Rationale VEGF impacts angiogenesis, atherosclerosis and cancer. Although the heritability of circulating VEGF levels is high, little is known about its genetic underpinnings. Objective Our aim was to identify genetic variants associated with circulating VEGF levels using an unbiased genome-wide approach and explore their functional significance with gene expression and pathway analysis. Methods and results We undertook a genome-wide association study (GWAS) of serum VEGF levels in 3,527 participants of the Framingham Heart Study (FHS), with pre-planned replication in 1,727 participants from two independent samples, the STANISLAS Family Study (SFS) and the Prospective Investigation of the Vasculature in Uppsala Seniors study (PIVUS). One hundred and forty SNPs reached genome-wide significance (p<5×10−8). We found evidence of replication for the most significant associations in both replication datasets. In a conditional GWAS 4 SNPs mapping to 3 chromosomal regions were independently associated with circulating VEGF levels: rs6921438 and rs4416670 (6p21.1, p=6.11×10−506 and p=1.47×10−12), rs6993770 (8q23.1, p=2.50×10−16) and rs10738760 (9p24.2, p=1.96×10−34). A genetic score including these four SNPs explained 48% of the heritability of serum VEGF levels. Six of the SNPs that reached genome-wide significance in the GWAS were significantly associated with VEGF mRNA levels in PBMCs. Ingenuity pathway analyses showed found plausible biological links between VEGF and 2 novel genes in these loci (ZFPM2 and VLDLR). Conclusions Genetic variants explaining up to half the heritability of serum VEGF levels were identified. These new insights provide important clues to the pathways regulating circulating VEGF levels.

Background-Neuregulin-1 (NRG-1) is a paracrine factor released by microvascular endothelial cells that has cardioprotective effects in animal models of heart failure. However, circulating NRG-1 has not been studied in human heart disease. We used a novel immunoassay to test whether circulating NRG-1␤ is associated with disease severity and clinical outcomes in chronic heart failure. Methods and Results-Serum NRG-1␤ was quantified in 899 outpatients in the Penn Heart Failure Study, a referral cohort representing a broad spectrum of systolic heart failure. Circulating NRG-1␤ was significantly elevated in patients with worse disease severity (median, 6.2 ng/mL for New York Heart Association class IV versus 4.4 ng/mL for class I; Pϭ0.002). In adjusted models, NRG-1␤ was independently associated with an increased risk of death or cardiac transplantation over a median follow-up of 2.4 years (adjusted hazard ratio, 1.58; 95% confidence interval, 1.04 to 2.39; Pϭ0.03 comparing fourth versus first NRG-1␤ quartile). Associations with outcome differed by heart failure cause and symptom severity, with the strongest associations observed in patients with ischemic cardiomyopathy (interaction Pϭ0.008) and New York Heart Association class III/IV symptoms (interaction Pϭ0.01). These findings were all independent of brain natriuretic peptide, and assessment of NRG-1␤ and brain natriuretic peptide jointly provided better risk stratification than each biomarker individually in patients with ischemic or New York Heart Association class III/IV heart failure. Conclusions-Circulating NRG-1␤ is independently associated with heart failure severity and risk of death or cardiac transplantation. These findings support a role for NRG-1/ErbB signaling in human heart failure and identify serum NRG-1␤ as a novel biomarker that may have clinical applications. (Circulation. 2009;120:310-317.)

Height is a classic complex trait with common variants in a growing list of genes known to contribute to the phenotype. Using a genecentric genotyping array targeted toward cardiovascular-related loci, comprising 49,320 SNPs across approximately 2000 loci, we evaluated the association of common and uncommon SNPs with adult height in 114,223 individuals from 47 studies and six ethnicities. A total of 64 loci contained a SNP associated with height at array-wide significance (p < 2.4 × 10(-6)), with 42 loci surpassing the conventional genome-wide significance threshold (p < 5 × 10(-8)). Common variants with minor allele frequencies greater than 5% were observed to be associated with height in 37 previously reported loci. In individuals of European ancestry, uncommon SNPs in IL11 and SMAD3, which would not be genotyped with the use of standard genome-wide genotyping arrays, were strongly associated with height (p < 3 × 10(-11)). Conditional analysis within associated regions revealed five additional variants associated with height independent of lead SNPs within the locus, suggesting allelic heterogeneity. Although underpowered to replicate findings from individuals of European ancestry, the direction of effect of associated variants was largely consistent in African American, South Asian, and Hispanic populations. Overall, we show that dense coverage of genes for uncommon SNPs, coupled with large-scale meta-analysis, can successfully identify additional variants associated with a common complex trait.

Objective-The metabolic and genetic correlates of circulating insulin-like growth factor-1 (IGF-1) and its main circulating carrier, IGF-1-binding-protein-3 (IGFBP-3), are unclear. Methods and Results-We measured serum IGF-1 and IGFBP-3 concentrations in a sample of the Framingham Heart Study (Nϭ3977, aged 40Ϯ9 years, 46% male) and evaluated their relations to cardiovascular risk factors using multivariable regression. Serum IGF-1 was inversely correlated with age, body mass index, total cholesterol, the presence of diabetes, alcohol consumption, and glomerular filtration rate (all PϽ0.01), whereas the ratio of IGF-1:IGFBP-3 was lower in women and inversely related to age, triglycerides, high-density lipoprotein cholesterol, systolic blood pressure, and alcohol consumption (all PϽ0.0001). Circulating IGF-1 correlated negatively with insulin resistance (homeostatic model assessment) (rϭϪ0.1; PϽ0.0001) and was lower in participants with more components of the metabolic syndrome (Adult Treatment Panel III criteria) (PϽ0.0001). Additive genetic factors (heritability) accounted for 43% and 39% of the variation of IGF-1 and IGFBP-3, respectively (both PϽ10 Ϫ27 ). Conclusion-Our cross-sectional observations in a large community-based sample link lower circulating IGF-1 to greater metabolic risk burden and underscore substantial genetic influences on IGF-1 concentrations. Prospective studies are warranted to elucidate whether lower IGF-1 concentrations predict greater metabolic risk longitudinally. (Arterioscler

In our community-based sample, circulating VEGF and HGF demonstrated high heritabilities and a sexual dimorphism. Increased angiogenesis and greater endothelial cell turnover may underlie associations of these growth factors with risk factors including smoking.

Background-Experimental studies suggest that endothelial growth factors play an important role in angiogenesis and vascular remodeling. The clinical and genetic correlates of circulating angiopoietin-2 (Ang-2) and its soluble receptor/regulator Tie-2 (sTie-2) have not been determined in a community-based sample. Methods and Results-Serum Ang-2 and sTie-2 were assayed in 3778 third-generation cohort participants of the Framingham Heart Study (mean age, 40Ϯ9 years; 53% women). Clinical correlates and heritability of both biomarkers were assessed using generalized estimating equations and variance-component analyses. Ang-2 levels were higher and sTie-2 levels were lower in women than in men. Ang-2 was positively related to age, smoking, systolic blood pressure, hypertension treatment, and diabetes (PϽ0.05 for all) but was inversely associated with total cholesterol and diastolic blood pressure (PϽ0.0001 for both), and sTie-2 was positively associated with body mass index, diabetes, and triglycerides but was inversely related to age, alcohol consumption, and glomerular filtration rate (PϽ0.05 for all). Both Ang-2 and sTie-2 were higher in participants with metabolic syndrome (PϽ0.005), with stronger associations of Ang-2 with blood pressure traits and of sTie-2 with obesity-dyslipidemia components. Heritability estimates for Ang-2 and sTie-2 were 27% and 56%, respectively (PϽ0.0001). A region on chromosome 9 was significantly linked to circulating sTie-2 levels (logarithm of the odds score, 8.31). Conclusion-Circulating levels of Ang-2 and sTie-2 are heritable traits associated with cardiovascular disease risk factors, including the metabolic syndrome. These observations are consistent with the notion that angiogenesis and vascular remodeling are determined in part by genetic influences and associated with metabolic risk factors. (Circ Cardiovasc Genet. 2010;3:300-306.)

Mean and pulsatile components of hemodynamic load are related to cardiovascular disease. Vascular growth factors play a fundamental role in vascular remodeling. The links between growth factors and hemodynamic load components are not well described. In 3496 participants from the Framingham Heart Study Third Generation cohort (mean age 40±9 years, 52% women) we related 4 tonometry derived measures of central arterial load (carotid femoral pulse wave velocity and forward pressure wave, mean arterial pressure, and the global reflection coefficient) to circulating concentrations of angiopoietin 2, its soluble receptor; vascular endothelial growth factor, its soluble receptor; hepatocyte growth factor; insulin-like growth factor-1, and its binding protein3. Using multivariable linear regression models, adjusted for standard cardiovascular risk factors, serum insulin-like growth factor-1concentrations were negatively associated with carotid femoral pulse wave velocity, mean arterial pressure, and reflection coefficient (p≤0.01 for all), whereas serum vascular endothelial growth factor levels were positively associated with carotid femoral pulse wave velocity and mean arterial pressure (p≤0.02). Serum insulin-like growth factor binding protein −3 and soluble angiopoietin-2 receptor levels were positively related to mean arterial pressure and to forward pressure wave, respectively (p<0.05). In our cross-sectional study of a large community-based sample, circulating vascular growth factor levels were related to measures of mean and pulsatile hemodynamic load in a pattern consistent with the known physiological effects of insulin-like growth factor-1 and vascular endothelial growth factor.

Background Coronary artery disease (CAD) is the leading killer in the U.S. Patients with severe CAD and ischemia have worse prognosis. Therefore expansion of biomarker research, to identify at risk individuals and explain the complex biology between cardiovascular growth factors and atherosclerosis is needed. Neuregulin-1β (NRG-1β) is a myocardial stress activated growth and survival factor released from endocardial and endothelial cells. NRG-1β is essential for cardiovascular development and a regulator of angiogenesis. We postulated that plasma and serum levels of NRG-1β would vary in relation to CAD severity and the presence of stress-induced ischemia. Methods We measured serum and plasma levels of NRG-1β and vascular endothelial growth factor (VEGF) in 60 patients undergoing cardiac catheterization. CAD severity was calculated from angiographic results using a modified Duke jeopardy score. Results Serum NRG-1β (sNRG-1β), plasma NRG-1β (pNRG-1β), serum VEGF (sVEGF), and plasma VEGF (pVEGF) were detectable in the majority of patients. The pNRG-1β levels were approximately two fold higher than sNRG-1β. Both sNRG-1β and pNRG-1β correlated inversely with CAD severity. Plasma NRG-1β levels were statistically higher in patients with stress-induced ischemia denoted by a positive myocardial perfusion imaging study that correlated with angiographic findings (p = 0.02). Conclusions Both serum and plasma NRG-1β correlated inversely with angiographic severity of CAD. Plasma NRG-1β levels were two fold higher than serum and were higher in patients with stress-induced ischemia. Therefore we conclude that plasma is the optimal source for the further exploration of the biological significance of NRG-1β as a biomarker of CAD severity and ischemia.