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PubMed2006

Vitamin D receptor polymorphisms in hypocalcemic vitamin D-resistant rickets carriers.

BACKGROUND/AIMS: Hypocalcemic vitamin D-resistant rickets (HVDRR) is a rare autosomal recessive disorder characterized by severe rickets, hypocalcemia, secondary hyperparathyroidism, elevated levels of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], and occasionally, alopecia. In most cases, the disease is associated with mutations in the gene of the vitamin D receptor (VDR), the mediator of 1,25(OH)(2)D(3) action. The apparently healthy HVDRR heterozygotes express both normal and mutant VDR alleles, and they present higher levels of 1,25(OH)(2)D(3) than their respective controls. Because VDR function, except for the disease-causative mutations, might be influenced by the presence of certain polymorphisms, we investigated the distribution of four common VDR polymorphisms--BsmI, ApaI, TaqI and FokI--in HVDRR carriers compared with their respective controls. METHODS: Sixty-seven relatives of 2 HVDRR patients, all members of an extended Greek kindred, were included in the study. VDR allelic polymorphisms were assessed by restriction fragment length polymorphisms after specific polymerase chain reaction amplification. RESULTS: The distribution of genotypic and allelic frequencies differed between HVDRR carriers and their respective controls regarding BsmI and TaqI polymorphisms. The bb genotype and the T allele (presence of BsmI and absence of TaqI polymorphisms) were less frequent in the HVDRR carrier group than in the control group in a statistically significant manner (p = 0.029 and p = 0.025, respectively). CONCLUSIONS: Our findings showed that the apparently healthy HVDRR carriers present a different distribution of BsmI and TaqI VDR polymorphisms than their controls, suggesting that further investigation of the HVDRR carrier population may elucidate the implication of VDR alleles in VDR function and the vitamin D endocrine system.

Adolescent↗

PubMed1990

Distribution of chromosomal polymorphisms in three subspecies of squirrel monkeys (genus Saimiri).

The presence of nucleolar organizer regions (NORs) and C-band polymorphisms has been examined in three subspecies of squirrel monkeys, Saimiri sciureus sciureus, S. boliviensis boliviensis, and S. boliviensis peruviensis. Pericentric inversions in chromosomes 15 and 16 were also examined in the three groups. Chromosome 15 was acrocentric in S. s. sciureus and submetacentric in S.b. boliviensis and S.b. peruviensis. Chromosome 16 was acrocentric in S.s. sciureus and S.b. boliviensis while being submetacentric in S.b. peruviensis. There was a significant difference in the distribution of the C-band polymorphisms on chromosomes 5 and 14 in the three groups, as determined by Chi-square analysis, while no difference was observed in the distribution of the NOR polymorphism on chromosome 2. The NOR polymorphism and the interstitial C-band polymorphism of chromosome 14 were found in all three groups; the C-band polymorphism of chromosome 5 was found only in S.s. sciureus. Twelve pedigreed families were examined. Pedigree analyses were consistent with codominant inheritance of each polymorphism. The results of these cytogenetic studies in squirrel monkeys are pertinent to genetic management and research protocols.

Animals↗

PubMed2004

Influence of polymorphisms in the factor VII gene promoter on activated factor VII levels and on the risk of myocardial infarction in advanced coronary atherosclerosis.

In this study, we investigate the influence of three factor VII (FVII) gene polymorphisms on activated FVII levels (FVIIa), and also on the risk of myocardial infarction (MI) in patients with advanced coronary atherosclerotic disease (CAD). The -323A2 allele in the promoter is known to be associated with low FVII levels, and has been suggested to protect against MI in some studies. The -402GA promoter polymorphism, that in vitro has been associated with having opposite effect, is less well studied clinically. For this study, plasma FVIIa levels and three FVII gene polymorphisms were assessed in 934 subjects of both sexes, all with an angiographic documentation of coronary vessels. Our results show that two promoter polymorphisms, plasma cholesterol, and gender, were significant predictors of FVIIa levels. The -402A allele was associated to a significant increase of FVIIa levels in males (by 19.2%). In a selected clinical model including the patients with severe CAD, with or without a thrombotic complication (MI), male carriers of the -402A had an increased risk of MI (OR=1.79; 95% CI 1.15-2.80). The -323A2 allele was associated to a significant decrease in FVIIa (by 36.02% in males, and 39.7% in females). Male carriers of the -323A2 were protected from MI (OR=0.6; 95% CI 0.39-0.94), but only after correction for the confounding effect of combined heterozygosity for the promoter polymorphisms. We can conclude that FVII gene polymorphisms with an opposite effect on FVIIa levels may modulate the risk of MI in males with advanced CAD. This study highlights a "within-gene" interaction, and the need to explore polymorphisms in candidate gene(s) in detail.

Case-Control Studies↗

PubMed2004

Prognosis of young ischemic stroke in Taiwan: impact of prothrombotic genetic polymorphisms.

We investigated the effects of genetic factors on the prognosis of cerebral infarction in young adults in Taiwan. Because ischemic stroke with arterial occlusion or undetermined etiology is more likely to be related to a genetic prothrombotic state, 231 patients younger than 50 years (mean age 44.6 years, range 25 to 49 years) with acute ischemic stroke due to large artery atherosclerosis (n=90), small artery occlusion (n=114) or undetermined cause (n=27) were recruited and prospectively followed up for pre-determined outcome. On each patient, we screened the PlA1/PlA2 polymorphism of the platelet glycoprotein IIIa gene, 4G/5G polymorphism of the plasminogen activator inhibitor-1 gene, G10976A polymorphism of the factor VII gene, C677T polymorphism of the methylenetetrahydrofolate reductase gene, and 27 base-pair repeat polymorphism of the endothelial nitric oxide synthase gene. End points were the composite outcome events of stroke, myocardial infarction, and death from all causes. During a mean duration follow-up of 29 months, composite outcome events occurred in 33 patients. There was a higher annual incidence rate of composite outcome events during the first year (9.1%, 95% CI 5.9-13.9%) than in the subsequent 2 years (2.6%, 95% CI 1.2-5.6%, p=0.038). None of the genetic polymorphism was associated with the composite outcome events. Past history of coronary artery disease or cerebrovascular disease was the only independent predictor of the composite outcome events (HR 3.71, 95% CI 1.69-8.14, p=0.001) at the Cox regression analysis. Our data indicate that the prothrombotic genetic polymorphisms do not have a significant influence on the prognosis in young ischemic stroke due to arterial occlusion or undetermined causes in Taiwan.

Adult↗

PubMed2003

Extensive association analysis between polymorphisms of PON gene cluster with coronary heart disease in Chinese Han population.

OBJECTIVE: An extensive association analysis of PON gene cluster (PONs) with coronary heart disease (CHD) was performed in Chinese Han population. METHODS AND RESULTS: Thirty polymorphisms of PON1, PON2, and PON3 gene were identified by direct sequencing of genomic DNA derived from 48 randomly selected patients. Twelve polymorphisms were additionally investigated for association with CHD in 474 male patients and 475 controls. Univariate analyses showed the cases had significantly higher frequencies of PON1 192Q allele, 160R allele, -162A allele, and PON2 311C allele than were seen in the controls. Logistic regression analyses revealed only the PON1 R160G and -162G/A polymorphisms remained significantly associated with CHD (P=0.0054 and P=0.0002). Haplotype analyses for various polymorphism combinations additionally confirmed the results of individual polymorphism analyses. Only the frequencies of haplotypes containing -162A allele were significantly higher, whereas only the frequencies of haplotypes containing 160G allele were significantly lower in cases than in controls in various polymorphism combinations. CONCLUSIONS: This extensive association study has identified the PON1 -162G/A and R160G polymorphisms to be independently associated with CHD in Chinese Han population and warrants additional study to elucidate the biological mechanism.

Alleles↗

PubMedDate not supplied

Association of DNA polymorphism at the apolipoprotein B gene locus with coronary heart disease and serum very low density lipoprotein levels.

The role of genetic variation at the 3' end of the apolipoprotein B gene locus in the development of coronary heart disease and the regulation of the serum levels of various lipoproteins was studied by using two common restriction fragment length polymorphisms detected with the enzymes Xba I and EcoR I. A group of 106 male patients with coronary heart disease and 118 matched controls of Austrian origin were investigated. The frequency of the R2 allele of the EcoR I polymorphism at cDNA position 12,669 defined by the absence of the polymorphic EcoR I cutting site was significantly higher among patients than among controls. The controls with the R2 allele had significantly higher levels of total triglycerides, very low density lipoprotein (VLDL) triglycerides, and VLDL cholesterol than did the controls without this allele. Among the patients, the R2 allele was associated with higher serum VLDL apolipoprotein B levels. The chemical composition of VLDL in individuals with different genotypes for the EcoR I polymorphism did not differ significantly. For the Xba I polymorphism at cDNA position 7673, no correlation with coronary risk could be demonstrated. Patients and controls homozygous for the X2 allele characterized by the presence of the polymorphic Xba I cutting site showed a higher total and low density lipoprotein cholesterol level than did subjects with the genotype X1X1 or X1X2. This difference, however, was not statistically significant. These findings indicate that the R2 allele of the EcoR I polymorphism is associated with the occurrence of coronary heart disease and that variation at the 3' end of the apo B gene is involved in the regulation of VLDL metabolism.

Alleles↗

PubMedDate not supplied

Effects of the apolipoprotein E polymorphism on levels of lipids, lipoproteins, and apolipoproteins among Mexican-Americans in Starr County, Texas.

Genetic variability has been implicated as a significant contributor to the variation in levels of lipids, lipoproteins, and apolipoproteins (apos) through a variety of direct and indirect investigations. Among the direct investigations, apo E has been shown to be polymorphic and to explain a small but statistically significant proportion of the variability in cholesterol. The apo E polymorphism was typed in 964 randomly selected Mexican-Americans from Starr County, Tex., and its effects determined on levels of cholesterol, triglycerides, total high density lipoprotein (HDL) cholesterol, subfractions (HDL2 and HDL3), alpha- and beta-lipoprotein cholesterol, low density lipoprotein (LDL) cholesterol, and apos A-I, A-II, B, C-II, C-III, and E. Effects are reported for the entire sample and in each of three groups, namely, premenopausal females, postmenopausal women, and males. In the entire sample, significant effects were observed on cholesterol, beta-lipoprotein cholesterol, LDL, apo B, and apo E. There is evidence for significant physiological interaction of the apo E polymorphism effect in females by menopausal status. This is most evident for apo E levels, in which 5.9% of the variability in the entire sample is explained by the apo E polymorphism. In premenopausal females, however, the polymorphism accounts for 27.5% of the variability. In postmenopausal women and males, there is no significant effect. It is shown that the apo E polymorphism can be treated as a two-locus, two-allele system. Doing so identifies substitutions in amino acid position 158 as the mediators of most of the observed effects of this polymorphism.

Adolescent↗

PubMed1994

Role of common genetic polymorphisms in the LDL receptor gene in affecting plasma cholesterol levels in the general population.

A large number of rare mutations in the low-density lipoprotein (LDL) receptor gene cause the autosomal dominant disorder familial hypercholesterolemia. In addition, a number of common DNA polymorphisms have been identified in the LDL receptor gene, but their significance in affecting plasma cholesterol levels in the general population has not been studied widely. We investigated the role of two common DNA polymorphisms, Ava II (exon 13) and Nco I (exon 18), at the LDL receptor locus in affecting plasma lipid profiles in normolipidemic Hispanics (n = 385) and non-Hispanic whites (NHWs; n = 543) from the San Luis Valley, Colorado. While the distribution of the Nco I polymorphism was comparable between Hispanics and NHWs, the allele frequencies at the Ava II restriction site differed significantly between the two ethnic groups (P < .001). The Ava II and Nco I polymorphisms were in linkage disequilibrium (P < .05) in both Hispanics and NHWs. Both polymorphisms revealed a gender-specific effect on total and LDL cholesterol (LDL-C) confined to women only in both ethnic groups. The AVA II polymorphism was associated significantly with total cholesterol and LDL-C in NHW women (P = .001 and P = .014) and in Hispanic women (P = .011 and P = .057). The effect of the Nco I polymorphism was significant on total cholesterol and LDL-C (P = .019 and P = .035) in Hispanic women only. Although a similar trend was observed in NHW women, the effect was not significant at the 5% level.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗

PubMed1999

Polymorphisms of the tissue factor pathway inhibitor (TFPI) gene in patients with acute coronary syndromes and in healthy subjects : impact of the V264M substitution on plasma levels of TFPI.

-Mutations of the gene encoding tissue factor pathway inhibitor (TFPI), an inhibitor of TF-induced activation of the coagulation cascade, were screened for in 130 patients and 142 healthy controls to determine whether these variants contribute to acute coronary syndromes or modify plasma TFPI levels. The following 3 new polymorphisms were identified: 384T-->C in exon IV, which does not change the corresponding amino acid (tyrosine 57); -33C-->T in intron 7 (the T/T, C/T, and C/C genotypes were found in approximately 50%, 40%, and 10% of subjects in both groups); and 874G-->A in exon IX (GTG-->ATG), which predicts a valine to methionine change (V264M) in the carboxy-terminus tail of TFPI. The V264M polymorphism was found in 9.2% of the cases and 4.9% of the controls; the associated odds ratio (OR) for acute coronary syndromes was 2.0 (95% confidence interval [CI], 0.7 to 5.1). The OR increased to 3.6 (95% CI, 0.8 to 15.7) and 3.2 (95% CI, 0.9 to 11.8) in nonsmokers and patients without other risk factors, respectively. The possible link between the V264M polymorphism and coronary heart disease was checked in a large case-control study of myocardial infarction (Etude Cas-Témoins de l'Infarctus du Myocarde [the ECTIM Study]). The results showed no link between the V264M polymorphism and coronary syndromes. Interestingly, however, 5 patients heterozygous for the V264M polymorphism had significantly lower plasma TFPI levels than did 13 patients with the most common genotype. Although our present results do not support an association between TFPI polymorphisms and acute coronary syndromes, the possibility that 1 of them, especially the exon IX polymorphism, is associated with subtypes of myocardial infarction or to evolutive particularities that were not assessed in this study, cannot be excluded and is currently being evaluated.

Acute Disease↗

PubMed2000

Factor VII gene polymorphism, factor VII levels, and prevalent cardiovascular disease: the Framingham Heart Study.

Elevated factor VII levels have been associated with increased cardiovascular risk in some studies. The arginine/glutamine (Arg/Gln) polymorphism of the factor VII gene has been previously shown to modify factor VII levels. However, the presence of a gene/environment interaction on factor VII levels or a link with cardiovascular disease (CVD) remains uncertain. We studied subjects from the Framingham Heart Study to determine (1) the extent to which this genetic polymorphism affects factor VII levels; (2) whether interactions exist between this polymorphism and environmental factors on factor VII levels; and (3) the association between the polymorphism and CVD. Genotype data and factor VII antigen levels were available in 1816 subjects. Factor VII levels differed significantly among genotypes in an additive fashion: Gln homozygous, 82.7+/-2.5%; heterozygous, 92.2+/-0.7%; and Arg homozygous, 100. 5+/-0.4% (P<0.0001). The polymorphism was the strongest, single predictor of factor VII levels, explaining 7.7% of the total variance of factor VII levels, whereas other traditional risk factors combined explained an additional 11.5% of the variance. There was an interaction (P=0.02) between the genotype and total cholesterol on factor VII levels, such that the correlation coefficient and slope (factor VII level/total cholesterol) were greatest in Gln/Gln subjects. Among 3204 subjects characterized for genotype and CVD, there was no significant relationship between the genotype and CVD (P=0.12). In the Framingham Heart Study, the Arg/Gln polymorphism was significantly associated with factor VII antigen levels. The strength of the association suggests that genetic variation plays an important role in determining factor VII levels. However, despite being associated with factor VII levels, the Arg/Gln polymorphism was not associated with prevalent CVD.

Amino Acid Sequence↗

PubMed1995

Angiotensin-converting enzyme gene polymorphism has no influence on the circulating renin-angiotensin-aldosterone system or blood pressure in normotensive subjects.

BACKGROUND: Angiotensin-converting enzyme (ACE) is involved in the metabolism of two major vasoactive peptides, converting angiotensin (Ang) I into Ang II and inactivating bradykinin. An insertion/deletion (I/D) polymorphism is present in the 16th intron of the ACE gene and is strongly associated with plasma and cellular ACE levels. Contrasting with the lack of relation between ACE gene polymorphism and blood pressure level, a large case-control study has shown that the deletion marker allele of the ACE gene was associated with an increased risk of myocardial infarction. The pathophysiological link between ACE gene polymorphism and cardiovascular events remains hypothetical. One hypothesis is that this polymorphism influences Ang II and bradykinin concentrations in the peripheral and/or local circulations through its effects on ACE levels in plasma and endothelial cells. The aim of this study was to investigate the effect of the ACE gene I/D polymorphism on blood pressure, plasma active renin, and aldosterone regulation in normal subjects. METHODS AND RESULTS: Twenty-four normotensive male volunteers homozygous for the ACE I/D polymorphism (12 DD and 12 II) received a renin inhibitor infusion (remikiren 0.1 mg.kg-1.h-1 for 130 minutes) to suppress endogenous Ang I and Ang II production. Forty minutes after initiating the remikiren infusion, an exogenous Ang I infusion was begun and increased gradually every 15 minutes from 1 to 10 ng.kg-1.min-1. Median (range) plasma ACE levels (mU/mL) were 39 (32 to 57) and 24 (12 to 30) in the DD and II groups, respectively. Remikiren suppressed plasma Ang I and Ang II, increased plasma active renin (from 23 +/- 12 to 154 +/- 161 pg/mL), decreased plasma aldosterone (from 106 +/- 42 to 82 +/- 33 pg/mL), and slightly decreased diastolic blood pressure (from -2.4 +/- 2.7 mm Hg). The blood pressure and hormonal responses to Ang I infusion after renin inhibition and the slope of the rise in plasma Ang II with increasing Ang I dose were identical in both groups, as was the plasma Ang I/Ang II ratio before (DD, 2.09 +/- 1.04; II, 2.59 +/- 0.76) and after (DD, 0.15 +/- 0.13; II, 0.09 +/- 0.03) combined renin inhibitor and Ang I infusion. CONCLUSIONS: Despite its association with a major difference in plasma ACE levels, the ACE I/D polymorphism did not influence the Ang II and plasma aldosterone production, plasma active renin decrease, or diastolic blood pressure increase induced by exogenous Ang I infusion, suggesting that ACE has no limiting influence on systemic Ang II generation and effects under these experimental conditions.

Adolescent↗

PubMed1996

Common DNA polymorphisms at the lipoprotein lipase gene. Association with severity of coronary artery disease and diabetes.

BACKGROUND: DNA variants of the lipoprotein lipase gene are associated with changes in lipid metabolism similar to those in diabetes and may relate to the development of atherosclerotic lesions, particularly premature lesions. METHODS AND RESULTS: To determine whether lipoprotein lipase gene variants are relevant to ongoing atherogenesis, we explored relationships between two common lipoprotein lipase gene polymorphic markers, Pvu II at intron 6 and HindIII at intron 8; the severity of coronary artery disease (CAD); and lipid variables in 475 white patients 65 years of age or younger. We assessed CAD severity as the number of significantly stenosed (> 50% luminal obstruction) major coronary arteries at angiography and by the Green Lane coronary score. We found a significant association between the Pvu II polymorphism and the number of significantly diseased vessels (P = .0099) and coronary score (P = .028), with the Pvu II(-) alleles associated with less severe disease. The HindIII polymorphism was not associated with severity but had an additive effect with the Pvu II polymorphism. There was a close relationship between the Pvu II(+/+) genotype and the presence of diabetes (P = .0025), with an OR of 3.12 (95% CI, 1.30 to 7.49) compared with the Pvu II(-/-) genotype. The interaction between these polymorphisms and CAD severity (rather than occurrence) was independent of the levels of triglycerides and HDL cholesterol and of other lipid variables. There was also a dosage-dependent relationship between the Pvu II polymorphism and levels of triglyceride. The Pvu II(-) allele was associated with low levels and variances of triglycerides. CONCLUSIONS: We conclude that the lipoprotein lipase Pvu II polymorphism is significantly associated with CAD severity and with type II diabetes in CAD patients, independent of changes in circulating lipid levels. These findings may be relevant to mechanisms mediating atherogenesis.

Aged↗

PubMed2004

C242T CYBA polymorphism of the NADPH oxidase is associated with reduced respiratory burst in human neutrophils.

Oxidative stress contributes to the pathogenesis of atherosclerosis. p22phox-based NAD(P)H oxidases exist in the vessel wall, acting as important superoxide-generating systems in the vasculature. Some studies have identified reduced atherosclerosis in the presence of the C242T CYBA polymorphism, whereas others have not. Because vascular p22phox is identical to neutrophil p22phox, we studied the association between the C242T, A640G, and -930A/G CYBA polymorphisms and the quantity of superoxide produced from neutrophils isolated from healthy adults to determine if these polymorphisms had any functional impact on NADPH oxidase function. Neutrophils were isolated from 90 subjects by Percoll density gradient centrifugation. Genotypes were determined by polymerase chain reaction (PCR) and restriction mapping, as well as real-time PCR. The oxidative burst was stimulated with phorbol 12-myristate 13-acetate. Superoxide was quantified using the superoxide dismutase inhibitable oxidation of the spin probe hydroxylamine 1-hydroxy-3-carboxy-pyrrolidine, detected by electron paramagnetic resonance. Superoxide production was significantly affected by the C242T polymorphism, being 8.7+/-0.7, 7.9+/-0.6, and 5.9+/-1.2 micromol/L per minute per 10(6) neutrophils for the C242T CC, CT, and TT genotypes, respectively (P<0.05). In contrast, the A640G and the -930A/G polymorphisms did not alter the neutrophil respiratory burst. Phagocytic respiratory burst activity in homozygous individuals with the T allele of the C242T CYBA polymorphism is significantly lower than of wild-type carriers and heterozygous individuals. Because p22phox exists in both the neutrophil and vessel wall, vascular oxidative stress is likely diminished in individuals with this polymorphism.

Adult↗

PubMed2004

Functional effect of the p22phox -930A/G polymorphism on p22phox expression and NADPH oxidase activity in hypertension.

Oxidative stress induced by superoxide is implicated in hypertension. NADPH oxidase is the main source of superoxide in phagocytic and vascular cells, and the p22phox subunit is involved in NADPH oxidase activation. Recently we reported an association of -930A/G polymorphism in the human p22phox gene promoter with hypertension. This study was designed to investigate the functional role of this polymorphism in hypertension. We thus investigated the relationships between the -930A/G polymorphism and p22phox expression and NADPH oxidase-mediated superoxide production in phagocytic cells from 70 patients with essential hypertension and 70 normotensive controls. Genotyping of the polymorphism was performed by restriction fragment length polymorphism. NADPH oxidase activity was determined by chemiluminescence assays, and p22phox mRNA and protein expression was measured by Northern and Western blotting, respectively. Compared with hypertensive subjects with the AA/AG genotype, hypertensive subjects with the GG genotype exhibited increased (P<0.05) phagocytic p22phox mRNA (1.26+/-0.06 arbitrary unit [AU] versus 0.99+/-0.03 AU) and protein levels (0.58+/-0.05 AU versus 0.34+/-0.04 AU) and enhanced NADPH oxidase activity (1998+/-181 counts/s versus 1322+/-112 counts/s). No differences in these parameters were observed among genotypes in normotensive cells. Transfection experiments on vascular smooth muscle cells showed that the A-to-G substitution of this polymorphism produced an increased reporter gene expression in hypertensive cells. Nitric oxide production, as assessed by measurement of serum nitric oxide metabolites, was lower in GG hypertensive subjects than in AA/AG hypertensive subjects. In conclusion, these results suggest that hypertensive subjects carrying the GG genotype of the p22phox -930A/G polymorphism are highly exposed to NADPH oxidase-mediated oxidative stress.

Animals↗

PubMed2000

alpha-adducin and angiotensin I-converting enzyme polymorphisms in essential hypertension.

This study focused on two genes that have previously been implicated in hypertension and may influence renal sodium handling, adducin, and angiotensin I-converting enzyme (ACE). We compared their polymorphic frequencies and interaction in patients with essential hypertension (n=128) and individually age- and gender-matched normotensive control subjects. The alpha-adducin G460W polymorphism was genotyped by DNA amplification and restriction digestion. The ACE I/D polymorphism was assayed by a triple-primer method, with a "nested" polymerase chain reaction primer situated completely within the insertion sequence of the I: allele. The distributions of genotypes and alleles for the two polymorphisms were not significantly different between the case and control populations, and the cross-classification of cases by alpha-adducin and ACE genotype gave a distribution similar to that of control subjects. We have previously reported that the distributions of genotypes for two linked polymorphisms in the aldosterone synthase gene (one in the steroidogenic factor-1 [SF-1] binding site and the other an intronic conversion [IC]) were significantly different between this cohort of essential hypertensives and matched control subjects. The cross-classification of cases by alpha-adducin and SF-1, alpha-adducin and IC, ACE and SF-1, and ACE and IC genotype gave a distribution similar to that of control subjects. Hence, no evidence was found to suggest an association between either the alpha-adducin G460W or the ACE I/D polymorphism and hypertension in a careful case-control study. Furthermore, the alpha-adducin G460W, ACE I/D, and aldosterone synthase SF-1 and IC polymorphisms do not appear to interact in our hypertensive population.

Calmodulin-Binding Proteins↗

PubMed2007

The Thr715Pro polymorphism of the P-selectin gene is not associated with ischemic stroke risk.

BACKGROUND AND PURPOSE: A Thr>Pro polymorphism at codon 715 in the coding region of the P-selectin gene has recently been described. Individuals carrying the Pro715 allele were reported to have a reduced risk of myocardial infarction. A possible association of this polymorphism with the risk of ischemic stroke is currently under discussion. METHODS: We investigated the prevalence of the 715 Thr>Pro polymorphism in 450 patients aged younger than 60 years with ischemic stroke or transient ischemic attack and in 450 controls without vascular disease matched for age and gender. We also investigated possible interactions of the polymorphism with other vascular risk factors, stroke severity and stroke etiology. RESULTS: The distribution of the two allelic variants of the 715Thr>Pro polymorphism did not differ significantly between patients and control subjects (78% versus 81% for Thr/Thr, 21% versus 18% for Thr/Pro and 1% versus 1% for Pro/Pro in patients and controls, respectively; adjusted odds ratio for carriers of the C allele: 1.0 [0.8 to 1.2; P=0.695]). We found no significant interaction of this polymorphism with vascular risk factors, stroke severity, or stroke etiology. CONCLUSIONS: Our study supports results from previous investigation showing that the 715Thr>Pro polymorphism of the P-selectin gene was not associated with a risk or clinical characteristics of ischemic stroke.

Alleles↗

PubMed2005

No replication of association between estrogen receptor alpha gene polymorphisms and susceptibility to myocardial infarction in a large sample of patients of European descent.

BACKGROUND: The effects of estrogen on blood vessels are partly due to changes in vascular cell gene expression and protein synthesis that are mediated by estrogen receptors. In previous association studies, the -397T/C (rs2234693) and -351A/G (rs9340799) single nucleotide polymorphisms in the estrogen receptor alpha gene (ESR1) have been implicated in the risk of coronary atherosclerosis and myocardial infarction. To test these findings, we examined the relationship of the polymorphisms to myocardial infarction in a large sample of white patients and control individuals of predominantly European descent. METHODS AND RESULTS: The case group included 3657 patients with myocardial infarction, and the control group comprised 1211 individuals with angiographically normal coronary arteries and without signs or symptoms of myocardial infarction. TaqMan assays were used for the determination of genotypes. Genotype distributions of the -397T/C and -351A/G polymorphisms were not significantly different between the control and patient groups (P> or =0.85). The frequencies of haplotypes defined by the -397T/C and -351A/G polymorphisms were similar in the control group and the patient group (P=0.42). In addition, the distributions of haplotype-defined genotypes (diplotypes) were not significantly different between the control group and the patient group (P=0.81). Separate analyses in women and men did not reveal sex-related associations of specific genotypes or haplotypes of the polymorphisms with myocardial infarction (P> or =0.25). CONCLUSIONS: The results indicate that the -397T/C and -351A/G polymorphisms of ESR1 or haplotypes based on these polymorphisms are not associated with myocardial infarction in a white population.

Aged↗

PubMed2006

SCN5A polymorphism restores trafficking of a Brugada syndrome mutation on a separate gene.

BACKGROUND: Brugada syndrome is associated with a high risk of sudden cardiac death and is caused by mutations in the cardiac voltage-gated sodium channel gene. Previously, the R282H-SCN5A mutation in the sodium channel gene was identified in patients with Brugada syndrome. In a family carrying the R282H-SCN5A mutation, an asymptomatic individual had a common H558R-SCN5A polymorphism and the mutation on separate chromosomes. Therefore, we hypothesized that the polymorphism could rescue the mutation. METHODS AND RESULTS: In heterologous cells, expression of the mutation alone did not produce sodium current. However, coexpressing the mutation with the polymorphism produced significantly greater current than coexpressing the mutant with the wild-type gene, demonstrating that the polymorphism rescues the mutation. Using immunocytochemistry, we demonstrated that the R282H-SCN5A construct can traffic to the cell membrane only in the presence of the H558R-SCN5A polymorphism. Using fluorescence resonance energy transfer and protein fragments centered on H558R-SCN5A, we demonstrated that cardiac sodium channels preferentially interact when the polymorphism is expressed on one protein but not the other. CONCLUSIONS: This study suggests a mechanism whereby the Brugada syndrome has incomplete penetrance. More importantly, this study suggests that genetic polymorphisms may be a potential target for future therapies aimed at rescuing specific dysfunctional protein channels.

Arrhythmias, Cardiac↗