Polymorphism in LEP and LEPR May Modify Leptin Levels and Represent Risk Factors for Thyroid Cancer

Leptin and Leptin Receptor Polymorphisms in Infants and Their Parents: Correlation with Preterm Birth

It has been proven that single-nucleotide polymorphisms (SNPs) in LEP and LEPR genes could predispose individuals to an increased risk of pregnancy adverse outcomes (PAOs) such as recurrent pregnancy loss (RPL) and pre-eclampsia. Preterm birth (PTB) is the leading cause of infant mortality. We decided to investigate the correlation between PTB and LEP and LEPR SNPs. The study cohort included families who underwent spontaneous PTB and control samples of families who had at-term-born (≥37 weeks of gestational age) children. Swabs were performed by rubbing the sticky end for about 30 s on the gum and on the inside of the cheek, allowing us to collect the flaking cells of the oral mucosa. Genotyping of the three SNPs-LEPRA668G, LEPG2548A and A19G-was carried out via an ARMS-MAMA real-time PCR procedure, as previously described. Regarding LEPG2548A, we found that the most expressed genotype in infants both in the preterm and the at-term group was AG; however, we did not discover any statistically significant difference (p = 0.97). Considering LEPA19G, none among the infants and parents were found to carry the AA genotype. No statistically significant differences were found between children, mothers and fathers belonging to preterm and at-term groups. We did not find a statistically significant association in newborns and their mother, but our results show a statistical correlation with the LEPRA668G genotype GG of the father. This fact can contribute to defining genetic risk factors for PTB. Further studies are certainly needed to better clarify the role of genetics in influencing preterm delivery.

Serum Leptin Receptor and the rs1137101 Variant of the LEPR Gene Are Associated with Bladder Cancer

Globally, bladder cancer (BC) is one of the ten most common tumors. Obesity is a worldwide problem associated with an increased BC risk. Considering that levels of leptin and/or its receptor are often deregulated in obese individuals, we hypothesized that they could contribute to BC. To test this hypothesis, we utilized a case-control study in which 116 patients with a confirmed diagnosis of BC and 116 controls were recruited. The serum levels of leptin and leptin receptor were measured. Patients and controls were also genotyped for SNPs in the LEP (rs7799039, rs791620, and rs2167270) and LEPR genes (rs1137100, rs1137101, and rs1805094). The univariate analysis indicated that BC patients had significantly higher levels of leptin and lower levels of leptin receptor (p < 0.05). Moreover, rs7799039 of LEP and rs1137101 of LEPR were associated with BC (p < 0.05). In the multivariate analysis, leptin receptor levels were protective (OR: 0.98, 95% CI = 0.97-0.99, p = 0.002) while the GG genotype of rs1137101 of LEPR increased BC risk (OR: 3.42, 95% CI = 1.27-9.20, p = 0.02). These findings highlight that lifestyle changes could be useful in preventing BC and that disturbances in energy metabolism could play a role in the pathobiology of BC.

Leptin and the rs2167270 Polymorphism Are Associated with Glycemic Control in Type Two Diabetes Mellitus Patients on Metformin Therapy

Background and Objectives: Type two diabetes mellitus (T2DM) is a chronic disease with debilitating complications and high mortality. Evidence indicates that good glycemic control delays disease progression and is hence a target of disease management protocols. Nonetheless, some patients cannot maintain glycemic control. This study aimed to investigate the association between serum leptin levels and several SNPs of the LEP gene with the lack of glycemic control in T2DM patients on metformin therapy. Materials and Methods: In a hospital-based case-control study, 170 patients with poor glycemic control and 170 patients with good glycemic control were recruited. Serum leptin was measured. Patients were genotyped for three SNPs in the LEP gene (rs7799039, rs2167270, and rs791620). Results: Serum leptin was significantly lower in T2DM patients with poor glycemic control (p < 0.05). In multivariate analysis, serum leptin levels significantly lowered the risk of having poor glycemic control (OR = 0.985; CI: 0.976-0.994; p = 0.002); moreover, the GA genotype of rs2167270 was protective against poor glycemic control compared to the GG genotype (OR = 0.417; CI: 0.245-0.712; p = 0.001). Conclusions: Higher serum leptin and the GA genotype of the rs2167270 SNP of the LEP gene were associated with good glycemic control in T2DM patients on metformin therapy. Further studies with a larger sample size from multiple institutions are required to validate the findings.

A GWAS top hit for circulating leptin is associated with weight gain but not with leptin protein levels in lithium-augmented patients with major depression

Lithium-treated patients often suffer from weight gain as a common adverse event. In an earlier investigation, we found an impact of two single-nucleotide polymorphisms (rs10487506 and rs2278815) at the leptin gene on weight gain but not on leptin protein levels in serum under lithium augmentation. A recent genome-wide association study identified a polymorphism at the leptin gene locus (rs10487505) associated with circulating leptin protein levels. To characterize potential effects of this variant in acute major depressive disorder, we investigated body mass indices from 180 lithium-augmented patients and serum concentrations of leptin protein from 89 patients using linear mixed model analyses and rs6979832, a proxy SNP of rs10487505. Body mass index was measured before and after 4 weeks of lithium augmentation, in a subsample also after 4 and 7 months. Leptin serum levels were measured before and during lithium augmentation. G-allele homozygotes of rs6979832 had a significantly lower body mass index increase during observation compared to A-allele hetero- and homozygotes. However, we found no influence on leptin serum levels. Joint analyses of rs6979832 with the previously investigated polymorphisms rs10487506 and rs2278815, and expressed quantitative trait data, suggest a complex interplay between SNP alleles at the leptin locus. These results strongly support our earlier findings that common genetic variation at the leptin gene locus may be involved in lithium augmentation-associated weight gain in major depressive disorder.

Association of leptin G2548A and leptin receptor Q223R polymorphisms and their serum levels with infertility and recurrent pregnancy loss in Iranian women with polycystic ovary syndrome

Background

Adipokine leptin plays a crucial role in metabolic and reproductive functions. Leptin receptor has a soluble form that binds to leptin, thus modulating its level in the circulation. It has been indicated that the levels of leptin and leptin receptor and also LEP rs7799039 and LEPR rs1137101 polymorphisms are associated with metabolic disorders. In the present study, we assessed the levels of leptin and soluble leptin receptor (sOB-R), and also the frequency of rs7799039 and rs1137101 polymorphisms in healthy fertile women and patients with polycystic ovary syndrome (PCOS), inclusive of PCOS-infertile and PCOS-recurrent pregnancy loss (RPL) subjects.

Methods

A total of 324 PCOS patients- including 199 infertile cases and 125 patients with a history of RPL- and 144 healthy controls were enrolled in this study. Biochemical parameters and plasma leptin and sOB-R levels were measured by ELISA and the genotypes of rs7799039 and rs1137101 polymorphisms were determined using PCR- RFLP.

Results

Plasma leptin and sOB-R levels were significantly higher and lower in PCOS, PCOS-infertile and PCOS RPL groups, respectively. The GG genotype frequencies of rs7799039 and rs1137101 polymorphisms were significantly different between PCOS-infertile women and non-PCOS subjects (P = 0.043, OR = 0.47, 95% CI = 0.22–0.97, and P = 0.01, OR = 0.31, 95% CI = 0.12–0.75, respectively). Increased LEP levels were associated with the risk of PCOS and RPL in women with PCOS (P = 0.039, OR = 1.203, 95%CI = [1.009–1.435] and P = 0.012, OR = 1.267, 95% CI = [1.054–1.522], respectively).

Conclusion

Polymorphisms rs7799039 and rs1137101 and circulating leptin and sOB-R levels were associated with infertility in Iranian women with PCOS. Further studies are needed to reveal the role of leptin in PCOS pathogenesis.

Polymorphisms of IL-4 and IL-4R are associated to some demographic characteristics of differentiated thyroid cancer patients but are not determinants of risk in the Brazilian population

BACKGROUND

IL-4 is known to present abnormal expression in thyroid tumors and SNPs in the IL-4 and its receptor IL-4R genes are associated to risk and mortality of various types of cancer.

METHODS

In order to evaluate their role in differentiated thyroid cancer (DTC), we investigated genetic frequencies of two IL-4 promoter SNPs (rs2070874 C>T, rs2243250 C>T) and four non-synonymous SNPs of the IL-4R gene (rs1805010 A>G, rs1805012 C>T, rs1805013 C>T, rs1801275 A>G) in 300 DTC patients matched to 300 controls. All patients were managed according to current guidelines and followed-up for a period of 12-252 months (69.20 ± 52.70 months).

RESULTS

Although none of the six investigated SNPs showed association with risk of DTC, rs1805010 was associated with age of diagnosis and the SNPs rs1805012 and rs1801275 were associated to gender. Further, in-silico analysis showed that all these three SNPs were able to cause decreased stability of the protein. We were not able to demonstrate any other association to clinical features of aggressiveness or to patients' prognosis.

CONCLUSIONS

These findings indicate that although genetic variants in IL-4 and IL-4R do not influence the risk or outcome of DTC patients, their influence on the behavior of thyroid tumors deserves further investigation.

The Inter-Relation between Leptin Receptor (Q223R) Gene Polymorphism and the Risk of Egyptian Patients with HCC

Background:

The relationship of leptin (LEP) and polymorphism of leptin receptor (LEPR) were studied in patients with hepatocellular carcinoma (HCC) and compared with those with liver cirrhosis to find out the extent of the risk of LEPR on patients with HCC.

Methods:

Serum LEP level and LEPR Q223R gene polymorphism were determined in 300 patients with liver disease categorized equally into five groups’ healthy volunteers, patients with hepatitis C (HCV), patients with non-alcoholic steatohepatitis (NASH), liver cirrhosis and HCC. LEPR gene was amplified by polymerase chain reaction (PCR) then digested by the MSP1 restriction enzyme.

Results:

The isolated 212 bp of LEPR was sequenced. The serum LEP level was reduced in patients with cirrhotic and HCC. Serum LEP level had negatively correlated with both tumor grade and size in HCC patients. The data obtained from restriction fragment length polymorphismPCR and sequencing revealed the existence of a novel synonymous Q223R single nucleotide polymorphism (SNP) in exon 223 of LEPR gene (1137101). LEPR Gln223Arg, GG and GA genotypes were found in all studied groups. LEPR Gln223Arg, AA genotype was found in NASH, HCC, and control. LEPR Gln223Arg GA genotype is associated with some patients with HCC.

Conclusion:

GA genotype of LEPR Gln223Arg may be regarded as a probable genetic risk factor for Egyptian patients with HCC.

Investigation of Leptin and its receptor (LEPR) for single nucleotide polymorphisms in colorectal cancer: a case-control study involving 2,306 subjects

Single nucleotide polymorphisms (SNPs) in the genes coding for leptin (LEP) and its receptor (LEPR) might regulate energy balance and be implicated in the development of colorectal cancer (CRC). In the present investigation, 1,003 CRC cases and 1,303 matched controls was compared. Five functional SNPs in LEP and LEPR genes were chosen to evaluate the correlation of these chosen SNPs with CRC susceptibility. We used the SNPscan^TM genotyping assay to genotype LEP and LEPR SNPs. A significantly decreased risk of CRC was found to be associated with the LEPR rs6588147 polymorphism (GA vs. GG: crude P=0.007 and GA/AA vs. GG: crude P=0.018). With adjustments for risk factors (e.g. age, gender, drinking, BMI and smoking), these associations were not changed. In subgroup analyses, the association of LEP rs2167270 with a decreased risk of CRC was found in the ≥61 years old subgroup. For LEPR rs1137100, the association of this SNP with an increased susceptibility of CRC was found in the BMI <24 kg/m² subgroup. In subgroup analyses for LEPR rs6588147, we identified that this locus also decreased the susceptibility of CRC in the male subgroup, <61 years old subgroup, never smoking subgroup and never drinking subgroup. For LEPR rs1137101, the relationship of this polymorphism with a decreased susceptibility to CRC was found in the never drinking subgroup. In summary, the present study highlights that LEPR rs6588147, rs1137101 and LEP rs2167270 may decrease the risk of CRC. However, LEPR rs1137100 is associated with susceptibility to CRC. Further case-control studies with larger sample sizes should be conducted to validate our findings.

Association of LEPR gene polymorphisms with the risk of hepatitis B virus-related liver disease in Guangxi Chinese: A case-control study

BACKGROUND AND OBJECTIVE

Leptin receptor (LEPR) signaling inhibits apoptosis, promotes angiogenesis and proliferation, and plays a critical role in carcinogenesis. Variants of the LEPR gene may be key factors in the growth of human malignant tumors. However, the relationship between LEPR polymorphisms and hepatocellular carcinoma (HCC) has not been thoroughly investigated. Therefore, we further investigated the association between LEPR polymorphisms and the risk of chronic hepatitis B (CHB), hepatitis B virus (HBV)-related liver cirrhosis (LC), and HCC in a southern Guangxi Chinese population.

METHOD

Two LEPR polymorphisms (rs1137100 and rs1137101) were genotyped in 138 CHB patients, 136 patients with LC, 149 HCC patients, and 146 healthy controls using the SNaPshot method.

RESULTS

We did not observe any significant difference in the LEPR rs1137100 and rs1137101 polymorphisms between the groups of healthy controls and patients (all p > 0.05), regardless of genotypes, alleles, or haplotypes.

CONCLUSIONS

Our data suggest that the genetic variants of the LEPR gene are not associated with the risk of HBV-related liver diseases (CHB, LC, and HCC) in the Guangxi population. Further studies are necessary to validate these results.

Update on the genetic and epigenetic etiology of gestational diabetes mellitus: a review

Background

Many studies have been conducted on the genetic and epigenetic etiology of gestational diabetes mellitus (GDM) in the last two decades because of the disease’s increasing prevalence and role in global diabetes mellitus (DM) explosion. An update on the genetic and epigenetic etiology of GDM then becomes imperative to better understand and stem the rising incidence of the disease. This review, therefore, articulated GDM candidate genes and their pathophysiology for the awareness of stakeholders.

Main body (genetic and epigenetic etiology, GDM)

The search discovered 83 GDM candidate genes, of which TCF7L2, MTNR1B, CDKAL1, IRS1, and KCNQ1 are the most prevalent. Certain polymorphisms of these genes can modulate beta-cell dysfunction, adiposity, obesity, and insulin resistance through several mechanisms. Environmental triggers such as diets, pollutants, and microbes may also cause epigenetic changes in these genes, resulting in a loss of insulin-boosting and glucose metabolism functions. Early detection and adequate management may resolve the condition after delivery; otherwise, it will progress to maternal type 2 diabetes mellitus (T2DM) and fetal configuration to future obesity and DM. This shows that GDM is a strong risk factor for T2DM and, in rare cases, type 1 diabetes mellitus (T1DM) and maturity-onset diabetes of the young (MODY). This further shows that GDM significantly contributes to the rising incidence and burden of DM worldwide and its prevention may reverse the trend.

Conclusion

Mutations and epigenetic changes in certain genes are strong risk factors for GDM. For affected individuals with such etiologies, medical practitioners should formulate drugs and treatment procedures that target these genes and their pathophysiology.

Methylation of the LEP gene promoter in blood at 12 months and BMI at 4 years of age-a population-based cohort study

Increasing evidence links epigenetic variation to anthropometric and metabolic measures. Leptin signalling regulates appetite and energy expenditure, and in pregnancy is important for nutrient supply to the foetus. Maternal metabolic health and foetal growth are linked to infant blood leptin gene (LEP) methylation, which has been cross-sectionally associated with adolescent obesity. Despite this, few studies have explored the relationship between infant LEP methylation and childhood anthropometry, or the impact of genetic variation on these relationships. Using a prospective birth cohort, we investigated whether blood LEP promoter methylation at birth and 12 months predicts weight and adiposity at 4-years. Locus-specific methylation data was analysed by partial correlation tests and multivariable linear regression. There was weak evidence of an association of birth LEP methylation with anthropometry measures at 4 years. Methylation at a specific site (cg19594666) at 12 months was inversely associated with 4-year weight (r = -0.11, p = 0.02) and body-mass index (BMI) (r = -0.13, p = 0.007), which persisted following adjustment for weight at birth and at 12 months. Neither association was influenced by genotype. We report the first evidence of an association between LEP methylation in infancy and childhood weight. Replication in additional cohorts is required to determine if this relationship persists.

Leptin gene polymorphisms are associated with weight gain during lithium augmentation in patients with major depression

Weight gain is a common adverse effect of lithium augmentation. Previous studies indicate an impact of genetic variants at the leptin gene on weight gain as a consequence of psychopharmacological treatment. The primary aim of our study was to identify variants at the leptin locus that might predict lithium-induced weight gain. The secondary aim was to investigate if these variants modulate leptin levels. In 180 patients with acute major depressive disorder, body mass index was measured before and after 4 weeks of lithium augmentation, in a subsample also after 4 and/or 7 months. In a subsample of 89 patients, leptin serum concentrations were measured before and during lithium augmentation. We used linear mixed model analyzes to investigate the effects of 2 polymorphisms at the leptin locus (rs4731426 and rs7799039, employing the respective proxy SNPs rs2278815 and rs10487506) on changes in body mass index and leptin levels. For both polymorphisms, which are in high linkage disequilibrium, body mass index was significantly lower in homozygous A-allele carriers than in carriers of other genotypes at baseline. Over the follow-up period, body mass index increased less in homozygous A-allele carriers of rs4731426 than in carriers of other genotypes. This was not the case for rs7799039. Neither polymorphism modulated leptin protein expression. Our study strongly supports the hypothesis that genetic variability at the leptin locus is involved in lithium augmentation-associated weight gain in major depressive disorder. Furthermore, Genotype-Tissue Expression data provide strong evidence that rs4731426 influences the expression of leptin messenger ribonucleic acid in fibroblasts.

Genetic variation, intrauterine growth, and adverse pregnancy conditions predict leptin gene DNA methylation in blood at birth and 12 months of age

BACKGROUND

Leptin regulates satiety and energy homoeostasis, and plays a key role in placentation in pregnancy. Previous studies have demonstrated regulation of leptin gene (LEP) expression and/or methylation in placenta and cord blood in association with early life exposures, but most have been small and have not considered the influence of genetic variation. Here, we investigated the relationship between maternal factors in pregnancy, infant anthropometry and LEP genetic variation with LEP promoter methylation at birth and 12 months of age.

METHODS

LEP methylation was measured in cord (n = 877) and 12-month (n = 734) blood in the Barwon Infant Study, a population-based pre-birth cohort. Infant adiposity at birth and 12-months was measured as triceps and subscapular skinfold thickness. Cross-sectional regression tested associations of methylation with pregnancy and anthropometry measures, while longitudinal regression tested if birth anthropometry predicted 12-month LEP methylation levels.

RESULTS

Male infants had lower LEP methylation in cord blood (-2.07% average methylation, 95% CI (-2.92, -1.22), p < 0.001). Genetic variation strongly influenced DNA methylation at a single CpG site, which was also negatively associated with birth weight (r = -0.10, p = 0.003). Pre-eclampsia was associated with lower cord blood methylation at another CpG site (-6.06%, 95% CI (-10.70, -1.42), p = 0.01). Gestational diabetes was more modestly associated with methylation at two other CpG units. Adiposity at birth was associated with 12-month LEP methylation, modified by rs41457646 genotype. There was no association of LEP methylation with 12-month anthropometric measures.

CONCLUSIONS

Infant sex, weight, genetic variation, and exposure to pre-eclampsia and gestational diabetes, are associated with LEP methylation in cord blood. Infant adiposity at birth predicts 12-month blood LEP methylation in a genotype-dependent manner. These findings are consistent with genetics and anthropometry driving altered LEP epigenetic profile and expression in infancy. Further work is required to confirm this and to determine the long-term impact of altered LEP methylation on health.

Leptin rs2167270 G > A (G19A) polymorphism may decrease the risk of cancer: A case-control study and meta-analysis involving 19 989 subjects

Accumulating evidence has suggested that leptin (LEP) is very important for the development of cancer. Recently, a number of case-control studies about the relationship of the rs2167270 G > A (G19A) variants in the LEP gene with the risk of cancer have yielded inconsistent results. In this study, we have carried out a case-control study [1063 esophagogastric junction adenocarcinoma (EGJA) cases and 1677 controls] in a Chinese population. Furthermore, we carried out a pooled-analysis of 13 studies involving 8059 cancer patients and 11 930 controls to assess whether the LEP G19A locus was associated with overall cancer susceptibility. Odds ratios (ORs) with the corresponding 95% confidence intervals (CIs) were harnessed to evaluate the potential association. In our case-control study, we found an association between the carriers of LEP 19A allele and EGJA risk. In addition, the results of meta-analysis also suggested significant associations with cancer risk (A vs G: OR = 0.92, 95% CI = 0.88-0.97, P = 0.001; AA vs GG: OR = 0.83, 95% CI = 0.74-0.93, P = 0.001, GA/AA vs GG: OR = 0.93, 95% CI = 0.88-0.99, P = 0.023 and AA vs GG/GA: OR = 0.83, 95% CI = 0.74-0.92, P < 0.001). Upon conducting a stratified analysis, we found that LEP 19A allele might decrease the susceptibility of non-Hodgkin lymphoma (NHL) and colorectal cancer (CRC). In a stratified-by-ethnicity analysis, significant associations were also found in Asians, Caucasians, and mixed populations. We can conclude that the LEP G19A polymorphism constitutes a decreased risk of cancer.

Leptin gene variants and colorectal cancer risk: Sex-specific associations

BACKGROUND

High levels of serum leptin and low levels of serum adiponectin are strongly correlated with obesity, a well-established risk factor for colorectal cancer (CRC). Growing evidence suggests that dysregulation of leptin and adiponectin levels may play an etiological role in colorectal carcinogenesis. We evaluated 20 candidate variants in 4 genes previously shown to alter serum leptin and adiponectin levels for associations with obesity (BMI>30 kg/m2) and CRC risk.

METHODS

We analyzed 6,246 CRC cases and 7,714 population-based controls from 11 studies within the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Associations of each variant with obesity or CRC were evaluated using multivariate logistic regression models stratified by sex and adjusted for age, a study variable, and the first three principal components of genetic ancestry. Gene-specific False Discovery Rate (FDR)-adjusted p-values <0.05 denoted statistical significance.

RESULTS

Two variants in the leptin gene showed statistically significant associations with CRC among women: LEP rs2167270 (OR = 1.13, 95% CI: 1.06-1.21) and LEP rs4731426 (OR = 1.09, 95% CI: 1.02-1.17). These associations remained significant after adjustment for obesity, suggesting that leptin SNPs may influence CRC risk independent of obesity. We observed statistically significant interactions of the leptin variants with hormone replacement therapy (HRT) for CRC risk; these variant associations were strengthened when analyses were restricted to post-menopausal women with low estrogen exposure, as estimated by 'never use' of HRT and/or non-obese BMI. No variants were associated with CRC among men.

CONCLUSIONS

Leptin gene variants may exhibit sex-specific associations with CRC risk. Endogenous and exogenous estrogen exposure may modify the association between these variants, leptin levels, and CRC risk.

The Role of Adipokines in the Establishment and Progression of Head and Neck Neoplasms

Adipokines constitute a family of protein factors secreted by white adipose tissue (WAT), that regulate the functions of WAT and other sites. Leptin, adiponectin and resistin, are the main adipokines present in serum and saliva, targeting several tissues and organs, including vessels, muscles, liver and pancreas. Besides body mass regulation, adipokines affect glucose homeostasis, inflammation, angiogenesis, cell proliferation and apoptosis, and other crucial cell procedures. Their involvement in tumor formation and growth is well established and deregulation of adipokine and adipokine receptors' expression is observed in several malignancies including those located in the head and neck region. Intracellular effects of adipokines are mediated by a plethora of receptors that activate several signaling cascades including Janus kinase/ Signal transducer and activator of transcription (JAK/ STAT pathway), Phospatidylinositol kinase (PI3/ Akt/ mTOR) and Peroxisome proliferator-activated receptor (PPAR). The present review summarizes the current knowledge on the role of adipokines family members in carcinogenesis of the head and neck region. The diagnostic and prognostic significance of adipokines and their potential role as serum and saliva biomarkers are also discussed.

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.

Investigation of LEP and LEPR polymorphisms with the risk of hepatocellular carcinoma: a case-control study in Eastern Chinese Han population

Background

Leptin (LEP) and LEP receptor (LEPR) polymorphisms may be associated with the development of cancer.

Methods

In this study, we selected five functional LEP and LEPR single-nucleotide polymorphisms (SNPs) and conducted a case–control study to determine the relationship of LEP and LEPR polymorphisms with hepatocellular carcinoma (HCC) risk in Eastern Chinese Han population. There were 584 HCC cases and 923 cancer-free controls included in our study. HCC patients and controls were fully matched by age and sex. SNPscan™ genotyping method was used to analyze the genotyping of LEP rs2167270 G>A, rs7799039 A>G, LEPR rs6588147 G>A, rs1137100 G>A, and rs1137101 G>A SNPs.

Results

We found that LEP rs7799039 A>G and rs2167270 G>A polymorphisms were associated with the susceptibility of HCC in this population (LEP rs7799039 A>G: GG vs AA: adjusted odds ratio [OR]=2.03, 95% CI, 1.22–3.38, P=0.006 and GG vs AA/AG: adjusted OR=1.97, 95% CI, 1.20–3.22, P=0.007; rs2167270 G>A: AA vs GG: adjusted OR=2.03, 95% CI, 1.10–3.75, P=0.024 and AA vs GG/GA: adjusted OR=2.01, 95% CI, 1.10–3.68, P=0.023). However, LEPR rs6588147 G>A polymorphism decreased the risk of HCC (GA vs GG: adjusted OR=0.62, 95% CI, 0.45–0.86, P=0.005 and AA/GA vs GG: adjusted OR=0.64, 95% CI, 0.47–0.88, P=0.007).

Conclusion

This case–control study highlights that LEP rs7799039 A>G and rs2167270 G>A polymorphisms increase the susceptibility to HCC; however, LEPR rs6588147 G>A polymorphism may be a protective factor for HCC in Eastern Chinese Han population.

Effects of maternal and fetal LEP common variants on maternal glycemic traits in pregnancy

Previous studies suggest that leptin (LEP) has an important role in glucose metabolism in the nonpregnant state. During pregnancy, circulating maternal concentrations of leptin rise significantly, mainly due to increased secretion of leptin from maternal adipose tissue and placenta. This study aimed to analyze the impact of maternal and fetal common LEP variants on glucose homeostasis in the pregnant state. Several glycemic traits, including fasting plasma glucose, fasting plasma insulin (FPI), and plasma glucose 1 hour after a 50-g oral glucose load, were measured in 1,112 unrelated Chinese Han pregnant women at 24–28 weeks gestation. Homeostatic model assessment (HOMA) was used to assess beta cell function (HOMA1-β and HOMA2-β) and insulin resistance (HOMA1-IR and HOMA2-IR).The relationships between glycemic traits and 12 LEP variants were determined. After applying the Bonferroni correction, we detected that (1) maternal rs10954173 and fetal rs10244329 were associated with maternal FPI although the effect of fetal rs10244329 may be not independent of maternal rs10244329, and (2) maternal rs12537573 was associated with maternal FPI and HOMA2-IR. This study provides genetic evidence that both maternal and fetal LEP polymorphisms may affect maternal glucose metabolism in pregnancy.

Genetic polymorphisms of IL-23R (rs7517847) and LEP (rs7799039) among Egyptian patients with hepatocellular carcinoma

BACKGROUND

Genetic polymorphisms of IL-23 R (rs7517847) and LEP (rs7799039) have been stated to be associated with various types of human cancers. The purpose of this work is to test the association of these genetic polymorphisms with hepatocellular carcinoma (HCC) among Egyptian patients.

SUBJECTS AND METHODS

This study involved 150 unrelated Egyptian HCC patients in addition to 100 healthy controls from the same locality. DNA was genotyped for these genetic polymorphisms using the PCR-RFLP technique.

RESULTS

The frequency of the IL-23 R (rs7517847) G and LEP (rs7799039) G alleles were significantly higher among HCC patients compared to controls (p = .004 and .02). However, HCC patients with the IL-23 R GG and LEP GG genotypes showed no significant difference compared to others regarding their clinical and laboratory markers.

CONCLUSIONS

IL-23 R (rs7517847) and LEP (rs7799039) polymorphisms were associated with an increased risk but not affecting the clinical presentation of HCC among Egyptian patients.

A new panel of SNPs to assess thyroid carcinoma risk: a pilot study in a Brazilian admixture population

BACKGROUND

Thyroid cancer is a common malignant disease of the endocrine system with increasing incidence rates over the last few decades. In this study, we sought to analyze the possible association of 45 single nucleotide polymorphisms (SNPs) with thyroid cancer in a population from Rio Grande do Norte, Brazil.

METHODS

Based on histological analysis by a pathologist, 80 normal thyroid specimens of tissue adjacent to thyroid tumors were obtained from the biobank at the Laboratory of Pathology of Liga Norte Riograndense Contra o Câncer, Natal, RN. Patient samples were then genotyped using the MassARRAY platform (Sequenon, Inc) followed by statistical analysis employing the SNPassoc package in R program. The genotypic frequencies of all 45 SNPs obtained from the International HapMap Project database and based on data from the ancestral populations of European and African origin were used to compose the control study group.

RESULTS

In our study, the following 9 SNPs showed significant differences in their frequency when comparing the study and control groups: rs3744962, rs258107, rs1461855, rs4075022, rs9943744, rs4075570, rs2356508, rs17485896, and rs2651339. Furthermore, the SNPs rs374492 C/T and rs258107 C/T were associated with a relative risk for thyroid carcinoma of 3.78 (p = 6.27 × 10e^-5) and 2.91 (p = 8.27 × 10e^-5), respectively, after Bonferroni's correction for multiple comparisons.

CONCLUSIONS

These nine polymorphisms could be potential biomarkers of predisposition to thyroid carcinoma in the population from Rio Grande do Norte. However, complementary studies including a control group with samples obtained from healthy subjects in Rio Grande do Norte state, should be conducted to confirm these results.

Investigation of TCF7L2, LEP and LEPR polymorphisms with esophageal squamous cell carcinomas

Single nucleotide polymorphisms (SNPs) in energy metabolism related gene may be key agents in the development of human malignancies. In this study, we aimed to examine the association of transcription factor 7-like 2, Leptin (LEP) and LEP receptor (LEPR) polymorphisms with esophageal squamous cell carcinoma (ESCC). A total of 507 ESCC cases and 1,496 controls were enrolled. We found that LEPR rs6588147 AA genotype was associated with ESCC risk (AA vs. GG/GA: adjusted OR=1.90, 95%CI=1.00-3.61, P=0.049). In the stratified analyses, LEPR rs6588147 G>A polymorphism increased the risk of ESCC (<63 years subgroup: AA vs. GG: adjusted OR=2.58, 95%CI=1.00-6.62, P=0.049 and AA vs. GA/GG: adjusted OR=2.71, 95%CI=1.06-6.91, P=0.038; male subgroup: AA vs. GG: adjusted OR=2.19, 95%CI=1.02-4.67, P=0.044 and AA vs. GA/GG: adjusted OR=2.26, 95%CI=1.06-4.80, P=0.035). However, LEP rs7799039 A>G decreased the risk of ESCC (≥63 years subgroup: GG vs. AA: adjusted OR=0.47, 95%CI=0.23-0.95, P=0.035 and GG vs. AA/AG: adjusted OR=0.48, 95%CI=0.24-0.96, P=0.038; BMI≥24 kg/m² subgroup: AG vs. AA: adjusted OR=0.66, 95%CI=0.45-0.99, P=0.044). In addition, LEPR rs1137101 G>A polymorphism decreased ESCC risk in some subgroups (ever smoking subgroup: GA vs. GG: adjusted OR=0.66, 95%CI=0.44-1.00, P=0.049; ever drinking subgroup: GA vs. GG: adjusted OR=0.54, 95%CI=0.31-0.95, P=0.031 and GA/AA vs. GG: adjusted OR=0.54, 95%CI=0.31-0.93, P=0.027). Our findings suggest that LEPR rs6588147 G>A polymorphism is associated with the increased risk of ESCC; however, LEP rs7799039 A>G and LEPR rs1137101 G>A polymorphisms may be protective factors for ESCC.

Maternal pre-pregnancy BMI downregulates neonatal cord blood LEP methylation

BACKGROUND

Neonatal adiposity has many determinants and may be a risk factor for future obesity. Epigenetic regulation of metabolically important genes is a potential contributor.

OBJECTIVES

The objective of the study is to determine whether methylation changes in the LEP gene in cord blood DNA are impacted by the maternal environment or affect neonatal adiposity measures.

METHODS

A cross-sectional study of 114 full-term neonates born to healthy mothers with normal glucose tolerance was performed. Cord blood was assayed for leptin and genome-wide DNA methylation profiles via the Illumina 450K platform. Neonatal body composition was measured by air displacement plethysmography. Multivariate linear regression models and semi-partial correlation coefficients were used to analyze associations. False discovery rate was estimated to account for multiple comparisons.

RESULTS

Maternal pre-pregnancy BMI was associated with decreased methylation at five CpG sites near the LEP transcription start site in an adjusted model (false discovery rate <0.022 for each site). The association between maternal BMI and cord blood leptin approached significance (r = 0.18, p = 0.054). Cord blood leptin was positively correlated with neonatal adiposity measures including birth weight (r = 0.45, p < 0.001), fat mass (r = 0.47, p < 0.001) and percent body fat (r = 0.44, p < 0.001).

CONCLUSIONS

Maternal pre-pregnancy BMI is strongly associated with decreased cord blood LEP gene methylation and may mediate the well-known association between maternal pre-pregnancy BMI and neonatal adiposity.

Gender Differences in Adipocyte Metabolism and Liver Cancer Progression

Liver cancer is the third most common cancer type and the second leading cause of deaths in men. Large population studies have demonstrated remarkable gender disparities in the incidence and the cumulative risk of liver cancer. A number of emerging risk factors regarding metabolic alterations associated with obesity, diabetes and dyslipidemia have been ascribed to the progression of non-alcoholic fatty liver diseases (NAFLD) and ultimately liver cancer. The deregulation of fat metabolism derived from excessive insulin, glucose, and lipid promotes cancer-causing inflammatory signaling and oxidative stress, which eventually triggers the uncontrolled hepatocellular proliferation. This review presents the current standing on the gender differences in body fat compositions and their mechanistic linkage with the development of NAFLD-related liver cancer, with an emphasis on genetic, epigenetic and microRNA control. The potential roles of sex hormones in instructing adipocyte metabolic programs may help unravel the mechanisms underlying gender dimorphism in liver cancer and identify the metabolic targets for disease management.

The Relationship Between Gene Polymorphism of Leptin and Leptin Receptor and Growth Hormone Deficiency

BACKGROUND Growth hormone deficiency (GHD) is a major cause of congenital short stature. GHD patients have significantly decreased serum leptin levels, which are regulated by gene polymorphism of leptin and leptin receptor. This study thus investigated the relationship between gene polymorphism and susceptibility to GHD. MATERIAL AND METHODS A case-control study was performed using 180 GHD children in addition to 160 healthy controls. After the extraction of whole genomic DNA, the genotypes of leptin and leptin receptor gene loci were analyzed by sequencing for single-nucleotide polymorphism. RESULTS The frequency distribution of all alleles identified in leptin gene (loci rs7799039) and leptin receptor gene (loci rs1137100 and rs1137101) fit Hardy-Weinberg equilibrium. There was a significant difference in allele frequency at loci rs7799039 or rs1137101, as individuals with heterozygous GA allele had lower (rs7799039) or higher (rs1137101) GHD risk. No significant difference in allele frequency was discovered at loci rs1137100 (p>0.05), which was unrelated to GHD susceptibility. CONCLUSIONS Gene polymorphism of leptin (loci rs7799039) and leptin receptor (loci rs1137101) are correlated with GHD susceptibility.

Genetic Determination of Serum Levels of Diabetes-Associated Adipokines

Adipose tissue secretes an abundance of proteins. Some of these proteins are known as adipokines and adipose-derived hormones which have been linked with metabolic disorders, including type 2 diabetes, and even with cancer. Variance in serum adipokine concentration is often closely associated with an increase (obesity) or decrease (lipodystrophy) in fat tissue mass, and it is affected by age, gender, and localization of the adipose tissue. However, there may be genetic variants which, in consequence, influence the serum concentration of a certain adipokine, and thereby promote metabolic disturbances or, with regard to the "protective" allele, exert beneficial effects. This review focuses on the genetic determination of serum levels of the following adipokines: adiponectin, chemerin, leptin, progranulin, resistin, retinol binding protein 4, vaspin, adipsin, apelin, and omentin. The article reports on the latest findings from genome-wide association studies (GWAS) and candidate gene studies, showing variants located in/nearby the adipokine genes and other (non-receptor) genes. An extra chapter highlights adipokine-receptor variants. Epigenetic studies on adipokines are also addressed.