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Supti DA, Akter F, Rahman MI, Munim MA, Tonmoy MIQ, Tarin RJ, Afroz S, Reza HA, Yeasmin R, Alam MR, Hossain MS. Meta-analysis investigating the impact of the LEPR rs1137101 (A>G) polymorphism on obesity risk in Asian and Caucasian ethnicities. Heliyon 2024; 10:e27213. [PMID: 38496879 PMCID: PMC10944198 DOI: 10.1016/j.heliyon.2024.e27213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 12/12/2023] [Accepted: 02/26/2024] [Indexed: 03/19/2024] Open
Abstract
Obesity is a chronic condition which is identified by the buildup of excess body fat caused by a combination of various factors, including genetic predisposition and lifestyle choices. rs1137101 (A > G) polymorphism in the CHR1 domain of LEPR protein linked to different diseases including obesity. Nevertheless, the connection between this polymorphism and the likelihood of developing obesity has not been determined definitively. Therefore, a meta-analysis was conducted to assess the relationship between rs1137101 and the risk of obesity. The meta-analysis included all studies meeting pre-defined criteria, found through searching databases up until February 2023. A combined odds ratio with a 95% confidence interval was estimated as overall and in continent subgroups for homozygous, heterozygous, recessive, dominant and allelic models using the fixed or the random-effects model. The meta-analysis identified 39 eligible studies with cases and controls (6099 cases/6711 controls) in 38 articles under different ethnic backgrounds. The results indicated a significant relationship between rs1137101 and the likelihood of developing obesity in each of the genetic models [the homozygous model (GG vs. AA: 95% Confidence Interval = 1.12-1.73, Odds Ratio = 1.39, P value = 0.003); the heterozygous model (AG vs. AA: 95% Confidence Interval = 1.07-1.42, Odds Ratio = 1.23, P value = 0.005); the dominant model (AG/GG vs AA: 95% Confidence Interval = 1.10-1.49, Odds Ratio = 1.28, P value = 0.001); the recessive model (GG vs AA/AG: 95% Confidence Interval = 1.02-1.45, Odds Ratio = 1.21, P value = 0.03); and the allelic model (G vs A; 95% Confidence Interval = 1.07-1.33, Odds Ratio = 1.19, P value = 0.002)] tested. Additionally, with an FDR <0.05, all genotypic models demonstrated statistical significance. The association remained significant among subgroups of Asian and Caucasian populations, although analysis in some genetic models did not show a significant association. Begg's and Egger's tests did not show publication biases. In sensitivity analysis, one particular study was found to have an impact on the Recessive model's significance, but other models remained unaffected. The current meta-analysis found significant indications supporting the association between rs1137101 and obesity. To avail a deeper understanding of this association, future research should include large-scale studies conducted in diverse ethnic populations.
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Affiliation(s)
- Dilara Akhter Supti
- Department of Food Technology and Nutrition Science, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Farzana Akter
- Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Md Imranur Rahman
- Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Md Adnan Munim
- Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali, Bangladesh
| | | | - Rabia Jahan Tarin
- Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Sumaiya Afroz
- Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Hasan Al Reza
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka, Bangladesh
| | - Roksana Yeasmin
- Department of Biochemistry, Ibrahim Medical College, Dhaka, Bangladesh
| | - Mohammad Rahanur Alam
- Department of Food Technology and Nutrition Science, Noakhali Science and Technology University, Noakhali, Bangladesh
| | - Md Shahadat Hossain
- Department of Biotechnology and Genetic Engineering, Noakhali Science and Technology University, Noakhali, Bangladesh
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El Fessikh M, Elkarhat Z, Flatters D, Camproux AC, Belghiti H, Guerinech H, Bakri Y, Dakka N, El Baghdadi J. Association study of leptin receptor polymorphisms in women with obesity and their impact on protein domains: a case-control study and in silico analyses. J Biomol Struct Dyn 2022:1-13. [DOI: 10.1080/07391102.2022.2109755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
- Meriem El Fessikh
- Genetics Unit, Military Hospital Mohammed V, Rabat, Morocco
- Laboratory of Human Pathologies Biology, and Genomic Center of Human Pathologies, Faculty of Sciences, Mohammed V University, Rabat, Morocco
| | - Zouhair Elkarhat
- Laboratory of Genomics and Human Genetics, Pasteur Institute of Casablanca, Casablanca, Morocco
| | - Delphine Flatters
- Université Paris Cité, CNRS, INSERM, Unité de Biologie Fonctionnelle et Adaptative, Paris, France
| | - Anne-Claude Camproux
- Université Paris Cité, CNRS, INSERM, Unité de Biologie Fonctionnelle et Adaptative, Paris, France
| | - Hakim Belghiti
- Clinical Nutrition Unit, Hygiene and Collectivity Medicine Ward, Military Hospital Mohammed V, Rabat, Morocco
| | - Hassania Guerinech
- Clinical Nutrition Unit, Hygiene and Collectivity Medicine Ward, Military Hospital Mohammed V, Rabat, Morocco
| | - Youssef Bakri
- Laboratory of Human Pathologies Biology, and Genomic Center of Human Pathologies, Faculty of Sciences, Mohammed V University, Rabat, Morocco
| | - Nadia Dakka
- Laboratory of Human Pathologies Biology, and Genomic Center of Human Pathologies, Faculty of Sciences, Mohammed V University, Rabat, Morocco
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Socol CT, Chira A, Martinez-Sanchez MA, Nuñez-Sanchez MA, Maerescu CM, Mierlita D, Rusu AV, Ruiz-Alcaraz AJ, Trif M, Ramos-Molina B. Leptin Signaling in Obesity and Colorectal Cancer. Int J Mol Sci 2022; 23:4713. [PMID: 35563103 PMCID: PMC9102849 DOI: 10.3390/ijms23094713] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 12/05/2022] Open
Abstract
Obesity and colorectal cancer (CRC) are among the leading diseases causing deaths in the world, showing a complex multifactorial pathology. Obesity is considered a risk factor in CRC development through inflammation, metabolic, and signaling processes. Leptin is one of the most important adipokines related to obesity and an important proinflammatory marker, mainly expressed in adipose tissue, with many genetic variation profiles, many related influencing factors, and various functions that have been ascribed but not yet fully understood and elucidated, the most important ones being related to energy metabolism, as well as endocrine and immune systems. Aberrant signaling and genetic variations of leptin are correlated with obesity and CRC, with the genetic causality showing both inherited and acquired events, in addition to lifestyle and environmental risk factors; these might also be related to specific pathogenic pathways at different time points. Moreover, mutation gain is a crucial factor enabling the genetic process of CRC. Currently, the inconsistent and insufficient data related to leptin's relationship with obesity and CRC indicate the necessity of further related studies. This review summarizes the current knowledge on leptin genetics and its potential relationship with the main pathogenic pathways of obesity and CRC, in an attempt to understand the molecular mechanisms of these associations, in the context of inconsistent and contradictory data. The understanding of these mechanisms linking obesity and CRC could help to develop novel therapeutic targets and prevention strategies, resulting in a better prognosis and management of these diseases.
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Affiliation(s)
| | - Alexandra Chira
- 2nd Medical Clinic, Department of Internal Medicine, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400006 Cluj-Napoca, Romania;
| | - Maria Antonia Martinez-Sanchez
- Obesity and Metabolism Laboratory, Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain; (M.A.M.-S.); (M.A.N.-S.)
| | - Maria Angeles Nuñez-Sanchez
- Obesity and Metabolism Laboratory, Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain; (M.A.M.-S.); (M.A.N.-S.)
| | | | - Daniel Mierlita
- Department of Nutrition, University of Oradea, 410048 Oradea, Romania;
| | - Alexandru Vasile Rusu
- Life Science Institute, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 400372 Cluj-Napoca, Romania;
- Faculty of Animal Science and Biotechnology, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, 400372 Cluj-Napoca, Romania
| | - Antonio Jose Ruiz-Alcaraz
- Department of Biochemistry and Molecular B and Immunology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain;
| | - Monica Trif
- Department of Food Research, Centiv GmbH, 28857 Syke, Germany;
| | - Bruno Ramos-Molina
- Obesity and Metabolism Laboratory, Biomedical Research Institute of Murcia (IMIB), 30120 Murcia, Spain; (M.A.M.-S.); (M.A.N.-S.)
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Bains V, Kaur H, Badaruddoza B. Association analysis of polymorphisms in LEP (rs7799039 and rs2167270) and LEPR (rs1137101) gene towards the development of type 2 diabetes in North Indian Punjabi population. Gene 2020; 754:144846. [PMID: 32512158 DOI: 10.1016/j.gene.2020.144846] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 05/29/2020] [Accepted: 06/02/2020] [Indexed: 12/18/2022]
Abstract
OBJECTIVES Obesity is a major risk factor in aetiology of type 2 diabetes mellitus (T2DM). Leptin (LEP) is an anti-obesity hormone which regulates food intake, energy expenditure and glucose metabolism. The genetic variants in leptin and leptin receptor gene (LEPR) may play major role in the pathogenesis of T2DM and obesity. The current study aimed to investigate the association of polymorphisms in LEP (rs7799039, -2548G/A and rs2167270, 19G/A) and LEPR (rs1137101, 668A/G) gene with type 2 diabetes in North Indian Punjabi population. METHODS A total of 817 subjects were included for the present case-control study, consisting of 417 T2DM patients and 400 healthy controls. The anthropometric, physiometric and biochemical measurements were taken from all the subjects. The genotyping of LEP and LEPR gene variants were carried out by polymerase chain reaction based restriction fragment length polymorphism method (PCR-RFLP), followed by genotyping of 10% of the samples for each polymorphism by Sanger sequencing method for quality control measurement. RESULTS The risk genotype frequencies were found to be significantly higher in T2DM cases than control subjects (rs7799039, p = 0.001; rs2167270, p = 0.019 and rs1137101, p = 0.003). Under recessive genetic model LEPrs7799039 and LEPRrs1137101 polymorphism conferred 3.4 and 2.1 fold risk towards the development of T2DM after adjustment of various covariates (OR = 3.44, 95%CI: 1.768-6.681, p = 0.001 and OR: 2.12, 95%CI: 1.256-3.569, p = 0.005, respectively). In the stratified analysis of LEP variant rs7799039 by age, gender, BMI and alcohol use, a significantly increased risk of T2DM was found in female, BMI ≥ 23 and never drinking subgroups. However, in the LEPR variant rs1137101, significantly increased risk of T2DM was observed in age <50, male, BMI ≥ 23 and never drinking subgroup. The A-G haplotype combination of rs7799039A and rs2167270G conferred significant 2 fold risk towards T2DM (OR = 2.35, 95%CI: 1.34-4.12, p = 0.002). In control group, the genetic variants rs7799039 and rs1137101 were significantly associated with levels of random blood sugar and low density lipoprotein cholesterol levels. CONCLUSION The present study revealed the association of LEP rs7799039 and LEPR rs1137101 with type 2 diabetes mellitus, which suggest its predominant role in the estimation of type 2 diabetes mellitus in North Indian Punjabi population.
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Affiliation(s)
- Veena Bains
- Department of Human Genetics, Guru Nanak Dev University (GNDU), Amritsar 143 005, Punjab, India
| | - Harjit Kaur
- Department of Human Genetics, Guru Nanak Dev University (GNDU), Amritsar 143 005, Punjab, India
| | - Badaruddoza Badaruddoza
- Department of Human Genetics, Guru Nanak Dev University (GNDU), Amritsar 143 005, Punjab, India.
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Association of leptin receptor genetic variants (LEPR) with obesity and leptin level in unexplained infertility in northern Indian population. CLINICAL EPIDEMIOLOGY AND GLOBAL HEALTH 2020. [DOI: 10.1016/j.cegh.2019.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Polymorphism in leptin receptor gene was associated with obesity in Yogyakarta, Indonesia. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2016. [DOI: 10.1016/j.ejmhg.2015.12.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Ng ZY, Veerapen MK, Hon WM, Lim RLH. Association of leptin/receptor and TNF-α gene variants with adolescent obesity in Malaysia. Pediatr Int 2014; 56:689-97. [PMID: 24628746 DOI: 10.1111/ped.12336] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 01/07/2014] [Accepted: 03/03/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND Leptin (LEP) G-2548A (rs7799039), leptin receptor (LEPR) Q223R (rs1137101) and tumor necrosis factor (TNF)-α G-308A (rs1800629) gene variants have been reported to be associated with obesity, although results for subjects from different countries have been controversial. The aim of this study was to determine the prevalence of overweight and obesity in Malaysian adolescents and the association of these polymorphisms with overweight and obese or over-fat adolescents. METHODS A total of 613 adolescents (241 Malay, 219 Chinese, 153 Indian) were enrolled. Anthropometric measurements of body mass index (BMI) and body fat percentage were used to classify subjects as controls (non-overweight/obese or normal fat) or as cases (overweight/obese or over-fat). Genomic DNA was extracted from oral buccal mucosa cells for genotyping using polymerase chain reaction-restriction fragment length polymorphism and data obtained were statistically analyzed. RESULTS A total of 23.3% of subjects were overweight/obese whereas 11.4% were over-fat; there were significantly more overweight/obese and over-fat Indian and Malay adolescents compared to Chinese (P < 0.001). A allele was the minor one for LEPR Q223R and TNF-α G-308A in all ethnic groups, whereas G allele was minor for LEP G-2548A in Chinese and Malay adolescents, except for Indian adolescents. Indian male adolescents with AA genotype for LEP G-2548A were associated with overweight/obesity (P = 0.025; odds ratio, 3.64; 95% confidence interval: 1.15-11.54). Despite the lack of association observed for LEPR Q223R and TNF-α G-308A, Indian and Chinese subjects with AA risk genotype for LEPR Q223R/LEP G-2548A and TNF-α G-308A/LEP G-2548A, respectively, had increased mean BMI (P = 0.049, P = 0.016). CONCLUSIONS Genotype distribution and association of these polymorphisms with overweight/obesity vary between ethnic groups and genders. Nevertheless, the LEP G-2548A risk allele may be associated with overweight/obese Indian male adolescents in Malaysia.
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Affiliation(s)
- Zoe Yi Ng
- Faculty of Applied Sciences, UCSI University, Kuala Lumpur, Malaysia
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Fan SH, Say YH. Leptin and leptin receptor gene polymorphisms and their association with plasma leptin levels and obesity in a multi-ethnic Malaysian suburban population. J Physiol Anthropol 2014; 33:15. [PMID: 24947733 PMCID: PMC4073586 DOI: 10.1186/1880-6805-33-15] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 06/04/2014] [Indexed: 02/06/2023] Open
Abstract
Background This study was to investigate the prevalence of single nucleotide polymorphisms (SNPs) in leptin gene LEP (A19G and G2548A) and leptin receptor gene LEPR (K109R and Q223R) and their association with fasting plasma leptin level (PLL) and obesity in a Malaysian suburban population in Kampar, Perak. Methods Convenience sampling was performed with informed consents, and the study sample was drawn from patients who were patrons of the Kampar Health Clinic. A total of 408 subjects (mean age, 52.4 ± 13.7 years; 169 men, 239 women; 190 obese, 218 non-obese; 148 Malays, 177 ethnic Chinese, 83 ethnic Indians) participated. Socio-demographic data and anthropometric measurements were taken, and genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results The LEP A19G, G2548A and LEPR K109R, Q223R variant allele frequencies were 0.74, 0.67 and 0.61, 0.79, respectively. The genotype and allele distributions of these gene variants were significantly different among ethnic groups, but not among body mass index (BMI) classes. Subjects with LEPR K109 and Q223 allele had significantly higher systolic blood pressure and adiposity indices after adjustment for ethnicity (higher BMI, total body and subcutaneous fat; lower skeletal muscle percentage). Subjects with LEPR 109R allele had lower PLL than their wild-type allele counterparts. The influence of LEP A19G and G2548A SNPs on blood pressures, anthropometrics, and PLL was not evident. Interestingly, synergistic effect of the LEP and LEPR SNPs was observed as subjects homozygous for all four SNPs studied exhibited significantly higher subcutaneous fat and PLL than those with other genotype combinations. Conclusions The LEP and LEPR SNPs in this study may not be an obesity marker among Malaysians in this population, but were associated with ethnicity. Our findings suggest that each of these SNPs contributes to minor but significant variation in obesity-related traits and in combination they display synergistic effects on subcutaneous fat and PLL.
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Affiliation(s)
| | - Yee-How Say
- Department of Biomedical Science, Faculty of Science, Universiti Tunku Abdul Rahman (UTAR) Perak Campus, Kampar, Malaysia.
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Analysis of Gln223Agr polymorphism of Leptin Receptor Gene in type II diabetic mellitus subjects among Malaysians. Int J Mol Sci 2013; 14:19230-44. [PMID: 24051404 PMCID: PMC3794830 DOI: 10.3390/ijms140919230] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 08/26/2013] [Accepted: 08/27/2013] [Indexed: 11/25/2022] Open
Abstract
Leptin is known as the adipose peptide hormone. It plays an important role in the regulation of body fat and inhibits food intake by its action. Moreover, it is believed that leptin level deductions might be the cause of obesity and may play an important role in the development of Type 2 Diabetes Mellitus (T2DM), as well as in cardiovascular diseases (CVD). The Leptin Receptor (LEPR) gene and its polymorphisms have not been extensively studied in relation to the T2DM and its complications in various populations. In this study, we have determined the association of Gln223Agr loci of LEPR gene in three ethnic groups of Malaysia, namely: Malays, Chinese and Indians. A total of 284 T2DM subjects and 281 healthy individuals were recruited based on International Diabetes Federation (IDF) criteria. Genomic DNA was extracted from the buccal specimens of the subjects. The commercial polymerase chain reaction (PCR) method was carried out by proper restriction enzyme MSP I to both amplify and digest the Gln223Agr polymorphism. The p-value among the three studied races was 0.057, 0.011 and 0.095, respectively. The values such as age, WHR, FPG, HbA1C, LDL, HDL, Chol and Family History were significantly different among the subjects with Gln223Agr polymorphism of LEPR (p < 0.05).
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Swellam M, Hamdy N. Association of nonalcoholic fatty liver disease with a single nucleotide polymorphism on the gene encoding leptin receptor. IUBMB Life 2012; 64:180-6. [PMID: 22215535 DOI: 10.1002/iub.597] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 09/29/2011] [Indexed: 02/01/2023]
Abstract
Leptin (Lep), a 16-kDa polypeptide hormone, exerts its action through the leptin receptor (LepRb), a member of the class I cytokine receptor family. Both leptin and LepRb probably have been implicated in pathogenesis of nonalcoholic fatty liver disease (NAFLD). This study was designed to assess the role of soluble leptin and LepRb in NAFLD and to investigate whether leptin receptor gene (LepR) single nucleotide polymorphism (SNP; ID rs6700896) influences NAFLD complicated with or without type 2 diabetes mellitus (T2DM). Blood samples from 90 obese NAFLD cases and 30 lean controls of matched age and sex were recruited in the study. Among the NAFLD patients, 32 were T2DM. Plasma leptin and LepRb levels were measured by enzyme linked immunoassay (ELISA). Lipids profile, glucose metabolic parameters, and insulin concentration were measured for all participants. Body mass index (BMI) and insulin resistance (IR) were calculated as well. Genotyping was done using SNP (rs6700986) for LepR gene. Significant difference was reported between NAFLD with or without T2DM and control regarding biochemical markers and LepR genotype and allele frequencies. Mutant homozygous and heterozygous LepR genotype and mutant allele were significantly higher in mild-severe steatosis and in NAFLD with T2DM when compared with mild steatosis and those without T2DM. Frequencies of mutant LepR polymorphism were significantly associated with IR increment. Elevated leptin level seems to be a feature of steatosis, and it appears to increase as hepatocyte steatosis develops. Moreover, polymorphism of LepR gene contributes to the onset of NAFLD by regulating lipid metabolism and affecting insulin sensitivity.
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Affiliation(s)
- Menha Swellam
- Genetic Engineering and Biotechnology Research Division, Department of Biochemistry, National Research Center, Dokki, Giza, Egypt.
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Yu Z, Han S, Cao X, Zhu C, Wang X, Guo X. Genetic polymorphisms in adipokine genes and the risk of obesity: a systematic review and meta-analysis. Obesity (Silver Spring) 2012; 20:396-406. [PMID: 21660081 DOI: 10.1038/oby.2011.148] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Polymorphisms in adipokine genes, such as leptin (LEP), leptin receptor (LEPR), resistin (RETN), adiponectin (ADIPOQ), interleukin-1β (IL-1β), IL-6 (IL-6), and tumor necrosis factor-α (TNF-α) may be involved in the development of obesity. We conducted a systematic review of published evidence on the association between different adipokine genes and the risk of obesity. Librarian-designed searches of PubMed and HuGeNet, review of reference lists from published reviews and content expert advice identified potentially eligible studies. The genotyping information and polymorphisms of different adipokine genes, numbers of genotyped cases and controls and frequencies of genotypes were extracted from 48 eligible studies included in this review. Twenty-one polymorphisms each associated with obesity in at least one study were identified. Polymorphisms in the adipokine genes, LEP, LEPR, and RETN were not associated with obesity susceptibility, whereas ADIPOQ G276T (T vs. G: odds ratio (OR), 1.59; 95% confidence interval (CI), 1.39-1.81), IL-1β C3953T (CC vs. CT+TT: OR, 1.61; 95% CI, 1.18-2.20), and TNF-α G308A (GG vs. GA+AA: OR, 1.19; 95% CI, 1.02-1.39) polymorphisms were associated with an increased risk of obesity. The IL-6 G174C polymorphism was also associated obesity when using allelic comparisons, the recessive genetic model and the dominant genetic model with OR (95% CI) of 1.95 (1.37-2.77), 1.44 (1.15-1.80), and 1.36 (1.16-1.59), respectively. No significant evidence of publication bias was present. However, these "null" results were underpowered due to a small pooled sample size, and analysis of additional case-control studies with larger sample sizes should provide further clarifications.
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Affiliation(s)
- Zhangbin Yu
- Department of Pediatrics, Nanjing Maternal and Child Health Hospital, Nanjing Medical University, Nanjing, PR China
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