High-density association study and nomination of susceptibility genes for hypertension in the Japanese National Project.

Essential hypertension is one of the most common, complex diseases, of which considerable efforts have been made to unravel the pathophysiological mechanisms. Over the last decade, multiple genome-wide linkage analyses have been conducted using 300-900 microsatellite markers but no single study has yielded definitive evidence for 'principal' hypertension susceptibility gene(s). Here, we performed a three-tiered, high-density association study of hypertension, which has been recently made possible. For tier 1, we genotyped 80 795 SNPs distributed throughout the genome in 188 male hypertensive subjects and two general population control groups (752 subjects per group). For tier 2 (752 hypertensive and 752 normotensive subjects), we genotyped a panel of 2676 SNPs selected (odds ratio >or= 1.4 and P

PPARgamma Pro12Ala Pro/Pro and resistin SNP-420 G/G genotypes are synergistically associated with plasma resistin in the Japanese general population.

OBJECTIVE: The Ala allele of the Pro12Ala polymorphism (rs1801282) of peroxisome proliferator-activated receptor gamma (PPARgamma) is protective against type 2 diabetes (T2DM). Resistin, secreted from adipocytes, causes insulin resistance in rodents. Resistin gene expression is reduced by the PPARgamma ligand. We previously reported that subjects with the G/G genotype of a resistin gene single nucleotide polymorphism (SNP) at -420 (rs1862513) had the highest circulating resistin levels, followed by C/G and C/C. The aim of this study was to determine the relationship among PPARgamma Pro12Ala polymorphism, resistin SNP-420, and plasma resistin. DESIGN, PATIENTS AND MEASUREMENTS: We cross-sectionally analysed 2077 community-dwelling subjects attending an annual medical check-up. Genotypes were determined by TaqMan analysis. Fasting plasma resistin was measured using ELISA. RESULTS: Plasma resistin appeared to be higher in subjects with the Pro/Pro genotype of PPARgamma than those with Pro/Ala and Ala/Ala genotypes (mean +/- SE, 11.6 +/- 0.2 vs. 10.4 +/- 0.5 microg/l). Multiple regression analysis, adjusted for age, gender, BMI, and resistin SNP-420, revealed that the Pro/Pro genotype was a positive predictor of plasma resistin (PPARgamma , Pro/Pro vs. Pro/Ala + Ala/Ala, unstandardized regression coefficient (beta) = 1.03, P = 0.0384). The effects of the Pro/Pro genotype of PPARgamma (Pro/Pro vs. Pro/Ala + Ala/Ala) and the G/G genotype of resistin SNP-420 (G/G vs. C/C) on plasma resistin were synergistic (beta = 4.76, P = 0.011). CONCLUSIONS: The PPARgamma Pro12Ala Pro/Pro and resistin SNP-420 G/G genotypes were synergistically associated with plasma resistin, when adjusted for age, gender, and BMI, in the Japanese general population.

Reduced high-molecular-weight adiponectin and elevated high-sensitivity C-reactive protein are synergistic risk factors for metabolic syndrome in a large-scale middle-aged to elderly population: the Shimanami Health Promoting Program Study.

OBJECTIVE: In Western countries, one of the most important modifiable targets for the prevention of cardiovascular diseases is metabolic syndrome. Adiponectin is an adipose tissue-specific plasma protein that inversely associates with metabolic syndrome. Among several molecular isoforms, high-molecular-weight (HMW) complex is considered the active form. Increased serum high-sensitivity C-reactive protein (hsCRP) concentration also associates with metabolic syndrome, and adiponectin could modulate plasma C-reactive protein levels. Here, through cross-sectional investigation, we investigated whether reduced HMW adiponectin and increased hsCRP levels in plasma are synergistically associated with metabolic syndrome. Measurement of HMW complex of adiponectin is one of the novelties of this study. DESIGN: We analyzed 1845 community-dwelling middle-aged to elderly subjects (62+/-13 yr). Plasma HMW adiponectin levels were measured by ELISA. Clinical parameters were obtained from the subjects' personal health records, evaluated at their annual medical check-up. RESULTS: Each component of metabolic syndrome, except for raised blood pressure, showed significantly lower plasma HMW adiponectin concentrations for both men and women (P<0.001). In contrast, plasma hsCRP levels were significantly higher in subjects with metabolic disorders (P<0.001). After adjusting for other confounding factors, HMW adiponectin [log normalized, odds ratio 0.084 (95% confidence interval 0.050-0.142), P<0.001] and hsCRP [3.009 (2.175-4.163), P<0.001] were identified as independent determinants of metabolic syndrome. In addition to the direct associations, we also observed a synergistic effect between these two molecules (F=11.8, P<0.001). CONCLUSIONS: Reduced HMW adiponectin and elevated hsCRP are synergistically associated with the accumulation of metabolic disorders. The combination of these markers would be useful for identifying at-risk populations.

Identification of hypertension-susceptibility genes and pathways by a systemic multiple candidate gene approach: the millennium genome project for hypertension.

A multiple candidate-gene approach was used to investigate not only candidate genes, but also candidate pathways involved in the regulation of blood pressure. We evaluated 307 single nucleotide polymorphisms (SNPs) in 307 genes and performed an association study between 758 cases and 726 controls. Genes were selected from among those encoding components of signal transduction pathways, including receptors, soluble carrier proteins, binding proteins, channels, enzymes, and G-proteins, that are potentially related to blood pressure regulation. In total, 38 SNPs were positively (p<0.05) associated with hypertension. Replication of the findings and possible polygenic interaction was evaluated in five G-protein-related positive genes (GNI2, GNA14, RGS2, RGS19, RGS20) in a large cohort population (total n=9,700, 3,305 hypertensives and 3,827 normotensive controls). In RGS20 and GNA14, dominant models for the minor allele were significantly associated with hypertension. Multiple dimension reduction (MDR) analysis revealed the presence of gene-gene interaction between GNA14 and RGS20. The MDR-proved combination of two genotypes showed a significant association with hypertension (chi2=9.93, p=0.0016) with an odds ratio of the high-risk genotype of 1.168 (95% confidence interval [CI] [1.061-1.287]). After correction for all possible confounding parameters, the MDR-proved high-risk genotype was still a risk for hypertension (p=0.0052). Furthermore, the high-risk genotype was associated with a significantly higher systolic blood pressure (133.08+/-19.46 vs. 132.25+/-19.19 mmHg, p=0.04) and diastolic blood pressure (79.65+/-11.49 vs. 79.01+/-11.32 mmHg, p=0.019) in the total population. In conclusion, a systemic multiple candidate gene approach can be used to identify not only hypertension-susceptibility genes but also hypertension-susceptibility pathways in which related genes may synergistically collaborate through gene-gene interactions to predispose to hypertension.

Migraine is associated with enhanced arterial stiffness.

Migraine is a common subtype of headache. Epidemiological studies have revealed that migraine could be an independent risk factor for ischemic stroke even in elderly subjects. Arterial stiffness is one of the major pathophysiological bases of stroke. In the present study, we cross-sectionally investigated the possible relationship between migraine and arterial stiffness in community-dwelling subjects. The study subjects were independently recruited from two sources (Group A, n=134, 68+/-5 years; Group B, n=138, 68+/-7 years). Augmentation index (AI), the ratio of augmented pressure by the reflection pressure wave to the pulse pressure, was obtained from the radial arterial waveform as an index of arterial stiffness. Brachial blood pressure was also measured simultaneously. Migraine was diagnosed using a previously validated questionnaire. The prevalence of migraine was 5.2% (Group A) and 16.7% (Group B). Subjects with migraine had higher radial AI in both Group A (migraine, 101+/-15%; other headache, 88+/-12%; no headache, 86+/-12%, p=0.003) and Group B (95+/-11%, 90+/-11%, 91+/-14%, p=0.058). Multiple linear regression analysis revealed that migraine was an independent determinant of AI (beta=0.154, p=0.002) after adjustment for other confounding factors: age (beta=-0.024, p=0.654); sex (beta=0.141, p=0.069); body height (beta=-0.215, p=0.005); systolic blood pressure (beta=0.174, p=0.001); medication for hypertension, hyperlipidemia, and diabetes mellitus (beta=-0.014, p=0.787); and heart rate (beta=-0.539, p<0.001). In a separate analysis by sex, migraine was also a significant determinant for AI (male, beta=0.246, p=0.019; female, beta=0.159, p=0.008). Migraine in the elderly could be a clinical manifestation of enhanced arterial stiffness.

Interaction between serotonin 2A receptor and endothelin-1 variants in association with hypertension in Japanese.

Serotonin has been implicated in the pathogenesis of hypertension because of its ability to induce vasoconstriction via stimulation of serotonin 2 (5-HT2) receptors. Recently, an association between the T102C functional polymorphism of the serotonin 2A (5-HT2A) receptor gene and hypertension in the UK has been reported. Another association study, however, failed to replicate this association in a Chinese population. We therefore investigated the possible association between the 5-HT2A T102C polymorphism and hypertension in two large Japanese populations (n = 2,968 total). We also investigated the possible interaction between the 5-HT2A T102C polymorphism and the G/T (Lys198Asn) polymorphism of the endothelin-1 (ET-1) gene, based on robust biological evidence for the existence of an interaction between the serotonin and endothelin systems. The results showed that there was no significant difference in the frequencies of the alleles and genotypes between the hypertensive and normotensive subjects. However, a significant interaction between the 5-HT2A T102C and ET-1 G/T polymorphisms in their association with hypertension (p = 0.0040) and with diastolic blood pressure (p = 0.0013) was revealed. A marginally significant interaction in the association with systolic blood pressure was also shown (p = 0.045). The associations of the 5-HT2A T102C polymorphism with hypertension and diastolic blood pressure in ET-1 T allele carriers were significant (p = 0.0056 and 0.021, respectively). The association of the 5-HT2A T102C polymorphism with systolic blood pressure in ET-1 T allele carriers was marginally significant (p = 0.054). Thus, the present study suggests that the 5-HT2A T102C and ET-1 G/T polymorphisms are interactively associated with hypertension.

Endothelial nitric oxide synthase gene polymorphism (Glu298Asp) in patients with coexistent hypertrophic cardiomyopathy and coronary spastic angina.

Coronary vasospasm appears to play a significant role in the etiology of myocardial ischemia in patients with hypertrophic cardiomyopathy (HCM). Furthermore, the management of patients with coexistent HCM and coronary spastic angina (CSA) presents a therapeutic challenge. The purpose of this study was to examine the Glu298Asp variant of the endothelial nitric oxide synthase (eNOS) gene to determine whether this polymorphism was associated with susceptibility to CSA in patients with HCM. The eNOS gene polymorphism (Glu298Asp) was genotyped in 150 HCM patients by the TaqMan chemical method. Patients were classified into group A (n=12) if they had CSA provoked by intracoronary acetylcholine, and group B (n=138) if they did not. In group A, the frequency of Glu/Glu, Glu/Asp, and Asp/Asp genotypes was 5 (41.7%), 6 (50%), and 1 (8.3%), respectively. In group B, it was 119 (86.2%), 17 (12.3%), and 2 (1.5%), respectively. The frequency of the Asp298 variant was significantly higher in group A than in group B (P<0.001). Multivariate logistic regression analysis showed that the Asp298 variant was a significant risk factor for CSA (odds ratio 11.8; P<0.001) that was independent of age, gender, smoking status or body mass index. Significantly more drugs were used by the patients in group A than those in group B and the patients with the Asp298 variant were treated with significantly more drugs than those without it. In conclusion, the Asp298 variant of the eNOS gene may be associated with CSA in HCM patients. HCM patients with CSA or the Asp298 variant may need more drugs to relieve their symptoms.

[A case of Werner syndrome with chromosomal abnormality].

A 52-year-old woman with diabetes mellitus (DM) complained of weakness of the arms and legs. She was referred to our hospital in November 2002 because of anemia, thyroid tumor and meningioma including DM. She was short in stature, juvenile bilateral cataract, intractable skin ulcers, clavus on the sole of her foot, a bird-like face and high-pitched voice. Typical physical features led to the final diagnosis of Werner's syndrome. Although the myelogram revealed no abnormal findings except erythroid hypoplasia, cytogenetic analysis of bone marrow cells showed deletion of chromosome 20 in 10% of the analyzed cells, which suggested the possibility of that myelodysplastic syndrome (MDS) or acute myeloblastic leukemia (AML) could occur. She had a thyroidectomy because both lobes of the thyroid gland were enlarged and caused hoarseness, In addition, it is common knowledge that the goiter could become malignant. We need to follow her carefully because she might be vulnerable to malignant disease, including leukemia and malignant meningioma.

Orthostatic systolic hypotension and the reflection pressure wave.

Orthostatic hypotension (OH) is a potent predictor of cardiovascular frailty. Although OH is determined by changes in brachial blood pressure (BP), it has been reported that there are significant differences between central BP and peripheral BP. The prevalence of OH has been reported to be higher in subjects with isolated systolic hypertension. Since an early returning of the reflection pressure wave due to advanced arterial stiffness is one of the underlying mechanisms of systolic hypertension, a significant association between alterations of the reflection pressure wave and OH has been hypothesized. To explore this hypothesis, the orthostatic changes in carotid BP and arterial waveform were evaluated. The study subjects were 155 community residents (69 +/- 7 years old). Carotid and brachial BP were measured simultaneously in the supine position and 1 min after standing using a cuff-oscillometric and tonometric method. The carotid augmentation index (AIx) was obtained from the pressure waveform. The orthostatic decline of BP was more prominent in the carotid artery than the brachial artery. Nine subjects were diagnosed with orthostatic systolic hypotension (OSH) from brachial BP, while 21 subjects were diagnosed from carotid BP (p < 0.001). The orthostatic change in carotid systolic BP was significantly associated with that in carotid AIx (r = 0.361, p < 0.001). The decline of the reflection component of carotid pulse pressure (-4.0 +/- 8.4 mmHg) was more prominent than that of the incident component (-1.2 +/- 9.9 mmHg, p = 0.002). These results indicate that evaluation of brachial BP may not represent the orthostatic changes in central BP. Alteration of the reflection pressure wave could be one of the underlying mechanisms of OSH in the central artery.

Association of dopamine beta-hydroxylase polymorphism with hypertension through interaction with fasting plasma glucose in Japanese.

Dopamine-beta-hydroxylase (DBH) catalyzes the conversion of dopamine to norepinephrine and is released from sympathetic neurons into the circulation. Several lines of evidence, including the finding of elevated plasma DBH activity in essential hypertension, suggest an important role of DBH in hypertension. Recently, a novel polymorphism (-1021C/T) in the 5' flanking region of the DBH gene has been shown to account for 35-52% of the variation in plasma DBH activity. We therefore investigated the possible association between the DBH -1021C/T polymorphism and hypertension in a large Japanese population. Moreover, because the development of hypertension is considered to be due at least partly to gene-environmental interactions, we also investigated the possible interactions between the DBH -1021C/T polymorphism and environmental factors. Consequently, we found a significant interaction between the DBH -1021C/T polymorphism and fasting plasma glucose (FPG) in the association with hypertension. CC homozygotes showed a steeper increase in probability of hypertension with FPG than T allele carriers. We also found a marginally significant trend suggesting the presence of an interaction between the DBH -1021C/T polymorphism and FPG in the association with blood pressure. Consistent with the presence of the interaction, we found that a 19 bp sequence containing the DBH -1021C/T polymorphism includes two palindromic non-canonical E boxes separated by 5 bps, and closely resembles the glucose response element of the L-type pyruvate kinase gene. These findings could be helpful in conducting further molecular and biological studies on the relationship among glucose metabolism, the sympathetic nervous system, and hypertension.

Association of I27L polymorphism of hepatocyte nuclear factor-1 alpha gene with high-density lipoprotein cholesterol level.

The serum level of high-density lipoprotein cholesterol (HDL-c), which protects against the development of atherosclerosis, is under genetic control. However, the genetic components responsible for the serum HDL-c level are yet to be determined. A recent knockout mouse study demonstrated that hepatocyte nuclear factor-1 alpha (HNF-1 alpha) is an essential transcriptional regulator of HDL-c metabolism. In this study, the association of an HNF-1 alpha gene polymorphism, isoleucine (Ile) 27 leucine (Leu), with lipid parameters, in particular with serum HDL-c level, was studied in 356 unrelated Japanese men. Though no significant difference was observed in total cholesterol and triglyceride levels among the three genotypes, the serum HDL-c level was significantly associated with the genotype (P < 0.01, trend test). Subjects with the Ile/Ile genotype had low serum HDL-c levels, and those with the Leu/Leu genotype had high serum HDL-c levels. These results demonstrate that the HNF-1 alpha gene locus is associated with serum HDL-c level and suggest that the Ile27 allele is a risk marker for atherosclerosis.

Microalbuminuria and arterial stiffness in a general population: the Shimanami Health Promoting Program (J-SHIPP) study.

Microalbuminuria is an early marker of renal damage and has been shown to predict future cardiovascular mortality and morbidity in patients with diabetes or hypertension, as well as in subjects in the general population. In this study, we investigated the hypothesis that the presence of microalbuminuria reflects the advancement of arterial stiffness by using a study group of 136 community residents who had no cardiovascular diseases except for hypertension and who were not taking any medications. Urinary albumin concentration was determined by the standard method and corrected by creatinine. Microalbuminuria was defined as a urinary albumin/creatinine ratio of 2.0-30.0 mg/mmol creatinine. Arterial stiffness was evaluated by pulse wave velocity (PWV) determined at three points: from the heart to the carotid artery, to the brachial artery, and to the ankle. Carotid arterial pressure was determined using a tonometric sensor. Carotid ultrasonography was performed to measure carotid intima-media thickness (IMT) and carotid arterial internal dimension. Subjects with microalbuminuria had higher blood pressure and wider pulse pressure not only in the brachial artery but also in the carotid artery. Microalbuminuria was associated with significantly higher PWV compared with that of normoalbuminuric subjects at all sites studied (mean PWV: 821.2+/-137.4 cm/s vs. 933.8+/-137.5 cm/s, p<0.0001). Stepwise regression analysis revealed that the presence of mircroalbuminuria (p=0.047) was a significant independent predictor of PWV in addition to age, sex, and systolic blood pressure. These findings suggest that microalbuminuria is associated with advanced atherosclerosis in the general population. Underlying arterial stiffness may explain the high cardiovascular mortality in subjects with microalbuminuria. Hypertension may be the mechanism linking microalbuminuria and arterial stiffness in the general population.

Polymorphism of the monocyte chemoattractant protein (MCP-1) gene is associated with the plasma level of MCP-1 but not with carotid intima-media thickness.

Monocyte chemoattractant protein-1 (MCP-1) plays an important role in atherosclerosis. Recently, single nucleotide polymorphisms (SNPs) in the MCP-1 regulatory region have been identified, and an in vitro study demonstrated that the SNP at position -2518 of the MCP-1 gene affected transcription of the gene. The purpose of this study was to clarify the association of the plasma level of MCP-1 and the SNP of the MCP-1 gene with carotid atherosclerosis in community-based subjects. The study subjects consisted of 325 community residents, aged 50 years or older (mean age, 70.5 +/- 9.4 years) and free from any cardiovascular complications. Carotid intima-media thickness (IMT) was measured in the right common carotid artery using ultrasonography. The plasma level of MCP-1 was measured by enzyme-linked immunosorbent assay (ELISA). The SNP of the MCP-1 gene was determined by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique. The plasma level of MCP-1 was significantly associated with IMT (r = 0.12, p < 0.05) and carotid arterial dimension (r = 0.13, p < 0.05). There was a significant difference in plasma MCP-1 level between the genotypes (AA, 166 +/- 36 ng/ml; GG + AG, 184 +/- 56 ng/ml; p = 0.036). Analysis restricted to the subjects not receiving antihypertensive drugs or other medication further increased the statistical significance. However, carotid IMT and carotid arterial diameter were not significantly different among the MCP-1 genotypes. Stepwise regression analysis for plasma MCP-1 revealed that the MCP-1 genotype was an independent determinant of plasma MCP-1 level. These findings indicate that plasma MCP-1 is associated with carotid atherosclerosis. Although -2518 SNP is associated with the plasma level of MCP-1, it was not directly associated with carotid atherosclerosis.

Plasma hepatocyte growth factor and the relationship between risk factors and carotid atherosclerosis.

Hepatocyte growth factor (HGF) has been shown to have a unique stimulating property on the endothelium as well as an anti-apoptotic action on the endothelium. Through these mechanisms, HGF has been shown to have an anti-atherogenic action in animal models. In atherosclerotic disorders, the circulating level of HGF has been shown to be increased to compensate for its decline in tissue. However, whether increased circulating HGF has any influence on the development of atherosclerosis has not been elucidated. In the present study, the association between plasma HGF concentration and the risk factor-carotid atherosclerosis relationship was evaluated. Three hundred and seventeen community-dwelling subjects participated in the study. The plasma concentration of HGF was determined by enzyme-linked immunosorbent assay (ELISA). The subjects were divided into two groups according to the plasma level of HGF: a low HGF group (n=199, plasma HGF < 150 pg/ml) and a high HGF group (n=118, plasma HGF > or = 150 pg/ml). Risk factors for atherosclerosis were evaluated in each subject. Carotid ultrasonography was performed to measure carotid arterial intima-media thickness (IMT) and the presence of plaque. The association between carotid IMT and risk factors was then evaluated in the two HGF groups. The regression lines between age and carotid IMT were significantly different between the low HGF and high HGF groups (F[1,313]=5.98, p=0.015). The regression lines between systolic blood pressure and carotid IMT were also significantly different between the two HGF groups (F[1,313]=5.17, p=0.024). A general linear model showed that the interaction between age and plasma level of HGF was significantly associated with carotid IMT, suggesting that the plasma level of HGF modifies the age-related increase in carotid IMT. In addition, clustering of risk factors was evaluated in subjects with carotid atherosclerosis. The number of total risk factors in carotid atherosclerosis subjects with high plasma HGF was significantly greater than that in those with low HGF, even though the two groups had a similar magnitude of carotid atherosclerosis. In conclusion, these findings indicate that risk factor-dependent augmentation of carotid atherosclerosis could be influenced by circulating HGF.

Genotype-specific association between circulating soluble cellular adhesion molecules and carotid intima-media thickness in community residents: J-SHIPP study. Shimanami Health Promoting Program.

Plasma levels of soluble forms of cellular adhesion molecules (CAMs) and their relationships with carotid intima-media thickness (IMT) were investigated in community residents. Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured by ELISA in 200 community residents in Japan. Carotid IMT showed a weak but significant positive correlation with the plasma levels of both sICAM-1 (r=0.175, p=0.013) and sVCAM-1 (r=0.19, p=0.0075). Gene polymorphisms of angiotensin converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) M235T, angiotensin II type 1 receptor (AT1R) A1166C and apolipoprotein E (apoE) were determined for each subject. The plasma level of sVCAM-1 tended to be lower in subjects with the ACE DD genotype than in those with the ACE ID and II genotypes (373+/-94, 421+/-133, 443+/-135 ng/ml, respectively, p=0.056). However, there were no genotype-specific differences in the plasma levels of soluble forms of CAMs for the other genes examined. In a separate analysis, the plasma level of sICAM-1 was significantly associated with carotid IMT in ACE D carriers (ID + DD) (r=0.28, p=0.002), AGT M carriers (MT + MM) (r=0.32, p=0.0045), and subjects with apoE4 (r=0.35, p=0.036). In contrast, the plasma level of sVCAM-1 showed significant positive correlations with carotid IMT in subjects with the ACE II genotype (r=0.33, p=0.0027) or AGT TT genotype (r= 0.22, p=0.015), and subjects with apoE E2/E3 or E3/E3 (r=0.16, p=0.043). Stepwise regression analysis showed that plasma sVCAM-1 was independently associated with carotid IMT in subjects with the ACE II genotype or apoE4 genotype. Similarly, the plasma level of sICAM-1 was independently associated with carotid IMT in AGT M carriers. These findings suggest that genetic background could be involved in the association between plasma CAMs and atherosclerosis.

Association of the GNAS1 gene variant with hypertension is dependent on alcohol consumption.

The beta-adrenoceptor (beta-AR)-stimulatory guanine nucleotide-binding (Gs) protein system has been shown to play important roles in the cardiovascular system. The gene encoding the alpha-subunit of Gs proteins (GNAS1) is a candidate genetic determinant for hypertension. Because alcohol consumption is known to affect blood pressure partly through the beta-AR-Gs protein system, we examined the possible interaction between GNAS1 T393C polymorphism and drinking status in the association with hypertension in the present study. As a result, a non-significant but reasonable trend supporting the presence of an interaction was shown (p = 0.076). In line with this trend, the T393C polymorphism significantly interacted with drinking status in the association with systolic blood pressure (p = 0.028). Moreover, supporting the presence of an interaction, T allele carriers consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than CC homozygotes in non-drinkers and light drinkers. In contrast, CC homozygotes consistently had a higher probability of hypertension, higher systolic blood pressure, and higher diastolic blood pressure than T allele carriers in moderate to heavy drinkers. The present study also showed a significant interaction between the T393C polymorphism and drinking status in the association with pulse pressure (p = 0.026), reflected by a significant association between the T393C polymorphism and pulse pressure in moderate to heavy drinkers (p = 0.026). These findings may be helpful in conducting further molecular and biological studies on the relationship among the effects of alcohol, the beta-AR-Gs protein system, and hypertension.

Genome-wide linkage disequilibrium mapping of hypertension in Japan.

Hypertension is a common, complex phenotype resulting from the interaction between genetic and environmental factors. To select candidate regions potentially responsible for hypertension, we are conducting a genome-wide linkage disequilibrium (LD) mapping of hypertension using dinucleotide repeat markers in 146 hypertensive and 136 normotensive subjects. Although the LD mapping is still underway, 19 alleles of 15 markers have already shown a nominally significant association (p<0.05), with odds ratios ranging from 0.08 to 5.12, suggesting the presence of many hypertension-related loci with weak effects in the human genome. These markers should be further assessed, adjusting for confounding factors and considering gene-gene and gene-environmental interactions in additional samples. In this report, we discuss our ongoing LD mapping project and describe the 15 markers thus far discovered. Among the 15 markers, D10S537 had a highly significant association with hypertension (p=5.3x10(-5); OR=3.80; 95% CI=1.98-7.27; where OR indicates the odds ratio and 95% CI indicates the 95% confidence interval). Further analysis in a large Japanese population showed that D10S537 was significantly associated with hypertension (p=0.044; OR=1.27; 95% CI=1.01-1.59). D10S537 was more significantly associated with hypertension in subjects with normotriglyceridemia in our population (p=0.007; OR=1.47; 95% CI=1.11-1.95).

Association of angiotensin II type 2 receptor gene variant with hypertension.

The renin-angiotensin system plays an important role in blood pressure regulation by influencing salt-water homeostasis and vascular tone. Angiotensin II, the major biologically active component of this system, exerts its effect via two pharmacologically distinct subtypes of angiotensin II receptors, the angiotensin II type 1 receptor (AT1-R) and the angiotensin II type 2 receptor (AT2-R). Thus, the AT2-R gene may be involved in hypertension. Accordingly, our objective was to examine whether polymorphisms of the AT2-R gene are involved in hypertension. The entire AT2-R gene including the promoter region was screened to find polymorphisms. As a result, two novel single nucleotide polymorphisms (SNPs), A1818T in intron 2 and G4303A in exon 3, as well as two known SNPs, A1675G in intron 1 and C4599A in exon 3, were identified. These four SNPs had similar allele frequencies, and the A1675G and C4599A polymorphisms were in almost complete linkage disequilibrium. Because the AT2-R gene is located on the X chromosome, we analyzed the possible association between the C4599A polymorphism and hypertension in men and in women separately in two large Japanese populations. This analysis showed that the C4599A polymorphism was associated with hypertension in women (p=0.0058), but not in men. Moreover, this female-specific association was pronounced in premenopausal women. The female-specific association may be helpful in conducting further molecular and biological studies on the relationship among sex, the renin-angiotensin system, and hypertension.

Association of a GNAS1 gene variant with hypertension and diabetes mellitus.

Previous studies have shown that the T allele of the GNAS1 T393C polymorphism is associated with poor responsiveness to beta-blockade and that the T393C polymorphism interacts with cigarette smoking and alcohol consumption in the pathogenesis of hypertension. Thus, the T393C polymorphism is likely to interact with beta-adrenoceptor (beta-AR) stimulation in the pathogenesis of hypertension. Although this interaction might be caused by a direct effect of Gs proteins on the cardiovascular system, it could also result from an indirect effect of Gs proteins mediated by glucose metabolism. Moreover, association studies are often irreproducible. We therefore examined the possible interaction between the T393C polymorphism and gamma-glutamyl transpeptidase (GGT), which is an established biomarker of alcohol consumption, in the association with glucose metabolism as well as with hypertension in a Japanese population. Genotyping for GNAS1 was performed by using the polymerase chain reaction-restriction fragment length polymorphism method in all 821 samples. The present study showed a significant interaction between the T393C polymorphism and GGT in the association with hypertension (p =0.033). This interaction was even more significant after adjustment for all confounding factors (p =0.0025). In contrast, analysis of the possible interaction of the T393C polymorphism with GGT in the association with diabetes mellitus or fasting plasma glucose failed to show a significant result. These results did not support the hypothesis that the interaction between the T393C polymorphism and GGT in the association with hypertension could be caused by an indirect effect of Gs proteins mediated by glucose metabolism.

Effect of genetic polymorphism of OATP-C (SLCO1B1) on lipid-lowering response to HMG-CoA reductase inhibitors.

The effect of genetic polymorphism of human organic anion transporting polypeptide C (OATP-C) on the lipid-lowering response to 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors was assessed. A retrospective study was conducted on 66 patients who underwent treatment of hyperlipidemia with HMG-CoA reductase inhibitors in a municipal hospital in a community-based cohort of Ehime prefecture in the southern part of Japan. Plasma lipid concentrations before and after administration were analyzed in patients in relation to the 521T/C (Val-174-->Ala) polymorphism in the OATP-C gene (TT: n=44 (66.7%), TC: n=20 (30.3%), CC: n=0 (0.0%), undetermined: n=2 (3.0%)). Total cholesterol level was significantly lowered after treatment with HMG-CoA reductase inhibitors in all patients (p<0.001); moreover, subjects with the 521C allele showed an attenuated total-cholesterol-lowering effect compared with those homozygous for the 521T allele (-22.3+/-8.7% vs. -16.5+/-10.5%, p<0.05). These data suggest that the 521T/C polymorphism of the OATP-C gene modulates the lipid-lowering efficacy of HMG-CoA reductase inhibitors.