Heritabilities of the metabolic syndrome and its components in the Northern Manhattan Family Study

Genome-wide association study and polygenic score assessment of insulin resistance

Insulin resistance (IR) and beta cell dysfunction are the major drivers of type 2 diabetes (T2D). Genome-Wide Association Studies (GWAS) on IR have been predominantly conducted in European populations, while Middle Eastern populations remain largely underrepresented. We conducted a GWAS on the indices of IR (HOMA2-IR) and beta cell function (HOMA2-%B) in 6,217 non-diabetic individuals from the Qatar Biobank (QBB; Discovery cohort; n = 2170, Replication cohort; n = 4047) with and without body mass index (BMI) adjustment. We also developed polygenic scores (PGS) for HOMA2-IR and compared their performance with a previously derived PGS for HOMA-IR (PGS003470). We replicated 11 loci that have been previously associated with HOMA-IR and 24 loci that have been associated with HOMA-%B, at nominal statistical significance. We also identified a novel locus associated with beta cell function near VEGFC gene, tagged by rs61552983 (P = 4.38 × 10-8). Moreover, our best performing PGS (Q-PGS4; Adj R2 = 0.233 ± 0.014; P = 1.55 x 10-3) performed better than PGS003470 (Adj R2 = 0.194 ± 0.014; P = 5.45 x 10-2) in predicting HOMA2-IR in our dataset. This is the first GWAS on HOMA2 and the first GWAS conducted in the Middle East focusing on IR and beta cell function. Herein, we report a novel locus in VEGFC that is implicated in beta cell dysfunction. Inclusion of under-represented populations in GWAS has potentials to provide important insights into the genetic architecture of IR and beta cell function.

Co-methylation analyses identify CpGs associated with lipid traits in Chinese discordant monozygotic twins

To control genetic background and early life milieu in genome-wide DNA methylation analysis for blood lipids, we recruited Chinese discordant monozygotic twins to explore the relationships between DNA methylations and total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). 132 monozygotic (MZ) twins were included with discordant lipid levels and completed data. A linear mixed model was conducted in Epigenome-wide association study (EWAS). Generalized estimating equation model was for gene expression analysis. We conducted Weighted correlation network analysis (WGCNA) to build co-methylated interconnected network. Additional Qingdao citizens were recruited for validation. Inference about Causation through Examination of Familial Confounding (ICE FALCON) was used to infer the possible direction of these relationships. A total of 476 top CpGs reached suggestively significant level (P < 10-4), of which, 192 CpGs were significantly associated with TG (FDR < 0.05). They were used to build interconnected network and highlight crucial genes from WGCNA. Finally, four CpGs in GATA4 were validated as risk factors for TC; six CpGs at ITFG2-AS1 were negatively associated with TG; two CpGs in PLXND1 played protective roles in HDL-C. ICE FALCON indicated abnormal TC was regarded as the consequence of DNA methylation in CpGs at GATA4, rather than vice versa. Four CpGs in ITFG2-AS1 were both causes and consequences of modified TG levels. Our results indicated that DNA methylation levels of 12 CpGs in GATA4, ITFG2-AS1, and PLXND1 were relevant to TC, TG, and HDL-C, respectively, which might provide new epigenetic insights into potential clinical treatment of dyslipidemia.

Heterogeneity in familial clustering of metabolic syndrome components in the multiethnic GENNID study

OBJECTIVE

Metabolic syndrome (MetS) is defined by clustering of cardiometabolic components, which may be present in different combinations. The authors evaluated clustering in individuals and extended families within and across ancestry groups.

METHODS

The prevalence of different combinations of MetS components (high fasting glucose, low high-density lipoprotein cholesterol, high triglycerides, high blood pressure, and abdominal obesity) was estimated in 1651 individuals (340 families) self-reporting as European American (EA), Hispanic/Mexican American (MA), African American (AA), and Japanese American (JA). Odds ratios were estimated using logistic regression with generalized estimating equations comparing individual MetS components, number, and combinations of components for each ancestry group versus EA.

RESULTS

Clustering of all five components (Combination #16) was more prevalent in EA (29.9%) and MA (25.2%) individuals than in AA (18.7%) and JA (15.5%) individuals. Compared with EA individuals, AA individuals were 64% and 66% less likely to have high triglycerides and low high-density lipoprotein cholesterol, whereas JA individuals were 85% and 56% less likely to have abdominal obesity and high blood pressure, respectively. Compared with EA individuals, the odds of having two, four, or five components were at least 77% lower in JA individuals, whereas the odds of having three, four, or five components were at least 3.79 times greater in MA individuals.

CONCLUSIONS

Understanding heterogeneity in MetS clustering may identify factors important in reducing health disparities.

A Genome-Wide Association Study of Metabolic Syndrome in the Taiwanese Population

The purpose of this study was to investigate genetic factors associated with metabolic syndrome (MetS) by conducting a large-scale genome-wide association study (GWAS) in Taiwan, addressing the limited data on Asian populations compared to Western populations. Using data from the Taiwan Biobank, comprehensive clinical and genetic information from 107,230 Taiwanese individuals was analyzed. Genotyping data from the TWB1.0 and TWB2.0 chips, including over 650,000 single nucleotide polymorphisms (SNPs), were utilized. Genotype imputation using the 1000 Genomes Project was performed, resulting in more than 9 million SNPs. MetS was defined based on a modified version of the Adult Treatment Panel III criteria. Among all participants (mean age: 50 years), 23% met the MetS definition. GWAS analysis identified 549 SNPs significantly associated with MetS, collectively mapping to 10 genomic risk loci. Notable risk loci included rs1004558, rs3812316, rs326, rs4486200, rs2954038, rs10830963, rs662799, rs62033400, rs183130, and rs34342646. Gene-set analysis revealed 22 associated genes: CETP, LPL, APOA5, SIK3, ZPR1, APOC1, BUD13, MLXIPL, TOMM40, GCK, YKT6, RPS6KB1, FTO, VMP1, TUBD1, BCL7B, C19orf80 (ANGPTL8), SIDT2, SENP7, PAFAH1B2, DOCK6, and FOXA2. This study identified genomic risk loci for MetS in a large Taiwanese population through a comprehensive GWAS approach. These associations provide novel insights into the genetic basis of MetS and hold promise for the potential discovery of clinical biomarkers.

Genetic variants associated with weight loss and metabolic outcomes after bariatric surgery: A systematic review

The extent to which genetic variations contribute to interindividual differences in weight loss and metabolic outcomes after bariatric surgery is unknown. Identifying genetic variants that impact surgery outcomes may contribute to clinical decision making. This review evaluates current evidence addressing the association of genetic variants with weight loss and changes in metabolic parameters after bariatric surgery. A search was conducted using Medline, Embase, Scopus, Web of Science, and Cochrane Library. Fifty-two eligible studies were identified. Single nucleotide polymorphisms (SNPs) at ADIPOQ (rs226729, rs1501299, rs3774261, and rs17300539) showed a positive association with postoperative change in measures of glucose homeostasis and lipid profiles (n = 4), but not with weight loss after surgery (n = 6). SNPs at FTO (rs11075986, rs16952482, rs8050136, rs9939609, rs9930506, and rs16945088) (n = 10) and MC4R (rs11152213, rs476828, rs2229616, rs9947255, rs17773430, rs5282087, and rs17782313) (n = 9) were inconsistently associated with weight loss and metabolic improvement. Four studies examining the UCP2 SNP rs660339 reported associations with postsurgical weight loss. In summary, there is limited evidence supporting a role for specific genetic variants in surgical outcomes after bariatric surgery. Most studies have adopted a candidate gene approach, limiting the scope for discovery, suggesting that the absence of compelling evidence is not evidence of absence.

Current Data and New Insights into the Genetic Factors of Atherogenic Dyslipidemia Associated with Metabolic Syndrome

Atherogenic dyslipidemia plays a critical role in the development of metabolic syndrome (MetS), being one of its major components, along with central obesity, insulin resistance, and hypertension. In recent years, the development of molecular genetics techniques and extended analysis at the genome or exome level has led to important progress in the identification of genetic factors (heritability) involved in lipid metabolism disorders associated with MetS. In this review, we have proposed to present the current knowledge related to the genetic etiology of atherogenic dyslipidemia, but also possible challenges for future studies. Data from the literature provided by candidate gene-based association studies or extended studies, such as genome-wide association studies (GWAS) and whole exome sequencing (WES,) have revealed that atherogenic dyslipidemia presents a marked genetic heterogeneity (monogenic or complex, multifactorial). Despite sustained efforts, many of the genetic factors still remain unidentified (missing heritability). In the future, the identification of new genes and the molecular mechanisms by which they intervene in lipid disorders will allow the development of innovative therapies that act on specific targets. In addition, the use of polygenic risk scores (PRS) or specific biomarkers to identify individuals at increased risk of atherogenic dyslipidemia and/or other components of MetS will allow effective preventive measures and personalized therapy.

The crucial role and mechanism of insulin resistance in metabolic disease

Insulin resistance (IR) plays a crucial role in the development and progression of metabolism-related diseases such as diabetes, hypertension, tumors, and nonalcoholic fatty liver disease, and provides the basis for a common understanding of these chronic diseases. In this study, we provide a systematic review of the causes, mechanisms, and treatments of IR. The pathogenesis of IR depends on genetics, obesity, age, disease, and drug effects. Mechanistically, any factor leading to abnormalities in the insulin signaling pathway leads to the development of IR in the host, including insulin receptor abnormalities, disturbances in the internal environment (regarding inflammation, hypoxia, lipotoxicity, and immunity), metabolic function of the liver and organelles, and other abnormalities. The available therapeutic strategies for IR are mainly exercise and dietary habit improvement, and chemotherapy based on biguanides and glucagon-like peptide-1, and traditional Chinese medicine treatments (e.g., herbs and acupuncture) can also be helpful. Based on the current understanding of IR mechanisms, there are still some vacancies to follow up and consider, and there is also a need to define more precise biomarkers for different chronic diseases and lifestyle interventions, and to explore natural or synthetic drugs targeting IR treatment. This could enable the treatment of patients with multiple combined metabolic diseases, with the aim of treating the disease holistically to reduce healthcare expenditures and to improve the quality of life of patients to some extent.

Transethnic meta-analysis of exome-wide variants identifies new loci associated with male-specific metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) is a group of very common human conditions promoting strong understand the impact of rare variants, beyond exome-wide association studies, to potentially discover causative variants, across different ethnic populations.

OBJECTIVE

We performed transethnic, exome-wide MetS association studies on MetS in men.

METHODS

We analyzed genotype data of 5302 European subjects (2658 cases and 2644 controls), in the discovery stage of the European METabolic Syndrome In Men study, generated from exome chips, and 2481 subjects (714 cases and 1767 controls), in the replication stage, across 6 independent cohorts of 5 ancestries (T2D-GENES consortium), using whole-exome sequencing. We therefore evaluated gene-level and variant-level associations, of rare variants for MetS, using logistic regression (LR) and multivariate analyses (MulA).

RESULTS

Gene-based association found the gene for the cholesteryl ester transfer protein (CETP) (from MulA, p value = 4.67 × 10-9; from LR, p value = 0.009) to well associate with MetS. At two missense variants, from 8 rare variants in CETP, Ala390Pro (rs5880) (from MulA, p value = 1.28 × 10-7; from LR, p value = 1.34 × 10-4) and Arg468Gln (rs1800777) (from MulA, p value = 2.40 × 10-5; from LR, p value = 1.49 × 10-3) significantly associated with MetS across five ancestries.

CONCLUSIONS

Our findings highlight novel rare variants of genes that confer MetS susceptibility, in Europeans, that are shared with diverse populations, emphasizing an opportunity to further understand the biological target or genes that underlie MetS, across populations.

Genetic and environmental correlational structure among metabolic syndrome endophenotypes

Metabolic syndrome (MetS) is diagnosed by the presence of high scores on three or more metabolic traits, including systolic and diastolic blood pressure (SBP, DBP), glucose and insulin levels, cholesterol and triglyceride (TG) levels, and central obesity. A diagnosis of MetS is associated with increased risk of cardiovascular disease and type 2 diabetes. The components of MetS have long been demonstrated to have substantial genetic components, but their genetic overlap is less well understood. The present paper takes a multi-prong approach to examining the extent of this genetic overlap. This includes the quantitative genetic and additive Bayesian network modeling of the large TwinsUK project and examination of the results of genome-wide association study (GWAS) of UK Biobank data through use of LD score regression and examination of the number of genes and pathways identified in the GWASes which overlap across MetS traits. Results demonstrate a modest genetic overlap, and the genetic correlations obtained from TwinsUK and UK Biobank are nearly identical. However, these correlations imply more genetic dissimilarity than similarity. Furthermore, examination of the extent of overlap in significant GWAS hits, both at the gene and pathway level, again demonstrates only modest but significant genetic overlap. This lends support to the idea that in clinical treatment of MetS, treating each of the components individually may be an important way to address MetS.

Metabolic syndrome and underlying genetic determinants-A systematic review

The metabolic syndrome is a cluster of heritable and related traits which has been associated with a range of pathophysiological factors including dyslipidaemia, abdominal obesity, increased fasting plasma glucose (FPG) and hypertension. The documented genetic basis of the metabolic syndrome include several chromosomal positions, numerous candidate gene-associated polymorphisms, different genetic variants, which are linked to the syndrome either as a trait or entities mainly linked to metabolic process. Additionally, the latest findings related to the contribution of epigenetic mechanisms, microRNAs, sporadic variants, non-coding RNAs, and assessing the role of genes in molecular systems has enhanced our understanding of the syndrome. Considerable work has been done to understand the underlying disease mechanisms by elucidating its genetic etiology. Nonetheless, a common shared genetic cause has not been established to clarify the coexistence of their components and further investigation is required. While mostly neglected and rarely known, hereditary predisposition needs to be studied, including with the current defective phenotypic condition descriptions. Metabolic syndrome is a multi-faceted characteristic with abundant properties and the condition can arise from interactions between environmental variables such as physical inactivity, caloric obesity and genetic susceptibility. Although there is support for genetic determinants from family and twin research, there is still no recognised genomic DNA marker for genetic association and linkages with quite a long way off potential for clinical application. In the present review efforts have been made to through light on the various genetic determinants with large effects that underlie with the association of these traits to this syndrome. The heterogeneity and multifactorial heritability of MetS, however, has been a challenge towards understanding the factors underlying the association of these traits.

Prevalence of Metabolic Syndrome and Associated Risk Factors in the United Arab Emirates: A Cross-Sectional Population-Based Study

Aims

To estimate the prevalence of metabolic syndrome (MetS) and its associated risk factors among the United Arab Emirates (UAE) residents.

Methods

A cross-sectional population-based study was conducted among adults living in Sharjah and Northern Emirates using the UAE National Diabetes and Lifestyle Study (UAEDIAB) data. Anthropometric measurements and fasting blood samples were obtained. The National Cholesterol Education Program's Adult Treatment Panel III (NCEP/ATP III) guidelines were used to define metabolic syndrome (MetS).

Results

A total of 3,212 subjects (74.1% men, 25.9% women, mean age 39 ± 11.3 years old) were included in this study. The overall prevalence of MetS was 37.4% (32.7% in women and 39% in men). The prevalence was 33.6% in the Emirati population (38.7% in women and 28.8% in men), 34.5% in the Arab non-Emirati population (29.8% in women and 36.3% in men) and 40.7% in the Asian non-Arab population (25.8% in women and 43.1% in men). Age, gender, ethnicity, educational level, marital status and body mass index were positively associated with MetS.

Conclusions

This study indicates a high burden of MetS in the UAE, particularly among Emirati women and Asian non-Arab men. The young adult population in the UAE has a high prevalence of MetS compared to global estimates in the same age group. Aggressive intervention strategies targeting the whole population as well as individuals at a high risk are recommended to prevent the development of cardiovascular diseases.

Clusters of Cardiometabolic Risk Factors and Their Association with Atherosclerosis and Chronic Inflammation among Adults and Elderly in Florianópolis, Southern Brazil

Fundamento

O aumento significativo de doenças cardiovasculares em países em desenvolvimento alerta sobre seu impacto em populações carentes.

Objetivo

Identificar a relação de agrupamentos de componentes da síndrome metabólica (SM) com aterosclerose e inflamação crônica em adultos e idosos.

Métodos

Análise transversal usando dados de dois estudos populacionais de tipo coorte realizados em Florianópolis, sul do Brasil (EpiFloripa Adult Cohort Study, n = 862, 39,9±11,5 anos; EpiFloripa Aging Cohort Study, n = 1197, 69,7±7,1 anos). Pressão arterial (PA), circunferência da cintura (CC), e níveis plasmáticos de lipídio e glicose foram analisados como fatores individuais ou como agrupamentos de componentes da SM (como número de componentes presentes em um indivíduo ou como combinações). Os desfechos incluíram espessura intima-media carotídea (EIMC), placas ateroscleróticas, e níveis de proteína C reativa (CRP). Regressão linear múltipla e regressão logística, ajustadas quanto aos fatores de confusão, foram usadas para análise. O nível de significância adotado foi de 5%.

Resultados

Indivíduos com PA e CC elevadas, dislipidemia e hiperglicemia (61,5%) apresentaram maiores valores de EIMC e PCR que aqueles que não apresentaram componentes de SM. CC elevada foi um determinante comum de inflamação sistêmica, ao passo que a coexistência de PA elevada e CC elevada (agrupamentos de dois ou três fatores) associou-se com maior EIMC (β entre +3,2 e +6,1 x 10-2 mm; p < 0,05) e PCR (_EXPβ entre 2,18 e 2,77; p < 0,05).

Conclusão

A coexistência de PA e CC elevadas associou-se com maiores valores de EIMC e níveis de PCR. A obesidade central, isolada ou em combinação com outros fatores de risco, teve efeito sobre a inflamação sistêmica.

Are caveolin-1 minor alleles more likely to be risk alleles in insulin resistance mechanisms in metabolic diseases?

OBJECTIVES

Obesity and insulin resistance (IR) are interrelated in a range of ways. The IR-obesity relationship is not a cause-and-effect association. Molecular biology research has made tremendous strides in discovering contributors to find this association. Genes that control adipocyte function such as caveolin-1 (CAV1); probably interact in the pathogenesis of human IR in this context. The involvement of CAV1 in glucose/lipid homeostasis is revealed and could modify the signaling of the insulin receptor. We examined the association between CAV1 and insulin signaling in modifying dyslipidemia and fat composition in overweight and obese women with a prevalent variant in the CAV1 gene.

RESULTS

Minor allele carriers were slightly older and had higher BMI (p = 0.02), FMI (p = 0.006), and VLF (p = 0.01) values; and tended to have lower total cholesterol TC (p = 0.04), low-density lipoprotein cholesterol (LDL-C) (p = 0.001) and high-density lipoprotein cholesterol (HDL-C) (p = 0.003). HOMA-IR levels predicted fat mass index (FMI) 0.47 (0.08, 0.87), visceral fat level (VFL) 0.65 (0.23, 1.07), TC 6.82 (1.76, 11.88) and HDL-C - 1.663 (- 3.11, - 0.214) only between minor allele carriers in adjusted models. (β, CI). Our results cast a new light on the IR mechanism and future studies will elucidate the clinical relevance of CAV1-IR in patients with dyslipidemia and high fat composition.

Heritability and genome-wide association analyses of fasting plasma glucose in Chinese adult twins

Background

Currently, diabetes has become one of the leading causes of death worldwide. Fasting plasma glucose (FPG) levels that are higher than optimal, even if below the diagnostic threshold of diabetes, can also lead to increased morbidity and mortality. Here we intend to study the magnitude of the genetic influence on FPG variation by conducting structural equation modelling analysis and to further identify specific genetic variants potentially related to FPG levels by performing a genome-wide association study (GWAS) in Chinese twins.

Results

The final sample included 382 twin pairs: 139 dizygotic (DZ) pairs and 243 monozygotic (MZ) pairs. The DZ twin correlation for the FPG level (r_DZ = 0.20, 95% CI: 0.04–0.36) was much lower than half that of the MZ twin correlation (r_MZ = 0.68, 95% CI: 0.62–0.74). For the variation in FPG level, the AE model was the better fitting model, with additive genetic parameters (A) accounting for 67.66% (95% CI: 60.50–73.62%) and unique environmental or residual parameters (E) accounting for 32.34% (95% CI: 26.38–39.55%), respectively. In the GWAS, although no genetic variants reached the genome-wide significance level (P < 5 × 10^− 8), 28 SNPs exceeded the level of a suggestive association (P < 1 × 10^− 5). One promising genetic region (2q33.1) around rs10931893 (P = 1.53 × 10^− 7) was found. After imputing untyped SNPs, we found that rs60106404 (P = 2.38 × 10^− 8) located at SPATS2L reached the genome-wide significance level, and 216 SNPs exceeded the level of a suggestive association. We found 1007 genes nominally associated with the FPG level (P < 0.05), including SPATS2L, KCNK5, ADCY5, PCSK1, PTPRA, and SLC26A11. Moreover, C1orf74 (P = 0.014) and SLC26A11 (P = 0.021) were differentially expressed between patients with impaired fasting glucose and healthy controls. Some important enriched biological pathways, such as β-alanine metabolism, regulation of insulin secretion, glucagon signaling in metabolic regulation, IL-1 receptor pathway, signaling by platelet derived growth factor, cysteine and methionine metabolism pathway, were identified.

Conclusions

The FPG level is highly heritable in the Chinese population, and genetic variants are significantly involved in regulatory domains, functional genes and biological pathways that mediate FPG levels. This study provides important clues for further elucidating the molecular mechanism of glucose homeostasis and discovering new diagnostic biomarkers and therapeutic targets for diabetes.

Genetics of Equine Endocrine and Metabolic Disease

A role for a genetic contribution to equine metabolic syndrome (EMS) and pars pituitary intermedia dysfunction (PPID) has been hypothesized. Heritability estimates of EMS biochemical measurements were consistent with moderately to highly heritable traits. Further, genome-wide association analyses have identified hundreds of regions of the genome contributing to EMS and candidate variants have been identified. The genetics of PPID has not yet been proven. Continued research for the specific genetic risk factors for both EMS and PPID is crucial for gaining a better understanding of the pathophysiology of both conditions and allowing development of genetic tests.

Mitochondrial dysfunction in metabolic syndrome

Metabolic syndrome is co-occurrence of obesity, insulin resistance, atherogenic dyslipidemia (high triglyceride, low high density lipoprotein cholesterol), and hypertension. It is a global health problem. An estimated 20%-30% of adults of the world have metabolic syndrome. Metabolic syndrome is associated with increased risk of type 2 diabetes mellitus, nonalcoholic fatty liver disease, myocardial infarction, and stroke. Thus, it is a major cause of morbidity and mortality worldwide. However, molecular pathogenesis of metabolic syndrome is not well known. Recently, there has been interest in the role of mitochondria in pathogenesis of metabolic problems such as obesity, metabolic syndrome, and type 2 diabetes mellitus. Mitochondrial dysfunction contributes to the oxidative stress and systemic inflammation seen in metabolic syndrome. Role of mitochondria in the pathogenesis of metabolic syndrome is intriguing but far from completely understood. However, a better understanding will be very rewarding as it may lead to novel approaches to control this major public health problem. This brief review explores pathogenesis of metabolic syndrome from a mitochondrial perspective.

Genetic and Environmental Influences on the Correlations between Traits of Metabolic Syndrome and CKD

BACKGROUND AND OBJECTIVES

Metabolic syndrome is a cluster of risk factors associated with CKD. By studying the genetic and environmental influences on how traits of metabolic syndrome correlate with CKD, the understanding of the etiological relationships can be improved.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

From the population-based TwinGene project within the Swedish Twin Registry, 4721 complete twin pairs (9442 European ancestry participants) were included in this cross-sectional twin study. Metabolic syndrome-related continuous traits were measured, and the binary components as well as the status of metabolic syndrome were defined according to the National Cholesterol Education Program-Adult Treatment Panel III. The eGFR was calculated by cystatin C-based equations from the CKD epidemiology collaboration group, and CKD was defined by eGFR<60 ml/min per 1.73 m². Genetic and environmental contributions to the correlations between traits of metabolic syndrome and CKD were estimated by using twin-based bivariate structural equation models.

RESULTS

The correlation between metabolic syndrome and eGFR-defined CKD was 0.16 (95% confidence interval [95% CI], 0.12 to 0.20), out of which 51% (95% CI, 12% to 90%) was explained by genes, whereas 15% (95% CI, 0% to 42%) and 34% (95% CI, 16% to 52%) was explained by the shared and nonshared environment, respectively. The genetic and environmental correlations between metabolic syndrome and CKD were 0.29 (95% CI, 0.07 to 0.51) and 0.27 (95% CI, 0.13 to 0.41), respectively. For the correlation between abdominal obesity and eGFR, 69% (95% CI, 10% to 100%) was explained by genes and 23% (95% CI, 5% to 41%) was explained by environment. The genetic correlation between abdominal obesity and eGFR was -0.30 (95% CI, -0.54 to -0.06), whereas the environmental correlation was -0.14 (95% CI, -0.22 to -0.06).

CONCLUSIONS

Both genes and environment contribute to the correlation between metabolic syndrome and eGFR-defined CKD. The genetic contribution is particularly important to the correlation between abdominal obesity and eGFR.

Clusters of cardiovascular risk factors and its association with muscle strength in adults

BACKGROUND

Cardiovascular diseases are the leading cause of death globally. The aim of the study was to investigate the relationship between muscle strength (MS) and clusters of metabolic syndrome (MetS) components in adults.

METHODS

Population-based cross-sectional study comprising 533 adults (45.3±11.1 years) from Florianópolis, Brazil. MS - calculated as the ratio between absolute strength (kgf) and body mass (kg) - was measured by handgrip dynamometry. Data on blood pressure, waist circumference, lipids and blood glucose were used to identify MetS components that were analyzed as individual variables and clusters. Multiple linear regression adjusted was used.

RESULTS

Individually, MS was inversely associated with all MetS components (1, 2, 3 and 4 factors, β of at least -0.08 kgf/kg). In addition, MS was negatively associated with number of positive MetS components (1, 2, 3 and 4 factors; β of at least -0.05 kgf/kg). Individually or combined in clusters of two, three and four risk factors (β of at least -0.20 kgf/kg), abdominal obesity was directly associated with lower MS values. All combinations of 3 and 4 MetS components (β of at least -0.13 kgf/kg) were inversely associated with MS.

CONCLUSIONS

Greater number of individual MetS components were related to lower MS values.

Heritability of blood pressure traits in diverse populations: a systematic review and meta-analysis

To understand the genetic architecture and make inferences about transmissible resemblance of systolic and diastolic blood pressure (SBP and DBP) traits in relatives, the polygenic effect of individual alleles in terms of narrow heritability (h²) is usually assessed. The heritability estimates for BP traits are population specific parameters with a wide range in different studies (6-68%), and there is no comprehensive evidence comparing its source(s) of heterogeneity. To fill the gap, this systematic review and meta-analysis study was carried out. Using MeSH terms, 647 records were detected through searching, "Pubmed," "Ebsco," "Web of Science," and "Scopus" databases. From these, 24 relevant full-text articles with 47 comparisons for final quantitative meta-analysis were included in our review over the five continents. The additive genetic effects of both traits showed a widespread distribution (h²_SBP: 17-52%, h²_DBP:19-41%). Different categories of transmissible resemblance for BP traits were explained by ethnicity; higher heritability was estimated in Europeans and Mexican Americans, while lower heritability was seen in the Middle Eastern, Asians, Africans, Latinos, Hispanics, and American Indians. Low heterogeneity of polygenic effects was seen for both traits in subgroups of the Middle East, Asians, Africans, and Latinos, Hispanics, American Indians. However, there was a substantial heterogeneity of h² within European and Mexican American studies. Neither pedigree type nor other covariates explained the variance of additive genetic effects of BP traits in different ethnicities.

Association of BDNF rs6265 and MC4R rs17782313 with metabolic syndrome in Pakistanis

The current case-control study sought the association of BDNF rs6265 and MC4R rs17782313 with metabolic syndrome (MetS), MetS components and other related metabolic parameters in a sample of Pakistani subjects. Fasting high-density lipoprotein cholesterol (HDL-C) and homeostatic model assessment of insulin sensitivity showed a significantly lower mean whereas body mass index (BMI), waist circumference, systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose, insulin, total cholesterol (TC), low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, triglycerides (TG), cholesterol to HDL-C ratio, TG to HDL-C ratio, homeostatic model assessment of insulin resistance, visceral adiposity index, lipid accumulation product and the product of TG and glucose showed a significantly higher mean in the presence of MetS. Reduced HDL-C appeared as the most frequent and hypertriglyceridemia as the least frequent component of MetS whereas clustering of reduced HDL-C + abdominal obesity (AO) + hyperglycemia appeared as the most prevalent combination of MetS components. Moreover, BDNF rs6265 showed BMI and gender independent association with increased risk of MetS in Pakistani individuals whereas MC4R rs17782313 showed BMI and gender dependent association with increased risk of MetS in Pakistani females. In addition, BDNF rs6265 and MC4R rs17782313 showed gender-dependent associations with decreased risk of having low HDL-C in males and increased risk of having abdominal obesity in females, respectively. However, no association was observed for metabolic variables other than components of MetS across genotypes of both BDNF rs6265 and MC4R rs17782313.

Combined effects of the rs9810888 polymorphism in calcium voltage-gated channel subunit alpha1 D (CACNA1D) and lifestyle behaviors on blood pressure level among Chinese children

Backgrounds

A recent GWAS Study found a new locus (rs9810888 in CACNA1D) was associated with blood pressure (BP) in Chinese adults. But whether the association exists in children is unknown. Whether lifestyle behaviors could interact with rs9810888 on BP is not clear. This study aimed to identify the association between rs9810888 and BP in children, and also explore the gene-lifestyle interaction.

Methods

A case-control study was conducted among 2030 Chinese children aged 7 to 18 years. Genotyping was conducted by using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Lifestyle behaviors were investigated with questionnaire.

Results

With adjustment for age, age square, sex, study group and body mass index (BMI), rs9810888 was significantly associated with diastolic BP (DBP) (b = 1.69, p = 0.021) and mean arterial BP (MAP) (b = 1.56, p = 0.010). Stratified analysis showed that the rs9810888 GG genotype carriers had higher DBP than GT/TT carriers (b = 3.78, p = 0.023) in the subgroup having protein intake (meat/fish/soybeans/egg) <twice/day, but not in the subgroup ≥twice/day. In addition, in the subgroup with screen time≥2h/day, the rs9810888 GG genotype carriers had higher DBP than GT/TT carriers (b = 5.49, p = 0.012), but not in the subgroup with screen time<2h/day. For MAP, in the subgroup having either fruits or vegetables < twice/day, the rs9810888 GG genotype carriers had higher MAP than GT/TT carriers (b = 2.64, p = 0.037), but not in the subgroup with both fruits and vegetables intake ≥twice/day. Additionally, in the subgroup with screen time≥2h/day, the rs9810888 GG genotype carriers had higher MAP than GT/TT carriers (b = 4.80, p = 0.017), but not in those with screen time<2h/day.

Conclusions

The CACNA1D rs9810888 polymorphism was significantly associated with DBP and MAP. In addition, unhealthy lifestyle behaviors and rs9810888 GG genotype had combined effects on BP level among Chinese children.

Sibling Similarity in Metabolic Syndrome: The Portuguese Sibling Study on Growth, Fitness, Lifestyle and Health

This study aims to estimate sibling resemblance in metabolic syndrome (MS) markers, and to investigate the associations of biological and behavioral characteristics with MS. The sample comprises 679 biological siblings (363 females; 316 males) aged 9-20 years. MS markers included waist circumference (WC), high-density lipoprotein cholesterol (HDL-C), triglycerides (TRI), fasting glucose (GLU) and systolic blood pressure (SBP). Body mass index (BMI), biological maturation, muscular, and cardiorespiratory fitness were also assessed. Behavioral characteristics, including dietary intake and physical activity, were self-reported by questionnaire. Multilevel models were used, and sibling resemblance was estimated using the intraclass correlation (ρ). In general, same-sex siblings showed higher resemblance in MS markers than opposite-sex siblings. However, variability in sibling resemblance in MS markers was evident with the inclusion of covariates. Biological characteristics including age, BMI and maturity offset influenced all MS markers except for TRI. Importantly, behavioral characteristics diversely influenced MS markers: fruit and vegetables only influenced SBP, whereas physical activity affected HDL-C. Additionally, muscular fitness impacted significantly on MS Z-score, WC, SBP and GLU, whilst cardiorespiratory fitness only affected WC. In conclusion, biological and behavioral characteristics influenced the expression of MS markers. These results confirmed the importance of considering individual characteristics when designing individualized programs for diminishing the adverse effects of specific MS markers.

Metabolic fitness in relation to genetic variation and leukocyte DNA methylation

Metabolic syndrome (MetS) is a highly prevalent condition causing increased risk of several life-threatening diseases. MetS has a pronounced hereditary basis but is also influenced by environmental factors, partly through epigenetic mechanisms. In this study, the five phenotypes underlying MetS were incorporated into a continuous score for metabolic fitness (MF), and associations with both genotypic variation and leukocyte DNA methylation were investigated. Baseline MF phenotypes (waist circumference, blood pressure, blood glucose, serum triglycerides, and high-density lipoproteins) of 710 healthy Flemish adults were measured. After a 10 yr period, follow-up measures were derived from 618 of these subjects. Genotyping was performed for 65 preselected MF-related genetic variants. Next, full genetic predisposition scores (GPSs) were calculated, combining genotype scores of multiple genetic variants. Additionally, stepwise GPSs were constructed, including only the most predictive genetic variants for the different MF phenotypes. For a subset of 68 middle-aged men, global and gene-specific DNA methylation was investigated, and a biological pathway analysis was performed. The full GPSs were predictive for some baseline MF phenotypes, but not for changes over time. Only a limited number of genetic variants were significantly predictive individually. On the contrary, global and gene-specific DNA methylation was associated with changes in the MF phenotypes rather than with the baseline measures, indicating that effects of DNA methylation on MF are somewhat delayed. Furthermore, several biological pathways were associated with the MF phenotypes through gene promoter methylation. For CETP, G6PC2, MC4R, and TFAP2B both a genetic and epigenetic relationship was found with MF.

Rat Models of Metabolic Syndrome

Metabolic syndrome is a complex disorder that comprises several other complex disorders, including obesity, hypertension, dyslipidemia, and diabetes. There are several rat models that encompass component features of MetS. Some models are inbred strains selected for one or more traits underlying MetS; others are population models with genetic risk for MetS traits, are induced by environmental stressors such as diet, are spontaneous monogenic mutant models, or are congenic strains derived from a combination of these models. Together they can be studied to identify the genetic and physiological underpinnings of MetS to identify candidate genes or mechanisms for study in human MetS subjects.

The investigations of genetic determinants of the metabolic syndrome

Metabolic syndrome is the aggregation of cardiovascular risk factors that increases the risk of type 2 diabetes and cardiovascular diseases. Family and twin studies, heritability spectrum for its components and different prevalence among ethnicities, have provided genetic susceptibility to the metabolic syndrome. The investigations of genetic base for the disorder have recognized numerous chromosomes, various DNA polymorphisms in candidate genes and many gene variants, that are associated with metabolic syndrome as an entity or its traits, which mostly are related to lipid metabolism. In addition, recent finding of the role of rare variants, epigenetic mechanisms, non-coding RNAs and evaluating the function of genes in molecular networks have improved our knowledge. However, a common genetic basis explaining the co-occurrence of its components has not been identified and more researches are essential.

Different metabolic responses induced by long-term interdisciplinary therapy in obese adolescents related to ACE I/D polymorphism

Introduction:

The main purpose of the present study was to investigate whether I/D polymorphism of the ACE gene might affect metabolic changes related to the metabolic syndrome through a long-term interdisciplinary therapy in obese adolescents.

Methods:

In total, 125 obese adolescents who entered the interdisciplinary obesity programme were assigned to the following two subgroups: metabolic syndrome or non-metabolic syndrome. They were evaluated at baseline and after 1 year. Genomic DNA was extracted from circulating leukocytes.

Results:

Subjects with the II genotype in the non-metabolic syndrome group were only to increase their fat-free mass after therapy. Regarding lipid profile, subjects with ID and DD genotypes from both groups reduced their low-density lipoprotein cholesterol levels significantly. The metabolic parameters from the ID and DD genotypes of the non-metabolic syndrome group showed a significantly improved insulin response.

Conclusion:

In the present study, we showed that the ACE polymorphism was able to influence the fat-free mass in the I-carry allele in the non-metabolic syndrome group positively. In addition, the I-carry allele was able to improve the insulin resistance of the metabolic syndrome group significantly. These results suggest that the ACE I/D genotypes can influence, in different ways, the specific parameters of metabolism among obese adolescents submitted for long-term interdisciplinary therapy.

Genetics of Insulin Resistance and the Metabolic Syndrome

Insulin resistance and the metabolic syndrome are complex metabolic traits and key risk factors for the development of cardiovascular disease. They result from the interplay of environmental and genetic factors but the full extent of the genetic background to these conditions remains incomplete. Large-scale genome-wide association studies have helped advance the identification of common genetic variation associated with insulin resistance and the metabolic syndrome, and more recently, exome sequencing has allowed the identification of rare variants associated with the pathogenesis of these conditions. Many variants associated with insulin resistance are directly involved in glucose metabolism; however, functional studies are required to assess the contribution of other variants to the development of insulin resistance. Many genetic variants involved in the pathogenesis of the metabolic syndrome are associated with lipid metabolism.

Heritability and genetic correlation between GERD symptoms severity, metabolic syndrome, and inflammation markers in families living in Mexico City

Objective

The aim of this study was to estimate the heritability (h²) and genetic correlation (ρG) between GERD symptoms severity, metabolic syndrome components, and inflammation markers in Mexican families.

Methods

Cross-sectional study which included 32 extended families resident in Mexico City. GERD symptoms severity was assessed by the ReQuest in Practice questionnaire. Heritability and genetic correlation were determined using the Sequential Oligogenic Linkage Analysis Routines software.

Results

585 subjects were included, the mean age was 42 (±16.7) years, 57% were women. The heritability of the severity of some GERD symptoms was h² = 0.27, 0.27, 0.37, and 0.34 (p-value <1.0x10^-5) for acidity complaints, lower abdominal complaints, sleep disturbances, and total ReQuest score, respectively. Heritability of metabolic syndrome components ranged from 0.40 for fasting plasma glucose to 0.61 for body mass index and diabetes mellitus. The heritability for fibrinogen and C-reactive protein was 0.64 and 0.38, respectively. Statistically significant genetic correlations were found between acidity complaints and fasting plasma glucose (ρG = 0.40); sleep disturbances and fasting plasma glucose (ρG = 0.36); acidity complaints and diabetes mellitus (ρG = 0.49) and between total ReQuest score and fasting plasma glucose (ρG = 0.43). The rest of metabolic syndrome components did not correlate with GERD symptoms.

Conclusion

Genetic factors substantially explain the phenotypic variance of the severity of some GERD symptoms, metabolic syndrome components and inflammation markers. Observed genetic correlations suggest that these phenotypes share common genes. These findings suggest conducting further investigation, as the determination of a linkage analysis in order to identify regions of susceptibility for developing of GERD and metabolic syndrome.

The effect of heritability and host genetics on the gut microbiota and metabolic syndrome

OBJECTIVE

Metabolic syndrome (MetS) arises from complex interactions between host genetic and environmental factors. Although it is now widely accepted that the gut microbiota plays a crucial role in host metabolism, current knowledge on the effect of host genetics on specific gut microbes related to MetS status remains limited. Here, we investigated the links among host genetic factors, gut microbiota and MetS in humans.

DESIGN

We characterised the gut microbial community composition of 655 monozygotic (n=306) and dizygotic (n=74) twins and their families (n=275), of which approximately 18% (121 individuals) had MetS. We evaluated the association of MetS status with the gut microbiota and estimated the heritability of each taxon. For the MetS-related and heritable taxa, we further investigated their associations with the apolipoprotein A-V gene (APOA5) single nucleotide polymorphism (SNP) rs651821, which is known to be associated with triglyceride levels and MetS.

RESULTS

Individuals with MetS had a lower gut microbiota diversity than healthy individuals. The abundances of several taxa were associated with MetS status; Sutterella, Methanobrevibacter and Lactobacillus were enriched in the MetS group, whereas Akkermansia, Odoribacter and Bifidobacterium were enriched in the healthy group. Among the taxa associated with MetS status, the phylum Actinobacteria, to which Bifidobacterium belongs, had the highest heritability (45.7%). Even after adjustment for MetS status, reduced abundances of Actinobacteria and Bifidobacterium were significantly linked to the minor allele at the APOA5 SNP rs651821.

CONCLUSIONS

Our results suggest that an altered microbiota composition mediated by a specific host genotype can contribute to the development of MetS.

A Cross-Sectional Study of the Prevalence of Metabolic Syndrome and Associated Factors in Colombian Collegiate Students: The FUPRECOL-Adults Study

Metabolic syndrome (MetS) is one of the major public health problems worldwide. The objective of the present study is to investigate the prevalence and the associated variables of MetS in Colombian collegiate students. This cross-sectional study included a total of 890 (52% women) healthy collegiate students (21.3 ± 3.2 years old). The prevalence of MetS was determined by the definition provided by the International Diabetes Federation (IDF). We further examined associations between the prevalence of MetS and related factors, such as age, gender, anthropometric and body composition, weight status, and nutrition profile. The overall prevalence of MetS was 6.0% (95% CI = 4.5% to 7.6%), and it was higher in men than women. The most prevalent components were low high-density lipoprotein cholesterol, high triglyceride levels, waist circumference, and blood pressure levels. The predisposing factors for having a MetS included: being male, over 23 years old, overweight or obese, and having an unhealthy waist-to-height ratio. In conclusion, the occurrence of MetS in young adults is substantial. These findings may be relevant to health promotion efforts for collegiate students in order to develop prospective studies and screening for young adults, which will aid in targeted intervention development to decrease cardiometabolic risk factors.

Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer?

In the past few decades, the incidence of thyroid cancer (TC), namely of its papillary hystotype (PTC), has shown a steady increase worldwide, which has been attributed at least in part to the increasing diagnosis of early stage tumors. However, some evidence suggests that environmental and lifestyle factors can also play a role. Among the potential risk factors involved in the changing epidemiology of TC, particular attention has been drawn to insulin-resistance and related metabolic disorders, such as obesity, type 2 diabetes, and metabolic syndrome, which have been also rapidly increasing worldwide due to widespread dietary and lifestyle changes. In accordance with this possibility, various epidemiological studies have indeed gathered substantial evidence that insulin resistance-related metabolic disorders might be associated with an increased TC risk either through hyperinsulinemia or by affecting other TC risk factors including iodine deficiency, elevated thyroid stimulating hormone, estrogen-dependent signaling, chronic autoimmune thyroiditis, and others. This review summarizes the current literature evaluating the relationship between metabolic disorders characterized by insulin resistance and the risk for TC as well as the possible underlying mechanisms. The potential implications of such association in TC prevention and therapy are discussed.

Is there any relationship between different phenotypes of metabolic syndrome and cardiovascular mortality rate?

BACKGROUND

This study aimed to focus on different phenotypes of metabolic syndrome (MetS) and their impact on the cardiovascular disease (CVD) events among a sample of the Iranian population.

MATERIALS AND METHODS

The Isfahan cohort study is a population-based, on-going longitudinal study of adults aged 35 years old or more, living in urban and rural areas of three counties in central Iran namely Isfahan, Najafabad and Arak. Participants were selected by multistage random sampling and were recruited to reflect the age, sex and urban/rural distribution of the community. The sample was restricted to subjects with MetS based on the National Cholesterol Education Program Adult Treatment Panel III criteria and no history of coronary heart disease, stroke, or cancer at the time of the baseline clinical examination.

RESULTS

Among different phenotypes of MetS components, clustering of high triglycerides (TGs), low high-density lipoprotein (HDL) and abdominal obesity (ABO) was the most related to the all-cause mortality among women and followed in order by high TGs, hypertension (HTN) and ABO. In men, the highest rate of all-cause mortality was related to high TGs, low HDL, and HTN. Clustering of four components (high TGs, low HDL and HTN and obesity) is the most related to all-cause mortality in the both sexes (12.1% in men, and 21.5% in women).

CONCLUSION

This study showed different phenotypes of MetS related with all-cause mortality rate and existing HTN in the phenotype of MetS increased the incidence of CVD mortality.

Genetic determinants of cardiometabolic risk factors in rural families in Brazil

OBJECTIVES

The purpose of this study was to estimate the heritability of genetic and environmental correlations between cardiometabolic risk factors in extended pedigrees.

METHODS

The Jequitinhonha Community Family Study Cohort (JCFSC) consists of individuals aged ≥18 years living in rural villages. Family pedigrees were constructed of the cohort. The following data were collected: demographic and socioeconomic status, lifestyle variables, anthropometrics, and lipid traits.

RESULTS

The JCFSC consists of 931 individuals distributed into 69 pedigrees with 4,907 members in total. The heritabilities were 0.47 for total cholesterol (TC), 0.44 for triglycerides (TG) and 0.42 for high-density lipoprotein cholesterol (HDLc), 0.49 for metabolic syndrome, approximately 0.60 for anthropometric traits and 0.30 for blood pressure/hypertension. Significant genetic correlations (ρg ) were found mainly between TG and TC (ρg  = 0.58) and hypertension and TG (ρg  = 0.52). Systolic blood pressure (SBP) was correlated with TG (ρg  = 0.39) and HDLc (ρg  = -0.30). Diastolic blood pressures correlated with TG (ρg =0.56) and TC (ρg =0.30). Genetic correlations were also found between anthropometric traits, including: body mass index (BMI) and TG (ρg =0.34), waist circumference (WC) and TG (ρg =0.42), and WC and HDLc (ρg =-0.33). Household effects were found for HDLc (c(2) = 0.19), SBP (c(2)  = 0.14) and Hypertension (c(2) = 0.14).

CONCLUSIONS

To some phenotypes, including lipids, hypertension, blood pressure, and anthropometric traits, genetic contribution is important in the determination of cardiometabolic risk factors. This study provides a foundation for future studies. These will mainly focus on rare variants that could describe the genetic mechanisms influencing cardiometabolic risk. Am. J. Hum. Biol. 28:619-626, 2016. © 2016 Wiley Periodicals, Inc.

The role of life-course socioeconomic and lifestyle factors in the intergenerational transmission of the metabolic syndrome: results from the LifeLines Cohort Study

BACKGROUND

The risk of metabolic syndrome is associated between parents and offspring, but studies are inconsistent on differences by sex of parents and offspring. Our aim is to investigate to what extent metabolic syndrome present in fathers and mothers is associated with risk of metabolic syndrome in sons and daughters. Furthermore, we investigate to what extent these associations are explained by socioeconomic factors and health behaviours.

METHODS

We used data from the LifeLines Cohort Study (N = 7239). Metabolic syndrome was defined according to the NCEP-ATPIII criteria. Logistic regression analyses were performed to investigate associations of metabolic syndrome present in parents with the risk of metabolic syndrome in offspring. Analyses were sequentially adjusted for: age and sex; childhood factors (socioeconomic position and parental smoking); and adult factors (education, income, smoking, physical activity, alcohol intake, and dietary factors).

RESULTS

Multivariate regression analysis adjusted for age and sex showed associations of the metabolic syndrome between father-son: odds ratio (OR) [95% confidence interval (CI)] 2.41 (1.93-3.00), father-daughter: OR (95% CI) 1.80 (1.39-2.33)), mother-son: OR (95% CI) 1.82 (1.44-2.29) and mother-daughter: OR (95% CI) 1.97 (1.52-2.55). Furthermore, each individual factor underlying the metabolic syndrome in parents was associated with metabolic syndrome in offspring, but not for all parent-offspring combinations. None of the parent-offspring associations was attenuated when adjusting for socioeconomic factors and health behaviours.

CONCLUSIONS

High risk of metabolic syndrome is transmitted from fathers and mothers to sons and daughters. Our results suggest that this transmission is irrespective of the socioeconomic position and health behaviours of the offspring.

Genome-wide association studies suggest sex-specific loci associated with abdominal and visceral fat

BACKGROUND

To identify loci associated with abdominal fat and replicate prior findings, we performed genome-wide association (GWA) studies of abdominal fat traits: subcutaneous adipose tissue (SAT); visceral adipose tissue (VAT); total adipose tissue (TAT) and visceral to subcutaneous adipose tissue ratio (VSR).

SUBJECTS AND METHODS

Sex-combined and sex-stratified analyses were performed on each trait with (TRAIT-BMI) or without (TRAIT) adjustment for body mass index (BMI), and cohort-specific results were combined via a fixed effects meta-analysis. A total of 2513 subjects of European descent were available for the discovery phase. For replication, 2171 European Americans and 772 African Americans were available.

RESULTS

A total of 52 single-nucleotide polymorphisms (SNPs) encompassing 7 loci showed suggestive evidence of association (P<1.0 × 10(-6)) with abdominal fat in the sex-combined analyses. The strongest evidence was found on chromosome 7p14.3 between a SNP near BBS9 gene and VAT (rs12374818; P=1.10 × 10(-7)), an association that was replicated (P=0.02). For the BMI-adjusted trait, the strongest evidence of association was found between a SNP near CYCSP30 and VAT-BMI (rs10506943; P=2.42 × 10(-7)). Our sex-specific analyses identified one genome-wide significant (P<5.0 × 10(-8)) locus for SAT in women with 11 SNPs encompassing the MLLT10, DNAJC1 and EBLN1 genes on chromosome 10p12.31 (P=3.97 × 10(-8) to 1.13 × 10(-8)). The THNSL2 gene previously associated with VAT in women was also replicated (P=0.006). The six gene/loci showing the strongest evidence of association with VAT or VAT-BMI were interrogated for their functional links with obesity and inflammation using the Biograph knowledge-mining software. Genes showing the closest functional links with obesity and inflammation were ADCY8 and KCNK9, respectively.

CONCLUSIONS

Our results provide evidence for new loci influencing abdominal visceral (BBS9, ADCY8, KCNK9) and subcutaneous (MLLT10/DNAJC1/EBLN1) fat, and confirmed a locus (THNSL2) previously reported to be associated with abdominal fat in women.

Sasang Constitution May Play a Key Role in Increasing the Number of Sub-Elements of Metabolic Syndrome

BACKGROUND

Metabolic syndrome (MS), a representative cluster of chronic diseases, is defined by the presence of three or more of the following five elements: high blood glucose, high blood pressure, low high-density lipoprotein (HDL)cholesterol, high serum triglyceride levels, and abdominal obesity. Recently, innate factors have been continuously demonstrated as important risk factors for increasing the number of MS sub-elements. Sasang constitutional medicine (SCM) is a traditional Korean medicine in which each Sasang constitution (SC) type has a different susceptibility to pathology and diseases. The aim of this study is to determine whether the SC could be an independent risk factor for single and multiple MS sub-elements.

METHODS

Twenty-four Korean medical clinics joined the study, and 3334 participants aged 20-80 years were recruited. Clinical data related to MS and general characteristics were obtained. The chi-square test and a one-way analysis of variance were conducted, and the odds ratios (ORs) with 95% confidence intervals (CIs) were generated through multinomial logistic regression according to the SC.

RESULTS

The prevalence of single and multiple MS sub-elements was significantly different according to SC. The ORs of the Tae-Eumin (TE) type were significantly high for abdominal obesity, diabetes mellitus, hypertriglyceridemia, low HDL cholesterol, and hypertension. The ORs for the So-Yangin type were also high in hypertriglyceridemia and low HDL cholesterol compared with the So-Eumin type, even after being adjusted for sex, age, body mass index, and eating habits. As the numbers of MS sub-elements increased, the ORs of the TE type also increased.

CONCLUSIONS

This study showed that the SC types may be risk factors for not only single MS sub-elements but also multiple MS sub-elements and that the TE type's risk degree is associated with an increase in the number of MS sub-elements.

Genome-wide association study identifies African-ancestry specific variants for metabolic syndrome

The metabolic syndrome (MetS) is a constellation of metabolic disorders that increase the risk of developing several diseases including type 2 diabetes and cardiovascular diseases. Although genome-wide association studies (GWAS) have successfully identified variants associated with individual traits comprising MetS, the genetic basis and pathophysiological mechanisms underlying the clustering of these traits remain unclear. We conducted GWAS of MetS in 1427 Africans from Ghana and Nigeria followed by replication testing and meta-analysis in another continental African sample from Kenya. Further replication testing was performed in an African American sample from the Atherosclerosis Risk in Communities (ARIC) study. We found two African-ancestry specific variants that were significantly associated with MetS: SNP rs73989312[A] near CA10 that conferred increased risk (P=3.86 × 10(-8), OR=6.80) and SNP rs77244975[C] in CTNNA3 that conferred protection against MetS (P=1.63 × 10(-8), OR=0.15). Given the exclusive expression of CA10 in the brain, our CA10 finding strengthens previously reported link between brain function and MetS. We also identified two variants that are not African specific: rs76822696[A] near RALYL associated with increased MetS risk (P=7.37 × 10(-9), OR=1.59) and rs7964157[T] near KSR2 associated with reduced MetS risk (P=4.52 × 10(-8), Pmeta=7.82 × 10(-9), OR=0.53). The KSR2 locus displayed pleiotropic associations with triglyceride and measures of blood pressure. Rare KSR2 mutations have been reported to be associated with early onset obesity and insulin resistance. Finally, we replicated the LPL and CETP loci previously found to be associated with MetS in Europeans. These findings provide novel insights into the genetics of MetS in Africans and demonstrate the utility of conducting trans-ethnic disease gene mapping studies for testing the cosmopolitan significance of GWAS signals of cardio-metabolic traits.

Prevalence, associated factors and heritabilities of metabolic syndrome and its individual components in African Americans: the Jackson Heart Study

OBJECTIVE

Both environmental and genetic factors play important roles in the development of metabolic syndrome (MetS). Studies about its associated factors and genetic contribution in African Americans (AA) are sparse. Our aim was to report the prevalence, associated factors and heritability estimates of MetS and its components in AA men and women.

PARTICIPANTS AND SETTING

Data of this cross-sectional study come from a large community-based Jackson Heart Study (JHS). We analysed a total of 5227 participants, of whom 1636 from 281 families were part of a family study subset of JHS.

METHODS

Participants were classified as having MetS according to the Adult Treatment Panel III criteria. Multiple logistic regression analysis was performed to isolate independently associated factors of MetS (n=5227). Heritability was estimated from the family study subset using variance component methods (n=1636).

RESULTS

About 27% of men and 40% of women had MetS. For men, associated factors with having MetS were older age, lower physical activity, higher body mass index, and higher homocysteine and adiponectin levels (p<0.05 for all). For women, in addition to all these, lower education, current smoking and higher stress were also significant (p<0.05 for all). After adjusting for covariates, the heritability of MetS was 32% (p<0.001). Heritability ranged from 14 to 45% among its individual components. Relatively higher heritability was estimated for waist circumference (45%), high density lipoprotein-cholesterol (43%) and triglycerides (42%). Heritability of systolic blood pressure (BP), diastolic BP and fasting blood glucose was 16%, 15% and 14%, respectively.

CONCLUSIONS

Stress and low education were associated with having MetS in AA women, but not in men. Higher heritability estimates for lipids and waist circumference support the hypothesis of lipid metabolism playing a central role in the development of MetS and encourage additional efforts to identify the underlying susceptibility genes for this syndrome in AA.

Are there genetic paths common to obesity, cardiovascular disease outcomes, and cardiovascular risk factors?

Clustering of obesity, coronary artery disease, and cardiovascular disease risk factors is observed in epidemiological studies and clinical settings. Twin and family studies have provided some supporting evidence for the clustering hypothesis. Loci nearest a lead single nucleotide polymorphism (SNP) showing genome-wide significant associations with coronary artery disease, body mass index, C-reactive protein, blood pressure, lipids, and type 2 diabetes mellitus were selected for pathway and network analyses. Eighty-seven autosomal regions (181 SNPs), mapping to 56 genes, were found to be pleiotropic. Most pleiotropic regions contained genes associated with coronary artery disease and plasma lipids, whereas some exhibited coaggregation between obesity and cardiovascular disease risk factors. We observed enrichment for liver X receptor (LXR)/retinoid X receptor (RXR) and farnesoid X receptor/RXR nuclear receptor signaling among pleiotropic genes and for signatures of coronary artery disease and hepatic steatosis. In the search for functionally interacting networks, we found that 43 pleiotropic genes were interacting in a network with an additional 24 linker genes. ENCODE (Encyclopedia of DNA Elements) data were queried for distribution of pleiotropic SNPs among regulatory elements and coding sequence variations. Of the 181 SNPs, 136 were annotated to ≥ 1 regulatory feature. An enrichment analysis found over-representation of enhancers and DNAse hypersensitive regions when compared against all SNPs of the 1000 Genomes pilot project. In summary, there are genomic regions exerting pleiotropic effects on cardiovascular disease risk factors, although only a few included obesity. Further studies are needed to resolve the clustering in terms of DNA variants, genes, pathways, and actionable targets.

Metabolic syndrome: a closer look at the growing epidemic and its associated pathologies

Obesity is reaching epidemic proportions with recent worldwide figures estimated at 1.4 billion and rising year-on-year. Obesity affects all socioeconomic backgrounds and ethnicities and is a pre-requisite for metabolic syndrome. Metabolic syndrome is a clustering of risk factors, such as central obesity, insulin resistance, dyslipidaemia and hypertension that together culminate in the increased risk of type 2 diabetes mellitus and cardiovascular disease. As these conditions are among the leading causes of deaths worldwide and metabolic syndrome increases the risk of type 2 diabetes mellitus fivefold and cardiovascular disease threefold, it is of critical importance that a precise definition is agreed upon by all interested parties. Also of particular interest is the relationship between metabolic syndrome and cancer. Metabolic syndrome has been associated with a plethora of cancers including breast, pancreatic, colon and liver cancer. Furthermore, each individual risk factor for metabolic syndrome has also an association with cancer. Our review collates internationally generated information on metabolic syndrome, its many definitions and its associations with life-threatening conditions including type 2 diabetes mellitus, cardiovascular disease and cancer, providing a foundation for future advancements on this topic.

Parent-offspring association of metabolic syndrome in the Framingham Heart Study

BACKGROUND

Metabolic syndrome (MetS) is a clustering of five metabolic risk factors including abdominal obesity, elevated blood pressure, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C), and impaired fasting glucose. Few studies have fully reported the strength of clustering of these risk factors in a parent-offspring relationship. This analysis describes the associations between parents and their adult offspring in regard to MetS. It also estimates the association between each risk factor in parents and the presence of MetS in their offspring.

METHODS

We analyzed data for 1193 offspring (565 sons, and 628 daughters) from the Framingham Offspring Study who attended examinations 5, 6, and 7. Information about their parents was collected from examinations 13, 14 and 15 of the Framingham Original Cohort study. We used pedigree file to combine parental and offspring's data. Participants were classified as having the MetS according to the Adult Treatment Panel III criteria. Analyses were conducted separately for mothers and fathers. Logistic regression was used to estimate the associations.

RESULTS

After adjusting for age, education, smoking, alcohol consumption and physical activity level of offspring, no significant association was found between father's and their offspring's MetS. Mother's MetS was significantly and positively associated with their daughter's MetS (adjusted odds ratio or adj OR: 1.63; 95% confidence Interval, CI:1.02-2.61), but not with their sons' MetS. When analyzed by individual components, maternal impaired glucose (adj OR: 2.03; 95% CI: 1.02- 9.31), abdominal obesity (adj OR: 1.56; 95% CI: 0.98- 2.55) and low HDL-C (adj OR: 2.12; 95% CI: 1.36-3.32) were associated daughter's MetS. Maternal low HDL-C and raised total cholesterol showed marginal association with son's MetS. For fathers, only impaired glucose (adj OR: 4.91; 95% CI: 2.07- 11.68) was associated with their daughter's MetS.

CONCLUSIONS

Using the data from Framingham Heart Study, we demonstrate differential association of MetS and its components between parents and offspring. Mother's MetS was strongly related with daughter's MetS, but the association was inconsistent with son's MetS. No association was found between father's MetS and offspring's Mets. These results provide evidence that daughters with mother's MetS are in higher risk than daughters or sons with father's MetS.

Genetics of metabolic syndrome

Metabolic syndrome (MetS) is a cluster of metabolic traits associated with an increased risk of cardiovascular disease and type 2 diabetes mellitus. Central obesity and insulin resistance are thought to play key roles in the pathogenesis of the MetS. The MetS has a significant genetic component, and therefore linkage analysis, candidate gene approach, and genome-wide association (GWA) studies have been applied in the search of gene variants for the MetS. A few variants have been identified, located mostly in or near genes regulating lipid metabolism. GWA studies for the individual components of the MetS have reported several loci having pleiotropic effects on multiple MetS-related traits. Genetic studies have provided so far only limited evidence for a common genetic background of the MetS. Epigenetic factors (DNA methylation and histone modification) are likely to play important roles in the pathogenesis of the MetS, and they might mediate the effects of environmental exposures on the risk of the MetS. Further research is needed to clarify the role of genetic variation and epigenetic mechanisms in the development of the MetS.

Heritability of phenotypes associated with glucose homeostasis and adiposity in a rural area of Brazil

We aimed to estimate the heritability and genetic correlation between glucose homeostasis and adiposity traits in a population in a rural community in Brazil. The Jequitinhonha Community Family Study cohort consists of subjects aged ≥18 years residing in rural areas in Brazil. The data on the following traits were assembled for 280 individuals (51.7% women): body mass index (BMI), body fat percentage, waist and mid-upper arm circumferences, triceps skinfold, conicity index, insulin, glucose, high-density lipoprotein cholesterol (HDLc), triglycerides and C-reactive protein. Extended pedigrees were constructed up to the third generation of individuals using the data management software PEDSYS. The heritability and genetic correlations were estimated using a variance component method. The age- and sex-adjusted heritability values estimated for insulin (h(2) = 52%), glucose (h(2) = 51%), HDLc (h(2) = 58%), and waist circumference (WC; h(2) = 49%) were high. Significantly adjusted genetic correlations were observed between insulin paired with each of the following phenotypes; (BMI; ρg = 0.48), WC (ρg = 0.47) and HDLc (ρg = -0.47). The homeostasis model assessment of insulin resistance (HOMA-IR) was genetically correlated with BMI (ρg = 0.53) and HDLc (ρg = -0.58). The adjusted genetic correlations between traits were consistently higher compared with the environmental correlations. In conclusion, glucose metabolism and adiposity traits are highly heritable and share common genetic effects with body adiposity traits.

Association of arterial stiffness with single nucleotide polymorphism rs1333049 and metabolic risk factors

Background

Increased arterial stiffness is a cardiovascular outcome of metabolic syndrome (MetS). The chromosome 9p21 locus has been identified as a major locus for risk of coronary artery disease (CAD). The single nucleotide polymorphism (SNP), rs1333049 on chromosome 9p21.3 has been strongly associated with CAD and myocardial infarction. Increased arterial stiffness could be the link between the 9p21 polymorphism and increased cardiovascular risk. Since the impact of a genetic polymorphism on arterial stiffness especially in Asian populations has not been well defined, we aimed to investigate the association of arterial stiffness with rs 1333049 variant on chromosome 9p21.3 in Thai subjects with and without MetS risk factors.

Methods

A total of 208 Thai subjects, aged 35–75 years, 135 with and 73 without MetS, according to IDF and NCEP-ATPIII criteria, were included in this study. Aortic-femoral pulse wave velocity (afPWV), brachial-ankle pulse wave velocity (baPWV) and aortic ankle pulse wave velocity (aaPWV) were measured and used as markers of arterial stiffness. The chromosome 9p21.3 locus, represented by the rs 1333049 variant and blood biochemistry were evaluated.

Results

Arterial stiffness was elevated in subjects with MetS when compared with nonMetS subjects. PWV, especially afPWV increased progressively with increasing number of MetS risk factors (r = 0.322, P <0.001). We also found that the frequency distribution of the rs1333049 genotypes is significantly associated with the afPWV (P <0.05). In multivariate analyses, there was an association between homozygous C allele and afPWV (Odds ratio (OR), 8.16; 95% confidence interval (CI), 1.91 to 34.90; P = 0.005), while the GC genotype was not related to afPWV (OR, 1.79; 95% CI, 0.84 to 3.77; P = 0.129) when compared with the GG genotype.

Conclusions

Our findings demonstrate for the first time that arterial stiffness is associated with genetic polymorphism in 9p21 and metabolic risk factors in a Thai population.