Anna Evangelista

Atrial Natriuretic Peptide Gene Polymorphisms and Risk of Ischemic Stroke in Humans

Background and Purpose— A precise definition of genetic factors responsible for common forms of stroke is still lacking. The purpose of the present study was to investigate the contributory role of the genes encoding atrial natriuretic peptide (ANP) and type A natriuretic peptide receptor (NPRA) in humans’ susceptibility to develop ischemic stroke. Methods— Allele and genotype frequencies of ANP and NPRA were characterized in an Italian case-control study with patients affected by vascular disease or risk factors. Subjects were recruited from the island of Sardinia (206 cases, 236 controls). Results— A significant association between the ANP/TC2238 polymorphic site and stroke occurrence was found when a recessive model of inheritance was assumed. The risk conferred by this mutant genotype, when estimated by multivariate logistic regression analysis, was 3.8 (95% confidence interval, 1.4 to 10.9). A significantly increased risk of stroke recurrence was observed among cases carrying the ANP/CC2238 genotype compared with cases carrying the ANP/TT2238 genotype (P =0.04). No direct association of NPRA with stroke occurrence was detected. However, a significant epistatic interaction between the ANP/CC2238 genotype and an allelic variant of NPRA led to a 5.5-fold increased risk of stroke (95% confidence interval, 1.5 to 19.4). Conclusions— Our findings support a direct contributory role of ANP to stroke in humans. A significant interaction between ANP and NPRA on stroke occurrence was found.

Gene polymorphisms of the renin-angiotensin-aldosterone system and the risk of ischemic stroke: a role of the A1166C/AT1 gene variant.

Objective The role of the renin–angiotensin–aldosterone system (RAAS) genes on predisposition to develop stroke, a multifactorial and polygenic cardiovascular trait, is still under investigation. In the present study we characterized the contributory role of RAAS genes in the susceptibility to develop ischemic stroke in humans. Methods Allele and genotype frequencies of RAAS genes were characterized in a population of 215 cases (including only atherothrombotic and lacunar forms) and 236 controls selected in Sardinia, a large Mediterranean island with a well-known segregated population. Statistical analysis was performed in the whole population and, based on a significant interaction between angiotensin II receptor (AT1) genotype and hypertension, was also repeated in the hypertensive subgroup. Results A significant association of the C1166/AT1 gene allelic variant with stroke was found when assuming a dominant model of transmission [unadjusted odds ratio (OR) = 1.5, 95% confidence interval (CI) 1.1–2.2, P = 0.024]. The strength of the association became more evident in the subgroup of hypertensive individuals (135 cases and 110 controls). In fact, in this cohort the independent OR for the AT1 gene was 2.1, 95% CI 1.2–3.7, P = 0.006 in the dominant model and 2.0, 95% CI 1.3–3.2, P = 0.002 in the additive model. No other RAAS gene was identified as a contributor to stroke. Conclusions Our findings support a predisposing role of an AT1 gene variant in the development of ischemic stroke. In particular, the AT1 gene variant exerted a major impact on ischemic stroke occurrence in the presence of hypertension.

Influence of rs5065 atrial natriuretic peptide gene variant on coronary artery disease

OBJECTIVES The aim of this study was to investigate the impact of rs5065 atrial natriuretic peptide (ANP) gene variant on coronary artery disease (CAD) and its outcomes and to gain potential mechanistic insights on the association with CAD. BACKGROUND Either modified ANP plasma levels or peptide structural alterations have been involved in development of cardiovascular events. METHODS Three hundred ninety-three control subjects and 1,004 patients undergoing coronary angiography for suspected CAD (432 stable angina [SA], 572 acute coronary syndrome [ACS]) were genotyped for rs5065 ANP gene variant. Data in SA and ACS groups were replicated in an independent population of 482 stable angina patients (rSA) and of 675 ACS patients, respectively. Clinical follow-up was available for both SA and rSA patients. Plasma N-terminal-proANP, myeloperoxidase, lipoprotein-associated phospholipase A2, and oxidized low-density lipoprotein were assessed in a subgroup of rSA patients. RESULTS rs5065 minor allele (MA) was an independent predictor of ACS (odds ratio: 1.90; 95% confidence interval: 1.40 to 2.58, p < 0.001). At follow-up, rs5065 MA was independently associated with a significantly higher rate of major adverse cardiovascular events in the SA group, p < 0.001. Data were replicated in the rSA group at follow-up (p = 0.008). Cox proportional hazard analysis tested by 4 models confirmed higher major adverse cardiovascular events risk in rs5065 MA carriers in both SA and rSA cohorts. Significantly higher myeloperoxidase levels were detected in rs5065 MA carriers (n = 597 [345 to 832 μg/l] vs. n = 488 [353 to 612 μg/l], p = 0.038). No association of rs5065 was observed with N-terminal-proANP levels. CONCLUSIONS The MA of rs5065 ANP gene variant associates with increased susceptibility to ACS and has unfavorable prognostic value in CAD.

Polymorphisms in prothrombotic genes and their impact on ischemic stroke in a Sardinian population

Genetic factors are involved in the individual predisposition to develop ischemic stroke (IS). In the present study we tested the role of the Factor VII G10976A and -C122T polymorphisms on the susceptibility to develop IS in a genetically homogenous and clinically well ascertained case-control study including 294 cases (median age 75 years; 176 males/118 females) and 286 controls (median age 73 years; 163 males/123 females) in Sardinia, Italy. In addition, we carried out an exploratory analysis with respect to other frequently studied polymorphisms of haemostatic factor genes:Factor II G20210A, Factor V G1691A,,Fibrinogen alpha-chain Thr312Ala, Fibrinogen beta-chain -C148T, Factor XIII G185T, GPIIb/IIIa T1565C. Among all the genes tested, FVII -C122T showed a significant, independent contribution to IS predisposition both in crude and adjusted analyses (crude OR 1.52, 95% CI 1.09-2.10, P=0.013; adjusted OR 1.48, 95% CI 1.04-2.09, P=0.028, respectively). Haplotype analyses revealed a conserved population structure with high linkage disequilibrium between both FVII mutations tested. Blood levels of FVII had an inverse relationship with the polymorphism involved. Apart from genetic influence, there was a significant role for hypertension (OR=1.7, 95% CI 1.19-2.43, P=0.003), hypercholesterolemia (OR=2.21, 95% CI 1.38-3.54, P=0.001) and atrial fibrillation (OR=1.66, 95% CI 1.06-2.58, P=0.026) on IS occurrence. In summary, we describe evidence for a possible direct association of FVII gene molecular variants with the occurrence of IS in a genetically homogenous human sample.

Phosphodiesterase 4D and 5-lipoxygenase activating protein genes and risk of ischemic stroke in Sardinians

Genetic factors contribute to the risk of ischemic stroke (IS). The phosphodiesterase-4D (PDE4D) and the 5-lipoxygenase activating protein (ALOX5AP) genes were identified as contributors to stroke in an Icelandic population. In an attempt to better define the contributory role of PDE4D and ALOX5AP genes to the risk of IS in humans, we carried out the present association study in a well-characterized, earlier published, genetically homogenous population from the island of Sardinia, Italy. In this cohort, including 294 cases and 235 controls, age, hypertension, hypercholesterolemia, and atrial fibrillation represent risk factors for IS. The PDE4D gene was evaluated by four single nucleotide polymorphisms (SNP32, SNP45, SNP83, SNP87) and by the microsatellite AC008818-1; the ALOX5AP gene was characterized by three SNPs (SG13S32, SG13S89, ALO2A). The results of our study provide no evidence of association between any single PDE4D and ALOX5AP gene variant with the risk of IS in the Sardinian cohort. Haplotype analysis, including that constructed with allele 0 of microsatellite AC008818-1 and SNP45 of the PDE4D gene, was also negative. In conclusion, we found no evidence of association between PDE4D and ALOX5AP genes and the risk of IS in a genetically homogenous population from Sardinia.

Atrial natriuretic peptide (ANP) gene promoter variant and increased susceptibility to early development of hypertension in humans

Previous evidence supports a role of atrial natriuretic peptide (ANP) as a candidate gene for hypertension. We characterized an ANP gene promoter variant, which has been associated with lower peptide levels, in a sample of young male subjects from Southern Italy (n=395, mean age=35.2+/-2 years) followed up for 28 years. In this cohort, the ANP gene variant was associated with early blood pressure increase and predisposition to develop hypertension.

Determinants of N-terminal proatrial natriuretic peptide plasma levels in a survey of adult male population from Southern Italy

Objectives Natriuretic peptides control cardiovascular functions through diuretic, natriuretic, and vasodilatory properties. Several anthropometric, cardiac and renal variables were found to be independently correlated to their levels. Few studies, however, systematically investigated the independent determinants of natriuretic peptide levels in large populations. Design The present analysis was carried out in a large unselected sample of adult male population in Southern Italy (The Olivetti Heart Study, n = 806 men, mean age = 59.5, range 35–82 years). We examined the relationship of plasma natriuretic peptide–proatrial natriuretic peptide (NT-proANP) levels with relevant anthropometric, clinical and biochemical variables; the impact of age; and the association of NT-proANP levels with cardiovascular risk. Results NT-proANP was directly associated to age, pulse pressure (PP), renal sodium fractional excretion (FENa) (P < 0.005), and inversely to diastolic blood pressure (DBP), heart rate (HR), creatinine clearance, body mass index (BMI), arm and leg circumferences (P < 0.005). After adjustment for age, DBP, creatinine clearance, FENa and HR remained independent determinants of NT-proANP levels (all P < 0.01, cumulative R2 = 0.186). Upon stratification of our population by tertile of age, NT-proANP was significantly associated (P ≤ 0.01) to arm circumference in the lowest age tertile (mean age 53.8 years), and to FENa, DBP and creatinine clearance in the highest tertile (mean age 66.7 years). A direct significant association between NT-proANP levels and cardiovascular risk score, estimated by two independent algorithms, was observed (P < 0.001). Conclusions Anthropometric, cardiovascular and renal factors exerted a different impact on NT-proANP levels at different ages in our study population. Higher NT-proANP levels were associated with increased cardiovascular risk.

A protective role of a cholesteryl ester transfer protein gene variant towards ischaemic stroke in Sardinians

Objectives.  Cholesteryl ester transfer protein (CETP) plays a key role in the metabolism of high‐density lipoprotein (HDL), a strong, inverse, independent risk factor for cardiovascular disease.