Association with Leptin Gene c.-2548 G>A Polymorphism, Serum Leptin Levels, and Body Mass Index in Turkish Obese Patients

Abstract

Leptin is a protein hormone which plays a critical role in the regulation of both body-weight through reducing food intake and stimulating energy expenditure. Several polymorphisms in leptin gene (LEP), which encodes for leptin, have been described. However, its association with obesity is still controversial. Therefore, in the present study, we aimed to investigate whether LEP c.-2548 G>A polymorphism was associated with serum leptin levels, lipid parameters, and body mass index in Turkish obese patients. Forty-seven obese patients and 48 healthy individuals were included in the study. Blood samples were collected for DNA extraction. LEP c.-2548 G>A polymorphism were detected using polymerase chain reaction-restriction fragment length polymorphism technique. Serum leptin levels and lipid parameters were measured by ELISA and enzyme colorimetric assay techniques, respectively. GA or AA genotypes and A allele carrier frequencies of the c.-2548 G>A polymorphism in the LEP were higher in obese (38.3, 34.0 and 72.3 %) when compared with controls (14.6, 12.5, and 27.1 %; p = 0.011, 0.016, and 0.002, respectively). On the other hand, AA or AG genotypes were also related to increased serum leptin levels (p < 0.001) and body mass index (p < 0.0001). All these consequences showed that LEP -2548 AA or AG genotypes are important predictors for increased levels of leptin and BMI in Turkish obese patients and it may be a useful marker for obesity risk in our population.

Association of Leptin Gene -2548 G/A Polymorphism with Obesity: A Meta-Analysis

“…The detailed characteristics of these studies are shown in table 1. In 9 articles published between 2006 and 2012, 1,372 obese subjects and 1,616 controls were involved from a wide range of regions including Europe [19,21,22,27], South America [18,23,25] and North Africa [24,26]. Of the selected studies, 6 related to a Caucasian population and 3 to a South American population (mixed race).…”

“…Of the selected studies, 6 related to a Caucasian population and 3 to a South American population (mixed race). There were 2 studies in which the genotypes in the control group were not in HWE [26,27]. Two studies were performed by the same investigator [23,25], and it is not clear whether different individuals were genotyped or whether some individuals were counted twice (the author rejected our inquiry e-mail).…”

“…However, the direct association between the -2548 G/A polymorphism and obesity remains vague. While most current published studies have failed to identify a significant association in various populations [18,19,20,21,22,23,24], 3 studies found that the current variant was significantly associated with the risk of obesity (defined as BMI ≥30) in subjects of mixed race (South America) [25] and Caucasians (Turkish and Tunisian) [26,27]. Additionally, while most pieces of evidence have indicated that the frequency of the GG genotype or G allele is higher in the obesity or overweight group compared to that of the control in various populations [16,25,28], Nieters et al [29] found a sharply contrasting outcome, i.e.…”

Associations between LEP G2548A polymorphisms and lipids metabolism

“…The LEP gene, human homologue of the rat obese gene cloned and sequenced by Zhang et al (1994), is located on autosome 7 (7q31.3) and the length of its mRNA in adipose tissue is 4.5 kb (Mohammadzadeh et al, 2015). There are several studies indicating the significant association between polymorphisms in LEP gene and obesity (Duarte et al, 2006), hypertension (Mendoza-Núñez et al, 2006), coronary artery diseases and metabolic syndrome (Kim et al, 2008), insulin resistance (Chiu et al, 2004), type 2 diabetes mellitus (Han et al, 2008) and cancer (Mohammadzadeh et al, 2015).…”

“…There are several studies indicating the significant association between polymorphisms in LEP gene and obesity (Duarte et al, 2006), hypertension (Mendoza-Núñez et al, 2006), coronary artery diseases and metabolic syndrome (Kim et al, 2008), insulin resistance (Chiu et al, 2004), type 2 diabetes mellitus (Han et al, 2008) and cancer (Mohammadzadeh et al, 2015). The G2548A polymorphism (rs7799039: guanine > adenine) are studied widely because it has been associated with leptin production and secretion (Suriyaprom et al, 2014).…”