Type 2 diabetes and obesity: genomics and the clinic

TXLNG improves insulin resistance in obese subjects in vitro and in vivo by inhibiting ATF4 transcriptional activity

Lipotoxicity contributes to insulin resistance and dysfunction of pancreatic β-cells. Insulin promotes 3T3-L1 preadipocyte differentiation and facilitates glucose entry into muscle, adipose, and other tissues. In this study, differential gene expression was analyzed using four datasets, and taxilin gamma (TXLNG) was the only shared downregulated gene in all four datasets. TXLNG expression was significantly reduced in obese subjects according to online datasets and in high-fat diet (HFD)-induced insulin-resistant (IR) mice according to experimental investigations. TXLNG overexpression significantly improved IR induced by HFD in mouse models by reducing body weight and epididymal adipose weight, decreasing mRNA expression of pro-inflammatory factors interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α), and reducing adipocyte size. High-glucose/high-insulin-stimulated adipocytes exhibited decreased TXLNG and increased signal transducer and activator of transcription 3 (STAT3) and activating transcription factor 4 (ATF4). IR significantly decreased glucose uptake, cell surface glucose transporter type 4 (GLUT4) levels, and Akt phosphorylation, while increasing the mRNA expression levels of IL-6 and TNF-α in adipocytes. However, these changes were significantly reversed by TXLNG overexpression, while they were exacerbated by TXLNG knockdown. TXLNG overexpression had no effect on ATF4 protein levels, while ATF4 overexpression increased ATF4 protein levels. Furthermore, ATF4 overexpression notably abolished the improvements in IR adipocyte dysfunction caused by TXLNG overexpression. In conclusion, TXLNG improves IR in obese subjects in vitro and in vivo by inhibiting ATF4 transcriptional activity.

Lack of association between TCF7L2 gene variants and type 2 diabetes mellitus in a Brazilian sample of patients with the risk for cardiovascular disease

OBJECTIVE

Genetic variants in the transcription factor 7-like 2 (TCF7L2) gene have been described as the most noteworthy ones regarding the type 2 diabetes mellitus (T2DM) liability. This work is aimed to evaluate the association between rs12255372 and rs7903146 polymorphisms and T2DM in patients with cardiovascular disease (CAD) risk.

METHODS

A sample of six hundred and forty-seven patients that underwent the coronary angiography in a Cardiac Catheterization Lab was evaluated. The patients were investigated for the presence of T2DM and coronary stenosis. The TCF7L2 polymorphisms were genotyped by real-time PCR and the haplotype analysis was performed with the MLOCUS software. All genetic tests were carried out by considering the haplotype combinations in patients divided into three groups: 0 - carrying none disease risk allele, 1 - carrying one or two risk alleles and 2 - carrying three or four risk alleles.

RESULTS

No significant associations between TCF7L2 risk haplotypes and the presence of T2DM or CAD were detected.

CONCLUSIONS

Our results indicate that the TCF7L2 rs12255372 and rs7903146 polymorphisms do not influence T2DM in Brazilian patients with the high risk for CAD. Therefore, we assume that these variants may only be relevant for a specific subgroup of T2DM patients or some particular human population.

Loss-of-function mutations in the melanocortin-3 receptor gene confer risk for human obesity: A systematic review and meta-analysis

The association between rare coding loss-of-function (LOF) mutations in the melanocortin receptor 3 (MC3R) gene and human obesity is controversial. To fill this gap of knowledge, we performed a systematic review and meta-analysis of genetic association studies in all ages and ethnicities. Two reviewers independently performed risk of bias assessment and extracted data. We searched Medline, Embase, Web of Science Core Collection, BIOSIS Preview, CINAHL, ProQuest Dissertations & Theses, and reference lists of relevant studies. All case-control, cross-sectional, prospective, and retrospective studies that evaluated prevalence of rare (less than 1% frequency) coding partial/complete LOF mutations in MC3R among individuals with obesity and normal weight were included. Our systematic search identified 1925 references relevant to the present review. Six studies were deemed eligible. Meta-analysis of 2969 individuals with obesity and 2572 with normal weight showed a positive association between rare heterozygous coding partial/complete LOF mutations in MC3R and obesity in children and adults of European, North African, and Asian ancestries (odds ratio = 3.07; 95% CI, 1.48-7.00; P = 4.2 × 10^-3 ). Our data demonstrates that rare partial/complete LOF mutations in the coding region of MC3R confer three-time increased risk of obesity in humans, and implies that rare genetic variants with intermediate effects contribute to the missing heritability of obesity.

The association between leptin receptor gene polymorphisms and type 2 diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Several case-control studies have demonstrated a relationship between leptin receptor (LEPR) gene polymorphism and type 2 diabetes mellitus (T2DM) risk, though the results have not always been consistent among diverse populations. This meta-analysis was designed to assess a more accurate association between LEPR polymorphism and T2DM.

METHODS

Eight electronic databases were consulted and researchers searched for Chinese and English peer-reviewed articles, published between 2000 and 2015, that referred to the association between LEPR polymorphism and T2DM. Pooled odds ratios (OR) with a 95% confidence interval (CI) were calculated in allele contrast, recessive, dominant and additive genetic models to assess this association.

RESULTS

Four repeatedly reviewed polymorphisms, taken from 22 studies on Arg109Lys, Asn656Lys, Gln223Arg and Pro1019Pro with 31,260 controls and 25,560 cases, were included in the meta-analysis model. The meta-result demonstrated that only the Pro1019Pro polymorphism was substantially associated with T2DM risk-G vs. A: OR with 95% CI 0.58 (0.43-0.79), Z=3.51, p=0.0005; GG vs. AG+AA: 0.57 (0.42-0.77), Z=3.66, p=0.0002; GG+AG vs. AA: 0.55 (0.37-0.81), Z=3.01, p=0.003; GG vs. AA: 0.51 (0.37-0.69), Z=4.24, p<0.001.

CONCLUSIONS

Our meta-analysis suggested a significant association between the LEPR Pro1019Pro polymorphism and T2DM risk. Thus, targeted healthcare should be strengthened with regard to this gene carrier in order to prevent T2DM.

FNDC5 expression and circulating irisin levels are modified by diet and hormonal conditions in hypothalamus, adipose tissue and muscle

Irisin is processed from fibronectin type III domain-containing protein 5 (FNDC5). However, a controversy exists concerning irisin origin, regulation and function. To elucidate the relationship between serum irisin and FNDC5 mRNA expression levels, we evaluated plasma irisin levels and FNDC5 gene expression in the hypothalamus, gastrocnemius muscle and different depots of adipose tissue in models of altered metabolism. In normal rats, blood irisin levels diminished after 48-h fast and with leptin, insulin and alloxan treatments, and serum irisin concentrations increased in diabetic rats after insulin treatment and acute treatments of irisin increased blood insulin levels. No changes were observed during long-term experiments with different diets. We suggested that levels of circulating irisin are the result of the sum of the irisin produced by different depots of adipose tissue and skeletal muscle. This study shows for the first time that there are differences in FNDC5 expression depending on white adipose tissue depots. Moreover, a considerable decrease in visceral and epididymal adipose tissue depots correlated with increased FNDC5 mRNA expression levels, probably in an attempt to compensate the decrease that occurs in their mass. Hypothalamic FNDC5 expression did not change for any of the tested diets but increased with leptin, insulin and metformin treatments suggesting that the regulation of central and peripheral FNDC5/irisin expression and functions are different.

Minireview: Genome Editing of Human Pluripotent Stem Cells for Modeling Metabolic Disease

The pathophysiology of metabolic diseases such as coronary artery disease, diabetes, and obesity is complex and multifactorial. Developing new strategies to prevent or treat these diseases requires in vitro models with which researchers can extensively study the molecular mechanisms that lead to disease. Human pluripotent stem cells and their differentiated derivatives have the potential to provide an unlimited source of disease-relevant cell types and, when combined with recent advances in genome editing, make the goal of generating functional metabolic disease models, for the first time, consistently attainable. However, this approach still has certain limitations including lack of robust differentiation methods and potential off-target effects. This review describes the current progress in human pluripotent stem cell-based metabolic disease research using genome-editing technology.

Genetic risk of type 2 diabetes in populations of the African continent: A systematic review and meta-analyses

BACKGROUND

Type 2 diabetes (T2D) is growing faster in Africa than anywhere else, driven by the dual effects of genetic and environmental factors. We conducted a systematic review and meta-analyses of published studies on genetic markers of T2D in populations within Africa.

METHODS

Multiple databases were searched for studies of genetic variants associated with T2D in populations living in Africa. Studies reporting on the association of a genetic marker with T2D or indicators of glycaemia were included. Data were extracted on study design and characteristics, genetic determinants, effect estimates of associations with T2D.

FINDINGS

Overall, 100 polymorphisms in 57 genes have been investigated in relation with T2D in populations within Africa, in 60 studies. Almost all studies used the candidate gene approach, with >88% published during 2006-2014 and 70% (42/60) originating from Tunisia and Egypt. Polymorphisms in ACE, AGRP, eNOS, GSTP1, HSP70-2, MC4R, MTHFR, PHLPP, POL1, TCF7L2, and TNF-α gene were found to be associated with T2D, with overlapping effect on various cardiometabolic traits. The polymorphisms investigated in multiple studies mostly had consistent effects across studies, with only modest or no statistical heterogeneity. Effect sizes were modestly significant [e.g., odd ratio 1.49 (95%CI 1.33-1.66) for TCF7L2 (rs7903146)]. Underpowered genome-wide studies revealed no diabetes risk loci specific to African populations.

INTERPRETATION

Current evidence on the genetic markers of T2D in African populations mostly originate from North African countries, is overall scanty and largely insufficient to reliably inform the genetic architecture of T2D across Africa.

Association between DNA Methylation in Whole Blood and Measures of Glucose Metabolism: KORA F4 Study

Epigenetic regulation has been postulated to affect glucose metabolism, insulin sensitivity and the risk of type 2 diabetes. Therefore, we performed an epigenome-wide association study for measures of glucose metabolism in whole blood samples of the population-based Cooperative Health Research in the Region of Augsburg F4 study using the Illumina HumanMethylation 450 BeadChip. We identified a total of 31 CpG sites where methylation level was associated with measures of glucose metabolism after adjustment for age, sex, smoking, and estimated white blood cell proportions and correction for multiple testing using the Benjamini-Hochberg (B-H) method (four for fasting glucose, seven for fasting insulin, 25 for homeostasis model assessment-insulin resistance [HOMA-IR]; B-H-adjusted p-values between 9.2x10(-5) and 0.047). In addition, DNA methylation at cg06500161 (annotated to ABCG1) was associated with all the aforementioned phenotypes and 2-hour glucose (B-H-adjusted p-values between 9.2x10(-5) and 3.0x10(-3)). Methylation status of additional three CpG sites showed an association with fasting insulin only after additional adjustment for body mass index (BMI) (B-H-adjusted p-values = 0.047). Overall, effect strengths were reduced by around 30% after additional adjustment for BMI, suggesting that this variable has an influence on the investigated phenotypes. Furthermore, we found significant associations between methylation status of 21 of the aforementioned CpG sites and 2-hour insulin in a subset of samples with seven significant associations persisting after additional adjustment for BMI. In a subset of 533 participants, methylation of the CpG site cg06500161 (ABCG1) was inversely associated with ABCG1 gene expression (B-H-adjusted p-value = 1.5x10(-9)). Additionally, we observed an enrichment of the top 1,000 CpG sites for diabetes-related canonical pathways using Ingenuity Pathway Analysis. In conclusion, our study indicates that DNA methylation and diabetes-related traits are associated and that these associations are partially BMI-dependent. Furthermore, the interaction of ABCG1 with glucose metabolism is modulated by epigenetic processes.

Using Genetic Variation to Predict and Extend Long-term Kidney Transplant Function

Renal transplantation has transformed the life of patients with end-stage renal disease and other chronic kidney disorders by returning endogenous kidney function and enabling patients to cease dialysis. Several clinical indicators of graft outcome and long-term function have been established. Although rising creatinine levels and graft biopsy can be used to determine graft loss, identifying early predictors of graft function will not only improve our ability to predict long-term graft outcome but importantly provide a window of opportunity to therapeutically intervene to preserve graft function before graft failure has occurred. Since understanding the importance of matching genetic variation at the HLA region between donors and recipients and translating this into clinical practise to improve transplant outcome, much focus has been placed on trying to identify additional genetic predictors of transplant outcome/function. This review will focus on how candidate gene studies have identified variants within immunosuppression, immune response, fibrotic pathways, and specific ethnic groups, which correlate with graft outcome. We will also discuss the challenges faced by candidate gene studies, such as differences in donor and recipient selection criteria and use of small data sets, which have led to many genes failing to be consistently associated with transplant outcome. This review will also look at how recent advances in our understanding of and ability to screen the genome are starting to provide new insights into the mechanisms behind long-term graft loss and with it the opportunity to target these pathways therapeutically to ultimately increase graft lifespan and the associated benefits to patients.

The Influence of Age and Sex on Genetic Associations with Adult Body Size and Shape: A Large-Scale Genome-Wide Interaction Study

Genome-wide association studies (GWAS) have identified more than 100 genetic variants contributing to BMI, a measure of body size, or waist-to-hip ratio (adjusted for BMI, WHRadjBMI), a measure of body shape. Body size and shape change as people grow older and these changes differ substantially between men and women. To systematically screen for age- and/or sex-specific effects of genetic variants on BMI and WHRadjBMI, we performed meta-analyses of 114 studies (up to 320,485 individuals of European descent) with genome-wide chip and/or Metabochip data by the Genetic Investigation of Anthropometric Traits (GIANT) Consortium. Each study tested the association of up to ~2.8M SNPs with BMI and WHRadjBMI in four strata (men ≤50y, men >50y, women ≤50y, women >50y) and summary statistics were combined in stratum-specific meta-analyses. We then screened for variants that showed age-specific effects (G x AGE), sex-specific effects (G x SEX) or age-specific effects that differed between men and women (G x AGE x SEX). For BMI, we identified 15 loci (11 previously established for main effects, four novel) that showed significant (FDR<5%) age-specific effects, of which 11 had larger effects in younger (<50y) than in older adults (≥50y). No sex-dependent effects were identified for BMI. For WHRadjBMI, we identified 44 loci (27 previously established for main effects, 17 novel) with sex-specific effects, of which 28 showed larger effects in women than in men, five showed larger effects in men than in women, and 11 showed opposite effects between sexes. No age-dependent effects were identified for WHRadjBMI. This is the first genome-wide interaction meta-analysis to report convincing evidence of age-dependent genetic effects on BMI. In addition, we confirm the sex-specificity of genetic effects on WHRadjBMI. These results may provide further insights into the biology that underlies weight change with age or the sexually dimorphism of body shape.

Translational Genomics in Low- and Middle-Income Countries: Opportunities and Challenges

Translation of genomic discoveries into patient care is slowly becoming a reality in developed economies around the world. In contrast, low- and middle-income countries (LMIC) have participated minimally in genomic research for several reasons including the lack of coherent national policies, the limited number of well-trained genomic scientists, poor research infrastructure, and local economic and cultural challenges. Recent initiatives such as the Human Heredity and Health in Africa (H3Africa), the Qatar Genome Project, and the Mexico National Institute of Genomic Medicine (INMEGEN) that aim to address these problems through capacity building and empowerment of local researchers have sparked a paradigm shift. In this short communication, we describe experiences of small-scale medical genetics and translational genomic research programs in LMIC. The lessons drawn from these programs drive home the importance of addressing resource, policy, and sociocultural dynamics to realize the promise of precision medicine driven by genomic science globally. By echoing lessons from a bench-to-community translational genomic research, we advocate that large-scale genomic research projects can be successfully linked with health care programs. To harness the benefits of genomics-led health care, LMIC governments should begin to develop national genomics policies that will address human and technology capacity development within the context of their national economic and sociocultural uniqueness. These policies should encourage international collaboration and promote the link between the public health program and genomics researchers. Finally, we highlight the potential catalytic roles of the global community to foster translational genomics in LMIC.

Dissecting diabetes/metabolic disease mechanisms using pluripotent stem cells and genome editing tools

BACKGROUND

Diabetes and metabolic syndromes are chronic, devastating diseases with increasing prevalence. Human pluripotent stem cells are gaining popularity in their usage for human in vitro disease modeling. With recent rapid advances in genome editing tools, these cells can now be genetically manipulated with relative ease to study how genes and gene variants contribute to diabetes and metabolic syndromes.

SCOPE OF REVIEW

We highlight the diabetes and metabolic genes and gene variants, which could potentially be studied, using two powerful technologies - human pluripotent stem cells (hPSCs) and genome editing tools - to aid the elucidation of yet elusive mechanisms underlying these complex diseases.

MAJOR CONCLUSIONS

hPSCs and the advancing genome editing tools appear to be a timely and potent combination for probing molecular mechanism(s) underlying diseases such as diabetes and metabolic syndromes. The knowledge gained from these hiPSC-based disease modeling studies can potentially be translated into the clinics by guiding clinicians on the appropriate type of medication to use for each condition based on the mechanism of action of the disease.

The MCP-1 Gene A-2518G Polymorphism Confers an Increased Risk of Vascular Complications in Type 2 Diabetes Mellitus Patients

OBJECTIVE

We aimed to evaluate the correlation of the monocyte chemoattractant protein 1 (MCP-1) A-2518G polymorphism with type 2 diabetes mellitus (T2DM) and vascular complications in T2DM, to aid in understanding its role in pathogenesis.

METHODS

A total of 150 T2DM patients and 50 healthy controls (group A) were enrolled. The T2DM patients were divided into three groups based on the absence of complications (group B) presence of microvascular disease (group C) or macrovascular disease (group D). DNA of all enrolled subjects was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for the MCP-1 A-2518G polymorphism. Serum MCP-1 levels were measured by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Participants in group D had increased serum MCP-1 levels relative to group B, group C, and group A (all p<0.01). Compared with group A, the frequencies of the MCP-1 A-2518G G/G genotype and G allele were significantly higher in group C and group D (all p<0.05). In contrast to group B, group C had higher frequencies of the G/G genotype and G allele, while group D had higher G allele frequencies (all p<0.05). Logistic regression analysis showed that lower body-mass index (BMI) and free cholesterol (FC), as well as higher high-density lipoprotein cholesterol (HDL-C) levels may be the protective factors for T2DM, while higher levels of triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and G/G genotype frequency were independent risk factors for T2DM.

CONCLUSIONS

Our data indicates a correlation between the MCP-1 A-2518G polymorphism with macrovascular complications in T2DM patients; lower BMI and FC, as well as higher HDL-C levels may be the protective factors for T2DM, while higher levels of TG, LDL-C, and G/G genotype frequency were independent risk factors for T2DM.

I'm eating for two: parental dietary effects on offspring metabolism

It has long been understood that the pathogenesis of complex diseases such as diabetes includes both genetic and environmental components. More recently, it has become clear that not only does an individual's environment influence their own metabolism, but in some cases, the environment experienced by their parents may also contribute to their risk of metabolic disease. Here, we review the evidence that parental diet influences metabolic phenotype in offspring in mammals and provide a current survey of our mechanistic understanding of these effects.

Personalized medicine and type 2 diabetes: lesson from epigenetics

Similarly to genetic polymorphisms, epigenetic modifications may alter transcriptional activity and contribute to different traits of the Type 2 diabetes phenotype. The establishment of these epigenetic marks may precede diabetes onset and predict the disease. Current evidence now indicates that epigenetic differences represent markers of diabetes risk. Studies on epigenome plasticity revealed that cytokines and other metabolites, by affecting DNA methylation, may acutely reprogram gene expression and contribute to the Type 2 diabetes phenotype even in the adult life. The available evidence further indicates that epigenetic marks across the genome are subject to dynamic variations in response to environmental cues. Finally, different genes responsible for the interindividual variability in antidiabetic drug response are subjected to epigenetic regulation. Determining how specific epigenetic profiles determine diabetes is a challenging task. In the near future, the identification of epigenetic marks predictive of diabetes risk or response to treatment may offer unanticipated opportunities to personalize Type 2 diabetes management.

Leptin signaling molecular actions and drug target in hepatocellular carcinoma

Previous reports indicate that over 13 different tumors, including hepatocellular carcinoma (HCC), are related to obesity. Obesity-associated inflammatory, metabolic, and endocrine mediators, as well as the functioning of the gut microbiota, are suspected to contribute to tumorigenesis. In obese people, proinflammatory cytokines/chemokines including tumor necrosis factor-alpha, interleukin (IL)-1 and IL-6, insulin and insulin-like growth factors, adipokines, plasminogen activator inhibitor-1, adiponectin, and leptin are found to play crucial roles in the initiation and development of cancer. The cytokines induced by leptin in adipose tissue or tumor cells have been intensely studied. Leptin-induced signaling pathways are critical for biological functions such as adiposity, energy balance, endocrine function, immune reaction, and angiogenesis as well as oncogenesis. Leptin is an activator of cell proliferation and anti-apoptosis in several cell types, and an inducer of cancer stem cells; its critical roles in tumorigenesis are based on its oncogenic, mitogenic, proinflammatory, and pro-angiogenic actions. This review provides an update of the pathological effects of leptin signaling with special emphasis on potential molecular mechanisms and therapeutic targeting, which could potentially be used in future clinical settings. In addition, leptin-induced angiogenic ability and molecular mechanisms in HCC are discussed. The stringent binding affinity of leptin and its receptor Ob-R, as well as the highly upregulated expression of both leptin and Ob-R in cancer cells compared to normal cells, makes leptin an ideal drug target for the prevention and treatment of HCC, especially in obese patients.

Insights into the genetic basis of type 2 diabetes

Type 2 diabetes is one of the most common complex diseases, of which considerable efforts have been made to unravel the pathophysiological mechanisms. Recently, large‐scale genome‐wide association (GWA) studies have successfully identified genetic loci robustly associated with type 2 diabetes by searching susceptibility variants across the entire genome in an unbiased, hypothesis‐free manner. The number of loci has climbed from just three in 2006 to approximately 70 today. For the common type 2 diabetes‐associated variants, three features have been noted. First, genetic impacts of individual variants are generally modest; mostly, allelic odds ratios range between 1.06 and 1.20. Second, most of the loci identified to date are not in or near obvious candidate genes, but some are often located in the intergenic regions. Third, although the number of loci is limited, there might be some population specificity in type 2 diabetes association. Although we can estimate a single or a few target genes for individual loci detected in GWA studies by referring to the data for experiments in vitro, biological function remains largely unknown for a substantial part of such target genes. Nevertheless, new biology is arising from GWA study discoveries; for example, genes implicated in β‐cell dysfunction are over‐represented within type 2 diabetes‐associated regions. Toward translational advances, we have just begun to face new challenges – elucidation of multifaceted (i.e., molecular, cellular and physiological) mechanistic insights into disease biology by considering interaction with the environment. The present review summarizes recent advances in the genetics of type 2 diabetes, together with its realistic potential.

Oncogenic role and therapeutic target of leptin signaling in colorectal cancer

INTRODUCTION

Obesity is characterized by high secretion of several cytokines from adipose tissue and is a recognized risk factor for many cancers. Among these cytokines, leptin mainly produced by adipose tissue and cancer cells is the most studied adipokine. Leptin is an activator of cell proliferation, an antiapoptotic molecule and inducer of cancer stem cells in many cell types, and its critical roles in obesity-related tumorigenesis are based on its oncogenic, mitogenic, pro-inflammatory and pro-angiogenic actions.

AREAS COVERED

These leptin-induced signals and action are critical for their biological effects on energy balance, adiposity, endocrine systems, immunity, angiogenesis as well as oncogenesis. This review focuses on the up-to-date knowledge on the oncogenic role of leptin signaling, clinical significance and specific drug target development in colorectal cancer (CRC). Additionally, leptin-induced angiogenic ability and molecular mechanisms in CRC cells are discussed.

EXPERT OPINION

Stringent binding affinity of leptin/Ob-R and overexpression of leptin/Ob-R and their targets in cancer cells make it a unique drug target for prevention and treatment of CRC, particularly in obesity colorectal patients.

Perturbation of hypothalamic microRNA expression patterns in male rats after metabolic distress: impact of obesity and conditions of negative energy balance

The hypothalamus plays a crucial role in body weight homeostasis through an intricate network of neuronal circuits that are under the precise regulation of peripheral hormones and central transmitters. Although deregulated function of such circuits might be a major contributing factor in obesity, the molecular mechanisms responsible for the hypothalamic control of energy balance remain partially unknown. MicroRNAs (miRNAs) have been recognized as key regulators of different biological processes, including insulin sensitivity and glucose metabolism. However, the roles of miRNA pathways in the control of metabolism have been mostly addressed in peripheral tissues, whereas the potential deregulation of miRNA expression in the hypothalamus in conditions of metabolic distress remains as yet unexplored. In this work, we used high-throughput screening to define to what extent the hypothalamic profiles of miRNA expression are perturbed in two extreme conditions of nutritional stress in male rats, namely chronic caloric restriction and high-fat diet-induced obesity. Our analyses allowed the identification of sets of miRNAs, including let-7a, mir-9*, mir-30e, mir-132, mir-145, mir-200a, and mir-218, whose expression patterns in the hypothalamus were jointly altered by caloric restriction and/or a high-fat diet. The predicted targets of these miRNAs include several elements of key inflammatory and metabolic pathways, including insulin and leptin. Our study is the first to disclose the impact of nutritional challenges on the hypothalamic miRNA expression profiles. These data will help to characterize the molecular miRNA signature of the hypothalamus in extreme metabolic conditions and pave the way for targeted mechanistic analyses of the involvement of deregulated central miRNAs pathways in the pathogenesis of obesity and related disorders.

The emerging use of zebrafish to model metabolic disease

The zebrafish research community is celebrating! The zebrafish genome has recently been sequenced, the Zebrafish Mutation Project (launched by the Wellcome Trust Sanger Institute) has published the results of its first large-scale ethylnitrosourea (ENU) mutagenesis screen, and a host of new techniques, such as the genome editing technologies TALEN and CRISPR-Cas, are enabling specific mutations to be created in model organisms and investigated in vivo. The zebrafish truly seems to be coming of age. These powerful resources invoke the question of whether zebrafish can be increasingly used to model human disease, particularly common, chronic diseases of metabolism such as obesity and type 2 diabetes. In recent years, there has been considerable success, mainly from genomic approaches, in identifying genetic variants that are associated with these conditions in humans; however, mechanistic insights into the role of implicated disease loci are lacking. In this Review, we highlight some of the advantages and disadvantages of zebrafish to address the organism’s utility as a model system for human metabolic diseases.

Association of four insulin resistance genes with type 2 diabetes mellitus and hypertension in the Chinese Han population

Insulin resistance plays an important role in the development of type 2 diabetes mellitus (T2DM) and hypertension. The purpose of the present study was to evaluate the association between four insulin resistance genes (ADIPOQ, LEPR, RETN, and TRIB3) and both T2DM and hypertension. A total of 768 Han Chinese subjects were recruited into this study, including 188 cases who had T2DM alone, 223 cases who had hypertension alone, 181 cases with both T2DM and hypertension, and 176 control subjects with neither T2DM nor hypertension. Twenty-three tag SNPs in four insulin resistance genes were genotyped and analyzed for association with T2DM and hypertension. One intron SNP (rs13306519) in LEPR and one 3′UTR SNP (rs1063537) in ADIPOQ demonstrated a significant association with T2DM (P = 0.024 and 0.014 respectively). Another intron SNP (rs12037879) in LEPR and a promoter region SNP (rs266729) in ADIPOQ were significantly associated with hypertension (P = 0.041 and 0.042, respectively). These associations survived the permutation test (P = 0.023, 0.018, 0.026, and 0.035, respectively). These associations were still found to be significant in the additive model after adjusting for potential confounding factors including age, sex, BMI, HDL, LDL, total cholesterol, and triglyceride levels (P = 0.024, 0.016, 0.04, and 0.043, respectively). No other gene variants were found to be significantly associated with T2DM or hypertension (P > 0.05). None of the studied gene variants were found to be significantly associated with T2DM+ hypertension (P > 0.05). A significant interaction was observed between two SNPs rs13306519 in LEPR and rs266729 in ADIPOQ for T2DM (P_int = 0.012, OR_int = 2.67) and hypertension (P_int = 0.0041, OR_int = 2.23). These findings suggest that variants in ADIPOQ and LEPR are risk factors for T2DM and hypertension in the Chinese population and that variants in RETN and TRIB3 are not major risk factors for these diseases.

Insights into the genetic susceptibility to type 2 diabetes from genome-wide association studies of glycaemic traits

Over the past 8 years, the genetics of complex traits have benefited from an unprecedented advancement in the identification of common variant loci for diseases such as type 2 diabetes (T2D). The ability to undertake genome-wide association studies in large population-based samples for quantitative glycaemic traits has permitted us to explore the hypothesis that models arising from studies in non-diabetic individuals may reflect mechanisms involved in the pathogenesis of diabetes. Amongst 88 T2D risk and 72 glycaemic trait loci, only 29 are shared and show disproportionate magnitudes of phenotypic effects. Important mechanistic insights have been gained regarding the physiological role of T2D loci in disease predisposition through the elucidation of their contribution to glycaemic trait variability. Further investigation is warranted to define causal variants within these loci, including functional characterisation of associated variants, to dissect their role in disease mechanisms and to enable clinical translation.

Genetic epidemiology of type 2 diabetes and cardiovascular diseases in Africa

The burdens of type 2 diabetes (T2D) and cardiovascular diseases (CVD) are increasing in Africa. T2D and CVD are the result of the complex interaction between inherited characteristics, lifestyle, and environmental factors. The epidemic of obesity is largely behind the exploding global incidence of T2D. However, not all obese individuals develop diabetes and positive family history is a powerful risk factor for diabetes and CVD. Recent implementations of high throughput genotyping and sequencing approaches have advanced our understanding of the genetic basis of diabetes and CVD by identifying several genomic loci that were not previously linked to the pathobiology of these diseases. However, African populations have not been adequately represented in these global genomic efforts. Here, we summarize the state of knowledge of the genetic epidemiology of T2D and CVD in Africa and highlight new genomic initiatives that promise to inform disease etiology, public health and clinical medicine in Africa.

Association between type 2 diabetes and rs10811661 polymorphism upstream of CDKN2A/B: a meta-analysis

To assess the association between type 2 diabetes and rs10811661 polymorphism, upstream of CDKN2A/B, a literature-based search was conducted to collect data. The pooled OR (odds ratio) and 95 % confidence intervals (CI) were used to assess the strength of association between rs10811661 polymorphism and type 2 diabetes. OR with 95 % CI were performed for allele contrasts, additive genetic model, dominant genetic model and recessive genetic model, respectively. The effect model was used if there was heterogeneity between studies. Funnel plots were used to predict publication bias. 17 studies with 29,990 cases and 40,977 controls were enrolled in this meta-analysis. Significant association was found in all of the four genetic models: allele contrast (OR = 1.21, 95 % CI 1.18-1.24), additive genetic model (OR = 1.51, 95 % CI 1.40-1.63), dominant genetic model (OR = 1.37, 95 % CI 1.28-1.47) and recessive genetic model (OR = 1.25, 95 % CI 1.21-1.29). The meta-analysis indicated that rs10811661 polymorphism was significantly associated with the risk of type 2 diabetes.

Safety and effectiveness of LAP-BAND AP System: results of Helping Evaluate Reduction in Obesity (HERO) prospective registry study at 1 year

BACKGROUND

Laparoscopic adjustable gastric banding has several distinctive features, including band adjustability, easy reversibility, and lack of malabsorption, which contribute to its widespread use. The LAP-BAND AP System (LBAP; Allergan, Inc.), a redesigned and improved version of the original device, was approved by the US Food and Drug Administration in 2006. Because of limited information on LBAP, this study prospectively assesses the efficacy and safety of LBAP in real-world settings at clinical centers located in North America, Europe, and Australia.

STUDY DESIGN

This interim report of the ongoing 5-year prospective, observational, international, multicenter registry, Helping Evaluate Reduction in Obesity (HERO) Study (NCT00953173), describes clinical efficacy and safety of LBAP in real-world settings at 1 year.

RESULTS

One thousand one hundred and six patients were implanted with LBAP and 1-year data were available from 834 patients for efficacy analysis. At 1 year, the mean (SD) percentage of excess weight loss was 39.8% (22.3%), of weight loss was 16.9% (9.0%), and the mean (SD) body mass index decreased to 37.7 (7.0) kg/m(2) from 45.1 (6.9) kg/m(2) at baseline. Patients with type 2 diabetes mellitus or hypertension showed significant improvements at 1 year post LBAP (both p < 0.005). The most common device-related complications were port displacement (n = 20 [1.8%]), pouch dilation (n = 12 [1.1%]), band slippage (n = 7 [0.6%]), and band erosion (n = 5 [0.5%]). Eighteen (1.6%) patients had the device explanted.

CONCLUSIONS

At 1 year post LBAP, progressive weight loss was associated with improvement and/or resolution of comorbid conditions and was safe and well tolerated. Patient follow-up continues.

Genetic information and the prediction of incident type 2 diabetes in a high-risk multiethnic population: the EpiDREAM genetic study

OBJECTIVE

To determine if 16 single nucleotide polymorphisms (SNPs) associated with type 2 diabetes (T2DM) in Europeans are also associated with T2DM in South Asians and Latinos and if they can add to the prediction of incident T2DM in a high-risk population.

RESEARCH DESIGN AND METHODS

In the EpiDREAM prospective cohort study, physical measures, questionnaires, and blood samples were collected from 25,063 individuals at risk for dysglycemia. Sixteen SNPs that have been robustly associated with T2DM in Europeans were genotyped. Among 15,466 European, South Asian, and Latino subjects, we examined the association of these 16 SNPs alone and combined in a gene score with incident cases of T2DM (n = 1,016) that developed during 3.3 years of follow-up.

RESULTS

Nine of the 16 SNPs were significantly associated with T2DM, and their direction of effect was consistent across the three ethnic groups. The gene score was significantly higher among subjects who developed incident T2DM (cases vs. noncases: 16.47 [2.50] vs. 15.99 [2.56]; P = 0.00001). The gene score remained an independent predictor of incident T2DM, with an odds ratio of 1.08 (95% CI 1.05-1.11) per additional risk allele after adjustment for T2DM risk factors. The gene score in those with no family history of T2DM was 16.02, whereas it was 16.19 in those with one parent with T2DM and it was 16.32 in those with two parents with T2DM (P trend = 0.0004). The C statistic of T2DM risk factors was 0.708 (0.691-0.725) and increased only marginally to 0.714 (0.698-0.731) with the addition of the gene score (P for C statistic change = 0.0052).

CONCLUSIONS

T2DM genetic associations are generally consistent across ethnic groups, and a gene score only adds marginal information to clinical factors for T2DM prediction.

Are health professionals ready for direct-to-consumer genetic and genomic testing?

Direct-to-consumer genetic and genomic tests have been offered for over a decade. With the reduction in the cost of sequencing, the options for consumers will increase, with subsequent pressure on health services to interpret data and integrate the results into healthcare management. However, indications are that health professionals are grossly unprepared to deal with requests for support from those who have undertaken direct-to-consumer genetic or genomic tests. While benefits may be derived from patient-driven investigations, distinction needs to be made between the mostly uncertain clinical utility of susceptibility testing and the potential benefits of a reliably interpreted sequencing result. It is essential that we develop strategies, including enhanced professional education, to cope with the potential impact on the health services, rather than ignoring these developments. There may also be implications for the future of genetic counseling, with potential changes in the current paradigm.

Bringing genome-wide association findings into clinical use

Genome-wide association studies (GWASs) have been heralded as a major advance in biomedical discovery, having identified ~2,000 robust associations with complex diseases since 2005. Despite this success, they have met considerable scepticism regarding their clinical applicability; this scepticism arises from such aspects as the modest effect sizes of associated variants and their unclear functional consequences. There are, however, promising examples of GWAS findings that will or that may soon be translated into clinical care. These examples include variants identified through GWASs that provide strongly predictive or prognostic information or that have important pharmacological implications; these examples may illustrate promising approaches to wider clinical application.

No association between IRS‑1 promoter methylation and type 2 diabetes

As a candidate gene for type 2 diabetes (T2D), insulin receptor substrate-1 (IRS‑1) gene variations were found to be associated with the risk of T2D. The aim of our study was to investigate the contribution of promoter DNA methylation of the IRS‑1 gene to the risk of T2D. Using bisulphite pyrosequencing technology, the DNA methylation levels of 3 CpG dinucleotides within the IRS‑1 gene promoter were measured in 48 T2D patients and 48 age‑ and gender‑matched healthy controls. Our results indicated that there was no significant association between the methylation of the IRS‑1 gene promoter and the risk of T2D (P>0.1). A breakdown analysis by gender revealed that IRS‑1 promoter methylation was not associated with an increased risk of T2D for either gender (P>0.1), although there were significantly lower methy-lation levels of CpG1 (P=0.002) and CpG2 (P=0.043) within the IRS‑1 gene promoter in males than in females.

Association study of a common variant near IRS1 with type 2 diabetes mellitus in Chinese Han population

The insulin receptor substrate-1 (IRS1) plays an important role in insulin signaling. A recent genome-wide association study identified rs2943641C>T as a susceptibility locus for type 2 diabetes mellitus (T2DM) in Caucasian patients. Therefore, we determined whether this common variant near IRS1 is also associated with the risk of T2DM and T2DM-related phenotypes in a Chinese Han population. A total of 2,290 unrelated Chinese Han individuals residing in Beijing were recruited in this study, including 1177 T2DM patients and 1113 subjects with normal glucose tolerance (control group). The single nucleotide polymorphism (SNP) was genotyped using a MassARRAY iPLEX system. The frequency of risk allele C was 0.929 in the control group and 0.939 in patients with T2DM. We found no association between the C allele of rs2943641 and T2DM in a recessive model [OR 1.14, 95 % confidence interval (CI) 0.89-1.45, P = 0.298], or after adjusting for sex, age, and body mass index (BMI) (OR 1.10, 95 % CI 0.85-1.43, P = 0.301). Analysis of the clinical features of the control subjects with normal glucose tolerance revealed that the 30-min plasma glucose level during a 75-g oral glucose tolerance test was significantly different between the CC and CT+TT genotypes (P = 0.017). Linear regression analysis showed that the 30-min plasma glucose levels was significantly and positively associated with the CC genotype after adjusting for sex, age, and BMI (β = 0.065, 95 % CI 0.009-0.654, P = 0.044). In addition, a potential association between this SNP and increased waist circumference (β = 1.337, 95 % CI -0.179 to 2.853, P = 0.084) was observed with adjustment for the sex and age. Our study was not able to demonstrate the association between rs2943641 near IRS1 and T2DM in a Chinese Han population. However, this SNP may be associated with postprandial hyperglycemia.

Genetics of type 2 diabetes in East Asian populations

Because type 2 diabetes (T2D) is highly familial, there has been a concentrated effort to uncover the genetic basis of T2D worldwide over the last decade. In East Asians, T2D is experiencing a rapidly rising prevalence that is characterized by a relatively lower body mass index, as compared with that in Europeans. To date, at least 15 convincing T2D loci have been identified from large-scale genome-wide association studies and meta-analyses in East Asians. Many of these are likely responsible for pancreatic β cell function, as indicated in studies from Europeans. Many T2D loci have been replicated across the ethnic groups. There are, however, substantial interethnic differences in frequency and effect size of these risk alleles. Despite accumulating genetic information on T2D, there are still limitations in our ability to explain the rapidly rising prevalence and lean phenotype of disease observed in East Asians, suggesting that more extensive work using diverse research strategies is needed in the future.

Abnormal glucose tolerance and insulin secretion in pancreas-specific Tcf7l2-null mice

AIMS/HYPOTHESIS

Individuals carrying type 2 diabetes risk alleles in TCF7L2 display decreased beta cell levels of T cell factor 7 like-2 (TCF7L2) immunoreactivity, and impaired insulin secretion and beta cell sensitivity to glucagon-like peptide 1 (GLP-1). Here, we sought to determine whether selective deletion of Tcf7l2 in mouse pancreas impairs insulin release and glucose homeostasis.

METHODS

Pancreas-specific Tcf7l2-null (pTcf7l2) mice were generated by crossing mice carrying conditional knockout alleles of Tcf7l2 (Tcf7l2-flox) with mice expressing Cre recombinase under the control of the Pdx1 promoter (Pdx1.Cre). Gene expression was assessed by real-time quantitative PCR and beta cell mass by optical projection tomography. Glucose tolerance, insulin secretion from isolated islets, and plasma insulin, glucagon and GLP-1 content were assessed by standard protocols.

RESULTS

From 12 weeks of age, pTcf7l2 mice displayed decreased oral glucose tolerance vs control littermates; from 20 weeks they had glucose intolerance upon administration of glucose by the intraperitoneal route. pTcf7l2 islets displayed impaired insulin secretion in response to 17 (vs 3.0) mmol/l glucose (54.6 ± 4.6%, p < 0.01) or to 17 mmol/l glucose plus 100 nmol/l GLP-1 (44.3 ± 4.9%, p < 0.01) compared with control islets. Glp1r (42 ± 0.08%, p < 0.01) and Ins2 (15.4 ± 4.6%, p < 0.01) expression was significantly lower in pTcf7l2 islets than in controls. Maintained on a high-fat (but not on a normal) diet, pTcf7l2 mice displayed decreased expansion of pancreatic beta cell volume vs control littermates. No differences were observed in plasma insulin, proinsulin, glucagon or GLP-1 concentrations.

CONCLUSIONS/INTERPRETATION

Selective deletion of Tcf7l2 in the pancreas replicates key aspects of the altered glucose homeostasis in human carriers of TCF7L2 risk alleles, indicating the direct role of this factor in controlling beta cell function.

Bradykinin inhibits hepatic gluconeogenesis in obese mice

The kallikrein-kinin system (KKS) has been previously linked to glucose homeostasis. In isolated muscle or fat cells, acute bradykinin (BK) stimulation was shown to improve insulin action and increase glucose uptake by promoting glucose transporter 4 translocation to plasma membrane. However, the role for BK in the pathophysiology of obesity and type 2 diabetes remains largely unknown. To address this, we generated genetically obese mice (ob/ob) lacking the BK B2 receptor (obB2KO). Despite similar body weight or fat accumulation, obB2KO mice showed increased fasting glycemia (162.3 ± 28.2 mg/dl vs 85.3 ± 13.3 mg/dl), hyperinsulinemia (7.71 ± 1.75 ng/ml vs 4.09 ± 0.51 ng/ml) and impaired glucose tolerance when compared with ob/ob control mice (obWT), indicating insulin resistance and impaired glucose homeostasis. This was corroborated by increased glucose production in response to a pyruvate challenge. Increased gluconeogenesis was accompanied by increased hepatic mRNA expression of forkhead box protein O1 (FoxO1, four-fold), peroxisome proliferator-activated receptor gamma co-activator 1-alpha (seven-fold), phosphoenolpyruvate carboxykinase (PEPCK, three-fold) and glucose-6-phosphatase (eight-fold). FoxO1 nuclear exclusion was also impaired, as the obB2KO mice showed increased levels of this transcription factor in the nucleus fraction of liver homogenates during random feeding. Intraportal injection of BK in lean mice was able to decrease the hepatic mRNA expression of FoxO1 and PEPCK. In conclusion, BK modulates glucose homeostasis by affecting hepatic glucose production in obWT. These results point to a protective role of the KKS in the pathophysiology of type 2 diabetes mellitus.

Meta-analysis of association studies between five candidate genes and type 2 diabetes in Chinese Han population

The multiple small-scale association studies of candidate genes for type 2 diabetes mellitus in the Chinese Han population have shown inconsistent results. Here, we performed a meta-analysis to evaluate the contribution of five candidate genes to the pathogenesis of type 2 diabetes in the Chinese Han population. We searched for relevant published papers and used STATA v.11.0 to perform a meta-analysis on six single-nucleotide polymorphisms in five genes-ADIPOQ-rs2241766 (SNP45) and -rs1501299 (SNP276), ADRB3-rs4994 (Trp64Arg), CAPN10-rs3792267 (SNP43), ENPP1-rs1044498 (K121Q), and PPARGC1A-rs8192678 (Gly482Ser)-in the Chinese Han population under an additive genetic model. The pooled odds ratios (95% confidence intervals and P-values) were 0.71 (0.60-0.83; P < 0.001) for ADIPOQ-rs2241766, 0.79 (0.64-0.97; P = 0.027) for ADIPOQ-rs1501299, 1.27 (1.07-1.51; P = 0.006) for ADRB3-rs4994, 0.79 (0.57-1.10; P = 0.163) for CAPN10-rs3792267, 1.41 (1.13-1.76; P = 0.003) for ENPP1-rs1044498, and 1.54 (1.34-1.81; P < 0.001) for PPARGC1A-rs8192678. There was high heterogeneity for ADIPOQ-rs2241766, ADIPOQ-rs1501299, and CAPN10-rs3792267 (I² = 74.9, 69.4, and 75.8%, respectively), but not for ADRB3-rs4994, ENPP1-rs1044498, and PPARGC1A-rs8192678 (I² = 0.0, 43.4, and 23.3%, respectively). Under an additive genetic model, the C allele of ADRB3-rs4994, the C allele of ENPP1-rs1044498, and the A allele of PPARGC1A-rs8192678 increase the risk of type 2 diabetes in the Chinese Han population.

Association between variants of EXT2 and type 2 diabetes: a replication and meta-analysis

Recent publications have found an association between variants of exostosin 2 (EXT2) gene and the risk of type 2 diabetes in some population but not in others. In an attempt to address these inconsistencies, we investigated EXT2 variants in two independent cohorts, and conducted a literature-based meta-analysis. Through regression model, we assessed the relationship between the EXT2 single nucleotide polymorphisms (SNPs) (rs3740878, rs11037909 and rs1113132) and the risk of type 2 diabetes in Han Chinese population, including a total of 2,533 cases and 2,643 controls. We combined our data with that from previously published studies and performed a meta-analysis to evaluate the effect size of the gene. Consistent with some studies, we found marginal association for the rs3740878 (OR = 1.07, 95 % CI = 0.99, 1.16, p = 0.09), rs11037909 (OR = 1.07, 95 % CI = 0.99, 1.16, p = 0.08), and rs1113132 (OR = 1.08, 95 % CI = 1.00, 1.17, p = 0.06) in our 2 cohorts. Meta-analysis, comprising 9,224 type 2 diabetes and 10,484 controls, revealed that three SNPs (rs3740878, rs11037909 and rs1113132) in EXT2 were significantly associated with type 2 diabetes (ORs range from 1.06 to 1.07, p = 0.038, p = 0.008 and p = 0.005, respectively). Variation in the EXT2 locus appears to be associated with a small increase in the risk of type 2 diabetes. However, well-designed prospective studies with larger sample size and more ethnic groups are needed to further validate the results.

Adenovirus-36 is associated with obesity in children and adults in Sweden as determined by rapid ELISA

BACKGROUND

Experimental and natural human adenovirus-36 (Adv36) infection of multiple animal species results in obesity through increasing adipogenesis and lipid accumulation in adipocytes. Presence of Adv36 antibodies detected by serum neutralization assay has previously been associated with obesity in children and adults living in the USA, South Korea and Italy, whereas no association with adult obesity was detected in Belgium/The Netherlands nor among USA military personnel. Adv36 infection has also been shown to reduce blood lipid levels, increase glucose uptake by adipose tissue and skeletal muscle biopsies, and to associate with improved glycemic control in non-diabetic individuals.

PRINCIPAL FINDINGS

Using a novel ELISA, 1946 clinically well-characterized individuals including 424 children and 1522 non-diabetic adults, and 89 anonymous blood donors, residing in central Sweden representing the population in Stockholm area, were studied for the presence of antibodies against Adv36 in serum. The prevalence of Adv36 positivity in lean individuals increased from ∼7% in 1992-1998 to 15-20% in 2002-2009, which paralleled the increase in obesity prevalence. We found that Adv36-positive serology was associated with pediatric obesity and with severe obesity in females compared to lean and overweight/mildly obese individuals, with a 1.5 to 2-fold Adv36 positivity increase in cases. Moreover, Adv36 positivity was less common among females and males on antilipid pharmacological treatment or with high blood triglyceride level. Insulin sensitivity, measured as lower HOMA-IR, showed a higher point estimate in Adv36-positive obese females and males, although it was not statistically significant (p = 0.08).

CONCLUSION

Using a novel ELISA we show that Adv36 infection is associated with pediatric obesity, severe obesity in adult females and lower risk of high blood lipid levels in non-diabetic Swedish individuals.

The absence of longitudinal data limits the accuracy of high-throughput clinical phenotyping for identifying type 2 diabetes mellitus subjects

PURPOSE

To evaluate the impact of insufficient longitudinal data on the accuracy of a high-throughput clinical phenotyping (HTCP) algorithm for identifying (1) patients with type 2 diabetes mellitus (T2DM) and (2) patients with no diabetes.

METHODS

Retrospective study conducted at Mayo Clinic in Rochester, Minnesota. Eligible subjects were Olmsted County residents with ≥1 Mayo Clinic encounter in each of three time periods: (1) 2007, (2) from 1997 through 2006, and (3) before 1997 (N = 54,283). Diabetes relevant electronic medical record (EMR) data about diagnoses, laboratories, and medications were used. We employed the HTCP algorithm to categorize individuals as T2DM cases and non-diabetes controls. Considering the full 11 years (1997-2007) as the gold standard, we compared gold-standard categorizations with those using data for 10 subsequent intervals, ranging from 1998-2007 (10-year data) to 2007 (1-year data). Positive predictive values (PPVs) and false-negative rates (FNRs) were calculated. McNemar tests were used to determine whether categorizations using shorter time periods differed from the gold standard. Statistical significance was defined as P < 0.05.

RESULTS

We identified 2770 T2DM cases and 21,005 controls when the algorithm was applied using 11-year data. Using 2007 data alone, PPVs and FNRs, respectively, were 70% and 25% for case identification and 59% and 67% for control identification. All time frames differed significantly from the gold standard, except for the 10-year period.

CONCLUSIONS

The accuracy of the algorithm reduced remarkably as data were limited to shorter observation periods. This impact should be considered carefully when designing/executing HTCP algorithms.

Finding a place for genomics in health disparities research

The existence of pronounced differences in health outcomes between US populations is a problem of moral significance and public health urgency. Pursuing research on genetic contributors to such disparities, despite striking data on the fundamental role of social factors, has been controversial. Still, advances in genomic science are providing an understanding of disease biology at a level of precision not previously possible. The potential for genomic strategies to help in addressing population-level disparities therefore needs to be carefully evaluated. Using 3 examples from current research, we argue that the best way to maximize the benefits of population-based genomic investigations, and mitigate potential harms, is to direct research away from the identification of genetic causes of disparities and instead focus on applying genomic methodologies to the development of clinical and public health tools with the potential to ameliorate healthcare inequities, direct population-level health interventions or inform public policy. Such a transformation will require close collaboration between transdisciplinary teams and community members as well as a reorientation of current research objectives to better align genomic discovery efforts with public health priorities and well-recognized barriers to fair health care delivery.

The lessons of early-onset monogenic diabetes for the understanding of diabetes pathogenesis

Monogenic diabetes consists of different subtypes of single gene disorders comprising a large spectrum of phenotypes, namely neonatal diabetes mellitus or monogenic diabetes of infancy, dominantly inherited familial forms of early-onset diabetes (called Maturity-Onset Diabetes of the Young) and rarer diabetes-associated syndromic diseases. All these forms diagnosed at a very-young age are unrelated to auto-immunity. Their genetic dissection has revealed major genes in developmental and/or functional processes of the pancreatic β-cell physiology, and various molecular mechanisms underlying the primary pancreatic defects. Most of these discoveries have had remarkable consequences on the patients care and patient's long-term condition with outstanding examples of successful genomic medicine, which are highlighted in this chapter. Increasing evidence also shows that frequent polymorphisms in or near monogenic diabetes genes may contribute to adult polygenic type 2 diabetes. In this regard, unelucidated forms of monogenic diabetes represent invaluable models for identifying new targets of β-cell dysfunction.

Myricetin Increases Hepatic Peroxisome Proliferator-Activated Receptor α Protein Expression and Decreases Plasma Lipids and Adiposity in Rats

The aim of this study was to investigate the antiobesity and antihyperlipidaemic effects of myricetin. Myricetin exhibited a significant concentration-dependent decrease in the intracellular accumulation of triglyceride in 3T3-L1 adipocytes. The high-fat diet (HFD)-fed rats were dosed orally with myricetin or fenofibrate, once daily for eight weeks. Myricetin (300 mg kg⁻¹ per day) displayed similar characteristics to fenofibrate (100 mg kg⁻¹ per day) in reducing lowered body weight (BW) gain, visceral fat-pad weights and plasma lipid levels of HFD-fed rats. Myricetin also reduced the hepatic triglyceride and cholesterol contents, as well as lowered hepatic lipid droplets accumulation and epididymal adipocyte size in HFD-fed rats. Myricetin and fenofibrate reversed the HFD-induced down-regulation of the hepatic peroxisome proliferator activated receptor (PPAR)α. HFD-induced decreases of the hepatic protein level of acyl-CoA oxidase and cytochrome P450 isoform 4A1 were up-regulated by myricetin and fenofibrate. The elevated expressions of hepatic sterol regulatory element binding proteins (SREBPs) of HFD-fed rats were lowered by myricetin and fenofibrate. These results suggest that myricetin suppressed BW gain and body fat accumulation by increasing the fatty acid oxidation, which was likely mediated via up-regulation of PPARα and down-regulation of SREBP expressions in the liver of HFD-fed rats.

Oncogenic role and therapeutic target of leptin signaling in breast cancer and cancer stem cells

Significant correlations between obesity and incidence of various cancers have been reported. Obesity, considered a mild inflammatory process, is characterized by a high level of secretion of several cytokines from adipose tissue. These molecules have disparate effects, which could be relevant to cancer development. Among the inflammatory molecules, leptin, mainly produced by adipose tissue and overexpressed with its receptor (Ob-R) in cancer cells is the most studied adipokine. Mutations of leptin or Ob-R genes associated with obesity or cancer are rarely found. However, leptin is an anti-apoptotic molecule in many cell types, and its central roles in obesity-related cancers are based on its pro-angiogenic, pro-inflammatory and mitogenic actions. Notably, these leptin actions are commonly reinforced through entangled crosstalk with multiple oncogenes, cytokines and growth factors. Leptin-induced signals comprise several pathways commonly triggered by many cytokines (i.e., canonical: JAK2/STAT; MAPK/ERK1/2 and PI-3K/AKT1 and, non-canonical signaling pathways: PKC, JNK and p38 MAP kinase). Each of these leptin-induced signals is essential to its biological effects on food intake, energy balance, adiposity, immune and endocrine systems, as well as oncogenesis. This review is mainly focused on the current knowledge of the oncogenic role of leptin in breast cancer. Additionally, leptin pro-angiogenic molecular mechanisms and its potential role in breast cancer stem cells will be reviewed. Strict biunivocal binding-affinity and activation of leptin/Ob-R complex makes it a unique molecular target for prevention and treatment of breast cancer, particularly in obesity contexts.

Oncogenic role and therapeutic target of leptin signaling in breast cancer and cancer stem cells

Significant correlations between obesity and incidence of various cancers have been reported. Obesity, considered a mild inflammatory process, is characterized by a high level of secretion of several cytokines from adipose tissue. These molecules have disparate effects, which could be relevant to cancer development. Among the inflammatory molecules, leptin, mainly produced by adipose tissue and overexpressed with its receptor (Ob-R) in cancer cells is the most studied adipokine. Mutations of leptin or Ob-R genes associated with obesity or cancer are rarely found. However, leptin is an anti-apoptotic molecule in many cell types, and its central roles in obesity-related cancers are based on its pro-angiogenic, pro-inflammatory and mitogenic actions. Notably, these leptin actions are commonly reinforced through entangled crosstalk with multiple oncogenes, cytokines and growth factors. Leptin-induced signals comprise several pathways commonly triggered by many cytokines (i.e., canonical: JAK2/STAT; MAPK/ERK1/2 and PI-3K/AKT1 and, non-canonical signaling pathways: PKC, JNK and p38 MAP kinase). Each of these leptin-induced signals is essential to its biological effects on food intake, energy balance, adiposity, immune and endocrine systems, as well as oncogenesis. This review is mainly focused on the current knowledge of the oncogenic role of leptin in breast cancer. Additionally, leptin pro-angiogenic molecular mechanisms and its potential role in breast cancer stem cells will be reviewed. Strict biunivocal binding-affinity and activation of leptin/Ob-R complex makes it a unique molecular target for prevention and treatment of breast cancer, particularly in obesity contexts.

Future perspective on pharmacogenomics of severe hypoglycemia associated with sulfonylureas: reply from the authors

A letter in response to: Holstein JD, Kovacs P, Patzer O, Stumvoll M, Holstein A. The Ser1369Ala variant of ABCC8 and the risk for severe sulfonylurea-induced hypoglycemia in German patients with Type 2 diabetes. Pharmacogenomics 13(1), 5–7 (2012).