Abbas Dehghan

Novel Associations of Multiple Genetic Loci With Plasma Levels of Factor VII, Factor VIII, and von Willebrand Factor The CHARGE (Cohorts for Heart and Aging Research in Genome Epidemiology) Consortium

A complex cascade of coagulation factors underlies hemostasis and prevents life-threatening blood loss from damaged blood vessels. The hemostatic factors VII and VIII, both produced in the liver, play central roles in the initiation and propagation, respectively, of fibrin formation. In the tissue-factor pathway, blood coagulation factor VII (FVII), once activated, serves as a catalyst for factor X (FX) activation, which converts prothrombin to thrombin. During propagation, activated factor VIII (FVIII) activates FX in the presence of activated factor IX. Von Willebrand factor (vWF), produced by endothelial cells and megakaryocytes, has multiple roles in hemostasis. Its primary role is to serve as an adhesion molecule that anchors platelets to exposed collagen after endothelial cell damage. The factor also acts as a carrier protein of FVIII, thereby prolonging the half-life of FVIII. n nElevated circulating levels of FVIII and vWF are risk factors for venous thrombosis but the data supporting an association of FVII levels with arterial thrombosis are less consistent.1-5 Hemorrhagic complications are associated with deficiency in FVII and vWF (von Willebrand disease), as well as X-linked deficiency in FVIII (Hemophilia A).6-9 Plasma levels of these proteins are affected by environmental factors but they also are genetically influenced.10-13 Heritability estimates range from 0.53-0.63 for FVII, 0.40-0.61 for FVIII, and 0.31-0.75 for vWF.12, 13 To date, our understanding of genetic variation influencing plasma levels has been focused primarily on cis-acting variation in the genes encoding each protein product (F7, F8, and VWF, respectively). A large-scale genome-wide investigation of the genomic correlates of plasma levels has not been previously published. Using data from 23,608 adults, we investigated genome-wide associations between common genetic variation and plasma levels of FVII, FVIII, and vWF.Background— Plasma levels of coagulation factors VII (FVII), VIII (FVIII), and von Willebrand factor (vWF) influence risk of hemorrhage and thrombosis. We conducted genome-wide association studies to identify new loci associated with plasma levels. Methods and Results— The setting of the study included 5 community-based studies for discovery comprising 23 608 European-ancestry participants: Atherosclerosis Risk In Communities Study, Cardiovascular Health Study, British 1958 Birth Cohort, Framingham Heart Study, and Rotterdam Study. All subjects had genome-wide single-nucleotide polymorphism (SNP) scans and at least 1 phenotype measured: FVII activity/antigen, FVIII activity, and vWF antigen. Each study used its genotype data to impute to HapMap SNPs and independently conducted association analyses of hemostasis measures using an additive genetic model. Study findings were combined by meta-analysis. Replication was conducted in 7604 participants not in the discovery cohort. For FVII, 305 SNPs exceeded the genome-wide significance threshold of 5.0×10−8 and comprised 5 loci on 5 chromosomes: 2p23 (smallest P value 6.2×10−24), 4q25 (3.6×10−12), 11q12 (2.0×10−10), 13q34 (9.0×10−259), and 20q11.2 (5.7×10−37). Loci were within or near genes, including 4 new candidate genes and F7 (13q34). For vWF, 400 SNPs exceeded the threshold and marked 8 loci on 6 chromosomes: 6q24 (1.2×10−22), 8p21 (1.3×10−16), 9q34 (<5.0×10−324), 12p13 (1.7×10−32), 12q23 (7.3×10−10), 12q24.3 (3.8×10−11), 14q32 (2.3×10−10), and 19p13.2 (1.3×10−9). All loci were within genes, including 6 new candidate genes, as well as ABO (9q34) and VWF (12p13). For FVIII, 5 loci were identified and overlapped vWF findings. Nine of the 10 new findings were replicated. Conclusions— New genetic associations were discovered outside previously known biological pathways and may point to novel prevention and treatment targets of hemostasis disorders.

Uromodulin Levels Associate with a Common UMOD Variant and Risk for Incident CKD

Common variants in the region of the UMOD gene, which encodes uromodulin (Tamm-Horsfall protein), associate with chronic kidney disease (CKD) and estimated GFR (eGFR). Whether uromodulin levels associate with UMOD variants or with the risk for developing CKD is unknown. We conducted an age- and gender-matched case-control study (n = 200) of incident CKD (eGFR <60 ml/min per 1.73 m(2)) within the Framingham Heart Study (FHS). Baseline urinary uromodulin concentrations were related to case-control status 9.9 yr later and to genotype at rs4293393. As a replication set, we tested the genotype association with uromodulin concentration in the Atherosclerosis Risk in Communities (ARIC) Study (n = 42). Geometric means of uromodulin concentrations were 51% higher in case than in control subjects (P = 0.016). The adjusted odds ratio of CKD per 1-SD higher concentration of uromodulin was 1.72 (95% confidence interval 1.07 to 2.77; P = 0.03) after accounting for CKD risk factors and baseline eGFR. We observed lower urinary uromodulin concentrations per each copy of the C allele at rs4293393 in both cohorts. In summary, elevated uromodulin concentrations precede the onset of CKD and associate with a common polymorphism in the UMOD region.

Common Genetic Variants Associate with Serum Phosphorus Concentration

Phosphorus is an essential mineral that maintains cellular energy and mineralizes the skeleton. Because complex actions of ion transporters and regulatory hormones regulate serum phosphorus concentrations, genetic variation may determine interindividual variation in phosphorus metabolism. Here, we report a comprehensive genome-wide association study of serum phosphorus concentration. We evaluated 16,264 participants of European ancestry from the Cardiovascular Heath Study, Atherosclerosis Risk in Communities Study, Framingham Offspring Study, and the Rotterdam Study. We excluded participants with an estimated GFR <45 ml/min per 1.73 m(2) to focus on phosphorus metabolism under normal conditions. We imputed genotypes to approximately 2.5 million single-nucleotide polymorphisms in the HapMap and combined study-specific findings using meta-analysis. We tested top polymorphisms from discovery cohorts in a 5444-person replication sample. Polymorphisms in seven loci with minor allele frequencies 0.08 to 0.49 associate with serum phosphorus concentration (P = 3.5 x 10(-16) to 3.6 x 10(-7)). Three loci were near genes encoding the kidney-specific type IIa sodium phosphate co-transporter (SLC34A1), the calcium-sensing receptor (CASR), and fibroblast growth factor 23 (FGF23), proteins that contribute to phosphorus metabolism. We also identified genes encoding phosphatases, kinases, and phosphodiesterases that have yet-undetermined roles in phosphorus homeostasis. In the replication sample, five of seven top polymorphisms associate with serum phosphorous concentrations (P < 0.05 for each). In conclusion, common genetic variants associate with serum phosphorus in the general population. Further study of the loci identified in this study may help elucidate mechanisms of phosphorus regulation.

Association of novel genetic loci with circulating fibrinogen levels a genome-wide association study in 6 population-based cohorts

Background— Fibrinogen is both central to blood coagulation and an acute-phase reactant. We aimed to identify common variants influencing circulation fibrinogen levels.nnMethods and Results— We conducted a genome-wide association analysis on 6 population-based studies, the Rotterdam Study, the Framingham Heart Study, the Cardiovascular Health Study, the Atherosclerosis Risk in Communities Study, the Monitoring of Trends and Determinants in Cardiovascular Disease/KORA Augsburg Study, and the British 1958 Birth Cohort Study, including 22 096 participants of European ancestry. Four loci were marked by 1 or more single-nucleotide polymorphisms that demonstrated genome-wide significance ( P <5.0×10−8). These included a single-nucleotide polymorphism located in the fibrinogen β chain ( FGB ) gene and 3 single-nucleotide polymorphisms representing newly identified loci. The high-signal single-nucleotide polymorphisms were rs1800789 in exon 7 of FGB ( P =1.8×10−30), rs2522056 downstream from the interferon regulatory factor 1 ( IRF1 ) gene ( P =1.3×10−15), rs511154 within intron 1 of the propionyl coenzyme A carboxylase ( PCCB ) gene ( P =5.9×10−10), and rs1539019 on the NLR family pyrin domain containing 3 isoforms ( NLRP3 ) gene ( P =1.04×10−8).nnConclusions— Our findings highlight biological pathways that may be important in regulation of inflammation underlying cardiovascular disease.nnReceived October 1, 2008; accepted January 5, 2009. nn# CLINICAL PERSPECTIVE {#article-title-2}Background—Fibrinogen is both central to blood coagulation and an acute-phase reactant. We aimed to identify common variants influencing circulation fibrinogen levels. Methods and Results—We conducted a genome-wide association analysis on 6 population-based studies, the Rotterdam Study, the Framingham Heart Study, the Cardiovascular Health Study, the Atherosclerosis Risk in Communities Study, the Monitoring of Trends and Determinants in Cardiovascular Disease/KORA Augsburg Study, and the British 1958 Birth Cohort Study, including 22 096 participants of European ancestry. Four loci were marked by 1 or more single-nucleotide polymorphisms that demonstrated genome-wide significance (P<5.0×10−8). These included a single-nucleotide polymorphism located in the fibrinogen &bgr; chain (FGB) gene and 3 single-nucleotide polymorphisms representing newly identified loci. The high-signal single-nucleotide polymorphisms were rs1800789 in exon 7 of FGB (P=1.8×10−30), rs2522056 downstream from the interferon regulatory factor 1 (IRF1) gene (P=1.3×10−15), rs511154 within intron 1 of the propionyl coenzyme A carboxylase (PCCB) gene (P=5.9×10−10), and rs1539019 on the NLR family pyrin domain containing 3 isoforms (NLRP3) gene (P=1.04×10−8). Conclusions—Our findings highlight biological pathways that may be important in regulation of inflammation underlying cardiovascular disease.

Adiposity as a cause of cardiovascular disease: a Mendelian randomization study

BACKGROUNDnAdiposity, as indicated by body mass index (BMI), has been associated with risk of cardiovascular diseases in epidemiological studies. We aimed to investigate if these associations are causal, using Mendelian randomization (MR) methods.nnnMETHODSnThe associations of BMI with cardiovascular outcomes [coronary heart disease (CHD), heart failure and ischaemic stroke], and associations of a genetic score (32 BMI single nucleotide polymorphisms) with BMI and cardiovascular outcomes were examined in up to 22,193 individuals with 3062 incident cardiovascular events from nine prospective follow-up studies within the ENGAGE consortium. We used random-effects meta-analysis in an MR framework to provide causal estimates of the effect of adiposity on cardiovascular outcomes.nnnRESULTSnThere was a strong association between BMI and incident CHD (HR = 1.20 per SD-increase of BMI, 95% CI, 1.12-1.28, P = 1.9.10(-7)), heart failure (HR = 1.47, 95% CI, 1.35-1.60, P = 9.10(-19)) and ischaemic stroke (HR = 1.15, 95% CI, 1.06-1.24, P = 0.0008) in observational analyses. The genetic score was robustly associated with BMI (β = 0.030 SD-increase of BMI per additional allele, 95% CI, 0.028-0.033, P = 3.10(-107)). Analyses indicated a causal effect of adiposity on development of heart failure (HR = 1.93 per SD-increase of BMI, 95% CI, 1.12-3.30, P = 0.017) and ischaemic stroke (HR = 1.83, 95% CI, 1.05-3.20, P = 0.034). Additional cross-sectional analyses using both ENGAGE and CARDIoGRAMplusC4D data showed a causal effect of adiposity on CHD.nnnCONCLUSIONSnUsing MR methods, we provide support for the hypothesis that adiposity causes CHD, heart failure and, previously not demonstrated, ischaemic stroke.

Lifetime risk of developing impaired glucose metabolism and eventual progression from prediabetes to type 2 diabetes: a prospective cohort study

BACKGROUNDnData are scarce for the lifetime risk of developing impaired glucose metabolism, including prediabetes, as are data for the risk of eventual progression from prediabetes to diabetes and for initiation of insulin treatment in previously untreated patients with diabetes. We aimed to calculate the lifetime risk of the full range of glucose impairments, from normoglycaemia to prediabetes, type 2 diabetes, and eventual insulin use.nnnMETHODSnIn this prospective population-based cohort analysis, we used data from the population-based Rotterdam Study. We identified diagnostic events by use of general practitioners records, hospital discharge letters, pharmacy dispensing data, and serum fasting glucose measurements taken at the study centre (Rotterdam, Netherlands) visits. Normoglycaemia, prediabetes, and diabetes were defined on the basis of WHO criteria for fasting glucose (normoglycaemia: ≤6·0 mmol/L; prediabetes: >6·0 mmol/L and <7·0 mmol/L; and diabetes ≥7·0 mmol/L or use of glucose-lowering drug). We calculated lifetime risk using a modified version of survival analysis adjusted for the competing risk of death. We also estimated the lifetime risk of progression from prediabetes to overt diabetes and from diabetes free of insulin treatment to insulin use. Additionally, we calculated years lived with healthy glucose metabolism.nnnFINDINGSnWe used data from 10u2008050 participants from the Rotterdam Study. During a follow-up of up to 14·7 years (between April 1, 1997, and Jan 1, 2012), 1148 participants developed prediabetes, 828 developed diabetes, and 237 started insulin treatment. At age 45 years, the remaining lifetime risk was 48·7% (95% CI 46·2-51·3) for prediabetes, 31·3% (29·3-33·3) for diabetes, and 9·1% (7·8-10·3) for insulin use. In individuals aged 45 years, the lifetime risk to progress from prediabetes to diabetes was 74·0% (95% CI 67·6-80·5), and 49·1% (38·2-60·0) of the individuals with overt diabetes at this age started insulin treatment. The lifetime risks attenuated with advancing age, but increased with increasing BMI and waist circumference. On average, individuals with severe obesity lived 10 fewer years without glucose impairment compared with normal-weight individuals.nnnINTERPRETATIONnImpaired glucose metabolism is a substantial burden on population health, and our findings emphasise the need for more effective prevention strategies, which should be implemented as soon in a persons life as possible. The substantial lifetime risk of prediabetes and diabetes in lean individuals also supports risk factor control in non-obese individuals.nnnFUNDINGnErasmus MC and Erasmus University Rotterdam; Netherlands Organisation for Scientific Research; Netherlands Organisation for Health Research and Development; Research Institute for Diseases in the Elderly; Netherlands Genomics Initiative; Netherlands Ministry of Education, Culture and Science; Netherlands Ministry of Health, Welfare and Sports; European Commission; and Municipality of Rotterdam.

The role of epigenetic modifications in cardiovascular disease: A systematic review

BACKGROUNDnEpigenetic modifications of the genome, such as DNA methylation and histone modifications, have been reported to play a role in processes underlying cardiovascular disease (CVD), including atherosclerosis, inflammation, hypertension and diabetes.nnnMETHODSnEleven databases were searched for studies investigating the association between epigenetic marks (either global, site-specific or genome-wide methylation of DNA and histone modifications) and CVD.nnnRESULTSnOf the 3459 searched references, 31 studies met our inclusion criteria (26 cross-sectional studies and 5 prospective studies). Overall, 12,648 individuals were included, with total of 4037 CVD events. The global DNA methylation assessed at long-interspersed nuclear element (LINE-1) was inversely associated with CVD, independent of established cardiovascular risk factors. Conversely, a higher degree of global DNA methylation measured at Alu repeats or by the LUMA method was associated with the presence of CVD. The studies reported epigenetic regulation of 34 metabolic genes (involved in fetal growth, glucose and lipid metabolism, inflammation, atherosclerosis and oxidative stress) in blood cells to be related with CVD. Among them, 5 loci were validated and methylation at F2RL3 was reported in two large prospective studies to predict cardiovascular disease beyond the traditional risk factors.nnnCONCLUSIONSnCurrent evidence supports an association between genomic DNA methylation and CVD. However, this review highlights important gaps in the existing evidences including lack of large-scale epigenetic investigations, needed to reliably identify genomic loci where DNA methylation is related to risk of CVD.

Subclinical hypothyroidism and the risk of stroke events and fatal stroke: An individual participant data analysis

OBJECTIVEnThe objective was to determine the risk of stroke associated with subclinical hypothyroidism.nnnDATA SOURCES AND STUDY SELECTIONnPublished prospective cohort studies were identified through a systematic search through November 2013 without restrictions in several databases. Unpublished studies were identified through the Thyroid Studies Collaboration. We collected individual participant data on thyroid function and stroke outcome. Euthyroidism was defined as TSH levels of 0.45-4.49 mIU/L, and subclinical hypothyroidism was defined as TSH levels of 4.5-19.9 mIU/L with normal T4 levels.nnnDATA EXTRACTION AND SYNTHESISnWe collected individual participant data on 47 573 adults (3451 subclinical hypothyroidism) from 17 cohorts and followed up from 1972-2014 (489 192 person-years). Age- and sex-adjusted pooled hazard ratios (HRs) for participants with subclinical hypothyroidism compared to euthyroidism were 1.05 (95% confidence interval [CI], 0.91-1.21) for stroke events (combined fatal and nonfatal stroke) and 1.07 (95% CI, 0.80-1.42) for fatal stroke. Stratified by age, the HR for stroke events was 3.32 (95% CI, 1.25-8.80) for individuals aged 18-49 years. There was an increased risk of fatal stroke in the age groups 18-49 and 50-64 years, with a HR of 4.22 (95% CI, 1.08-16.55) and 2.86 (95% CI, 1.31-6.26), respectively (p trend 0.04). We found no increased risk for those 65-79 years old (HR, 1.00; 95% CI, 0.86-1.18) or ≥ 80 years old (HR, 1.31; 95% CI, 0.79-2.18). There was a pattern of increased risk of fatal stroke with higher TSH concentrations.nnnCONCLUSIONSnAlthough no overall effect of subclinical hypothyroidism on stroke could be demonstrated, an increased risk in subjects younger than 65 years and those with higher TSH concentrations was observed.

Normal Thyroid Function and the Risk of Atrial Fibrillation: the Rotterdam Study

CONTEXTnHyperthyroidism is an established risk factor for atrial fibrillation (AF), but information concerning the association with variations within the normal range of thyroid function and subgroups at risk is lacking.nnnOBJECTIVEnThis study aimed to investigate the association between normal thyroid function and AF prospectively and explore potential differential risk patterns.nnnDESIGN, SETTING, AND PARTICIPANTSnFrom the Rotterdam Study we included 9166 participants ≥ 45 y with TSH and/or free T4 (FT4) measurements and AF assessment (1997-2012 median followup, 6.8 y), with 399 prevalent and 403 incident AF cases.nnnMAIN OUTCOME MEASURESnOutcome measures were 3-fold: 1) hazard ratios (HRs) for the risk of incident AF by Cox proportional-hazards models, 2) 10-year absolute risks taking competing risk of death into account, and 3) discrimination ability of adding FT4 to the CHARGE-AF simple model, an established prediction model for AF.nnnRESULTSnHigher FT4 levels were associated with higher risks of AF (HR 1.63, 95% confidence interval, 1.19-2.22), when comparing those in the highest quartile to those in lowest quartile. Absolute 10-year risks increased with higher FT4 in participants ≤ 65 y from 1-9% and from 6-12% in subjects ≥ 65 y. Discrimination of the prediction model improved when adding FT4 to the simple model (c-statistic, 0.722 vs 0.729; P = .039). TSH levels were not associated with AF.nnnCONCLUSIONSnThere is an increased risk of AF with higher FT4 levels within the normal range, especially in younger subjects. Adding FT4 to the simple model slightly improved discrimination of risk prediction.

Genetic Variations in MicroRNA-Binding Sites Affect MicroRNA-Mediated Regulation of Several Genes Associated With Cardio-metabolic Phenotypes

Background—Genome-wide association studies enabled us to discover a large number of variants and genomic loci contributing to cardiovascular and metabolic disorders. However, because the vast majority of the identified variants are thought to merely be proxies for other functional variants, the causal mechanisms remain to be elucidated. We hypothesized that the part of the functional variants involved in deregulating cardiometabolic genes is located in microRNA (miRNA)-binding sites. Methods and Results—Using the largest genome-wide association studies available on glycemic indices, lipid traits, anthropometric measures, blood pressure, coronary artery diseases, and type 2 diabetes mellitus, we identified 11u2009067 variants that are associated with cardiometabolic phenotypes. Of these, 230 variants are located within miRNA-binding sites in the 3′-untranslated region of 155 cardiometabolic genes. Thirty-seven of 230 variants were found to fulfill our predefined criteria for being functional in their genomic loci. Ten variants were subsequently selected for experimental validation based on genome-wide association studies results, expression quantitative trait loci (eQTL) analyses, and coexpression of their host genes and regulatory miRNAs in relevant tissues. Luciferase reporter assays revealed an allele-specific regulation of genes hosting the variants by miRNAs. These cotransfection experiments showed that rs174545 (FADS1:miR-181a-2), rs1059611 (LPL:miR-136), rs13702 (LPL:miR-410), rs1046875 (FN3KRP:miR-34a), rs7956 (MKRN2:miR-154), rs3217992 (CDKN2B:miR-138-2-3p), and rs11735092 (HSD17B13:miR-375) decrease or abrogate miRNA-dependent regulation of the genes. Conversely, 2 variants, rs6857 (PVRL2:miR-320e) and rs907091 (IKZF3:miR-326), were shown to enhance the activity of miRNAs on their host genes. Conclusions—We provide evidence for a model in which polymorphisms in miRNA-binding sites can both positively and negatively affect miRNA-mediated regulation of cardiometabolic genes.