👤 Domenico Girelli

Activated factor VII-anti-thrombin (FVIIa-AT) complex is a potential biomarker of pro-thrombotic diathesis reflecting FVIIa-tissue factor (TF) interaction and has been associated with mortality in patients with coronary artery disease (CAD). Previous data indicated plasma lipids as predictors of FVIIa-AT variability, and plasma lipoproteins as potential stimulators of the coagulation cascade. Our aim was to evaluate the relationships between FVIIa-AT plasma concentration and a broad apolipoprotein profile (including ApoA-I, ApoB, ApoC-III and ApoE). Within the framework of the observational Verona Heart Study, we selected 666 subjects (131 CAD-free and 535 CAD, 75.4% males, mean age: 61.1 ± 10.9 years) not taking anticoagulant drugs and for whom plasma samples were available for both FVIIa-AT assay and a complete lipid profile. Plasma concentration of FVIIa-AT levels significantly and directly correlated with total and high-density lipoprotein cholesterol, triglycerides, ApoA-I, ApoC-III and ApoE levels. ApoC-III showed the strongest correlation ( Show less

Clinicians are well aware of the importance of a positive family history for coronary artery disease (CAD). Nonetheless, elucidation of the genetic basis of CAD has long proven difficult. The scenario changed in the last decade through the application of modern genomic technologies, like genome-wide association studies (GWAS) and next generation sequencing (NGS). GWAS have discovered over 60 common variants highly associated with CAD. For predictive purposes, such variants have been used to build up Genetic Risk Scores (GRSs), but their incorporation into classical prediction models does not appear substantially outperform the simple addition of family history. To date, the only strong case for the utility of incorporating genetic testing into clinical practice is represented by the diagnosis of Familial Hypercholesterolemia (FH). On the other hand, utilization of genomic techniques has driven formidable advances into the knowledge of CAD pathophysiology, particularly by addressing controversies on the causality of some lipid fractions that had long remained unsolved because of limitations of observational epidemiology. For example, NGS-derived rare variants with strong functional effects on key-genes like ANGPTL4, APOA5, APOC3, LPL, and SCARB1, have proven useful as proxies to demonstrate the causality of triglyceride-rich lipoproteins (TRLs) at variance with HDL-cholesterol concentration, thus contributing to tear down a dogma from classical epidemiology. Moreover, such variants have paved the way for the development of new biologic drugs (i.e. monoclonal antibodies or antisense oligonucleotides) targeting key proteins like PCSK9, Lipoprotein Show less

Genome-wide association studies have so far identified 56 loci associated with risk of coronary artery disease (CAD). Many CAD loci show pleiotropy; that is, they are also associated with other diseases or traits. This study sought to systematically test if genetic variants identified for non-CAD diseases/traits also associate with CAD and to undertake a comprehensive analysis of the extent of pleiotropy of all CAD loci. In discovery analyses involving 42,335 CAD cases and 78,240 control subjects we tested the association of 29,383 common (minor allele frequency >5%) single nucleotide polymorphisms available on the exome array, which included a substantial proportion of known or suspected single nucleotide polymorphisms associated with common diseases or traits as of 2011. Suggestive association signals were replicated in an additional 30,533 cases and 42,530 control subjects. To evaluate pleiotropy, we tested CAD loci for association with cardiovascular risk factors (lipid traits, blood pressure phenotypes, body mass index, diabetes, and smoking behavior), as well as with other diseases/traits through interrogation of currently available genome-wide association study catalogs. We identified 6 new loci associated with CAD at genome-wide significance: on 2q37 (KCNJ13-GIGYF2), 6p21 (C2), 11p15 (MRVI1-CTR9), 12q13 (LRP1), 12q24 (SCARB1), and 16q13 (CETP). Risk allele frequencies ranged from 0.15 to 0.86, and odds ratio per copy of the risk allele ranged from 1.04 to 1.09. Of 62 new and known CAD loci, 24 (38.7%) showed statistical association with a traditional cardiovascular risk factor, with some showing multiple associations, and 29 (47%) showed associations at p < 1 × 10 We identified 6 loci associated with CAD at genome-wide significance. Several CAD loci show substantial pleiotropy, which may help us understand the mechanisms by which these loci affect CAD risk. Show less

Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance. When MI occurs early in life, genetic inheritance is a major component to risk. Previously, rare mutations in low-density lipoprotein (LDL) genes have been shown to contribute to MI risk in individual families, whereas common variants at more than 45 loci have been associated with MI risk in the population. Here we evaluate how rare mutations contribute to early-onset MI risk in the population. We sequenced the protein-coding regions of 9,793 genomes from patients with MI at an early age (≤50 years in males and ≤60 years in females) along with MI-free controls. We identified two genes in which rare coding-sequence mutations were more frequent in MI cases versus controls at exome-wide significance. At low-density lipoprotein receptor (LDLR), carriers of rare non-synonymous mutations were at 4.2-fold increased risk for MI; carriers of null alleles at LDLR were at even higher risk (13-fold difference). Approximately 2% of early MI cases harbour a rare, damaging mutation in LDLR; this estimate is similar to one made more than 40 years ago using an analysis of total cholesterol. Among controls, about 1 in 217 carried an LDLR coding-sequence mutation and had plasma LDL cholesterol > 190 mg dl(-1). At apolipoprotein A-V (APOA5), carriers of rare non-synonymous mutations were at 2.2-fold increased risk for MI. When compared with non-carriers, LDLR mutation carriers had higher plasma LDL cholesterol, whereas APOA5 mutation carriers had higher plasma triglycerides. Recent evidence has connected MI risk with coding-sequence mutations at two genes functionally related to APOA5, namely lipoprotein lipase and apolipoprotein C-III (refs 18, 19). Combined, these observations suggest that, as well as LDL cholesterol, disordered metabolism of triglyceride-rich lipoproteins contributes to MI risk. Show less

Plasma triglyceride levels are heritable and are correlated with the risk of coronary heart disease. Sequencing of the protein-coding regions of the human genome (the exome) has the potential to identify rare mutations that have a large effect on phenotype. We sequenced the protein-coding regions of 18,666 genes in each of 3734 participants of European or African ancestry in the Exome Sequencing Project. We conducted tests to determine whether rare mutations in coding sequence, individually or in aggregate within a gene, were associated with plasma triglyceride levels. For mutations associated with triglyceride levels, we subsequently evaluated their association with the risk of coronary heart disease in 110,970 persons. An aggregate of rare mutations in the gene encoding apolipoprotein C3 (APOC3) was associated with lower plasma triglyceride levels. Among the four mutations that drove this result, three were loss-of-function mutations: a nonsense mutation (R19X) and two splice-site mutations (IVS2+1G→A and IVS3+1G→T). The fourth was a missense mutation (A43T). Approximately 1 in 150 persons in the study was a heterozygous carrier of at least one of these four mutations. Triglyceride levels in the carriers were 39% lower than levels in noncarriers (P<1×10(-20)), and circulating levels of APOC3 in carriers were 46% lower than levels in noncarriers (P=8×10(-10)). The risk of coronary heart disease among 498 carriers of any rare APOC3 mutation was 40% lower than the risk among 110,472 noncarriers (odds ratio, 0.60; 95% confidence interval, 0.47 to 0.75; P=4×10(-6)). Rare mutations that disrupt APOC3 function were associated with lower levels of plasma triglycerides and APOC3. Carriers of these mutations were found to have a reduced risk of coronary heart disease. (Funded by the National Heart, Lung, and Blood Institute and others.). Show less

The delta-5 and delta-6 desaturases, encoded by FADS1 and FADS2 genes, are key enzymes in polyunsaturated fatty acid (PUFA) metabolism that catalyze the conversion of linoleic acid (LA) into arachidonic acid (AA) and that of alpha-linolenic acid (ALA) into eicosapentaenoic acid (EPA). Single-nucleotide polymorphisms (SNPs) in FADS1 and FADS2 have been associated with different concentrations of AA and LA, and those associations have possible functional consequences for desaturase activity. We aimed to evaluate the possible association among FADS genotypes, desaturase activity, inflammation, and coronary artery disease (CAD). Thirteen FADS SNPs and the ratio of AA to LA (AA/LA) on red blood cell (RBC) membranes, a marker of desaturase activity, were evaluated in 876 subjects with (n = 610) or without (n = 266) angiographically documented CAD. Both AA/LA and the ratio of EPA to ALA (EPA/ALA) were higher in patients with CAD than in those without CAD, but, in a multiple logistic regression model, only a higher AA/LA resulted an independent risk factor for CAD (odds ratio: 2.55; 95% CI: 1.61, 4.05 for higher compared with lower ratio tertile; P for trend < 0.001). Furthermore, concentrations of high-sensitivity C-reactive protein increased progressively across tertiles of AA/LA. Graded increases in high-sensitivity C-reactive protein concentrations and CAD risk were related to the carriership of FADS haplotypes, including the alleles associated with a higher ratio. In populations following a Western diet, subjects carrying FADS haplotypes that are associated with higher desaturase activity may be prone to a proinflammatory response favoring atherosclerotic vascular damage. Show less

Polymorphisms of the human Delta-5 (FADS1) and Delta-6 (FADS2) desaturase genes have been recently described to be associated with the level of several long-chain n-3 and n-6 polyunsaturated fatty acids (PUFAs) in serum phospholipids. We have genotyped 13 single nucleotide polymorphisms (SNPs) located on the FADS1-FADS2-FADS3 gene cluster (chromosome 11q12-13.1) in 658 Italian adults (78% males; mean age 59.7 +/- 11.1 years) participating in the Verona Heart Project. Polymorphisms and statistically inferred haplotypes showed a strong association with arachidonic acid (C20:4n-6) levels in serum phospholipids and in erythrocyte cell membranes (rs174545 adjusted P value for multiple tests, P < 0.0001 and P < 0.0001, respectively). Other significant associations were observed for linoleic (C18:2n-6), alpha-linolenic (C18:3n-3) and eicosadienoic (C20:2n-6) acids. Minor allele homozygotes and heterozygotes were associated to higher levels of linoleic, alpha-linolenic, eicosadienoic and lower levels of arachidonic acid. No significant association was observed for stearidonic (C18:4n-3), eicosapentaenoic (C20:5n-3) and docosahexaenoic (C22:6n-3) acids levels. The observed strong association of FADS gene polymorphisms with the levels of arachidonic acid, which is a precursor of molecules involved in inflammation and immunity processes, suggests that SNPs of the FADS1 and FADS2 gene region are worth studying in diseases related to inflammatory conditions or alterations in the concentration of PUFAs. Show less

High plasma concentrations of triglycerides (TG) and apolipoprotein C-III (ApoC-III) are well-known risk factors for cardiovascular disease. Two variants of the recently discovered APOA5, 1131 C>T and S19W, have been associated with hypertriglyceridemia, whereas their relation with coronary artery disease (CAD) remains controversial. Nine hundred and thirteen angiografically defined patients (669 CAD and 244 CAD-free) were genotyped for APOA5 -1131 C>T and S19W polymorphisms. Carriership of the APOA5 -1131 C allele was identified, by multiple linear regression models, as a significant independent predictor for both TG (standardized beta-coefficient=0.112; p=0.010) and ApoC-III variability (standardized beta-coefficient=0.113; p=0.013). Similarly, APOA5 19W allele carriership was a significant independent predictor for both TG (standardized beta-coefficient=0.113; p=0.007) and ApoC-III variability (standardized beta-coefficient=0.088; p=0.045). Despite the association with at-risk lipid profile, no significant difference was detected in the distribution of both APOA5 gene polymorphisms between subjects with or without CAD. Moreover, homozygous carriers of the APOC3 -455 C, another TG- and ApoC-III raising variant, showed a significant increased risk for CAD (OR 1.90 with 95% CI 1.002-3.62; p=0.049; by multiple logistic regression). Different genotypes, i.e., APOA5 and APOC3 variants, may lead to similar biochemical phenotypes, namely hypertriglyceridemia, but to contrasting clinical phenotypes such as the presence of angiographically proven CAD. Show less

Apolipoprotein C-III (apo C-III) is a marker of cardiovascular disease risk associated with triglyceride (TG)-rich lipoproteins. The T-455C polymorphism in the insulin-responsive element of the APOC3 gene influences TG and apo C-III concentrations. Long-chain n-3 polyunsaturated fatty acids (PUFAs) contained in fish have well-known apo C-III-lowering properties. We investigated the possibility of an interactive effect between the APOC3 gene variant and erythrocyte n-3 PUFAs, suitable markers of dietary intake of fatty acids, on apo C-III concentrations in a population of 848 heart disease patients who had coronary angiography. In the population as a whole, apo C-III concentrations were significantly inversely correlated with total erythrocyte PUFAs, but the correlation was not significant when only -455CC homozygous individuals were taken into account. In the total population and in subgroups with the -455TT and -455CT genotypes, the relative proportions of individuals presenting with increased apo C-III (i.e., above the 75th percentile value calculated on the entire population after exclusion of individuals taking lipids-lowering medications) decreased progressively as the n-3 PUFA and docosahexaenoic acid concentrations increased. The opposite situation was observed in the homozygous -455CC subgroup, in whom increasing erythrocyte n-3 PUFA and docosahexaenoic acid concentrations were associated with higher proportions of individuals with high apo C-III. A formal interactive effect between genotype and n-3 PUFAs was confirmed even after adjustment for possible confounding variables [age, sex, body mass index, smoking, coronary artery disease (CAD)/CAD-free status, or use of lipid-lowering medications] by logistic models. Patients homozygous for the -455C APOC3 variant are poorly responsive to the apo C-III-lowering effects of n-3 PUFAs. Show less

Apolipoprotein C-III (apoC-III) is a marker of triglyceride (TG)-rich lipoproteins, which are often increased in metabolic syndrome (MS). The T-455C polymorphism in the insulin-responsive element of the APOC3 gene influences TG and apoC-III levels. To evaluate the contribution of apoC-III levels and T-455C polymorphisms in the coronary artery disease (CAD) risk of MS patients, we studied 873 patients, 549 with CAD and 251 with normal coronary arteries. Patients were classified also as having or not having MS (MS, n = 270; MS-free, n = 603). Lipids, insulin, apolipoprotein levels, and APOC3 T-455C genotypes were evaluated. ApoC-III levels were significantly increased in MS patients, and the probability of having MS was correlated with increasing quartiles of apoC-III levels. MS patients with CAD had significantly higher apoC-III levels than did CAD-free MS patients. The carriership for the -455C variant multiplied the probability of CAD in MS in an allele-specific way and was associated with increased apoC-III and TG levels. Obesity was less frequent in MS carriers of the -455C allele than in MS noncarriers (21.6% vs. 34.8%, P < 0.05). In conclusion, apoC-III-rich lipoprotein metabolism and the APOC3 polymorphism have relevant impacts on the CAD risk of MS patents. Show less