A missense mutation in melanocortin 1 receptor is associated with the red coat colour in donkeys.

The seven donkey breeds recognised by the French studbook are characterised by few coat colours: black, bay and grey. Normand bay donkeys seldom give birth to red foals, a colour more commonly seen and recognised in American miniature donkeys. Red resembles the equine chestnut colour, previously attributed to a mutation in the melanocortin 1 receptor gene (MC1R). We used a panel of 124 donkeys to identify a recessive missense c.629T>C variant in MC1R that showed a perfect association with the red coat colour. This variant leads to a methionine to threonine substitution at position 210 in the protein. We showed that methionine 210 is highly conserved among vertebrate melanocortin receptors. Previous in silico and in vitro analyses predicted this residue to lie within a functional site. Our in vivo results emphasised the pivotal role played by this residue, the alteration of which yielded a phenotype fully compatible with a loss of function of MC1R. We thus propose to name the c.629T>C allele in donkeys the e allele, which further enlarges the panel of recessive MC1R loss-of-function alleles described in animals and humans.

Large scale association analysis of novel genetic loci for coronary artery disease.

BACKGROUND: Combined analysis of 2 genome-wide association studies in cases enriched for family history recently identified 7 loci (on 1p13.3, 1q41, 2q36.3, 6q25.1, 9p21, 10q11.21, and 15q22.33) that may affect risk of coronary artery disease (CAD). Apart from the 9p21 locus, the other loci await substantive replication. Furthermore, the effect of these loci on CAD risk in a broader range of individuals remains to be determined. METHODS AND RESULTS: We undertook association analysis of single nucleotide polymorphisms at each locus with CAD risk in 11,550 cases and 11,205 controls from 9 European studies. The 9p21.3 locus showed unequivocal association (rs1333049, combined odds ratio [OR]=1.20, 95% CI [1.16 to 1.25], probability value=2.81 x 10(-21)). We also confirmed association signals at 1p13.3 (rs599839, OR=1.13 [1.08 to 1.19], P=1.44 x 10(-7)), 1q41 (rs3008621, OR=1.10 [1.04 to 1.17], P=1.02 x 10(-3)), and 10q11.21 (rs501120, OR=1.11 [1.05 to 1.18], P=4.34 x 10(-4)). The associations with 6q25.1 (rs6922269, P=0.020) and 2q36.3 (rs2943634, P=0.032) were borderline and not statistically significant after correction for multiple testing. The 15q22.33 locus did not replicate. The 10q11.21 locus showed a possible sex interaction (P=0.015), with a significant effect in women (OR=1.29 [1.15 to 1.45], P=1.86 x 10(-5)) but not men (OR=1.03 [0.96 to 1.11], P=0.387). There were no other strong interactions of any of the loci with other traditional risk factors. The loci at 9p21, 1p13.3, 2q36.3, and 10q11.21 acted independently and cumulatively increased CAD risk by 15% (12% to 18%), per additional risk allele. CONCLUSIONS: The findings provide strong evidence for association between at least 4 genetic loci and CAD risk. Cumulatively, these novel loci have a significant impact on risk of CAD at least in European populations.

Polymorphisms of the tumor necrosis factor-alpha (TNF) and the TNF-alpha converting enzyme (TACE/ADAM17) genes in relation to cardiovascular mortality: the AtheroGene study.

Tumor necrosis factor (TNF) is a major cytokine involved in inflammatory reaction and a mortality predictor in patients with coronary artery disease (CAD). Plasma levels of soluble TNF (sTNF) depend on the rate of its synthesis but also on its shedding from cell surface, a mechanism mainly regulated by the TNF alpha converting enzyme (TACE or ADAM17). We investigated the relationship between ADAM17 and TNF polymorphisms, circulating levels of shed ADAM17 substrates (sTNF, sTNFR1 and sTNFR2), and cardiovascular risk in a prospective cohort of CAD patients. Five tag single-nucleotide polymorphisms (SNPs) of the ADAM17 gene as well as four previously described TNF SNPs were genotyped in the Atherogene Study composed of 1,400 CAD patients among which 136 died from a cardiovascular (CV) cause. sTNF, sTNFR1, and sTNFR2 concentrations were all significantly elevated in patients with future CV death, independently of other clinical/biological variables. While none of the studied TNF SNPs was associated with sTNF, sTNFR1, nor sTNFR2 levels, the ADAM17 -154A allele was found associated with a 14% increase of sTNF levels as compared to the -154C allele (p = 0.0066). Moreover, individuals carrying the 747Leu allele displayed a borderline increased risk of future cardiovascular death [odds ratio, 2.06 (1.05-4.04), p = 0.03]. These results suggest a role of ADAM17 in the regulation of sTNF plasma levels and identifies ADAM17 gene as a candidate for CAD. Tumor necrosis factor (TNF) is a major cytokine involved in inflammatory reaction and a mortality predictor in patients with coronary artery disease (CAD). We have studied the association of ADAM17 and TNF polymorphisms with circulating levels of shed ADAM17 substrates (sTNF, sTNFR1 and sTNFR2) and with cardiovascular risk in a large population of individuals with CAD (Atherogene Study, n = 1,400). Two newly identified polymorphisms, obtained by a systematic sequencing of the ADAM17 gene, C-154A and Ser747leu, slightly influence respectively sTNF plasma levels and the risk of cardiovascular death.

Interbreed variation in serum serotonin (5-hydroxytryptamine) concentration in healthy dogs.

INTRODUCTION: Serotonin (5-hydroxytryptamine [5-HT]) has several biological functions. In different species, excessive 5-HT has been linked to valvular lesions, similar to those seen in dogs with myxomatous mitral valve disease. Previous studies suggest higher 5-HT in healthy Cavalier King Charles Spaniels (CKCSs), a breed highly affected by myxomatous mitral valve disease, compared to other breeds. OBJECTIVE: To investigate potential interbreed variation in serum 5-HT in healthy dogs. ANIMALS: 483 healthy dogs of nine breeds aged 1-7 years. METHODS: Dogs were examined at five European centers. Absence of cardiovascular, organ-related, or systemic diseases was ensured by thorough clinical investigations including echocardiography. Serum was frozen and later analyzed by enzyme-linked immunosorbent assay (ELISA). RESULTS: Median 5-HT concentration was 252.5 (interquartile range = 145.5-390.6) ng/mL. Overall breed difference was found (p<0.0001), and 42% of pairwise breed comparisons were significant. Univariate regression analysis showed association between serum 5-HT concentration and breed, center of examination, storage time, and sex, with higher 5-HT in females. In multiple regression analysis, the final model had an adjusted R2 of 0.27 with breed (p<0.0001), center (p<0.0001), and storage time (p=0.014) remaining significant. Within centers, overall breed differences were found at 3/5 centers (p≤0.028), and pairwise comparisons within those centers showed breed differences in 42% of comparisons. Among the included breeds, Newfoundlands, Belgian Shepherds and CKCSs had highest 5-HT concentrations. CONCLUSIONS: Interbreed variation in serum 5-HT concentration was found in healthy dogs aged 1-7 years. These differences should be taken into account when designing clinical studies.

Confirmation of associations between ion channel gene SNPs and QTc interval duration in healthy subjects.

Population-based association studies have identified several polymorphic variants in genes encoding ion channel subunits associated with the electrocardiographic heart-rate-corrected QT (QTc) length in healthy populations of Caucasian origin (KCNH2 rs1,805,123 (K897 T) and rs3,815,459, SCN5A rs1,805,126 (D1,819D), 1,141-3 C>A, rs1,805,124 (H558R), and IVS24+116 G>A, KCNQ1 rs757,092, KCNE1 IVS2-128 G>A and rs1,805,127 (G38S), and KCNE2 rs2,234,916 (T8A)). However, few of these results have been replicated in independent populations. We tested the association of SNPs KCNQ1 rs757,092, KCNH2 rs3,815,459, SCN5A IVS24+116 G>A, KCNE1 IVS2-128 G>A and KCNE2 rs2,234,916 with QTc length in two groups of 200 subjects presenting the shortest and the longest QTc from a cohort of 2,008 healthy subjects. All polymorphisms were in Hardy-Weinberg equilibrium in both groups. The minor allele SCN5A IVS24+116 A was more frequent in the group of subjects with the shortest QTc, whereas the minor alleles KCNQ1 rs757,092 G and KCNH2 rs3,815,459 A were more frequent in the group with the longest QTc. There was no significant difference for KCNE1 IVS2-128 G>A and KCNE2 rs2,234,916 between the two groups. Haplotype analysis showed a twofold increased risk of QTc lengthening for carriers of the haplotype, combining alleles C and A of the two common KCNE1 SNPs, IVS2-129 C>T (rs2,236,609) and rs1,805,127 (G38S), respectively. In conclusion, our study confirms the reported associations between QTc length and KCNQ1 rs757,092 and KCNH2 rs3,815,459.

Prognostic value of plasma tissue factor and tissue factor pathway inhibitor for cardiovascular death in patients with coronary artery disease: the AtheroGene study.

BACKGROUND: Tissue factor (TF) and its specific inhibitor, tissue factor pathway inhibitor (TFPI), are important contributors to the initiation of the coagulation process. OBJECTIVES: To compare plasma levels of soluble TF (sTF) and free-TFPI (f-TFPI) between patients with stable angina pectoris (SAP) and acute coronary syndrome (ACS) and to assess the impact of the two variables on long-term prognosis. PATIENTS/METHODS: Patients with SAPs (n = 1146) and acute coronary syndrome (n = 523) from the AtheroGene study were included and followed for 2.3 years. Because of the strong impact of unfractionated heparin (UFH) on f-TFPI levels, but not on sTF levels, patients having received UFH before blood drawing were excluded from the analyses on f-TFPI (n = 226). RESULTS: On admission, no significant differences in sTF levels were observed between SAP and ACS patients. By comparison to patients with stable angina, f-TFPI levels significantly increased in patients with acute unstable angina and further increased in patients presenting with non-ST-elevation myocardial infarction and ST-elevation myocardial infarction (P < 10(-4)). Among the 1669 individuals with a coronary artery disease, 56 died from a cardiovascular cause. In prospective analyses, high sTF levels were independently associated with an increased risk of cardiovascular death in individuals with ACS (fully adjusted hazard ratio associated with one quartile increase = 2.06; 95% confidence interval 1.24-3.45; P = 0.006) but not in those with SAP (hazard ratio = 1.07; 95% confidence interval 0.78-1.46; P = 0.67). In SAP and ACS patients, high f-TFPI levels were not independently associated with an increased risk of cardiovascular death. CONCLUSIONS: Plasma sTF levels were predictive of cardiovascular mortality in individuals with ACS, whereas f-TFPI levels were associated with the severity of myocardial damage on admission but were not independently related to outcome.

Haemostatic factors and the risk of cardiovascular death in patients with coronary artery disease: the AtheroGene study.

OBJECTIVE: To get a better insight into the role of hemostasis in coronary artery disease (CAD), we assessed the impact of von Willebrand factor (vWF), fibrinogen, thrombin-antithrombin (TAT) complexes, D-dimers, and plasmin-antiplasmin (PAP) complexes on the risk of cardiovascular event in a prospective cohort of CAD patients. METHODS AND RESULTS: The prospective Atherogene cohort includes 1057 individuals with an angiographically proven coronary artery disease at baseline. After a median follow-up of 6.6 years, 135 individuals died from a cardiovascular cause and 97 had a nonfatal cardiovascular event. Higher levels of all 5 hemostatic markers at baseline were associated with an increased risk of cardiovascular death, but not of nonfatal event. Except for vWF, these associations remained significant after adjustment for conventional cardiovascular risk factors and C-reactive protein (CRP) levels (P for trend according to increasing tertiles=0.20, 0.011, 0.026, 0.019, and 0.01 for vWF, fibrinogen, TAT, D-Dimer, and PAP, respectively). When including the 5 hemostatic markers in a stepwise Cox regression analysis where conventional risk factors and CRP were forced into the model, fibrinogen and D-dimers remained independently associated with the risk of cardiovascular death. Adjusted hazard ratios (95% CI) associated with one SD increase of fibrinogen and D-dimers were 1.27 (1.04 to 1.55) and 1.29 (1.09 to 1.53), respectively. CONCLUSIONS: In patients with coronary artery disease, fibrinogen and D-dimer levels are independent predictors of subsequent cardiovascular death. Our data support a role of impaired coagulation/fibrinolysis process in the complications of coronary artery disease.

Effect of Breed on Plasma Endothelin-1 Concentration, Plasma Renin Activity, and Serum Cortisol Concentration in Healthy Dogs.

BACKGROUND: There are breed differences in several blood variables in healthy dogs. OBJECTIVE: Investigate breed variation in plasma endothelin-1 (ET-1) concentration, plasma renin activity, and serum cortisol concentration. ANIMALS: Five-hundred and thirty-one healthy dogs of 9 breeds examined at 5 centers (2-4 breeds/center). METHODS: Prospective observational study. Circulating concentrations of ET-1 and cortisol, and renin activity, were measured using commercially available assays. Absence of organ-related or systemic disease was ensured by thorough clinical investigations, including blood pressure measurement, echocardiography, ECG, blood and urine analysis. RESULTS: Median ET-1 concentration was 1.29 (interquartile range [IQR], 0.97-1.82) pg/mL, median cortisol concentration 46.0 (IQR, 29.0-80.8) nmol/L, and median renin activity 0.73 (IQR, 0.48-1.10) ng/mL/h in all dogs. Overall, breed differences were found in ET-1 and cortisol concentrations, and renin activity (P < .0001 for all). Pair-wise comparisons between breeds differed in 67% of comparisons for ET-1, 22% for cortisol, and 19% for renin activity, respectively. Within centers, breed differences were found at 5/5 centers for ET-1, 4/5 centers for cortisol, and 2/5 centers for renin activity. Newfoundlands had highest median ET-1 concentration, 3 times higher than Cavalier King Charles Spaniels, Doberman Pinschers, and Dachshunds. Median renin activity was highest in Dachshunds, twice the median value in Newfoundlands and Boxers. Median cortisol concentration was highest in Finnish Lapphunds, almost 3 times higher than in Boxers. CONCLUSIONS AND CLINICAL IMPORTANCE: Breed variation might be important to take into consideration when interpreting test results in clinical studies.

Circulating cell adhesion molecules and death in patients with coronary artery disease.

BACKGROUND: Vascular cell adhesion molecule (VCAM)-1, intercellular adhesion molecule (ICAM)-1, and E-selectin mediate adhesion and transmigration of leukocytes to the vascular endothelial wall and may promote plaque growth and instability. In a prospective study, we evaluated the effect of soluble adhesion molecules on the risk of future cardiovascular events among patients with angiographically documented coronary artery disease (CAD). Methods and Results- -We obtained baseline samples from a prospective cohort of 1246 patients with CAD. Besides various markers of inflammation, soluble VCAM-1 (sVCAM-1), sICAM-1, and sE-selectin were determined. Follow-up information on cardiovascular events was obtained (mean, 2.7; maximum, 4.1 years). Independently higher levels of sVCAM-1 (1932 versus 1128 ng/mL; P<0.0001), sICAM-1 (353 versus 287 ng/mL; P=0.015), and sE-selectin (81 versus 63 ng/mL; P=0.003) were observed in patients with future death from cardiovascular causes. In a multivariate model, fatal risk was 2.1-fold (1.1 to 4.0) higher in patients within the top quartile of baseline sVCAM-1 concentrations compared with lower quartiles. This association was present independent of general inflammatory response as reflected by low or high C-reactive protein (hs-CRP) levels. In a model that simultaneously controlled for all inflammatory and soluble adhesion markers determined, only sVCAM-1 remained independently significant for future fatal cardiovascular events, with a 2.8-fold increase in risk (P=0.003). CONCLUSIONS: Soluble adhesion molecules sVCAM-1, sICAM-1, and sE-selectin were significantly related to future death from cardiovascular causes among patients with documented CAD. Especially sVCAM-1 added to the predictive value of classic risk factors and hs-CRP in determining the risk of future cardiovascular death.

Lack of association between polymorphisms of eight candidate genes and idiopathic dilated cardiomyopathy: the CARDIGENE study.

OBJECTIVES: The study investigated the potential role of eight candidate genes in the susceptibility to idiopathic dilated cardiomyopathy (IDC). BACKGROUND: Idiopathic dilated cardiomyopathy has a familial origin in 20% to 25% of cases, and several genetic loci have been identified in rare monogenic forms of the disease. These findings led to the hypothesis that genetic factors might also be involved in sporadic forms of the disease. In complex diseases that do not exhibit a clear pattern of familial aggregation, the candidate gene approach is a strategy widely used to identify susceptibility genes. All genes coding for proteins involved in biochemical or physiological abnormalities of cardiac function are potential candidates for IDC. METHODS: We studied 433 patients with IDC and 401 gender- and age-matched controls. Polymorphisms investigated were the I/D polymorphism of the angiotensin I-converting enzyme (ACE) gene, the T174M and M235T polymorphisms of the angiotensinogen (AGT) gene, the A-153G and A+39C polymorphisms of the angiotensin-II type 1 receptor (AGTR1) gene, the T-344C polymorphism of the aldosterone synthase (CYP11B2) gene, the G-308A polymorphism of the tumor necrosis factor-alpha (TNF) gene, the R25P polymorphism of the transforming growth factor beta1 (TGFB1) gene, the G+11/in23T polymorphism of the endothelial nitric oxide synthase (NOS3) gene and the C-1563T polymorphism of the brain natriuretic peptide (BNP) gene. RESULTS: None of the polymorphisms were significantly associated with the risk or the severity of the disease. CONCLUSIONS: We did not find evidence for an involvement of any of the 10 investigated polymorphisms in the susceptibility to IDC.

TAFI gene haplotypes, TAFI plasma levels and future risk of coronary heart disease: the PRIME Study.

OBJECTIVES: To evaluate the association of thrombin-activatable fibrinolysis inhibitor (TAFI) gene polymorphisms with the risk of coronary heart disease (CHD) and with TAFI levels measured by a newly developed enzyme-linked immunosorbent assay (ELISA) (TAFI-1B1), shown to be a reliable method for detecting quantitative variations in circulating TAFI. PATIENTS/METHODS: Six polymorphisms (C-2599G, G-438A, Ala147Thr, Thr325Ile, C + 1542G and T + 1583A) were genotyped and baseline plasma concentrations of TAFI were measured in a nested case-control design as part of the Prospective Epidemiological Study of Myocardial Infarction (PRIME) Study. Participants from France and Northern Ireland who had developed a CHD event during a 5-year follow-up (n = 321) were compared with 645 population- and age-matched control subjects. RESULTS: In France, the Thr147 allele was more frequent in cases than in controls (0.41 vs. 0.32; P = 0.02), whereas the reverse was observed in Northern Ireland (0.33 vs. 0.38; P = 0.19) (P = 0.01 for interaction). No other polymorphism was associated with CHD risk. Consistent with the results derived from the single-locus analysis, haplotype analysis revealed that the haplotype carrying the Thr147 allele was associated with increased risk of CHD in France while the reverse tended to hold in the Northern Ireland population. Single-locus and haplotype analyses revealed that two polymorphisms, C-2599G and Ala147Thr (or T + 1583A that is in nearly complete association with it), had additive effects on TAFI levels and explained >18% of TAFI variability. This effect was homogeneous in France and Northern Ireland, and in cases and controls who exhibited similar TAFI levels. CONCLUSIONS: Thrombin-activatable fibrinolysis inhibitor gene polymorphisms are strongly associated to plasma TAFI levels, but the relation to CHD risk is less clear.

Association between P-selectin gene polymorphisms and soluble P-selectin levels and their relation to coronary artery disease.

P-selectin is a cellular adhesion molecule that mediates the interaction of activated endothelial cells or platelets with leukocytes. Increased levels of soluble P-selectin have been reported in various cardiovascular disorders. We measured serum soluble P-selectin levels as well as 3 polymorphisms of the P-selectin gene (C-2123G, A-1969G, and Thr715Pro) in a large cohort of patients with documented coronary artery disease (n=869) and a healthy control group (n=334). The 3 P-selectin polymorphisms were strongly associated with P-selectin levels and altogether explained 7.3% and 18.6% of the P-selectin variability in patients and controls, respectively. Genotype distributions did not significantly differ between patients and controls. P-selectin levels were increased in patients younger than 55 years of age compared with controls (135.2 vs 114.3 ng/mL, P<0.01). On the contrary, patients older than 65 years of age had significantly lower P-selectin levels than did controls (121.5 vs 134.7 ng/mL, P<0.02). In intermediate age groups, P-selectin levels did not significantly differ between the 2 groups. In conclusion, this study revealed a strong association between P-selectin gene polymorphisms and serum P-selectin levels and a complex age-dependent relation between soluble P-selectin levels and coronary artery disease, which suggests that this molecule might have different roles in the atherothrombotic process.

Polymorphisms of the human matrix gla protein (MGP) gene, vascular calcification, and myocardial infarction.

The matrix Gla protein (MGP) is an important inhibitor of vessel and cartilage calcification that is strongly expressed in human calcified, atherosclerotic plaques and could modulate plaque calcification and coronary heart disease risk. Using a genetic approach, we explored this possibility by identifying polymorphisms of the MGP gene and testing their possible association with myocardial infarction (MI) and plaque calcification. Eight polymorphisms were identified in the coding and 5'-flanking sequences of the MGP gene. All polymorphisms were investigated in 607 patients with MI and 667 control subjects recruited into the ECTIM Study (Etude Cas-Témoins de l'Infarctus du Myocarde) and in 717 healthy individuals with echographically assessed arterial calcification and atherosclerosis who were participating in the AXA Study. In the ECTIM Study, alleles and genotypes were distributed similarly in patients and controls in the whole study group; in only 1 subgroup of subjects defined as being at low risk for MI were the concordant A-7 and Ala 83 alleles more frequent in patients with MI than in controls (P<0.003). In the AXA Study among subjects with femoral atherosclerosis, the same alleles were more common in the presence than the absence of plaque calcification (P<0.025). The other MGP polymorphisms were not associated with any investigated clinical phenotype. Transient transfection experiments with allelic promoter-reporter gene constructs and DNA-protein interaction assays were carried out to assess possible in vitro functionality of the promoter variants detected at positions -814, -138, and -7 relative to the start of transcription. When compared with the -138 T allele, the minor -138 C: allele consistently conferred a reduced promoter activity of -20% (P<0.0001) in rat vascular smooth muscle cells and of -50% (P<0.004) in a human fibroblast cell line, whereas the other polymorphisms, including -7, displayed no evidence of in vitro functionality. We conclude that the A-7 or Ala 83 alleles of the MGP gene may confer an increased risk of plaque calcification and MI; however, the observed relationships are weak or limited to subgroups of patients and therefore need confirmation.

The Pro12Ala polymorphism in the peroxisome proliferator-activated receptor gamma2 gene is not associated with postprandial responses to glucose or fat tolerance tests in young healthy subjects: the European Atherosclerosis Research Study II.

This study investigated whether the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor gamma2 (PPARgamma2) gene is associated with glucose and lipid metabolism in young healthy subjects participating in the European Atherosclerosis Research Study II. Men aged 18-28 years (n=675) were recruited from 14 university student populations in 11 European countries. At their first visit subjects had an oral glucose tolerance test and 1 week later an oral fat tolerance test. Lipid variables and genotype were measured centrally. The Ala allele frequency exhibited a clearcut north-to-south gradient through Europe, decreasing from 0.21 in Baltic countries to 0.07 in Mediterranean countries. There was no significant effect of the Pro12Ala polymorphism on fasting lipid, glucose, or insulin levels, nor on the postprandial changes in these variables after glucose and fat tolerance tests. Neither was the Pro12Ala polymorphism associated with body mass index. This study provides no evidence for a major effect of the Pro12Ala polymorphism on glucose and lipid metabolism in young healthy subjects. Since PPARgamma has a major role in adipogenesis, the differential effect of its polymorphism on weight and related metabolic disorders may become apparent only later in life.

Interleukin-6 gene polymorphisms and susceptibility to myocardial infarction: the ECTIM study. Etude Cas-Témoin de l'Infarctus du Myocarde.

There is growing evidence that interleukin (IL) 6 plays an important role in the atherosclerotic process because of its role in mediating immune and inflammatory responses and inducing cell proliferation. The present study examined whether molecular variations at the IL-6 locus are involved in the predisposition to myocardial infarction. The entire coding region, 1,158 bp of the 5' flanking region and 237 bp of the 3' flanking region of the IL-6 gene were screened. We detected three nucleotide substitutions in the 5' region at positions -174 (G/C), -572 (G/C), and -596 (G/A) from the transcription start site, and one insertion/deletion in the 3' region at position +528 after the Stop codon. These polymorphisms were genotyped in the Etude Cas-Témoin de l'Infarctus du Myocarde study comparing male patients (n=640) and age-matched controls (n=719) from Northern Ireland and France. The IL-6/G-174C and IL-6/G-596A polymorphisms were in nearly complete association. Carriers of the IL-6/-174 C allele were more frequent in patients than in controls. The population-adjusted odds ratio for myocardial infarction associated with genotype CC+CG vs. GG was estimated as 1.34. In French patients the number of coronary arteries with greater than 50% stenosis was assessed by angiography. The IL-6/-174 C allele was more frequent in patients with two or fewer stenosed vessels than in patients with three-vessel lesions. These results suggest that genetic variation at the IL-6 locus is associated with susceptibility to myocardial infarction, especially events occurring on less extended lesions. These findings would be compatible with a lower IL-6 secretion associated with the IL-6/-174 C allele, itself or in combination with other promoter polymorphisms, leading to more unstable plaques.

Angiotensin II type 1 receptor gene polymorphisms in human essential hypertension.

We conducted the present study to determine whether the angiotensin II type I receptor (AT1) gene might be implicated in human essential hypertension by using case-control and linkage studies. The entire coding and 3' untranslated regions of the AT1 receptor gene (2.2 kb) were amplified by polymerase chain reaction and submitted to single-strand conformation polymorphism in 60 hypertensive subjects with a familial susceptibility. We identified five polymorphisms (T573-->C, A1062-->G, A1166-->C, G1517-->T, and A1878-->G). However, no mutations that alter the encoded amino acid sequence were detected. A case-control study performed on white hypertensive (n = 206; blood pressure, 168 +/- 16/103 +/- 9 mm Hg) and normotensive (n = 298; blood pressure, 122 +/- 10/75 +/- 9 mm Hg) subjects using three of five polymorphisms showed a significant increase in allelic frequency of C1166 in hypertensive subjects (0.36 versus 0.28 for normotensive subjects, chi 2 = 6.8, P < .01). Frequencies for the alleles of the other two polymorphisms (T573-->C, A1878-->G) were similar in both groups. We performed a linkage study using the affected sib pair method and a highly polymorphic marker of the AT1 receptor gene. There was no evidence for linkage in 267 sib pairs analyzed from 138 pedigrees. These findings would be compatible with a common variant of the AT1 receptor imparting a small effect on blood pressure; further studies will be needed to address this possibility.

The 825C/T polymorphism of the G-protein subunit beta3 is not related to hypertension.

A polymorphism at position 825 (C-->T) of the cDNA that encodes the beta3 subunit (GNB3) of the pertussis toxin-sensitive G protein was recently shown to be associated with human hypertension. To verify this finding and to investigate whether this polymorphism could also be associated with coronary heart disease, we analyzed the GNB3 variant in subjects from 2 previously described studies: Projet d'Etude des Gènes de l'hypertension Artérielle Sévère à modérée Essentielle (PEGASE), a case-control study of moderate to severe hypertension (681 cases and 308 controls), and Etude Cas-Témoins de l'Infarctus du Myocarde (ECTIM), a case-control study of myocardial infarction (MI) (564 cases and 633 controls). Genotyping was performed with allele-specific oligonucleotides. Genotype and allele frequencies were in Hardy-Weinberg equilibrium in all groups. Allele and genotype frequencies did not differ significantly between case patients with essential hypertension or MI and control subjects. In the ECTIM study, the 825T allele frequencies in cases and controls from Belfast, Northern Ireland, were 0.31 and 0.30 (P=0.79), respectively; the corresponding frequencies in cases and controls from France were 0.33 and 0.31 (P=0.30), respectively. In the PEGASE study, the 825T allele frequency was 0.35 in female and male cases and 0.31 in male normotensive controls (P=0.12). The odds ratios for hypertension (PEGASE) and MI (ECTIM) associated with T-allele carrying were 1.23 (95% confidence interval, 0.94 to 1.62; P=0.13) and 1.11 (95% confidence interval, 0.88 to 1.39; P=0.37), respectively. There was no association of the GNB3 polymorphism with early onset of hypertension, familial history of hypertension, or blood pressure level. We conclude that the 825C/T polymorphism of the GNB3 gene did not contribute in any important way to the risk of essential hypertension or MI in these studies.

The Lys198Asn polymorphism in the endothelin-1 gene is associated with blood pressure in overweight people.

There is accumulating evidence that endothelin-1 plays an important role in vascular pathophysiology. Our objective was to examine whether molecular variations at the endothelin-1 locus were involved in susceptibility to myocardial infarction and variation in blood pressure. The entire coding sequence and 1.4 kb of the 5' flanking region were screened. Five polymorphisms were detected, which were genotyped in the ECTIM (Etude Cas-Témoin de l'Infarctus du Myocarde) Study, a multicenter study comparing 648 male patients who had survived a myocardial infarction and 760 population-based controls. The polymorphisms were not associated with myocardial infarction, nor did they contribute to blood pressure levels in the population at large. However, a G/T polymorphism predicting an Lys/Asn change (ET1/C198) strongly interacted (P<0.001) with body mass index in the determination of blood pressure levels. There was a steeper increase of blood pressure with body mass index in carriers of the T allele than in GG homozygotes. As a consequence, the T allele was associated with an increase of blood pressure in overweight subjects (body mass index >/=26 kg/m2), while no significant effect was observed in lean subjects (body mass index <26 kg/m2). To determine whether this finding could be replicated, the ET1/C198 was genotyped in the Glasgow Heart Scan Study, a population-based study including 619 men and 663 women. Subjects homozygous for the T allele had higher resting blood pressure levels than others (P<0.05). A similar interaction between the T allele and body mass index was observed on the maximum blood pressure achieved during a treadmill exercise test (P<0.001). In conclusion, results from 2 independent studies suggest that the ET1/C198 polymorphism is associated with blood pressure levels in overweight people.

Cox proportional hazards survival regression in haplotype-based association analysis using the Stochastic-EM algorithm.

It is now widely recognized that haplotype information inferred from genotypes can be of great interest to better characterize the role of a candidate gene in the etiology of a complex trait in the context of association studies. Several works have recently advocated the simultaneous estimation of haplotype frequencies and haplotype effects in order to get a better efficiency in parameter estimation. Most of the available models can deal with a binary or a quantitative phenotype, but none has yet discussed the application of haplotype-based association analysis to a survival outcome. We describe how the recently proposed Stochastic-EM (SEM) algorithm can be applied to estimate haplotype effects in censored data analysis using a standard Cox proportional hazards formulation. This model has been implemented in the THESIAS software freely available at http://www.genecanvas.org.

Serum myeloperoxidase concentration in a healthy population: biological variations, familial resemblance and new genetic polymorphisms.

Myeloperoxidase (MPO) has been involved in the pathogenesis of several diseases through excessive production of reactive oxygen species (ROS) as well as through its genetic polymorphism. The aims of this study were to identify the factors affecting MPO serum concentration, to study the familial resemblance of MPO levels and to investigate the association between newly described MPO polymorphisms as well as the G-463A one and MPO levels in a healthy population. MPO serum concentrations were measured by an enzymatic immuno-assay (EIA) in 82 healthy families of the STANISLAS Cohort and MPO genotype, determination was performed using PCR-restriction fragment length polymorphism or allele specific oligonucleotide assay. MPO concentrations were significantly higher in parents than in offspring. The factors affecting MPO levels were age, the number of white cells, smoking in fathers and oral contraceptive intake in mothers. They explain from 12.4% up to 35.9% of MPO variability in men and women, respectively. Family correlations of MPO concentrations were of similar magnitude. The -129A allele of a newly described G-129A substitution was significantly associated with decreased MPO levels, whereas the -463A allele was suggested to be associated with increased levels of lipid variables. In this study, we identified factors affecting MPO serum concentrations and showed that molecular variations of the gene have only a weak influence on MPO variability. In contrast, the association between the G-463A polymorphism and lipid levels would suggest a possible implication of MPO in the risk of cardiovascular diseases. These results have to be confirmed and further investigations will be conducted in that way.