Concordance of two multiple analytical approaches demonstrate that interaction between BMI and ADIPOQ haplotypes is a determinant of LDL cholesterol in a general French population.

Genetic and environmental factors are involved in insulin resistance (IR). IR and dyslipidemia associate with increased risk of cardiovascular diseases. Plasma low-density lipoprotein cholesterol (LDL-C) level is a marker of cardiovascular risk. In a Caucasian general population we aimed at determining the multifactorial components of LDL-C levels using 10 genes and 3 phenotypes. In the PPARG, UCP3, ADIPOQ, TNF, LIPC, CARTPT, PCSK9, SCAP, SCARB1 and ENPP1 genes known to be associated with IR or dyslipidemia we genotyped 19 single nucleotide polymorphisms (SNPs) in 846 subjects. When several SNPs were genotyped for a given gene we constructed haplotypes. Including genetic and environmental variables (gender, body mass index (BMI) and adiponectin level) we used (1) the multifactor dimensionality reduction method to explain clusters of high and low LDL-C, and (2) the restricted partition method to explain LDL-C levels. Both methods showed that BMI and haplotypes at the ADIPOQ adiponectin encoding gene but not adiponectin level itself, were discriminant regarding to LDL-C. Subjects bearing an at-risk combination of BMI and ADIPOQ genotypes were prone to have a higher LDL-C (OR=3.13, 95% CI=2.20-4.46, P<0.0001). Our results suggest that in interaction with BMI, ADIPOQ haplotypes capture genetic variation(s) from neighboring gene(s) that would modulate LDL-C level.

An age effect on the association of common variants of ACE with Alzheimer's disease.

It is now well established that vascular risk factors are associated with cognitive performances. The renin-angiotensin system (RAS) components, major determinants of the cardiovascular system, are expressed in the brain and were shown to play a role on amyloid metabolism, learning and memory. The angiotensin-converting enzyme (ACE), a pivotal RAS protein, is encoded by a huge gene containing many variants, one of them, the I/D variant (rs1799752), being associated with Alzheimer's disease (AD). Other variants, such as SNPs rs4291A>T located -240bp from the initiation codon, and rs4343G>A encoding a silent mutation in exon 16, were inconsistently associated with the risk of AD. In a case-control study including 376 late-onset AD patients and 444 control subjects, we showed a statistically significant effect on the risk of AD of two variants (rs4343 and rs1799752) and of the haplotype ATI (rs4343/rs4291/rs1799752) in subjects aged 73 years and above.

Low-density lipoprotein receptor-related protein 8 gene polymorphisms and dementia.

The sole known genetic risk factor for sporadic Alzheimer's disease (AD) is the gene encoding apolipoprotein E (APOE), but the underlying mechanism is still under debate. One hypothesis relies on an interaction between APOE and its receptors. Previous studies have shown association of LDL receptor-related protein (LRP1) with AD and we previously reported a modulation by LRP1 of the risk of AD conferred by the -499A>G promoter polymorphism of the MAPK8IP1, a gene encoding Islet-brain-1 (IB1), the human counterpart of c-Jun NH(2) terminal kinase interacting protein-1 (JIP-1). Here we tested in two independent population samples a possible impact of another receptor for APOE, namely the low-density lipoprotein receptor-related protein 8 (LRP8), on the risk of dementia. Our results did not reveal any direct impact of a LRP8 coding (Arg952Gln) mutation on the risk of AD. However, this polymorphism increased the risk of AD conferred by the MAPK8IP1 G allele.

Angiotensin I-converting enzyme I/D polymorphism and suicidal behaviors.

Suicide is one of the ten most common causes of death in Western countries. It involves genetic vulnerability factors and is often associated with major depression. A Japanese team reported an association between the insertion allele of the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism with completed suicide. The ACE I/D polymorphism was investigated in two independent case-control studies, one involving 64 suicide completers and 90 controls who all underwent forensic investigations, the second one consisting of 588 suicide attempters and 639 controls. In the two population samples studied a statistically significant risk of suicidal behavior was observed for subjects bearing the DD genotype. These results suggest a possible role of the renin-angiotensin system in suicidal behavior.

Haplotypes across ACE and the risk of Alzheimer's disease: the three-city study.

The purpose of this study was to examine the impact of two polymorphisms (rs4291A>T and rs4343G>A) in the ACE gene on the risk of Alzheimer's disease (AD), using a population-based cohort of 9294 subjects selected from the electoral rolls of three French cities (the Three-City Study). Two follow-up examinations took place 2 and 4 years after inclusion. Diagnosis of dementia was assessed at baseline and at each follow-up examination by neurologists independent of the 3C Study group. For the present analysis, subjects whose mother tongue was not French, those from abroad and those lost at follow-up were excluded, leaving a sample of 6791 subjects. 108 subjects were demented at baseline and 216 subjects, among which 141 had AD, developed a dementia during follow-up. The genotype distributions of the ACE SNPs rs4291 and rs4343 did not differ according to cognitive status. After adjustment for confounding variables, the risk of developing AD was similar whatever the genotype (rs4291 AT vs TT: OR=0.90, p=0.65; AA vs TT: OR=1.05, p= 0.84; rs4343 GA vs GG: OR=1.15, p= 0.48; AA vs GG: OR=1.25, p= 0.37). No global haplotype effect could be observed on the risk of AD.

An apolipoprotein A-I gene promoter polymorphism associated with cognitive decline, but not with Alzheimer's disease.

BACKGROUND/AIMS: Accumulating biological and epidemiological evidence suggests a close link between cholesterol metabolism and the pathophysiology of Alzheimer's disease (AD). The observation that the use of statins reduces the risk of AD sustains this hypothesis. Apolipoprotein A-I (APOA1) is the major component of the high-density lipoproteins, particles involved in reverse cholesterol transport. Therefore, genetic polymorphisms in the gene encoding APOA1 might influence cholesterol metabolism and be a risk factor for AD. A previous study suggested an impact of a G-->A polymorphism at position -75 bp in the APOA1 gene on the risk for early-onset AD and on the age at onset of the disease. We studied this polymorphism in 3 independent European population samples. METHODS: Genotyping was conducted asdescribed in the previous study. RESULTS: We were unable to show any impact of this polymorphism on the risk of AD. Conversely, subjects bearing the A allele of this polymorphism were at risk of cognitive decline. CONCLUSION: Our resultssuggest an impact of the G-->A polymorphism at position -75 bp in the APOA1 gene on cognitive impairment, but not on the risk of AD.

A prospective evaluation of left ventricular remodeling after inaugural anterior myocardial infarction as a function of gene polymorphisms in the renin-angiotensin-aldosterone, adrenergic, and metalloproteinase systems.

BACKGROUND: Left ventricular remodeling (LVR) is a strong predictor of cardiovascular events after myocardial infarction (MI). Although several factors have been shown to influence LVR, interindividual variability exists. Some studies have suggested that gene polymorphisms may be associated with LVR, but these studies were limited by either a retrospective design or the inclusion of limited patient numbers. The present study was designed to prospectively assess the impact of gene polymorphisms on LVR. METHODS: We included 266 patients with inaugural anterior MI. Systematic echocardiographic follow-ups were performed at 3 months and at 1 year after MI. The polymorphisms were selected using a candidate gene approach based on LVR pathophysiology. We analyzed 14 polymorphisms in 3 different systems: the renin-angiotensin-aldosterone system (ACE I/D, RAT1 1166A/C, angiotensinogen M235T, CYP11B2 -344C/T), the adrenergic system (beta1AR Ser49Gly, beta1AR Gly389Arg, beta2AR Gly16Arg, beta2AR Gln27Glu, beta2AR Thr164Ile, alpha2cAR Del322-325), and the metalloproteinase (MMP) system (-1607 1G/2G MMP-1, -1306 C/T MMP-2, -1171 5A/6A MMP-3, -1562 C/T MMP-9). RESULTS: Left ventricular remodeling was documented by a progressive increase in end-diastolic volume from 56.5 +/- 14.9 mL/m2 at baseline to 62.8 +/- 18.8 mL/m2 at 1 year (P < .0001). End-diastolic volume at baseline, 3 months, or 1 year did not differ significantly among genotypes for any polymorphism. The change in end-diastolic volume from baseline to 1 year was also similar among genotypes for all polymorphisms. CONCLUSIONS: Left ventricular remodeling after MI is not associated with common polymorphisms in the renin-angiotensin-aldosterone, adrenergic, or MMP systems.

Impact of the matrix metalloproteinase MMP-3 on dementia.

Cerebral accumulation of beta-amyloid peptide (Abeta) is a central event in the pathogenesis of Alzheimer's disease (AD). Several proteases were shown to hydrolyze Abeta in vitro or in cell-based assays, and are likely candidates for a role in Abeta clearance in brain. Previous reports suggest that matrix metalloproteinases (MMPs) could be involved in such a mechanism. A functional polymorphism at position -1171 (5A/6A) in MMP-3 was examined in two independent studies to investigate the impact of this polymorphism on the risk of developing dementia. We found that subjects APOE epsilon4 non-carriers and 6A/6A homozygous for the MMP-3 polymorphism were at increased risk of dementia. Our findings support the hypothesis that MMPs may influence the risk of dementia.

Impact of a CART promoter genetic variation on plasma lipid profile in a general population.

The cocaine and amphetamine regulated transcript (CART), an anorexigenic peptide responding to leptin, is expressed in various areas of the hypothalamus. The role of CART in humans and its potential contribution to abnormalities in feeding control are mostly unknown. Since CART plays an important role in the hypothalamic regulation of energy balance by reducing food intake and increasing lipid substrate utilization, it might affect cholesterol metabolism as Neuropeptide Y or pro-opiomelanocortin do. In the present work, we studied the potential effects of three SNPs of the CART promoter in a WHO-MONICA general population from North of France (n=840), untreated for hypercholesterolemia, hypertension, or diabetes mellitus since any treatment is likely to interfere with lipoprotein/lipid variables. Our results show associations between these SNPs and plasma LDL-cholesterol level and the LDL/HDL ratio, a marker of atherogenicity. A haplotypic study suggests that these effects are mainly attributable to the functional SNP -3608C>T. Subjects bearing the -3608 C allele present a plasma lipid profile protective against atherogenesis: decrease of plasma LDL-cholesterol level (p=0.001) and of the LDL/HDL ratio (p=0.0003). This result offers new evidences for a potential implication of the CART gene in lipid metabolism and in atherogenesis.

The impact of the AMPD1 gene polymorphism on exercise capacity, other prognostic parameters, and survival in patients with stable congestive heart failure: a study in 686 consecutive patients.

BACKGROUND: Previous studies have demonstrated that the adenosine monophosphate deaminase 1 (AMPD1) C34T polymorphism may be associated with survival in cardiac populations with a protective effect of the T allele. However, these studies included limited number of patients with few cardiovascular events. METHODS: We prospectively analyzed the impact of the C34T polymorphism of the AMPD1 gene in 686 unrelated white patients with stable congestive heart failure related to left ventricular systolic dysfunction. Patients underwent echocardiography, radionuclide angiography, and a cardiopulmonary exercise test. Blood samples were drawn for standard and hormonal determinations and for genetic analysis. RESULTS: There were 517 (75%) CC homozygotes, 155 (23%) CT heterozygotes, and 14 (2%) TT mutated homozygotes. We did not demonstrate any impact of this polymorphism on clinical, biologic, echocardiographic, radionuclide, and exercise parameters in the whole population and in ischemic and nonischemic subgroups of patients. During a median follow-up period of 3 years, there were 145 cardiac-related deaths and 6 urgent transplantations. There was no impact of this polymorphism on survival. CONCLUSIONS: In our population, we did not demonstrate any effect of the C34T polymorphism of the AMPD1 gene on major congestive heart failure parameters and on survival.

The serotonin transporter promoter polymorphism and suicide.

Serotonergic dysfunction has been implicated in mood disorders and in the pathophysiology of suicidality. A functional polymorphism (a 44-base pair insertion (L)/deletion (S)) in the promoter of the gene encoding the serotonin transporter (5-HTTLPR), associated with mood disorders, has been inconsistently associated with suicidality. To add to this debate, we designed a case-control study involving 62 suicide victims and 72 controls matched for age, gender and ethnicity. All subjects underwent forensic investigation. No association could be detected between the 5-HTTLPR polymorphism and suicide. This result is consistent with the proposal that different genes are involved in hopelessness and suicidal behavior or in depressive illness.

Impact of APOA5/A4/C3 genetic polymorphisms on lipid variables and cardiovascular disease risk in French men.

OBJECTIVE: The goal of the present study was to assess the impact of 4 single nucleotide polymorphisms (SNPs) of APOA5/A4/C3 gene cluster on lipid levels and coronary heart disease (CHD) risk in French men. METHODS: A total of 442 men with CHD were recruited from the university hospital and compared to 475 men free of CHD from the population of the same geographical area. The APOA5 S19W, APOA5 -l2,238T>C, APOA4 T347S and APOC3 -482C>T SNPs were examined. RESULTS: The APOA5 S19W polymorphism was associated with plasma triglyceride levels. In multivariate logistic regression analyses the odds ratio (OR [95% Cl]) of hypertriglyceridemia (3rd vs. 1st tertile of triglyceride distribution) was 3.60 [1.38-9.42] in control subjects bearing at least one APOA5 19W variant. Haplotype analyses revealed a significant association between the 2111 haplotype and high triglyceride levels (+1.94 +/- 0.63 vs. 0.74 +/- 0.36 mmol/l for the 1111 haplotype p < 0.002). There was, in contrast, no significant difference in SNP distribution between CHD patients and controls. The age-adjusted OR of CHD were 1.46 [0.96-2.23], 0.79 [0.60-1.05], 0.91 [0.69-1.21] and 0.91 [0.69-l.22] in carriers of the APOA5 19W, APOA5 -12,238C, APOA4 347S and APOC3 -482T variants, respectively. There was also no significant difference in APOA5/A4/C3 haplotype distribution in patients and controls. CONCLUSION: The APOA5 19W variant is associated with increased plasma triglycerides. However, there is no evidence that APOA5 S19W, -12,238T > C, APOA4 T347S and APCC3 -482C > T SNPs are major risk factors of CHD in French men.

The impact of beta-adrenoreceptor gene polymorphisms on survival in patients with congestive heart failure.

OBJECTIVE: Discordant results have been published regarding a possible association between beta-adrenoreceptor (betaAR) gene polymorphisms and survival in patients with congestive heart failure (CHF). The aim of the study was to analyze the impact of five functional betaAR gene polymorphisms in patients with stable CHF. METHODS: We prospectively studied 444 consecutive patients with CHF related to left ventricular systolic dysfunction. The beta1ARSer49Gly, beta1ARGly389Arg, beta2AR Arg16Gly, beta2AR Gln27Glu and beta2AR Thr164Ile polymorphisms were determined. Patients underwent echocardiography, radionuclide angiography and a cardiopulmonary exercise test. RESULTS: Mean age was 56.6+/-11.9 years old, left ventricular ejection fraction (LVEF) was 32+/-12%, and peak VO2 was 15.5+/-4.9 ml/min/kg or 63+/-18% of maximal predicted VO2. Most of the patients (95%) were receiving angiotensin converting enzyme inhibitors and 91% beta-blockers. There was no statistically significant differences between baseline characteristics among beta1AR and beta2AR genotypes. During a median follow-up period of 1232 days, there were 110 cardiac-related deaths and five urgent transplantations. Independent predictors of survival were percent (%) of maximal predicted VO2 (p<0.0001), age (p<0.0001), LVEF (p=0.004), creatinine (p=0.02) and atrial fibrillation (p=0.04). No betaAR polymorphisms were associated with survival. However, patients with the combined beta2ARGly16Gly/beta2ARGln27Gln genotype, who express receptors highly sensitive to down-regulation, had a significantly lower survival rate than patients with other genotypes but only in univariate analysis. CONCLUSIONS: In this prospective study, we found no association between five functional betaAR polymorphisms and survival in patients with stable CHF. However, we demonstrated, only in univariate analysis, a possible association between the combined beta2ARGly16Gly/beta2ARGln27Gln genotype and survival.

A common variant of endothelial nitric oxide synthase (Glu298Asp) is associated with collateral development in patients with chronic coronary occlusions.

BACKGROUND: Experimental studies support an important role for endothelial nitric oxide synthase (eNOS) in the regulation of angiogenesis. In humans, a common polymorphism exists in the eNOS gene that results in the conversion of glutamate to aspartate for codon 298. In vitro and in vivo studies have suggested a decreased NOS activity in patients with the Asp298 variant. We hypothesized that a genetic-mediated decreased eNOS activity may limit collateral development in patients with chronic coronary occlusions. METHODS: We selected 291 consecutive patients who underwent coronary angiography and who had at least one chronic (>15 days) total coronary occlusion. Collateral development was graded angiographically using two different methods: the collateral flow grade and the recipient filling grade. Genomic DNA was extracted from white blood cells and genotyping was performed using previously published techniques. RESULTS: Collateral development was lower in patients carrying the Asp298 variant than in Glu-Glu homozygotes (collateral flow grade: 2.64 +/- 0.08 and 2.89 +/- 0.08, respectively, p = 0.04; recipient filling grade: 3.00 +/- 0.08 and 3.24 +/- 0.07, respectively, p = 0.04). By multivariable analysis, three variables were independently associated with the collateral flow grade: female gender, smoking, and the Asp298 variant (p = 0.03) while the Asp298 variant was the sole variable independently associated with the recipient filling grade (p = 0.03). CONCLUSION: Collateral development is lower in patients with the Asp298 variant. This may be explained by the decreased NOS activity in patients with the Asp298 variant. Further studies will have to determine whether increasing eNOS activity in humans is associated with coronary collateral development.

Study of a new PPARgamma2 promoter polymorphism and haplotype analysis in a French population.

Peroxisome proliferator-activated receptor-gamma (PPARgamma) plays a role in adipocyte differentiation and insulin sensitization. We identified and characterized a new C/T substitution at position -689 (-689C>T) in the P2 promoter of PPARgamma in a putative GATA binding site. By electrophoretic mobility shift assay, both GATA2 and GATA3 proteins could bind weakly to the wild-type P2 -689 GATA binding site but not to the mutated site. Neither GATA2 nor GATA3 was able to regulate significantly the P2 promoter activity in a reporter-luciferase assay, whatever the allele at position -689 was, suggesting that the -689 putative GATA site was probably not a functional target for GATAs. However, the presence of the -689T allele rendered the P2 promoter less active at the basal state. We genotyped a population of 1155 men and women for the -689C>T polymorphism and looked for possible associations with anthropometric and lipid variables. The carriers of the -689T allele had elevated body weight and LDL-cholesterol concentrations compared with the homozygous for the common allele. Haplotype analyses including the -681C>G (P3 promoter), -689C>T (P2 promoter), and Pro12Ala (exon B) polymorphisms were performed. Carriers of the G-T-Ala haplotype (corresponding to the P3 -681C>G, P2 -689C>T and Pro12Ala polymorphisms in this order) had elevated LDL-cholesterol concentrations and body weight compared with C-C-Pro individuals. In conclusion, we identified a new polymorphism in the P2 promoter of PPARgamma. The P3 -681C>G, P2 -689C>T, and Pro12Ala polymorphisms and related haplotypes were associated with higher body weight and plasma LDL-cholesterol concentrations.

Analysis of sequence variability in the CART gene in relation to obesity in a Caucasian population.

BACKGROUND: Cocaine and amphetamine regulated transcript (CART) is an anorectic neuropeptide located principally in hypothalamus. CART has been shown to be involved in control of feeding behavior, but a direct relationship with obesity has not been established. The aim of this study was to evaluate the effect of polymorphisms within the CART gene with regards to a possible association with obesity in a Caucasian population. RESULTS: Screening of the entire gene as well as a 3.7 kb region of 5' upstream sequence revealed 31 SNPs and 3 rare variants; 14 of which were subsequently genotyped in 292 French morbidly obese subjects and 368 controls. Haplotype analysis suggested an association with obesity which was found to be mainly due to SNP-3608T>C (rs7379701) (p = 0.009). Genotyping additional cases and controls also of European Caucasian origin supported further this possible association between the CART SNP -3608T>C T allele and obesity (global p-value = 0.0005). Functional studies also suggested that the SNP -3608T>C could modulate nuclear protein binding. CONCLUSION: CART SNP -3608T>C may possibly contribute to the genetic risk for obesity in the Caucasian population. However confirmation of the importance of the role of the CART gene in energy homeostasis and obesity will require investigation and replication in further populations.

Association between beta-1 and beta-2 adrenergic receptor gene polymorphisms and the response to beta-blockade in patients with stable congestive heart failure.

Previous studies have clearly demonstrated the beneficial effect of beta-blockers in patients with stable congestive heart failure (CHF). beta-blockers improve left ventricular ejection fraction (LVEF) and reduce cardiac mortality. However, there is an interindividual variability in the response to these agents. Two studies have suggested a possible impact of some functional betaAR gene polymorphisms on the effects of beta-blockade. The objective of the study is to analyse the association between genetic variations in the beta1 or the beta2 adrenoreceptor (AR) gene and the effects of beta-blockade in patients with stable CHF. We studied 199 consecutive patients with stable CHF not treated with beta-blockers. Before introduction of beta-blockers and 3 months after the maximal tolerated dose was reached, patients underwent an echocardiography and a radionuclide angiography. The beta1ARGly389Arg, beta1ARSer49Gly, beta2ARGly16Arg, beta2ARGln27Glu and beta2ARThr164Ile polymorphisms were determined: beta-blockade resulted in a significant decrease in heart rate, a significant increase in LVEF (from 30+/-10% to 40+/-13%, P<0.0001). There was no association between the five polymorphisms and heart rate or LVEF, either before or after beta-blockade. Heart rate and LVEF responses to beta-blockade were not associated with the beta1AR or the beta2AR polymorphisms. betaAR polymorphisms did not explain the interindividual variability in the response to beta-blockers.

Role of transcription factor KLF11 and its diabetes-associated gene variants in pancreatic beta cell function.

KLF11 (TIEG2) is a pancreas-enriched transcription factor that has elicited significant attention because of its role as negative regulator of exocrine cell growth in vitro and in vivo. However, its functional role in the endocrine pancreas remains to be established. Here, we report, for the first time, to our knowledge, the characterization of KLF11 as a glucose-inducible regulator of the insulin gene. A combination of random oligonucleotide binding, EMSA, luciferase reporter, and chromatin immunoprecipitation assays shows that KLF11 binds to the insulin promoter and regulates its activity in beta cells. Genetic analysis of the KLF11 gene revealed two rare variants (Ala347Ser and Thr220Met) that segregate with diabetes in families with early-onset type 2 diabetes, and significantly impair its transcriptional activity. In addition, analysis of 1,696 type 2 diabetes mellitus and 1,776 normoglycemic subjects show a frequent polymorphic Gln62Arg variant that significantly associates with type 2 diabetes mellitus in North European populations (OR = 1.29, P = 0.00033). Moreover, this variant alters the corepressor mSin3A-binding activity of KLF11, impairs the activation of the insulin promoter and shows lower levels of insulin expression in pancreatic beta cells. In addition, subjects carrying the Gln62Arg allele show decreased plasma insulin after an oral glucose challenge. Interestingly, all three nonsynonymous KLF11 variants show increased repression of the catalase 1 promoter, suggesting a role in free radical clearance that may render beta cells more sensitive to oxidative stress. Thus, both functional and genetic analyses reveal that KLF11 plays a role in the regulation of pancreatic beta cell physiology, and its variants may contribute to the development of diabetes.

APOE promoter polymorphisms and dementia in the elderly.

Previous observations suggest a contribution of two APOE promoter polymorphisms (-219 G/T and -491 A/T) in dementia. From two independent populations of elderly (mean age of 84 and 85 years old, respectively), we observed that subjects bearing the -219T allele were at increased risk of dementia (OR = 1.9 (95% CI, 1.3-2.8), P = 0.0003) or AD (OR = 2.0 (95% CI, 1.2-3.4), P < 0.008). Conversely, the -491 A/T variant was not associated with this risk of dementia in the elderly, as previously described. Haplotype estimations including the two promoter and the coding APOE polymorphisms indicated that the -491A/-219T/4 haplotype was at risk for the development of dementia (OR = 3.5 (95% CI, 2.5-5.0), P < 0.0001), whereas the -491A/-219G/4 haplotype was not (OR = 1.1 (95% CI, 0.6-2.1)). Similar results were observed when restricted to Alzheimer's disease. In conclusion, these data indicate that the -219 G/T polymorphism is a genetic determinant of dementia in the elderly, independently of the 4 allele.