumatoid factor (RF) were quantified. RESULTS: RA patients had significant high serum leptin levels compared with CS; leptin levels correlated strongly with body composition measures, but not with inflammatory markers, disease evolution, and activity. The genotype and allele frequencies of the Q223R LEPR polymorphism were not associated with RA. Similarly, leptin levels did not differ between Q223R LEPR genotypes. CONCLUSION: The LEPR Q223R polymorphism was not associated with RA risk in patients from Mexican population, even though high levels of serum leptin were present and these could explain the low weight observed in RA patients when they were compared to control subjects. However, the serum leptin levels did not correlate with inflammatory markers, severity and disease evolution.
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INTRODUCTION: This study evaluated the association between obesity and the K109R, Q223R, and K656N polymorphisms of the leptin receptor (LEPR) locus. Such polymorphisms cause changes in the extracellular extreme of the LEPR gene product and appear to be related to signal transduction toward the cell. SUBJECTS AND METHODS: A total of 128 participants between 6 and 17 years of age from a Mexican Mestizo population were included in the study. Individuals were classified as overweight-obese (n = 76) and normal (n = 52), based on anthropomorphic measurements. The K109R, Q223R, and K656N polymorphisms of the LEPR were determined by the size of restriction fragments obtained from polymorphic fragment amplification (polymerase chain reaction-restriction fragment length polymorphism) obtained from genomic DNA. Allele frequency was compared using the chi-square test. Odds ratio was calculated to determine allele obesity risk factor. RESULTS: Variant allele frequency was 109R = 0.35, 223R = 0.49, and 656N = 0.11 for the K109R, Q223R, and K656N polymorphisms, respectively. No statistically significant association with obesity was found in any of the alleles. The N allele of the K656N polymorphism was associated with nonobesity markers, such as high concentrations of high-density lipoproteins, normal body mass index, less thickness of skinfolds, and body perimeters. None of the alleles studied were shown to be obesity risk factors. CONCLUSIONS: Our results suggest that there is no association between the K109R, Q223R, and K656N polymorphisms of the LEPR gene with obesity, and none of the alleles of the LEPR gene K109R, Q223R, and K656N polymorphisms are an obesity risk factor.