Effect of genetic variation in the leptin gene promoter and the leptin receptor gene on obesity risk in a population-based case-control study in Spain

There are no good genetic markers for incorporating the study of genetic susceptibility to obesity in epidemiological studies. In animal models, the leptin (LEP) and the leptin receptor (LEPR) genes have been shown to be very important in obesity because leptin functions as a negative feedback signal in regulating body-weight through reducing food intake and stimulating energy expenditure. In humans, several polymorphisms in these genes have been described. However, their association with obesity is still very controversial because there are no good case-control studies designed to specifically test this association. Our objective has been to conduct a population-based case-control study to estimate the risk of obesity arising from the −2548G > A and Q223R polymorphisms in the LEP and LEPR genes, respectively. 303 obese cases (101 men and 202 women) and 606 controls (202 men and 404 women) were selected from a Spanish Mediterranean population. Genetic, clinical and life-style characteristics were analyzed. No association was found between the −2548G > A polymorphism and obesity. However, the Q223R variant was significantly associated with obesity in a recessive model, the RR genotype being more prevalent in controls than in obese subjects. The inverse association between the Q223R polymorphism and obesity (OR = 0.62; 95% CI: 0.39–0.99) remained significant even after additional adjustment for education, tobacco smoking, alcohol, physical activity, origin of the obese patient, and the −2548G > A polymorphism in the LEP gene (OR = 0.54; 95% CI: 0.32–0.89). In conclusion, the −2548G > A polymorphism is not a relevant obesity marker in this Mediterranean population, although Q223R does seen to be so.     

Genetic variation in the leptin receptor gene,leptin, and weight gain in young Dutch adults

OBJECTIVE: To investigate the association between leptin levels, polymorphisms in the leptin receptor (LEPR) gene, and weight gain. RESEARCH METHODS AND PROCEDURES: From two large prospective cohorts in The Netherlands (n = 17,500), we compared the baseline leptin of 259 subjects who had gained an average of 12.6 kg (range 5.5 to 33 kg) with 277 subjects who kept stable weight (range -2.6 to 3.1 kg) after a mean follow-up of 6.8 years. Three polymorphisms in the LEPR gene (Lys109Arg, Gln223Arg, and Lys656Asn) were determined. RESULTS: Weight gainers had significantly higher baseline leptin levels than those who kept stable weight (odds ratio = 1.27, 95% confidence interval 1.1 to 1.5, per SD increase in log(e)-transformed leptin). Weight gainers with the Arg109 or the Arg223 alleles had higher leptin levels compared with the noncarriers of these alleles. Only among men, the association between leptin and weight gain tended to be stronger among those with an Arg223 allele compared with those without this mutation. DISCUSSION: Relatively high leptin levels predict weight gain, suggesting that leptin resistance plays a role in the development of obesity in the general population. Higher leptin levels for those with a Lys109Arg or Gln223Arg mutation (or a linked other marker) may imply that these subjects have a modified functional leptin receptor. However, the role of these mutations on weight gain is limited.     

Association of proopiomelanocortin gene polymorphisms with obesity in the IRAS family study

Proopiomelanocortin (POMC) has been found to be associated with rare Mendelian forms of obesity in children, and, in linkage studies, genomic regions containing the POMC locus have been linked to leptin levels, a predictor of obesity, in white, Mexican-American, and African-American families. POMC polymorphisms have not been investigated in detail for association with obesity in the general population. Five single nucleotide polymorphisms (SNPs) (G-3460C, C17T, G3473A, C3755T, and A7069G) were genotyped on 811 Hispanic individuals in the Insulin Resistance Atherosclerosis Family Study and tested for association with multiple obesity quantitative traits. General and family-based association analyses for each individual SNP and for haplotypes were performed using the generalized estimating equation and quantitative pedigree disequilibrium test (QPDT), respectively. Modest but consistent associations were observed for SNP C3755T, with p values ranging from 0.011 to 0.045 for association with BMI, waist, visceral adipose tissue, and subcutaneous adipose tissue. G-3460C, G3473A, and A7069G were also found to be associated with additional obesity measurements (p value 0.025 to 0.04), with comparable levels of evidence observed for linkage disequilibrium between these traits and these SNPs. Results of the haplotype analyses were also consistent with the single SNP analysis, with haplotypes containing C3755T showing the greatest evidence of association (p values ranging 0.004 to 0.048). Monte Carlo simulations (gene dropping) that account for the number of comparisons and the correlation structure indicate that the multivariate significance for these obesity traits with these polymorphisms was p = 0.0091. Collectively, the POMC polymorphisms showed consistent evidence for association with obesity traits in Hispanic Americans across several analytical approaches using SNP and haplotype analysis. These results support the hypothesis that POMC contributes genetically to the development of obesity.     

Genetische Ursachen der Adipositas

A small number of confirmed major genes for human obesity has been identified by molecular genetic studies; mutations of these have a strong influence on the development of excessive body weight. However, the underlying mutations are rare and do not explain the current obesity epidemic. The genetic predisposition to common obesity most likely has a polygenic basis, and each single gene variant has only a small influence on body weight. The introduction of genome-wide association scans (GWAS) offers new opportunities for the study of complex diseases. The receptor variant with the amino acid isoleucin (wildtype: valine) at position 103 of the melanocortin-4 receptor (MC4R) represents the first confirmed polygenic variant with an influence on body mass index; additional polymorphisms located 188 kb at the 3’ end of the MC4R have also been shown to have an effect on body weight. Variants in the first intron of the “fat mass and obesity associated” gene (FTO) confer the most pronounced polygenic effect on obesity (+0.4 kg/m² per allele); these variants were originally detected in 2007 in GWAS pertaining to type 2 diabetes mellitus. Recently, additional SNPs with a polygenic effect on obesity have been identified in three large GWAS. By December 2009, 17 solidly confirmed polygenes for body weight regulation have been reported.     

No association of defined variability in leptin,leptin receptor,adiponectin, proopiomelanocortin and ghrelin gene with food preferences in the Czech population

Abstract

Background: Previously, it has been reported that mutations in the genes encoding for adipokines may be associated with impaired food intake and may serve as potential obesity biomarkers. The aim of this study was to investigate the possible associations of defined variability in leptin, leptin receptor, adiponectin, proopiomelanocortin and ghrelin genes with food preferences in the obese and non-obese Czech population and evaluate their potential as the obesity susceptibility genes.

Patients and Methods: Using PCR followed by restriction analysis, we studied 185 volunteers. Basic anthropometrical characteristics associated to obesity were measured and the food intake was monitored using a 7-day record method. In the group of obese individuals, a subset of 34 morbidly obese patients was studied for plasma leptin and soluble leptin receptor levels.

Results: None of the examined polymorphisms was associated to anthropometrical or demographic characteristics of the study subjects. The Gln223Arg polymorphism within the leptin receptor gene was significantly associated with lower plasma leptin levels (the RR genotype being more frequent in patients with lower plasma leptin levels; P = 0.001). No associations of the examined polymorphisms with food preferences was observed.

Conclusions: Based on our results, the examined polymorphisms in the adipokine genes do not seem to be the major risk factor for obesity development in the Czech population nor significantly affect food preferences.     

Lifestyle and dietary correlates of plasma insulin-like growth factor binding protein-1 (IGFBP-1), leptin, and C-peptide: the Multiethnic Cohort

Circulating insulin-like growth factor binding protein 1 (IGFBP-1), leptin, and insulin are 3 proteins modified by obesity and have been associated with cancer at several sites in past studies. We conducted a cross-sectional study to describe the correlation of these proteins with gender, race/ethnicity, anthropometric indexes, and dietary and lifestyle factors. We measured fasting plasma levels of IGFBP-1, leptin, and C-peptide, used here as a stable measure of insulin secretion, in a random sample of 450 male and 352 postmenopausal female Hawaii and Los Angeles Multiethnic Cohort Study (MEC) participants (age range 47-82 yr at blood draw). Through a series of multiple linear regressions, we found that the most parsimonious model for plasma IGFBP-1 included inverse associations with age, body mass index (BMI), and regular soda intake. A term for interaction between age and BMI was positively associated with plasma IGFBP-1. Adjusted mean plasma leptins were highest among Whites and African Americans and lowest among Hawaiians and Japanese Leptin was also inversely associated with age and positively associated with the interaction between age and race/ethnicity, female gender, and BMI. A model with only race/ethnicity and BMI (positive association) was best for plasma C-peptide. Adjusted means for C-peptide were highest for Japanese and Whites and lowest for African Americans. The overall percent of variance in protein levels explained by these models was low for IGFBP-1(R2=0.17) and C-peptide (R(3)=0.11) and higher for leptin (R(2)=0.57). We saw no clear correlation between racial/ethnic trends in protein levels with those of colorectal, breast, or prostate cancer incidence rates in the MEC. Research to clarify factors associated with determination of these proteins and their relationship with cancer etiology is warranted.     

胰岛素抵抗和血糖代谢相关基因多态性与NAFLD的系统综述与Meta分析

目的 探讨胰岛素抵抗和血糖代谢相关基因多态性与非酒精性脂肪肝（NAFLD）易感性的关系。方法 通过文献检索收集胰岛素抵抗和血糖代谢相关基因多态性与NAFLD关系的病例对照研究,依据纳入、排除标准提取文献相关数据。采用R 1.3.1093软件进行meta分析。结果 共纳入50 项病例对照研究,涉及10个基因20个位点,其中,纳入系统综述研究27项,涉及9个基因16个位点。5个基因的7个位点与NAFLD存在关联,4个基因的7个位点不存在关联,其余两个位点存在争议。Meta分析的3个基因4个位点,GCKR rs780094 等位基因模型OR及95%CI:6.528（5.510～7.734）、GCKR rs1260326等位基因模型OR及95%CI:1.296（1.108～1.517）、ENPP1/PC1 rs1044498等位基因模型OR及95%CI:1.470（1.162～1.860）均显示增加NAFLD患病风险,而PPP1R3B rs4240624多态性与NAFLD易感性无关。结论 胰岛素抵抗和血糖代谢相关基因数目较多,但能进行meta分析的基因和位点较少,仅半数基因和位点与NAFLD存在关联。     

Polymorphisms in candidate obesity genes and their interaction with dietary intake of n-6 polyunsaturated fatty acids affect obesity risk in a sub-sample of the EPIC-Heidelberg cohort

Summary. Background, aim: In several genes coding for molecules involved in the regulation of body weight (fat mass) and thermogenesis, polymorphisms have been reported which possibly modify human obesity risk. The aim of this study was a) to reproduce these observations with data and biological material from the Heidelberg cohort of EPIC, a large European prospective investigation into diet and cancer, and b) to investigate potential effects of interactions between dietary fatty acid intake and allelic variants on obesity risk. Subjects and methods: Within EPIC-Heidelberg, 154 subjects with a body mass index > 35 kg/m² and 154 age- and sex-matched normal-weight controls were selected and genotypes determined for 11 candidate genes. Dietary intake was assessed by a validated food frequency questionnaire. Odds ratios (OR) were computed by means of unconditional logistic regression and different adjustment models. Genotyping was performed by PCR-RFLP and allele-specific PCR. Results: For most of the investigated genes (PPARA, PPARG2, UCP1, UCP2, UCP3, BAR-2, APM1, leptin, SORBS1, HSL, and TNFA) an indication for a minor effect on obesity risk was found. Indication of a risk-increasing effect was strongest for the homozygous form of leptin −2548AA with an adjusted OR of 3.53 (p < 0.009). Additionally, for the polymorphic sites of BAR-2 (Arg16Gly and Gln27Glu) a significant effect on obesity risk was seen. Importantly, the results of the analysis of gene-diet interactions suggest that the allelic variants of candidate genes (leptin, TNFA, PPARG2) might strongly affect diet-related obesity risk. Conclusions: The results support some but not all previous reports about a risk-modulating effect of polymorphisms in genes affecting obesity risk. The most important finding is an indication of substantial interaction between allelic variants of particular genes and fatty acid intake-related obesity risk. These observations suggest that future studies on polymorphisms in obesity genes should take data on dietary habits into account. Received: 3 May 2002, Accepted: 21 August 2002 Correspondence to: Dr. A. Nieters     

Genetic variation and obesity in Australian women: a prospective study.

OBJECTIVE: A number of candidate genes have been implicated in the pathogenesis of obesity in humans. This study examines associations between longitudinal changes in body mass and composition and the presence of polymorphisms in the beta-3 adrenergic receptor, tumor necrosis factor-alpha, leptin, and leptin receptor (Lepr) in a cohort of Australian women. RESEARCH METHODS AND PROCEDURES: Healthy white Australian women (n = 335) were randomly selected from the Barwon region of Victoria and underwent baseline anthropometry and double-energy X-ray absorptiometry for assessment of body mass and adiposity. These measurements were repeated again at 2-year follow-up. Genomic DNA was extracted and used for polymerase chain reaction-based genotyping of all polymorphisms. RESULTS: The Pro1019Pro Lepr polymorphism was associated with longitudinal increases in body weight (p = 0.02), fat mass (p = 0.05), and body mass index (p = 0.01) in this study, and individuals homozygous for the A allele at this locus had a greater propensity to gain body fat over time. The largest effects on body composition seemed to be in individuals already obese at baseline. Changes in body weight, fat mass, percent body fat, and body mass index over a 2-year period were not associated with genetic variation in the beta-3 adrenergic receptor (Trp64Arg), tumor necrosis factor-alpha promoter, or leptin genes in non-obese or obese women. DISCUSSION: These results suggest that a Lepr polymorphism is involved in the regulation of body mass and adiposity in obese Australian white women, which may have implications for the treatment of obesity in this population.     

瘦素受体基因多态性与壮族儿童单纯性肥胖的相关性研究

目的 探讨瘦素受体(leptin receptor,LEPR)基因单核苷酸多态性位点rs1137100 与壮族儿童单纯性肥胖的相关性。方法 对208名柳州某区小学学龄前儿童(年龄均<7岁)分别检测身高和体重,计算BMI。利用SNaPshot技术分析107例单纯性肥胖儿童和101例健康对照儿童的LEPR 基因型及等位基因频率分布状况。结果 肥胖和健康对照组LEPR 基因A/A型、A/G型及G/G型基因型频率分别为66.4%、29.9%、3.7%和68.3%、27.7%、4.0%,两组等位基因频率分别为81.3%、18.7%和82.2%、17.8%,A等位基因的OR值为1.06,95%CI为0.64~1.74。两组基因型与等位基因频率差异均无统计学意义(P>0.05);肥胖与健康对照组LEPR 基因型频率在性别分层中差异均无统计学意义(P>0.05)。肥胖组的BMI水平明显高于对照组,差异有统计学意义(P<0.05)。而肥胖组中各基因型间BMI水平的差异无统计学意义(P>0.05)。经Hardy-Weinberg遗传平衡定律检验,其等位基因在两种人群中的分布符合遗传平衡,说明样本具有群体代表性。而该位点的等位基因及基因型频率在所收集的肥胖组与对照组样本中分布未见显著异常。结论 LEPR基因rs1137100位点多态性与广西壮族学龄前儿童单纯性肥胖无相关性。     

Interaction between genes and lifestyle factors on obesity

Obesity originates from a failure of the body-weight control systems, which may be affected by changing environmental influences. Basically, the obesity risk depends on two important mutually-interacting factors: (1) genetic variants (single-nucleotide polymorphisms, haplotypes); (2) exposure to environmental risks (diet, physical activity etc.). Common single-nucleotide polymorphisms at candidate genes for obesity may act as effect modifiers for environmental factors. More than 127 candidate genes for obesity have been reported and there is evidence to support the role of twenty-two genes in at least five different populations. Gene-environment interactions imply that the synergy between genotype and environment deviates from either the additive or multiplicative effect (the underlying model needs to be specified to appraise the nature of the interaction). Unravelling the details of these interactions is a complex task. Emphasis should be placed on the accuracy of the assessment methods for both genotype and lifestyle factors. Appropriate study design (sample size) is crucial in avoiding false positives and ensuring that studies have enough power to detect significant interactions, the ideal design being a nested case-control study within a cohort. A growing number of studies are examining the influence of gene-environmental interactions on obesity in either epidemiological observational or intervention studies. Positive evidence has been obtained for genes involved in adiposity, lipid metabolism or energy regulation such as PPARgamma2 (Pro12Ala), beta-adrenoceptor 2 (Gln27Glu) or uncoupling proteins 1, 2 and 3. Variants on other genes relating to appetite regulation such as melanocortin and leptin receptors have also been investigated. Examples of some recently-identified interactions are discussed.     

Melanin-concentrating hormone receptor mutations and human obesity: functional analysis

Melanin-concentrating hormone (MCH), a neuropeptide highly expressed in the lateral hypothalamus, has an important role in the regulation of energy balance and body weight in rodents. We examined whether mutations in the two known MCH receptors might be associated with obesity-related phenotypes in humans. Among 106 subjects with severe early onset obesity and a history of hyperphagia, we found two missense variants in MCHR1: Y181H and R248Q. Neither of these was found in 192 normal weight controls. R248Q cosegregated with obesity across two generations; family data were unavailable for Y181H. When expressed in HEK293 cells, R248Q showed no evidence of constitutive activation or ligand hypersensitivity for extracellular signal-regulated kinase phosphorylation. In addition, R248Q showed no enhanced suppression of cAMP generation. Two common single-nucleotide polymorphisms were found to be in linkage disequilibrium: g.-114A>G and c.39C>T. No association between either of these single-nucleotide polymorphisms and obesity-related phenotypes was found among a population cohort of 541 whites. Only two rare noncoding variants were found in MCHR2. In conclusion, mutations in the MCH receptors are not commonly found in humans with severe early onset obesity. Clarification of the relationship of these variants to obesity must await study in other populations and/or in genetically modified mice.     

儿童肥胖症与瘦素相关因素的研究进展

儿童肥胖症作为一种多因素疾病 ,是遗传物质与环境因素相互作用的结果 ,它与成人期的发病率及死亡率密切相关。因此 ,人们需要制定出更有效的策略来辨识儿童期肥胖的危险因素和它们在儿童期肥胖形成过程中所起的作用。肥胖基因产生的瘦素 ,曾一度为治愈儿童肥胖症带来了曙光。瘦素是一种特殊蛋白质 ,绝大多数由白色脂肪细胞分泌入血液循环 ,人们认为它与从脂肪贮存到下丘脑之间的负反馈有关。在动物研究中 ,瘦素被发现在增加饱腹感与能量消耗上起作用 ,但人类的瘦素抵抗作用使得利用瘦素治疗儿童肥胖症成为难题。该文就儿童肥胖症与瘦素相关因素的研究进展作以综述     

Influence of two polymorphisms of the tumoral necrosis factor-alpha gene on the obesity phenotype

Several populational-based studies have suggested an association between tumoral necrosis factor-alpha (TNF-alpha) polymorphisms and obesity-related phenotypes. Therefore, this study aimed at assessing the situation (frequency and associated phenotype) of two TNF-alpha common polymorphisms in a Spanish population. In a case-control design study, a group of Spanish subjects (n=313) were genotyped for the TNF-alpha G/A -308 and -238 polymorphisms. Obese subjects (cases) were compared with lean individuals (controls) according to body mass index (BMI; cases: BMI >30 kg/m2, controls: BMI <25 kg/m2). Waist-to-hip ratio, body composition and some metabolic indicators were assessed. The frequency of the -308A allele (0.14) and -238A allele (0.09) was similar to those previously reported in other Caucasian populations. Interestingly, cases with the -308A allele of the TNF-alpha gene have significantly higher hip and waist circumferences (p<0.05), BMI (p<0.01) and body fat mass (p<0.05) values than obese individuals carrying the -308G allele, but not the waist-to-hip ratio. No apparent influence of the -308A polymorphism on other metabolic indicators (insulin and leptin levels) was found. We could not detect any association between the substitution at position -238 polymorphism of the TNF-alpha gene and obesity anthropometrical phenotypes in this Spanish population, despite some differences in plasma leptin. These results support the hypothesis that the G/A -308 polymorphism of the TNF-alpha gene is associated with a higher BMI as well as hip ad waist circumferences, particularly on female bearers, while no influence on such measurements was found for the G/A -238 TNF-alpha gene polymorphism, but only an effect on leptinaemia.     

Association of obesity-related genetic variants with endometrial cancer risk: a report from the Shanghai Endometrial Cancer Genetics Study

Obesity is a well-established risk factor for endometrial cancer, the most common gynecologic malignancy. Recent genome-wide association studies (GWAS) have identified multiple genetic markers for obesity. The authors evaluated the association of obesity-related single nucleotide polymorphisms (SNPs) with endometrial cancer using GWAS data from their recently completed study, the Shanghai Endometrial Cancer Genetics Study, which comprised 832 endometrial cancer cases and 2,049 controls (1996-2005). Thirty-five SNPs previously associated with obesity or body mass index (BMI; weight (kg)/height (m)(2)) at a minimum significance level of ≤5 × 10(-7) in the US National Human Genome Research Institute's GWAS catalog (http://genome.gov/gwastudies) and representing 26 unique loci were evaluated by either direct genotyping or imputation. The authors found that for 22 of the 26 unique loci tested (84.6%), the BMI-associated risk variants were present at a higher frequency in cases than in population controls (P = 0.0003). Multiple regression analysis showed that 9 of 35 BMI-associated variants, representing 7 loci, were significantly associated (P ≤ 0.05) with the risk of endometrial cancer; for all but 1 SNP, the direction of association was consistent with that found for BMI. For consistent SNPs, the allelic odds ratios ranged from 1.15 to 1.29. These 7 loci are in the SEC16B/RASAL, TMEM18, MSRA, SOX6, MTCH2, FTO, and MC4R genes. The associations persisted after adjustment for BMI, suggesting that genetic markers of obesity provide value in addition to BMI in predicting endometrial cancer risk.     

瘦素受体Gln223Arg基因多态性与肥胖关系的研究

目的 研究瘦素受体Gln223Arg基因多态性与肥胖的关系。方法 2004年在山西省盂县选取一组人群，凋查其心血管病危险因素，同时抽血检测瘦素受体Gln223Arg基因多态性的基因型，并分析Gln223Arg基因多态性与肥胖的关系。结果 该组人群GG、GA及AA的基因型频率分别为0．7679、0．2171和0．0151；G和A等位基因频率分别为0．8764和0．1236。基因型频率分布符合Hardy-Weinberg平衡（P=0．934）。单因素分析结果表明携带A等位基因的研究对象具有更高的体重（63．2kg vs．61．9kg；P=0．0307）和体重指数（24．4kg／m^2 vs．24．1kg／m^2；P=00898）；在调整年龄、性别、体力活动和膳食之后，携带A等位基因者仍然具有较高的体重指数（24．5kg／m^2 vs．24．1kg/m^2；P=0．0396）和肥胖患病率（OR=1．30，95％CI：0．957～1．767；P=0．0935）。结论 瘦素受体Gln223Arg基因多态性与肥胖可能有关。     

Obesity--a genetic disease of adipose tissue?

Although the rapid increase in the prevalence of obesity in many countries suggests that environmental factors (mainly overeating and physical inactivity) play the most important role in the development of overweight, it is very likely that genetic factors also contribute. It appears that one major gene in combination with one or several minor genes constitute the genetic components behind excess accumulation of body fat in most obese individuals. However, monogenic obesity has been described in a few families due to changes in leptin, leptin receptor, prohormone convertase, pro-opiomelanocortin or melanocortin-4 receptor. None of the monogenic variants is of great importance for common human obesity; the latter genes are unknown so far. Results from genomic scans suggest that major obesity genes are located on chromosomes 2, 10, 11 and 20. Studies of candidate genes indicate that the minor obesity genes control important functions of adipose tissue, and that structural variance in these genes may alter adipose tissue function in a way that promotes obesity. Such genes are beta 2- and beta 3-adrenoceptors, hormone-sensitive lipase, tumour necrosis factor alpha, uncoupling protein-1, low-density lipoprotein receptor, and peroxisome proliferator activator receptor gamma-2. Some of these genes may promote obesity by gene-gene interactions (for example beta 3-adrenoceptors and uncoupling protein-1) or gene-environment interactions (for example beta 2-adrenoceptors and physical activity). Some are important for obesity only among women (for example beta 2- and beta 3-adrenoceptors, low-density lipoprotein receptor and tumour necrosis factor alpha). Few 'non-adipose' genes have so far shown a firm association to common human obesity, which could suggest that the important genes for the development of excess body fat also control adipose tissue function.     

Developments in obesity genetics in the era of genome-wide association studies

Obesity is an important factor contributing to the global burden of morbidity and mortality. By identifying obesity susceptibility genes, scientists aim to elucidate some of its aetiology. Early studies used candidate gene and genome-wide linkage approaches to search for such genes with limited success. However, the advent of genome-wide association studies (GWAS) has dramatically increased the pace of gene discovery. So far, GWAS have identified at least 50 loci robustly associated with body mass index (BMI), waist-to-hip ratio, body fat percentage and extreme obesity. Some of these have been shown to replicate in non-white populations and in children and adolescents. Furthermore, for some loci interaction studies have shown that the BMI-increasing effect is attenuated in physically active individuals. Despite many successful discoveries, the effect sizes of the established loci are small, and combined they explain only a fraction of the inter-individual variation in BMI. The low predictive value means that their value in mainstream health care is limited. However, as most of these newly established loci were not previously linked to obesity, they may provide new insights into body weight regulation. Continued efforts in gene discovery, using a range of approaches, will be needed to increase our understanding of obesity.     

ATP结合盒转运子1基因R219K多态性与缺血性脑卒中关系的Meta分析

目的：探讨三磷酸腺苷结合盒转运子1（ATP-binding cassettetransporter 1,ABCA1）基因R219K多态性与缺血性脑卒中的易感性关系。方法：全面检索ABCA1基因R219K多态性与缺血性脑卒中关系的病例对照研究,剔除不符合标准的文献,并采用RevMan 4.2软件对结果进行统计分析。结果：共纳入6篇文献7个研究,累计病例1 349例,对照1 389例。各研究间经齐性检验后未发现发表偏倚和明显异质性,合并的（RK＋KK）基因型/RR基因型的OR值为0.80（95%CI为0.68~0.94）。结论：ABCA1基因R219K多态性可能与缺血性脑卒中相关,K等位基因可能是缺血性脑卒中的遗传保护因素。