The search for putative unifying genetic factors for components of the metabolic syndrome

Epitranscriptional Regulation: From the Perspectives of Cardiovascular Bioengineering

The central dogma of gene expression involves DNA transcription to RNA and RNA translation into protein. As key intermediaries and modifiers, RNAs undergo various forms of modifications such as methylation, pseudouridylation, deamination, and hydroxylation. These modifications, termed epitranscriptional regulations, lead to functional changes in RNAs. Recent studies have demonstrated crucial roles for RNA modifications in gene translation, DNA damage response, and cell fate regulation. Epitranscriptional modifications play an essential role in development, mechanosensing, atherogenesis, and regeneration in the cardiovascular (CV) system, and their elucidation is critically important to understanding the molecular mechanisms underlying CV physiology and pathophysiology. This review aims at providing biomedical engineers with an overview of the epitranscriptome landscape, related key concepts, recent findings in epitranscriptional regulations, and tools for epitranscriptome analysis. The potential applications of this important field in biomedical engineering research are discussed.

Role of m6A methylation in retinal diseases

Retinal diseases remain among the leading causes of visual impairment in developed countries, despite great efforts in prevention and early intervention. Due to the limited efficacy of current retinal therapies, novel therapeutic methods are urgently required. Over the past two decades, advances in next-generation sequencing technology have facilitated research on RNA modifications, which can elucidate the relevance of epigenetic mechanisms to disease. N6-methyladenosine (m6A), formed by methylation of adenosine at the N6-position, is the most widely studied RNA modification and plays an important role in RNA metabolism. It is dynamically regulated by writers (methyltransferases) and erasers (demethylases), and recognized by readers (m6A binding proteins). Although the discovery of m6A methylation can be traced back to the 1970s, its regulatory roles in retinal diseases are rarely appreciated. Here, we provide an overview of m6A methylation, and discuss its effects and possible mechanisms on retinal diseases, including diabetic retinopathy, age-related macular degeneration, retinoblastoma, retinitis pigmentosa, and proliferative vitreoretinopathy. Furthermore, we highlight potential agents targeting m6A methylation for retinal disease treatment and discuss the limitations and challenges of research in the field of m6A methylation.

Relationship between the FTO Genotype and Early Chronic Kidney Disease in Type 2 Diabetes: The Mediating Role of Central Obesity, Hypertension, and High Albuminuria

INTRODUCTION

Single nucleotide polymorphisms (SNP) in the fat mass and obesity-associated (FTO) gene have been associated with type 2 diabetes (T2D) and its complications. The aim of the present research was to investigate which and how (directly or indirectly) clinical and metabolic variables mediate the association between fat mass and the FTO gene and early chronic kidney disease (CKD) in individuals with T2D.

METHODS

This cross-sectional study was conducted in a sample of 236 participants with T2D (53.4% women, mean age 60 ± 10 years). DNA samples were genotyped for the rs7204609 polymorphism (C/T) in the FTO gene. Clinical, anthropometric, and metabolic data were collected. Path analysis was used to evaluate the associations.

RESULTS

Of the sample, 78 individuals with T2D had CKD (33%). Presence of the risk allele (C) was higher among participants with CKD (21.8 vs. 10.8%; p = 0.023). This polymorphism was positively associated with higher waist circumference, which in turn was associated with higher glycated hemoglobin and higher blood pressure. A higher blood-pressure level was associated with higher urinary albumin excretion (UAE) and as expected, higher UAE was associated with CKD. Path analysis showed an indirect relationship between the FTO gene and early CKD, mediated by waist circumference, blood-pressure levels, and UAE.

CONCLUSIONS

These findings suggest that the C allele may contribute to genetic susceptibility to CKD in individuals with T2D through the presence of central obesity, hypertension, and high albuminuria.

The metabolic syndrome - What is it and how should it be managed?

A cluster of metabolic factors have been merged into an entity named the metabolic syndrome. Although the characteristics of this syndrome have varied over time the presently used definition was established in 2009. The presence of three abnormal findings out of five components qualifies a person for the metabolic syndrome: elevated waist circumference, elevated triglycerides, reduced high-density lipoprotein cholesterol, elevated blood pressure and elevated fasting plasma glucose. Cut points have been defined for all components apart from waist circumference, for which national or regional values are used. The metabolic syndrome predicts cardiovascular disease and type 2 diabetes. This associated risk does not exceed its components whereof elevated blood pressure is the most frequent. A successful management should, however, address all factors involved. The management is always based on healthy lifestyle choices but has not infrequently to be supported by pharmacological treatment, especially blood pressure lowering drugs. The metabolic syndrome is a useful example of the importance of multiple targets for preventive interventions. To be successful management has to be individualized not the least when it comes to pharmacological therapy. Frail elderly people should not be over-treated. Knowledge transfer of how risk factors act should be accompanied by continuous trust building and motivation. In complex situations with a mix of biological risk factors, adverse social conditions and unhealthy lifestyle, everything cannot be changed at once. It is better to aim for small steps that are lasting than large, unsustainable steps with relapses to unhealthy behaviours. A person with the metabolic syndrome will always be afflicted by its components, which is the reason that management has to be sustained over a very long time. This review summarizes the knowledge on the metabolic syndrome and its management according to present state of the art.

IGF2BP1 silencing inhibits proliferation and induces apoptosis of high glucose-induced non-small cell lung cancer cells by regulating Netrin-1

Non-small cell lung cancer (NSCLC) accompanied by diabetes is an important risk factor affecting the prognosis of patients with NSCLC in clinical practice. However, the effect of high glucose (HG) in the pathogenesis of NSCLC remains elusive. It has been found that the RNA-binding protein Insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) plays important roles in various diseases, including NSCLC and diabetes. The aim of this study was to explore the role of IGF2BP1 in HG-treated NSCLC cells, and further investigate its underlying molecular mechanism. Results showed that IGF2BP1 was highly expressed in HG-treated NSCLC cells. Knockdown of IGF2BP1 inhibited cancer cell proliferation, migration and invasion, as well as induced cell cycle arrest and apoptosis. Besides, IGF2BP1 silencing decreased the Netrin-1 level in HG-treated NSCLC cells. Reintroduction of Netrin-1 expression rescued IGF2BP1 deficiency-induced cell proliferation reduction, migration suppression, cell cycle arrest and apoptosis. These findings suggest that IGF2BP1 silencing inhibits the occurrence of tumor events through down-regulating Netrin-1 expression, indicating that the IGF2BP1/Netrin-1 axis exerts an oncogenic role in HG-treated NSCLC cells.

The association of the metabolic syndrome with target organ damage: focus on the heart, brain, and central arteries

INTRODUCTION

The metabolic syndrome (MetS) is an adverse metabolic state composed of obesity, hyperglycemia/pre-diabetes, hypertension, and dyslipidemia. It substantially increases the risk of type 2 diabetes, cardiovascular disease (CVD) and mortality, and has a huge impact on public health.

AREA COVERED

The present review gives an update on the definition and prevalence of MetS, and its impact on cardiac structure and function as well as on the brain and central arteries. The association with CVD and mortality risk is discussed. Focus is mainly directed toward the subclinical target organ damage related to MetS. Data is also critically reviewed to provide evidence on the incremental prognostic value of overall MetS over its individual components.

EXPERT COMMENTARY

MetS is a clinical risk condition associated with subclinical and clinical CVD and mortality. Roughly, 30% of the world population suffer from MetS. As all components of the MetS are modifiable, optimal preventive and therapeutic measures should be initiated to improve CV risk control, particularly aggressively treating hypertension and hyperglycemia, and encouraging people to adopt healthy lifestyle as early as possible is of great importance.

Human Insulin Growth Factor 2 mRNA Binding Protein 2 Increases MicroRNA 33a/b Inhibition of Liver ABCA1 Expression and Alters Low-Density Apolipoprotein Levels in Mice

Genome-wide association studies (GWAS) have linked IGF2BP2 single-nucleotide polymorphisms (SNPs) with type 2 diabetes (T2D). Mice overexpressing mIGF2BP2 have elevated cholesterol levels when fed a diet that induces hepatic steatosis. These and other studies suggest an important role for insulin growth factor 2 mRNA binding protein 2 (IGF2BP2) in the initiation and progression of several metabolic disorders. The ATPase binding cassette protein ABCA1 initiates nascent high-density apolipoprotein (HDL) biogenesis by transferring phospholipid and cholesterol to delipidated apolipoprotein AI (ApoAI). Individuals with mutational ablation of ABCA1 have Tangier disease, which is characterized by a complete loss of HDL. MicroRNA 33a and 33b (miR-33a/b) bind to the 3' untranslated region (UTR) of ABCA1 and repress its posttranscriptional gene expression. Here, we show that IGF2BP2 works together with miR-33a/b in repressing ABCA1 expression. Our data suggest that IGF2BP2 is an accessory protein of the argonaute (AGO2)-miR-33a/b-RISC complex, as it directly binds to miR-33a/b, AGO2, and the 3' UTR of ABCA1 Finally, we show that mice overexpressing human IGF2BP2 have decreased ABCA1 expression, increased low-density lipoprotein-cholesterol (LDL-C) and cholesterol blood levels, and elevated SREBP-dependent signaling. Our data support the hypothesis that IGF2BP2 has an important role in maintaining lipid homeostasis through its modulation of ABCA1 expression, as its overexpression or loss leads to dyslipidemia.

Common genetic variation in obesity, lipid transfer genes and risk of Metabolic Syndrome: Results from IDEFICS/I.Family study and meta-analysis

As the prevalence of metabolic syndrome (MetS) in children and young adults is increasing, a better understanding of genetics that underlie MetS will provide critical insights into the origin of the disease. We examined associations of common genetic variants and repeated MetS score from early childhood to adolescence in a pan-European, prospective IDEFICS/I.Family cohort study with baseline survey and follow-up examinations after two and six years. We tested associations in 3067 children using a linear mixed model and confirmed the results with meta-analysis of identified SNPs. With a stringent Bonferroni adjustment for multiple comparisons we obtained significant associations(p < 1.4 × 10⁻⁴) for 5 SNPs, which were in high LD (r² > 0.85) in the 16q12.2 non-coding intronic chromosomal region of FTO gene with strongest association observed for rs8050136 (effect size(β) = 0.31, p_Wald = 1.52 × 10⁻⁵). We also observed a strong association of rs708272 in CETP with increased HDL (p = 5.63 × 10⁻⁴⁰) and decreased TRG (p = 9.60 × 10⁻⁵) levels. These findings along with meta-analysis advance etiologic understanding of childhood MetS, highlighting that genetic predisposition to MetS is largely driven by genes of obesity and lipid metabolism. Inclusion of the associated genetic variants in polygenic scores for MetS may prove to be fundamental for identifying children and subsequently adults of the high-risk group to allow earlier targeted interventions.

TCF7L2 gene variants predispose to the development of type 2 diabetes mellitus among individuals with metabolic syndrome

INTRODUCTION

Transcription factor 7-like 2 (TCF7L2) gene variants rs12255372 and rs7903146 have been consistently shown to raise genetic risk for type 2 diabetes mellitus (T2DM). The aim of this study was to investigate the possible role of these variants in the development of impaired glucose metabolism (IGM), including impaired fasting glucose (IFG) or T2DM, in patients with metabolic syndrome (MS).

PATIENTS AND METHODS

The study population consisted of 228 patients with MS who were divided into two groups. The first group consisted of 148 patients with MS and IGM [39M/109F, 59.8 ± 14.6 (mean ± SD) years] and the second group of 80 patients with MS and normoglycemia (NGM) (16M/64F, 56.1 ± 15.8 years). The diagnosis of MS was based on the criteria proposed by the American Heart Association/National Heart, Lung, and Blood Institute (AHA/NHLBI) Scientific Statement. Anthropometric parameters including BMI and waist circumference were recorded and blood samples were obtained after overnight fasting for biochemical tests. The rs12255372 and rs7903146 TCF7L2 polymorphisms were genotyped in peripheral blood leucocytes.

RESULTS

Analysis of the distribution of the TCF7L2 polymorphic alleles revealed that the frequency of the T allele of the TCF7L2 variant rs12255372 was 38.2% in the study population, while the frequency of the T allele of the TCF7L2 rs7903146 variant was 35.3%. The T allele of the rs12255372 variant was more frequently present in patients with MS and IGM (48.3%) compared to patients with MS and NGM (19.4%, p < 0.001). Also, the T allele of rs7903146 was more frequently present in patients with MS and IGM (44.6%) compared to patients with MS and NGM (18.1%, p < 0.001). Logistic regression analysis followed and revealed that the presence of the T allele for both rs12255372 and rs7903146 TCF7L2 gene variants is a very powerful predictor of the presence of glucose disorders, increasing the risk more than fourfold in patients with MS and after adjustment for potential confounders, such as age, gender, BMI, and waist circumference (TCF7L2 rs12255372: Exp(B) 4.917, p < 0.001 and TCF7L2 rs7903146: Exp(B) 5.460, p < 0.001).

CONCLUSION

The presence of the rs12255372 and rs7903146 TCF7L2 gene variants plays an important role in the development of T2DM among individuals with MS. These findings support the notion that among subjects with MS, those who finally develop T2DM have a genetic predisposition to β-cell dysfunction.

Genome organization: connecting the developmental origins of disease and genetic variation

An adverse early life environment can increase the risk of metabolic and other disorders later in life. Genetic variation can modify an individual's susceptibility to these environmental challenges. These gene by environment interactions are important, but difficult, to dissect. The nucleus is the primary organelle where environmental responses impact directly on the genetic variants within the genome, resulting in changes to the biology of the genome and ultimately the phenotype. Understanding genome biology requires the integration of the linear DNA sequence, epigenetic modifications and nuclear proteins that are present within the nucleus. The interactions between these layers of information may be captured in the emergent spatial genome organization. As such genome organization represents a key research area for decoding the role of genetic variation in the Developmental Origins of Health and Disease.

Transcription factor 7-like 2 polymorphism and context-specific risk of metabolic syndrome, type 2 diabetes, and dyslipidemia

BACKGROUND

The transcription factor 7-like 2 gene (TCF7L2) is an element of the Wnt signaling pathway. There is lack of evidence if TCF7L2 has a functional role in lipid metabolism and regulation of the components constitutes the metabolic syndrome (MetSyn). The aims of this study were to evaluate whether the risk allele of TCF7L2 gene polymorphism is associated with dyslipidemia and MetSyn.

MATERIALS AND METHODS

The MetSyn subjects were participated only based on the National Cholesterol Education Program - Third Adult Treatment Panel criteria. In this case-control study, the DNA from MetSyn patients without (n = 90) and with type 2 diabetes (T2D) (n = 94) were genotyped.

RESULTS

The results show that the genotype-phenotype for CC, CT/TT of TCF7L2 gene polymorphism correlated with body mass index and waist circumference in MetSyn and MetSyn + T2D subjects (r = -0.949 and r = -0.963, respectively). The subjects that only possess MetSyn but are not diabetics show the 2 h postprandial glucose and fasting blood glucose, glycated hemoglobin significantly lower (P < 0.05) than those subjects have both abnormality. The level of triglyceride in CT/TT carriers in MetSyn was higher than CC carriers (P = 0.025). A comparison with the controls subjects, the frequencies of the T allele in the groups of MetSyn (46.66%) and MetSyn + T2D (47.34%) show significantly different (P < 0.05). The odds ratios for T allele in (MetSyn)/(normal), (MetSyn + T2D)/(normal), and in (MetSyn + T2D)/(MetSyn) were 3.59 (95% confidence interval [CI], 1.33-9.67, P = 0.0093), 3.76 (95% CI, 1.40-10.07, P = 0.0068), and 1.08 (95% CI: 0.55- 2.11, P = 0.834), respectively.

CONCLUSION

The results revealed the important insights essential for the role of TCF7L2 that the T allele of TCF7L2 plays a significant role in the susceptibility to dyslipidemia, MetSyn, and T2D.

Physical activity, but not dietary intake, attenuates the effect of the FTO rs9939609 polymorphism on obesity and metabolic syndrome in Lithuanian adult population

OBJECTIVES

This study aimed to examine the associations between the fat mass and obesity associated (FTO) gene rs9939609 variant with obesity and metabolic syndrome and interactions between FTO alleles, dietary intake and physical activity in Lithuanian adult population.

STUDY DESIGN

Cross-sectional study.

METHODS

A health survey was carried out in randomly selected municipalities of Lithuania. The random sample was obtained from the lists of 25-64 year-old inhabitants. The data from 1020 individuals were analyzed. The single-nucleotide polymorphism, rs9939609, in the FTO gene was assessed using a real-time polymerase chain reaction. 24-hour recall was used for evaluation of dietary habits. Information on physical activity at work, traveling to and from work and at leisure time was gathered by a standard questionnaire.

RESULTS

The carriers of the AA genotype had the highest mean values of body mass index (BMI) and waist circumference (WC). They had 1.72 time higher odds of obesity (P = 0.009) and 1.67 time higher odds of increased WC (P = 0.013) than those with the TT genotype. Carriers of the T allele had lower prevalence of metabolic syndrome compared to carriers of the AA genotype (33.8% and 42.5% respectively; P = 0.018). No interaction between the rs9939609 variant and energy or dietary intakes on weight status was found. Significant effect of the interactions 'genotype×age' and 'genotype×physical activity' on BMI was demonstrated. The FTO rs9939609 polymorphism was associated with anthropometric parameters and metabolic syndrome in the younger age group (25-44 years) and in individuals having low level of physical activity.

CONCLUSIONS

Age and physical activity modulated the effect of the FTO polymorphism on weight status and metabolic syndrome in Lithuanian adult population.

A systematic review of genetic variants associated with metabolic syndrome in patients with schizophrenia

Metabolic syndrome (MetS) is a cluster of factors that increases the risk of cardiovascular disease (CVD), one of the leading causes of mortality in patients with schizophrenia. Incidence rates of MetS are significantly higher in patients with schizophrenia compared to the general population. Several factors contribute to this high comorbidity. This systematic review focuses on genetic factors and interrogates data from association studies of genes implicated in the development of MetS in patients with schizophrenia. We aimed to identify variants that potentially contribute to the high comorbidity between these disorders. PubMed, Web of Science and Scopus databases were accessed and a systematic review of published studies was conducted. Several genes showed strong evidence for an association with MetS in patients with schizophrenia, including the fat mass and obesity associated gene (FTO), leptin and leptin receptor genes (LEP, LEPR), methylenetetrahydrofolate reductase (MTHFR) gene and the serotonin receptor 2C gene (HTR2C). Genetic association studies in complex disorders are convoluted by the multifactorial nature of these disorders, further complicating investigations of comorbidity. Recommendations for future studies include assessment of larger samples, inclusion of healthy controls, longitudinal rather than cross-sectional study designs, detailed capturing of data on confounding variables for both disorders and verification of significant findings in other populations. In future, big genomic datasets may allow for the calculation of polygenic risk scores in risk prediction of MetS in patients with schizophrenia. This could ultimately facilitate early, precise, and patient-specific pharmacological and non-pharmacological interventions to minimise CVD associated morbidity and mortality.

The Association of Type 2 Diabetes Loci Identified in Genome-Wide Association Studies with Metabolic Syndrome and Its Components in a Chinese Population with Type 2 Diabetes

Metabolic syndrome (MetS) is prevalent in type 2 diabetes (T2D) patients. The comorbidity of MetS and T2D increases the risk of cardiovascular complications. The aim of the present study was to determine the T2D-related genetic variants that contribute to MetS-related components in T2D patients of Chinese ancestry. We successfully genotyped 25 genome wide association study validated T2D-related single nucleotide polymorphisms (SNPs) among 5,169 T2D individuals and 4,560 normal glycemic controls recruited from the Chinese National Diabetes and Metabolic Disorders Study (DMS). We defined MetS in this population using the harmonized criteria (2009) combined with the Chinese criteria for abdominal obesity. The associations between SNPs and MetS-related components, as well as the associations between SNPs and risk for T2D with or without MetS, were subjected to logistic regression analysis adjusted for age and sex. Results showed that the T2D risk alleles of rs243021 located near BCL11A, rs10830963 in MTNR1B, and rs2237895 in KCNQ1 were related to a lower risk for abdominal obesity in T2D patients (rs243021: 0.92 (0.84, 1.00), P = 4.42 × 10⁻²; rs10830963: 0.92 (0.85, 1.00), P = 4.07 × 10⁻²; rs2237895: 0.89 (0.82, 0.98), P = 1.29 × 10⁻²). The T2D risk alleles of rs972283 near KLF14 contributed to a higher risk of elevated blood pressure (1.10 (1.00, 1.22), P = 4.48 × 10⁻²), while the T2D risk allele of rs7903146 in TCF7L2 was related to a lower risk for elevated blood pressure (0.74 (0.61, 0.90), P = 2.56 × 10⁻³). The T2D risk alleles of rs972283 near KLF14 and rs11634397 near ZFAND6 were associated with a higher risk for elevated triglycerides (rs972283: 1.11 (1.02, 1.24), P = 1.46 × 10⁻²; rs11634397: 1.14 (1.00, 1.29), P = 4.66 × 10⁻²), while the T2D risk alleles of rs780094 in GCKR and rs7903146 in TCF7L2 were related to a lower risk of elevated triglycerides (rs780094: 0.86 (0.80, 0.93), P = 1.35 × 10⁻⁴; rs7903146: 0.82 (0.69, 0.98), P = 3.18 × 10⁻²). The genotype risk score of the 25 T2D-related SNPs was related to a lower risk for abdominal obesity (P_trend = 1.29 × 10⁻²) and lower waist circumference (P = 2.20 × 10⁻³). Genetic variants of WFS1, CDKAL1, CDKN2BAS, TCF7L2, HHEX, KCNQ1, TSPAN8/LGR5, FTO, and TCF2 were associated with the risk for T2D with MetS, as well as the risk for development of T2D with at least one of the MetS components (P < 0.05). In addition, genetic variants of BCL11A, GCKR, ADAMTS9, CDKAL1, KLF14, CDKN2BAS, TCF7L2, CDC123/CAMK1D, HHEX, MTNR1B, and KCNQ1 contributed to the risk for T2D without MetS (P < 0.05). In conclusion, these findings highlight the contribution of T2D-related genetic loci to MetS in a Chinese Han population. The study also provides insight into the pleotropic effects of genome-wide association loci of diabetes on metabolic regulation.

Haplotype analysis of the Apolipoprotein A5 gene in Moroccan patients with the metabolic syndrome

BACKGROUND

In this case-control study we investigated the relative contribution of commons APOA5 polymorphisms and haplotypes to the risk of metabolic syndrome in Moroccan patients.

METHODS

Using the International Diabetes Federation (IDF) criteria for metabolic syndrome, the study included 176 patients and 105 controls. We genotyped APOA5 polymorphisms (-1131 T > C, c.56C > G, c.553G > T and c.1259 T > C) by PCR-RFLP analysis. The effects of APOA5 polymorphisms and constructed haplotypes on metabolic syndrome were estimated using logistic regression analyses.

RESULTS

The statistical analysis showed a significant association between APOA5 -1131 T > C and APOA5 c.56C > G polymorphisms with metabolic syndrome in both Codominant and Dominant models. The APOA5 -1131 T > C polymorphism was associated with increased fasting glucose (p = 0.0295) and reduced HDL levels (p = 0.0091). Carriers of the APOA5 c.56G allele had increased triglyceride levels (p = 0.0435) and waist circumference (p = 0.0122). Similarly the APOA5 1259 T > C variant was associated with increased waist circumference (p = 0.0463). The haplotypes CCGT (OR = 3.223; p = 0.00278) and CGGT (OR = 8.234; p = 0.00534) were significantly associated with susceptibility to metabolic syndrome.

CONCLUSIONS

Our results confirms the association of APOA5 -1131 T > C and c.56C > G variants with the predisposition to metabolic syndrome complications.

Contribution of CDKAL1 rs7756992 and IGF2BP2 rs4402960 polymorphisms in type 2 diabetes, diabetic complications, obesity risk and hypertension in the Tunisian population

BACKGROUND

The insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) and the cyclin-dependent kinase 5 regulatory subunit-associated protein 1-like 1 (CDKAL1) identified through genome-wide association (GWA) studies have been shown to be associated with Type 2 diabetes in various ethnic groups. In this study, we investigated the association of the rs7756992 of CDKAL1 and the rs4402960 of IGF2BP2 with Type 2 diabetes, diabetic complications (nephropathy, retinopathy and cardiovascular disease), obesity and hypertension in a Tunisian population.

METHODS

A case-control association study including 200 Type 2 diabetes Tunisian patients (World Health Organization criteria) and 208 controls (age ≥40; fasting plasma glucose <6.1 mmol/L; without first degree family history of diabetes) has been performed. Other parameters such as diabetic nephropathy, diabetic retinopathy, cardiovascular disease, overweight/obesity and hypertension have been also collected. Genotyping was performed using TaqMan technology.

RESULTS

A significant association between the rs4402960 and Type 2 diabetes (OR = 1.86, 95% CI = 1.34-2.58, P < 10(-4) ) has been found. Overweight/obese subjects bearing the T-allele have an increased risk to develop Type 2 diabetes (OR = 2.06, 95% CI = 1.40-3.03, P < 10(-4) ). Furthermore, the rs7756992 was found to be associated with the reduced risk of diabetic nephropathy in patients with diabetes (OR = 0.44, 95% CI = 0.27-0.73, P = 0.001).

CONCLUSIONS

The present study confirms that the rs4402960 of IGF2BP2 gene is a strong candidate for Type 2 diabetes susceptibility and overweight/obesity risk in the Tunisian population. Interestingly, our data suggest that the rs7756992 of CDKAL1 gene have a protective effect against diabetic nephropathy.

The effect of IGF2BP2 gene polymorphisms on pioglitazone response in Chinese type 2 diabetes patients

BACKGROUND

Genome-wide association studies identified that insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) genetic polymorphisms are related to type 2 diabetes mellitus (T2DM) in several populations. This study aimed to investigate whether the IGF2BP2 gene rs1470579 and rs4402960 polymorphisms were associated with T2DM and pioglitazone efficacy in Chinese T2DM patients.

METHODS

A total of 281 T2DM patients and 111 healthy volunteers were enrolled to identify the IGF2BP2 gene rs1470579 and rs4402960 polymorphisms; 86 patients were randomly selected and given a 12-week pioglitazone treatment (30 mg/day). Fasting plasma glucose, postprandial plasma glucose (PPG), glycated hemoglobin, serum triglycerides (TG), total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol (HDL-C) were determined before and after pioglitazone treatment.

RESULTS

The results showed that the IGF2BP2 gene rs1470579 and rs4402960 polymorphisms were associated with T2DM in a Chinese population (OR = 2.002, 95% CI 1.170-3.426, p < 0.05; OR = 1.879, 95% CI 1.110-3.182, p < 0.05). The effect of pioglitazone on PPG (p < 0.05), TG (p < 0.01) and HDL-C (p < 0.05) was lower in patients with the rs1470579 AC+CC genotypes than in AA genotype carriers. Its effect on PPG level was also lower in patients with the GT+TT genotypes of rs4402960 than in patients with the GG genotype (p < 0.05).

CONCLUSIONS

The IGF2BP2 gene rs1470579 and rs4402960 polymorphisms were associated with T2DM and therapeutic efficacy of pioglitazone in this Chinese population.

FTO gene variant and risk of hypertension: a meta-analysis of 57,464 hypertensive cases and 41,256 controls

OBJECTIVES

Recent studies have suggested that fat mass and obesity-associated gene (FTO) may predispose individuals to develop hypertension. However, the results have been inconsistent. We performed a meta-analysis to investigate the relationship of FTO gene variant with risk of hypertension and influence of body mass index (BMI) on this risk.

MATERIALS/METHODS

A systematic literature search in PubMed, Embase and ISI web of science databases was performed to identify eligible published literatures. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

RESULTS

A total of seven studies comprising 57,464 hypertensive cases and 41,256 controls met the inclusion criteria and were included in the meta-analysis. The FTO gene variant(s) showed significant association with the risk of hypertension (OR=1.16, 95% CI=1.07-1.25, P<0.001) which disappeared on adjustment for BMI (OR=1.04, 95% CI=0.98-1.10, P=0.162). In addition, stratified analysis demonstrated a significant association of the FTO variant with the risk of hypertension in obese subjects (OR=1.10, 95% CI=1.01-1.19, P=0.032) but not in non-obese individuals (OR=1.00, 95% CI=0.97-1.03, P=0.832). Subgroup analysis based on ethnicity showed significant association between FTO variant and hypertension in both European (OR=1.07, 95% CI=1.01-1.14, P=0.028) and Asian populations (OR=1.37, 95% CI=1.23-1.53, P<0.001). However, the association remained significant only in Asians (OR=1.17, 95% CI=1.01-1.35, P=0.035) but not in the Europeans (OR=1.02, 95% CI=0.97-1.07, P=0.390) on adjustment for BMI.

CONCLUSIONS

The present meta-analysis confirms that FTO genotype mediates obesity-related hypertension.

A polymorphism of HMGA1 is associated with increased risk of metabolic syndrome and related components

The metabolic syndrome (MetS) is a common disorder, where systemic insulin-resistance is associated with increased risk for type 2 diabetes (T2D) and cardiovascular disease. Identifying genetic traits influencing risk and progression of MetS is important. We and others previously reported a functional HMGA1 gene variant, rs146052672, predisposing to T2D. Here we investigated the association of rs146052672 variant with MetS and related components. In a case-control study from Italy and Turkey, increased risk of MetS was seen among carriers of the HMGA1 variant. In the larger Italian cohort, this variant positively correlated with BMI, hyperglycemia and insulin-resistance, and negatively correlated with serum HDL-cholesterol. Association between rs146052672 variant and MetS occurred independently of T2D, indicating that HMGA1 gene defects play a pathogenetic role in MetS and other insulin-resistance-related conditions. Overall, our results indicate that the rs146052672 variant represents an early predictive marker of MetS, as well as a predictive tool for therapy.

Relation of the rs9939609 gene variant in FTO with metabolic syndrome in obese female patients

OBJECTIVES

Common polymorphisms of the fat mass and obesity associated gene (FTO) have been linked to obesity and diabetes mellitus type 2 in some populations. The aim of our study was to analyze the relationship of the rs9939609 FTO gene polymorphism with metabolic syndrome and its components.

MATERIAL AND METHODS

A population of 457 obese Caucasian females was analyzed in a cross-sectional survey. To estimate the prevalence of Metabolic Syndrome, the definitions of the ATPIII were considered. Genotype of FTO gene polymorphism (rs9939609) was studied.

RESULTS

One hundred and thirty patients (28.4%) had the genotype TT (wild group), whereas 227 patients (49.7%) had the genotype TA and 100 patients (21.9%) had the genotype AA. Prevalence of metabolic syndrome (MS) with ATP III definition was 40.7% (186 patients) and 59.3% patients had no MS (n = 271). Prevalence of mutant FTO genotypes was similar in patients with metabolic syndrome (27.4% wild genotype and 72.6% mutant genotype) and without metabolic syndrome (29.2% wild genotype and 70.8% mutant genotype).Odds ratio of metabolic syndrome in wild vs mutant genotype was 1.04 (95% CI: 0.87-1.22). Insulin levels (13.9±6.3 mUI/L vs. 12.6 ± 3.4 mUI/L; p<0.05), HOMA-R (3.3 ± 1.6 vs. 2.8 ± 1.4; p < 0.05) and triglycerides concentrations (110.8 ± 27.3 mg/dl vs. 103.1 ± 47.3 mg/dl; p < 0.05) were lower in the mutant type group than the wild type group in patients without metabolic syndrome.

CONCLUSION

The FTO gene polymorphism (rs9939609) was found to be associated with increased insulin resistance, insulin and triglyceride levels in obese females with TT variant and without metabolic syndrome. MS or its components were not associated with this polymorphism in obese females.

Nutrigenetics and metabolic disease: current status and implications for personalised nutrition

Obesity, particularly central adiposity, is the primary causal factor in the development of insulin resistance, the hallmark of the metabolic syndrome (MetS), a common condition characterized by dyslipidaemia and hypertension, which is associated with increased risk of cardiovascular disease (CVD) and type 2 diabetes (T2DM). Interactions between genetic and environmental factors such as diet and lifestyle, particularly over-nutrition and sedentary behavior, promote the progression and pathogenesis of these polygenic diet-related diseases. Their current prevalence is increasing dramatically to epidemic proportions. Nutrition is probably the most important environmental factor that modulates expression of genes involved in metabolic pathways and the variety of phenotypes associated with obesity, the MetS and T2DM. Furthermore, the health effects of nutrients may be modulated by genetic variants. Nutrigenomics and nutrigenetics require an understanding of nutrition, genetics, biochemistry and a range of “omic” technologies to investigate the complex interaction between genetic and environmental factors relevant to metabolic health and disease. These rapidly developing fields of nutritional science hold much promise in improving nutrition for optimal personal and public health. This review presents the current state of the art in nutrigenetic research illustrating the significance of gene-nutrient interactions in the context of metabolic disease.

The common SNP (rs9939609) in the FTO gene modifies the association between obesity and high blood pressure in Chinese children

Previous studies have suggested that common variants in fat mass- and obesity-associated (FTO) gene are associated with body mass index (BMI) and the risk of obesity. Since obesity plays an important role in the etiology of high blood pressure (HBP), we aim to investigate the association between obesity and HBP in a population with different variants of the FTO gene. A total of 3,494 children (1,775 boys, 50.8 %) aged 6-18 years were recruited for measuring pubertal status, BMI and systolic and diastolic blood pressure. The single nucleotide polymorphism rs9939609 of the FTO gene was genotyped. The blood pressure levels increased by 1.4, 1.5 and 1.8 mmHg for systolic blood pressure and 0.8, 0.9 and 1.2 mmHg for diastolic blood pressure per 1-unit BMI increase in subjects carrying TT, TA and AA genotypes, respectively. After stratifying for FTO rs9939609 genotypes (TT, TA and AA), the odds ratios (95 % confidence intervals) of HBP in obese versus non-obese children were 4.26 (3.18-5.71), 5.13 (2.96-8.90) and 10.37 (1.59-67.43), respectively, with adjustment for age, gender and pubertal status. The FTO rs9939609 SNP modifies the effect of obesity on HBP in Chinese children, with obese ones carrying the AA homozygous genotype of the FTO rs9939609 having the highest risk of developing HBP.

Single nucleotide polymorphisms (SNPs) involved in insulin resistance, weight regulation, lipid metabolism and inflammation in relation to metabolic syndrome: an epidemiological study

BACKGROUND

Mechanisms involved in metabolic syndrome (MetS) development include insulin resistance, weight regulation, inflammation and lipid metabolism. Aim of this study is to investigate the association of single nucleotide polymorphisms (SNPs) involved in these mechanisms with MetS.

METHODS

In a random sample of the EPIC-NL study (n = 1886), 38 SNPs associated with waist circumference, insulin resistance, triglycerides, HDL cholesterol and inflammation in genome wide association studies (GWAS) were selected from the 50K IBC array and one additional SNP was measured with KASPar chemistry. The five groups of SNPs, each belonging to one of the metabolic endpoints mentioned above, were associated with MetS and MetS-score using Goeman's global test. For groups of SNPs significantly associated with the presence of MetS or MetS-score, further analyses were conducted.

RESULTS

The group of waist circumference SNPs was associated with waist circumference (P=0.03) and presence of MetS (P=0.03). Furthermore, the group of SNPs related to insulin resistance was associated with MetS score (P<0.01), HDL cholesterol (P<0.01), triglycerides (P<0.01) and HbA1C (P=0.04). Subsequent analyses showed that MC4R rs17782312, involved in weight regulation, and IRS1 rs2943634, related to insulin resistance were associated with MetS (OR 1.16, 95%CI 1.02-1.32 and OR 0.88, 95% CI 0.79; 0.97, respectively). The groups of inflammation and lipid SNPs were neither associated with presence of MetS nor with MetS score.

CONCLUSIONS

In this study we found support for the hypothesis that weight regulation and insulin metabolism are involved in MetS development.MC4R rs17782312 and IRS1 rs2943634 may explain part of the genetic variation in MetS.

Strong association of common variants in the IGF2BP2 gene with type 2 diabetes in Lebanese Arabs

OBJECTIVE

Several genome-wide association studies and replication analyses have identified common variation at the insulin-like binding protein 2 (IGF2BP2) gene to be associated with type 2 diabetes (T2DM). The aim of this study was to replicate in a Lebanese Arab population identified associations of IGF2BP2 variants rs4402960 and rs1470579 with T2DM.

METHODS

This case-control study involved 544 T2DM patients and 606 control subjects. Genotyping was done by the allelic exclusion method.

RESULTS

T allele of rs440960 (P=6.5 × 10(-6)) and C allele of rs1470579 (P=5.3 × 10(-4)) were significantly associated with T2DM; both SNPs were in strong LD (D'=0.83, r(2)=0.58). While both IGF2BP2 SNPs were significantly associated with T2DM under additive and recessive models, only rs4402960 remained significantly associated with T2DM under the dominant model. Taking the common rs4402960/rs1470579 GA haplotype as reference, multivariate analysis confirmed the positive association of TC (P=0.009; OR, 1.43; 95%CI, 1.09-1.87), and TA (P<0.001; OR=5.49; 95%CI=2.09-14.39) haplotypes with increased T2DM risk. These differences remained significant after applying the Bonferroni correction for multiple testing.

CONCLUSION

We validate that IGF2BP2 susceptibility variants rs4402960 and rs1470579 associate with T2DM in Lebanese Arabs.

Genome-wide screen for metabolic syndrome susceptibility Loci reveals strong lipid gene contribution but no evidence for common genetic basis for clustering of metabolic syndrome traits

BACKGROUND

Genome-wide association (GWA) studies have identified several susceptibility loci for metabolic syndrome (MetS) component traits, but have had variable success in identifying susceptibility loci to the syndrome as an entity. We conducted a GWA study on MetS and its component traits in 4 Finnish cohorts consisting of 2637 MetS cases and 7927 controls, both free of diabetes, and followed the top loci in an independent sample with transcriptome and nuclear magnetic resonance-based metabonomics data. Furthermore, we tested for loci associated with multiple MetS component traits using factor analysis, and built a genetic risk score for MetS.

METHODS AND RESULTS

A previously known lipid locus, APOA1/C3/A4/A5 gene cluster region (SNP rs964184), was associated with MetS in all 4 study samples (P=7.23×10(-9) in meta-analysis). The association was further supported by serum metabolite analysis, where rs964184 was associated with various very low density lipoprotein, triglyceride, and high-density lipoprotein metabolites (P=0.024-1.88×10(-5)). Twenty-two previously identified susceptibility loci for individual MetS component traits were replicated in our GWA and factor analysis. Most of these were associated with lipid phenotypes, and none with 2 or more uncorrelated MetS components. A genetic risk score, calculated as the number of risk alleles in loci associated with individual MetS traits, was strongly associated with MetS status.

CONCLUSIONS

Our findings suggest that genes from lipid metabolism pathways have the key role in the genetic background of MetS. We found little evidence for pleiotropy linking dyslipidemia and obesity to the other MetS component traits, such as hypertension and glucose intolerance.

Interactions between the FTO rs9939609 polymorphism, body mass index, and lifestyle-related factors on metabolic syndrome risk

Whether the FTO polymorphisms interact with environmental factors has not yet been evaluated in associations with metabolic syndrome (MS) risk. The present study investigated the association of the FTO rs9939609 genotypes, body mass index (BMI), and lifestyle-related factors including smoking, alcohol drinking, physical activity, and diet with MS incidence. A population-based prospective cohort study comprised 3,504 male and female Koreans aged 40 to 69 years. At the beginning of the study, all individuals were free of MS and known cardiovascular disease. Incident cases of MS were identified by biennial health examinations during a follow-up period from April 17, 2003 to April 15, 2009. Pooled logistic regression analysis was applied to obtain relative odds (RO) of MS with its 95% confidence interval (CI). After controlling for potential MS risk factors, we observed no association between the rs9939609 genotypes and MS incidence. In analysis stratified by BMI, however, carriers with the FTO risk allele whose BMI is 29 kg/m² or greater showed an approximately 6-fold higher RO (95% CI: 3.82 to 9.30) compared with non-carriers with BMI less than 25 kg/m². In particular, the association between the rs9939609 variants and MS risk was significantly modified by high BMI (P-value for interaction < 0.05). Such significant interaction appeared in associations with central obesity and high blood pressure among the MS components. Because carriers of the FTO risk alleles who had BMI of 29 kg/m² or greater are considered a high risk population, we suggest that they may need intensive weight loss regimens to prevent MS development.

Common variant (rs9939609) in the FTO gene is associated with metabolic syndrome

Recent genome-wide association studies have showed that common variant (rs9939609) in fat mass and obesity associated (FTO) gene was significantly associated with type 2 diabetes through an effect on human body mass index/obesity. Further studies have suggested that this variant was also involved in the development of metabolic syndrome (MetS). However, the results have been inconsistent. In this study, we performed a meta-analysis to clarify the association between rs9939609 polymorphism and the risk of MetS. Published literature from PubMed, EMBASE and other databases were searched. All studies assessing the association between rs9939609 polymorphism and the risk of MetS were identified. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using fixed-effects model. Thirteen studies (8,370 cases and 23,156 controls) using NCEP ATPIII criteria for MetS were pooled with a meta-analysis. The overall result showed that there was a statistically significant association between rs9939609 polymorphism and MetS risk (OR = 1.11, 95% CI = 1.06-1.17). Subgroup analysis based on ethnicity showed that effect size was only statistically significant in Europeans (OR = 1.11, 95% CI = 1.05-1.16). Eight studies (1,256 cases and 2,551 controls) using IDF criteria for MetS were pooled with a meta-analysis. The overall analysis suggested that rs9939609 polymorphism was significantly associated with MetS risk (OR = 1.32, 95% CI = 1.13-1.54). Subgroup analysis stratified by ethnicity suggested that effect size was only statistically significant in Asians (OR = 1.33, 95% CI = 1.10-1.61). Our results suggested that FTO rs9939609 polymorphism was significantly associated with the increased risk of MetS in European and Asian populations. Mechanistic investigation is also needed to clarify the effect of FTO gene in the predisposition to MetS.

Metabolic syndrome in South Asians

South Asia is home to one of the largest population of people with metabolic syndrome (MetS). The prevalence of MetS in South Asians varies according to region, extent of urbanization, lifestyle patterns, and socioeconomic/cultural factors. Recent data show that about one-third of the urban population in large cities in India has the MetS. All classical risk factors comprising the MetS are prevalent in Asian Indians residing in India. The higher risk in this ethnic population necessitated a lowering of the cut-off values of the risk factors to identify and intervene for the MetS to prevent diabetes and cardiovascular disease. Some pharmacological and nonpharmacological interventions are underway in MetS to assess the efficacy in preventing the diabetes and cardiovascular disease in this ethnic population.

Genetic variants in FTO associated with metabolic syndrome: a meta- and gene-based analysis

The objective of this study was to examine the effect of genetic variants in fat mass and obesity associated (FTO) gene on metabolic syndrome (MetS). A systematic literature search was performed and random-effects meta-analysis was used to evaluate genetic variants in FTO with MetS. A gene-based analysis was conducted to investigate the cumulative effects of genetic polymorphisms in FTO. A total of 18 studies from 13 published papers were included in our analysis. Random-effects meta-analysis yielded an estimated odds ratio of 1.19 (95% CI 1.12-1.27; P = 1.38 × 10(-7)) for rs9939609, 1.19 (95% CI 1.05-1.35; P = 0.008) for rs8050136, and 1.89 (95% CI 1.20-2.96; P = 0.006) for rs1421085. The gene-based analysis indicated that FTO is strongly associated with MetS (P < 10(-5)). This association remains after excluding rs9939609, a SNP that was frequently reported to have strong association with obesity and MetS. In this study, we concluded that the FTO gene may play a critical role in leading to MetS. Targeting this gene may provide novel therapeutic strategies for the prevention and treatment of metabolic syndrome.

Genetic associations with metabolic syndrome and its quantitative traits by race/ethnicity in the United States

BACKGROUND

Elevated insulin resistance (IR), triglycerides (TG), body mass index (BMI), and waist circumference (WC) are features of the metabolic syndrome. Although several single-nucleotide polymorphisms (SNPs) associated with these traits have been reported, no study has reported their risk allele frequencies and effect sizes among the major U.S. race/ethnic groups in a nationally representative sample.

METHODS

We compared the risk allele frequencies of eight SNPs previously associated with IR, TG, BMI, or WC by race/ethnicity (non-Hispanic white, non-Hispanic black, Mexican American) in 3,030 participants of the National Health and Nutrition Examination Study III (NHANES III). In regression models predicting IR, TG, BMI, WC, and metabolic syndrome, we tested whether the SNP effect sizes on these traits varied by race/ethnicity.

RESULTS

Risk allele frequencies varied by race/ethnicity for all eight loci (P<0.0001). The directionality of effects of the variants on IR, TG, WC, and BMI was generally consistent with previous observations and did not differ by race/ethnicity (P>0.001), although our study had low power for this test. No SNP predicted metabolic syndrome in any of the three groups (P>0.05).

CONCLUSIONS

The significance of racial/ethnic differences in risk allele frequencies merits consideration if genetic discoveries are to have clinical and public health applicability.

A variant upstream of the CDH13 adiponectin receptor gene and metabolic syndrome in Swedes

Metabolic syndrome (MetS) constitutes a worldwide epidemic burst accounting for billions of cardiovascular disease events and deaths. The genetic basis of MetS is largely unknown. The rs11646213 T → A polymorphism maps at 16q23.3 upstream of the CDH13 gene codifying for cadherin-13 (also known as T-cadherin or H-cadherin), which is considered a vascular adiponectin receptor. This and other single-nucleotide polymorphisms have been associated with hypertension and adiponectin level in separate studies. The aim of the present study was to evaluate the effect of the CDH13 rs11646213 T → A polymorphism on individual components of MetS and on MetS. The polymorphism was genotyped in the cardiovascular cohort of the Malmö Diet and Cancer Study (n = 4,942) and successively in the Malmö Preventive Project (n = 17,675) cohort at baseline and after an average of 23 years of follow-up (reinvestigation). Four different definitions of MetS were applied to these cohorts. In the cardiovascular arm, CDH13 rs11646213 AA homozygotic women showed a trend toward higher triglycerides and lower high-density lipoprotein cholesterol and presented a higher MetS score (composite sum of MetS phenotypes). MetS (Adult Treatment Panel III definition) was more prevalent in AA homozygotic women compared to T-carriers, a result confirmed in the Malmö Preventive Project cohort at baseline and at reinvestigation with an increased risk from 19% to 45% in AA homozygotic women. In conclusion, the CDH13 rs11646213 T > A polymorphism was consistently associated with MetS in Swedish women recruited in 2 large cohorts. In light of the role of cadherin-13 as a vascular receptor for adiponectin, our study supports the genetic basis for the role of adiponectin in MetS pathogenesis.

Genetic variants and the metabolic syndrome: a systematic review

Several candidate gene studies on the metabolic syndrome (MetS) have been conducted. However, for most single nucleotide polymorphisms (SNPs) no systematic review on their association with MetS exists. A systematic electronic literature search was conducted until the 2nd of June 2010, using HuGE Navigator. English language articles were selected. Only genes of which at least one SNP-MetS association was studied in an accumulative total population ≥ 4000 subjects were included. Meta-analyses were conducted on SNPs with three or more studies available in a generally healthy population. In total 88 studies on 25 genes were reviewed. Additionally, for nine SNPs in seven genes (GNB3, PPARG, TCF7L2, APOA5, APOC3, APOE, CETP) a meta-analysis was conducted. The minor allele of rs9939609 (FTO), rs7903146 (TCF7L2), C56G (APOA5), T1131C (APOA5), C482T (APOC3), C455T (APOC3) and 174G>C (IL6) were more prevalent in subjects with MetS, whereas the minor allele of Taq-1B (CETP) was less prevalent in subjects with the MetS. After having systematically reviewed the most studied SNP-MetS associations, we found evidence for an association with the MetS for eight SNPs, mostly located in genes involved in lipid metabolism.

The rs7204609 polymorphism in the fat mass and obesity-associated gene is positively associated with central obesity and microalbuminuria in patients with type 2 diabetes from Southern Brazil

OBJECTIVE

Single nucleotide polymorphisms (SNPs) in the fat mass and obesity-associated (FTO) gene, especially the common rs9939609 (A/T) SNP, are associated with body mass index (BMI), diabetes, and metabolic syndrome (MetS). MetS is highly prevalent in patients with type 2 diabetes and has been associated with chronic diabetic complications. Therefore, the aim of this study was to evaluate possible associations of the scarcely investigated rs7204609 (C/T) polymorphism, as well as the rs9939609 (A/T) polymorphism, with MetS and chronic diabetic complications in type 2 diabetic patients from Southern Brazil.

DESIGN

This was a cross-sectional study.

PATIENTS AND METHODS

A total of 236 patients with type 2 diabetes (age: 60.0 ± 10.3 years; diabetes duration: 12.7 ± 8.2 years; 53.4% women) were genotyped for the FTO rs7204609 and rs9939609 polymorphisms (ABI PRISM 7000 Real-Time PCR System). Patients underwent clinical, laboratory, and nutritional evaluation. MetS was defined according to the 2009-Joint Interim Statement.

RESULTS

Carriers of C allele of the rs7204609 polymorphism (CT/CC genotypes, n = 35) were at increased risk for the presence of MetS (odds ratio [OR] = 4.56; 95% CI: 1.04 to 19.9), elevated waist circumference (OR = 8.66; 95% CI: 1.12 to 66.7), BMI: ≥ 30 kg/m(2) (OR = 3.71; 95% CI: 1.71 to 8.02), and microalbuminuria (OR = 2.30; 95% CI: 1.08 to 4.88), adjusted for gender and diabetes duration (P < .05 for all models). The rs9939609 polymorphism was not associated with MetS, elevated waist circumference or BMI, or diabetic complications. Daily energy and nutrient intakes did not differ according to the presence of the polymorphisms.

CONCLUSIONS

The C allele of the rs7204609 polymorphism in the FTO gene increased the chance for the presence of MetS, especially central obesity, and microalbuminuria, independently of energy and nutrient intakes in this sample of type 2 diabetic patients from Southern Brazil.

Dietary saturated fat, gender and genetic variation at the TCF7L2 locus predict the development of metabolic syndrome

Transcription factor 7-like 2 (TCF7L2) is the strongest genetic determinant of type 2 diabetes (T2DM) and insulin-related phenotypes to date. Dietary fat is a key environmental factor which may interact with genotype to affect risk of metabolic syndrome (MetS) and T2DM. This study investigated the relationship between the TCF7L2 rs7903146 polymorphism, insulin sensitivity/resistance and MetS in the LIPGENE-SU.VI.MAX study of MetS cases and matched controls (n=1754) and determined potential interactions with dietary fat intake. Female minor T allele carriers of rs7903146 had increased MetS risk (odds ratio [OR] 1.66, confidence interval [CI] 1.02-2.70, P=.04) and displayed elevated insulin concentrations (P=.005), impaired insulin sensitivity (P=.011), increased abdominal obesity (P=.008) and body mass index (P=.001) and higher blood pressure (P<.05) compared to the CC homozygotes. Metabolic syndrome risk was also modulated by dietary saturated fat (SFA) intake (P=.035 for interaction). High dietary SFA intake (≥15.5% energy) exacerbated MetS risk (OR 2.35, 95% CI 1.29-4.27, P=.005) and was associated with further impaired insulin sensitivity in the T allele carriers relative to the CC homozygotes (P=.025) and particularly to the T allele carriers with the lowest SFA intake (P=.008). No significant genotype effect on MetS risk or insulin sensitivity was evident among low-SFA consumers. In conclusion, the TCF7L2 rs7903146 polymorphism influences MetS risk, which is augmented by both gender and dietary SFA intake, suggesting novel gene-diet-gender interactions.

GCKR gene functional variants in type 2 diabetes and metabolic syndrome: do the rare variants associate with increased carotid intima-media thickness?

Background

Recent studies revealed that glucokinase regulatory protein (GCKR) variants (rs780094 and rs1260326) are associated with serum triglycerides and plasma glucose levels. Here we analyzed primarily the association of these two variants with the lipid profile and plasma glucose levels in Hungarian subjects with type 2 diabetes mellitus and metabolic syndrome; and also correlated the genotypes with the carotid intima-media thickness records.

Methods

A total of 321 type 2 diabetic patients, 455 metabolic syndrome patients, and 172 healthy controls were genotyped by PCR-RFLP.

Results

Both GCKR variants were found to associate with serum triglycerides and with fasting plasma glucose. However, significant association with the development of type 2 diabetes mellitus and metabolic syndrome could not be observed. Analyzing the records of the patients, a positive association of prevalence the GCKR homozygous functional variants and carotid intima-media thickness was found in the metabolic syndrome patients.

Conclusions

Our results support that rs780094 and rs1260326 functional variants of the GCKR gene are inversely associated with serum triglycerides and fasting plasma glucose levels, as it was already reported for diabetic and metabolic syndrome patients in some other populations. Besides this positive replication, as a novel feature, our preliminary findings also suggest a cardiovascular risk role of the GCKR minor allele carriage based on the carotid intima-media thickness association.

Transcription factor 7-like 2 (TCF7L2) regulates activin receptor-like kinase 1 (ALK1)/Smad1 pathway for development of diabetic nephropathy

Smad1 has previously been shown to play a key role in the development of diabetic nephropathy (DN), by increasing synthesis of extracellular matrix. However, the regulatory mechanism of Smad1 in DN is still unclear. This study aims to elucidate molecular interactions between activin receptor-like kinase 1 (ALK1)/Smad1 signaling pathway and transcription factor 7-like 2 (TCF7L2) in the progression of DN in vitro and in vivo. The expressions of TCF7L2 and ALK1 were induced by advanced glycation end products (AGEs) in parallel with Smad1, phosphorylated Smad1 (pSmad1), and alpha-smooth muscle actin (α-SMA) through TGF-β1 in cultured mesangial cells. Constitutively active ALK1 increased pSmad1 and α-SMA expressions. The binding of TCF7L2 to ALK1 promoter was confirmed by chromatin immunoprecipitation assay. Furthermore, TCF7L2 induced promoter activity of ALK1. AGEs and TGF-β1 induced a marked increase in TCF7L2 expression in parallel with ALK1. Overexpression of TCF7L2 increased the expressions of ALK1 and Smad1. Inversely, TCF7L2 knockdown by siRNA suppressed α-SMA expression as well as ALK1 and Smad1. The iNOS transgenic mice (iNOS-Tgm), which developed diabetic glomerulosclerosis resembling human diabetic nephropathy, exhibited markedly increased expressions of ALK1, TCF7L2, Smad1, pSmad1, and α-SMA in glomeruli in association with mesangial matrix expansion. These results provide a new evidence that the TCF7L2/ALK1/Smad1 pathway plays a key role in the development of DN.

A genome-wide association study of the metabolic syndrome in Indian Asian men

We conducted a two-stage genome-wide association study to identify common genetic variation altering risk of the metabolic syndrome and related phenotypes in Indian Asian men, who have a high prevalence of these conditions. In Stage 1, approximately 317,000 single nucleotide polymorphisms were genotyped in 2700 individuals, from which 1500 SNPs were selected to be genotyped in a further 2300 individuals. Selection for inclusion in Stage 1 was based on four metabolic syndrome component traits: HDL-cholesterol, plasma glucose and Type 2 diabetes, abdominal obesity measured by waist to hip ratio, and diastolic blood pressure. Association was tested with these four traits and a composite metabolic syndrome phenotype. Four SNPs reaching significance level p<5×10⁻⁷ and with posterior probability of association >0.8 were found in genes CETP and LPL, associated with HDL-cholesterol. These associations have already been reported in Indian Asians and in Europeans. Five additional loci harboured SNPs significant at p<10⁻⁶ and posterior probability >0.5 for HDL-cholesterol, type 2 diabetes or diastolic blood pressure. Our results suggest that the primary genetic determinants of metabolic syndrome are the same in Indian Asians as in other populations, despite the higher prevalence. Further, we found little evidence of a common genetic basis for metabolic syndrome traits in our sample of Indian Asian men.

IGF2BP1, IGF2BP2 and IGF2BP3 genotype, haplotype and genetic model studies in metabolic syndrome traits and diabetes

OBJECTIVE

Genetic variation at the insulin-like binding protein 2 (IGF2BP2) gene has been associated with type 2 diabetes (T2D) by genome-wide association studies and by replication analyses. Our aim was to explore the underlying genetic model and mechanism of action, factors accounting for non-replications of the associations, and the effect of variation from pathway-related genes IGF2BP1 and IGF2BP3.

METHOD

We analysed here the association between T2D (and related traits) and rs4402960 and rs1470579 in IGF2BP2, and rs46522 and rs6949019 (marking IGF2BP1 and IGF2BP3 respectively) from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study (N approximately 2500 aged 65-96 years). We undertook a retrospective analysis of the deviations from the multiplicative model in previous studies and the present study.

RESULTS

We replicated an association between rs4402960 and T2D status, and reported significant associations with anthropometric traits, fasting insulin, HOMA-IR and HOMA-%B. These associations were also observed for rs1470579, but not for the SNPs marking IGF2BP1 and IGF2BP3.

CONCLUSIONS

The lower fasting insulin levels and the impaired beta-cell function associated with IGF2BP2 SNPs are independent of obesity phenotypes. The action of these SNPs on T2D may result from an effect on beta-cell function. This could lead to lower insulin levels, the association with anthropometric traits being secondary. We discuss possible mechanisms of action relating IGF2BP2 with T2D traits. The occurrence of null alleles, the inclusion of T2D patients in analyses of metabolic syndrome risk traits and the genetic model, are possible factors accounting for non-replications of IGF2BP2 associations with T2D.

Association of rs780094 in GCKR with metabolic traits and incident diabetes and cardiovascular disease: the ARIC Study

Objective

The minor T-allele of rs780094 in the glucokinase regulator gene (GCKR) associates with a number of metabolic traits including higher triglyceride levels and improved glycemic regulation in study populations of mostly European ancestry. Using data from the Atherosclerosis Risk in Communities (ARIC) Study, we sought to replicate these findings, examine them in a large population-based sample of African American study participants, and to investigate independent associations with other metabolic traits in order to determine if variation in GKCR contributes to their observed clustering. In addition, we examined the association of rs780094 with incident diabetes, coronary heart disease (CHD), and stroke over up mean follow-up times of 8, 15, and 15 years, respectively.

Research Design and Methods

Race-stratified analyses were conducted among 10,929 white and 3,960 black participants aged 45–64 at baseline assuming an additive genetic model and using linear and logistic regression and Cox proportional hazards models.

Results

Previous findings replicated among white participants in multivariable adjusted models: the T-allele of rs780094 was associated with lower fasting glucose (p = 10⁻⁷) and insulin levels (p = 10⁻⁶), lower insulin resistance (HOMA-IR, p = 10⁻⁹), less prevalent diabetes (p = 10⁻⁶), and higher CRP (p = 10⁻⁸), 2-h postprandial glucose (OGTT, p = 10⁻⁶), and triglyceride levels (p = 10⁻³¹). Moreover, the T-allele was independently associated with higher HDL cholesterol levels (p = 0.022), metabolic syndrome prevalence (p = 0.043), and lower beta-cell function measured as HOMA-B (p = 0.011). Among black participants, the T-allele was associated only with higher triglyceride levels (p = 0.004) and lower insulin levels (p = 0.002) and HOMA-IR (p = 0.013). Prospectively, the T-allele was associated with reduced incidence of diabetes (p = 10⁻⁴) among white participants, but not with incidence of CHD or stroke.

Conclusions

Our findings indicate rs780094 has independent associations with multiple metabolic traits as well as incident diabetes, but not incident CHD or stroke. The magnitude of association between the SNP and most traits was of lower magnitude among African American compared to white participants.

The metabolic syndrome: useful concept or clinical tool? Report of a WHO Expert Consultation

This article presents the conclusions of a WHO Expert Consultation that evaluated the utility of the 'metabolic syndrome' concept in relation to four key areas: pathophysiology, epidemiology, clinical work and public health. The metabolic syndrome is a concept that focuses attention on complex multifactorial health problems. While it may be considered useful as an educational concept, it has limited practical utility as a diagnostic or management tool. Further efforts to redefine it are inappropriate in the light of current knowledge and understanding, and there is limited utility in epidemiological studies in which different definitions of the metabolic syndrome are compared. Metabolic syndrome is a pre-morbid condition rather than a clinical diagnosis, and should thus exclude individuals with established diabetes or known cardiovascular disease (CVD). Future research should focus on: (1) further elucidation of common metabolic pathways underlying the development of diabetes and CVD, including those clustering within the metabolic syndrome; (2) early-life determinants of metabolic risk; (3) developing and evaluating context-specific strategies for identifying and reducing CVD and diabetes risk, based on available resources; and (4) developing and evaluating population-based prevention strategies.

Survivors of acute lymphoblastic leukemia and body mass changes

IMPORTANCE OF THE FIELD

Obesity is a rapidly growing challenge that has now reached epidemic proportions. Along with malnutrition, it causes increasing morbidity and mortality in the general population. Survivors of pediatric leukemia are at increased risk of developing adverse body mass changes. Despite many studies, mechanisms of regulation of fat tissue metabolism are still poorly understood.

AREAS COVERED IN THIS REVIEW

The present article reviews the data from studies of leukemia survivors in the context of basic science studies and reports of nutritional situation in Europe published between 1994 and 2009. As regulation of appetite and energy balance is very complex, environmental, biochemical and genetic factors are presented.

WHAT THE READER WILL GAIN

Fat mass and obesity associated gene (FTO) has recently been found to contribute to the risk of obesity. The possible role of this gene as well as late consequences of body mass changes are discussed.

TAKE HOME MESSAGE

Both underweight and overweight leukemia survivors need to be monitored for ongoing health consequences of abnormal BMI. Parameters of metabolic syndrome should be included as routine assessments in outpatient clinics taking care of childhood leukemia survivors.

Genetic susceptibility to type 2 diabetes and implications for therapy

Since 2000, we have witnessed an explosion of known genetic determinants of type 2 diabetes risk. These findings have seeded the expectation that our ability to make personalized, predictive, therapeutic clinical decisions is imminent. However, the loci discovered to date explain only a small fraction of overall inheritable risk for this disease. In many cases, the reported associations merely signal regions of the genome that are overrepresented in disease versus health but do not identify the causal variants. Well-powered cohort studies have shown that the set of markers detected thus far does not significantly improve individual risk prediction or stratification over common clinical variables, with the possible exception of younger subjects. On the other hand, risk genotypes may help target subgroups for more intensive surveillance or prevention efforts, although whether such a strategy improves patient outcomes and/or is cost-effective should be examined. Similarly, whether genetic information will help guide therapeutic decisions must be tested in adequately designed and rigorously conducted clinical trials.