Association of genetic variants for susceptibility to obesity with type 2 diabetes in Japanese individuals

AIMS/HYPOTHESIS

In populations of East Asian descent, we performed a replication study of loci previously identified in populations of European descent as being associated with obesity measures such as BMI and type 2 diabetes.

METHODS

We genotyped 14 single nucleotide polymorphisms (SNPs) from 13 candidate loci that had previously been identified by genome-wide association meta-analyses for obesity measures in Europeans. Genotyping was done in 18,264 participants from two general Japanese populations. For SNPs showing an obesity association in Japanese individuals, we further examined diabetes associations in up to 6,781 cases and 7,307 controls from a subset of the original, as well as from additional populations.

RESULTS

Significant obesity associations (p < 0.1 two-tailed, concordant direction with previous reports) were replicated for 11 SNPs from the following ten loci in Japanese participants: SEC16B, TMEM18, GNPDA2, BDNF, MTCH2, BCDIN3D-FAIM2, SH2B1-ATP2A1, FTO, MC4R and KCTD15. The strongest effect was observed at TMEM18 rs4854344 (p = 7.1 × 10(-7) for BMI). Among the 11 SNPs showing significant obesity association, six were also associated with diabetes (OR 1.05-1.17; p = 0.04-2.4 × 10(-7)) after adjustment for BMI in the Japanese. When meta-analysed with data from the previous reports, the BMI-adjusted diabetes association was found to be highly significant for the FTO locus in East Asians (OR 1.13; 95% CI 1.09-1.18; p = 7.8 × 10(-10)) with substantial inter-ethnic heterogeneity (p = 0.003).

CONCLUSIONS/INTERPRETATION

We confirmed that ten candidate loci are associated with obesity measures in the general Japanese populations. Six (of ten) loci exert diabetogenic effects in the Japanese, although relatively modest in size, and independently of increased adiposity.

Evaluation of the Antiobesity Effects of an Amino Acid Mixture and Conjugated Linoleic Acid on Exercising Healthy Overweight Humans: A Randomized, Double-blind, Placebo-controlled Trial

This single-centre, randomized, double-blind, placebo-controlled trial investigated the effects of administering a mixture of four amino acids (lysine, proline, alanine and arginine) with or without conjugated linoleic acid to healthy overweight humans before and after exercising. Forty-one healthy subjects (body mass index ≥ 23 to < 30 kg/m2) completed the study following randomization to receive either placebo or one of three test supplements: amino acid mixture 0.76 g/day; amino acid mixture 1.52 g/day; or amino acid mixture 1.52 g/day coadministered with conjugated linoleic acid 1.6 g/day. Each of the study treatments was administered 30 min before and immediately after a period of daily exercise, which was delivered by an exercise expert, for a period of 12 weeks. When compared with the placebo group, several indicators, such as waist and hip circumferences, were found to have significantly decreased in the test supplement groups compared with the placebo. These results suggest that ingestion of these supplements might enhance the fat-burning effects of exercise.

Common variants at the GCK, GCKR, G6PC2-ABCB11 and MTNR1B loci are associated with fasting glucose in two Asian populations

AIMS/HYPOTHESIS

To test fasting glucose association at four loci recently identified or verified by genome-wide association (GWA) studies of European populations, we performed a replication study in two Asian populations.

METHODS

We genotyped five common variants previously reported in Europeans: rs1799884 (GCK), rs780094 (GCKR), rs560887 (G6PC2-ABCB11) and both rs1387153 and rs10830963 (MTNR1B) in the general Japanese (n = 4,813) and Sri Lankan (n = 2,319) populations. To identify novel variants, we further examined genetic associations near each locus by using GWA scan data on 776 non-diabetic Japanese samples.

RESULTS

Fasting glucose association was replicated for the five single nucleotide polymorphisms (SNPs) at p < 0.05 (one-tailed test) in South Asians (Sri Lankan) as well as in East Asians (Japanese). In fine-mapping by GWA scan data, we identified in the G6PC2-ABCB11 region a novel SNP, rs3755157, with significant association in Japanese (p = 2.6 x 10(-8)) and Sri Lankan (p = 0.001) populations. The strength of association was more prominent at rs3755157 than that of the original SNP rs560887, with allelic heterogeneity detected between the SNPs. On analysing the cumulative effect of associated SNPs, we found the per-allele gradients (beta = 0.055 and 0.069 mmol/l in Japanese and Sri Lankans, respectively) to be almost equivalent to those reported in Europeans.

CONCLUSIONS/INTERPRETATION

Fasting glucose association at four tested loci was proven to be replicable across ethnic groups. Despite this overall consistency, ethnic diversity in the pattern and strength of linkage disequilibrium certainly exists and can help to appreciably reduce potential causal variants after GWA studies.

Association of (pro)renin receptor gene polymorphism with blood pressure in Japanese men: the Ohasama study

BACKGROUND

Recent studies have revealed that (pro)renin receptor ((P)RR), a newly identified member of the renin-angiotensin system (RAS), is associated with blood pressure regulation in animals. However, there is no information on (P)RR in humans. We investigated the association of (P)RR gene polymorphisms with blood pressure in a Japanese population.

METHODS

Subjects (n = 1,112) were recruited from participants in the Ohasama study, a Japanese cohort study. For the association study, we selected three polymorphisms: -782A>G (rs2968915), intervening sequence (IVS)5+169C>T (rs5918007), and +1513A>G (rs6609080). Because the (P)RR gene is on the X chromosome, men (n = 357) and women (n = 755) were analyzed separately.

RESULTS

In men, 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP) values, daytime SBP and DBP values, and nighttime SBP and DBP values were significantly higher in IVS5+169T allele carriers than C allele carriers. Multiple regression analysis showed that IVS5+169C>T was significantly and independently related to ambulatory blood pressure (ABP). IVS5+169C>T was not associated with casual blood pressure (CBP) in men. In women, there were no significant differences in blood pressure values among the three genotypes of IVS5+169C>T. This polymorphism had no significant association with any other clinical characteristic. -782A>G was weakly associated with ABP in men. +1513A>G was not associated with blood pressure values in either men or women.

CONCLUSIONS

We demonstrated for the first time that polymorphism of the (P)RR gene IVS5+169C>T is associated with ABP in Japanese men. This association suggests that (P)RR has a role in blood pressure regulation.

Hypertension in a patient with Gitelman's syndrome

Gitelman's syndrome is an autosomal recessive disorder characterized by sodium wasting and hypotension. A middle-aged woman was diagnosed with Gitelman's syndrome because of typical clinical manifestations in the youth and homozygous mutations of 18-base-pair insertion in exon 6 of thiazide-sensitive NaCl-cotransporter gene. It was unusual that she showed hypertension with advancing age. Her serum potassium levels remained low at around 3.5 mEq/l despite potassium supplementation. This case demonstrates that hypertension could result in spite of the extremely decreased sodium reabsorption in Gitelman's syndrome and that essential hypertension is genetically heterogeneous, and abnormality of all genes may not be necessarily required to cause blood pressure rise.

Aldosterone synthase gene (CYP11B2) C-334T polymorphism, ambulatory blood pressure and nocturnal decline in blood pressure in the general Japanese population: the Ohasama Study

OBJECTIVE

The C-344T polymorphism in the 5'-flanking region of the aldosterone synthase (CYP11B2) gene has been suggested to be associated with hypertension and disturbed circadian blood pressure (BP) rhythm through its effect on aldosterone synthesis. However, previous findings on this topic have been inconsistent.

DESIGN

A cross-sectional study.

SUBJECTS AND METHODS

We investigated the CYP11B2 C-344T genotype in 802 subjects, aged 40 and over, in a Japanese community, who gave written informed consent and were monitored for 24 h ambulatory BP.

RESULTS

The frequencies of the CC, CT, and TT genotypes in these Japanese subjects were 0.14, 0.44, and 0.42, showing a higher frequency of the T allele (0.64) than in Caucasians. Although there was no significant difference in 24 h ambulatory BP levels among the genotypes, the nocturnal decline in BP was significantly greater in the CC homozygous subjects than in other subjects (P = 0.0065 for systolic and P = 0.031 for diastolic decline in nocturnal BP). Detailed analyses demonstrated that this association was significant only in aged (60 years and over) or male subjects. The prevalence of previous cardiovascular disease was significantly less in these subjects with the CC genotype than in those with the TC and TT genotypes, although age, body mass index, male gender, smoking, use of alcohol and antihypertensive medication did not differ among the three genotypes. There was no significant difference among the three genotypes in biochemical and hormonal parameters.

CONCLUSION

Although the C-344 T polymorphism of CYP11B2 did not directly influence the level of 24 h BP, the CC genotype was associated with decreased nocturnal BP in elderly or male Japanese. Since prevalence of previous cardiovascular disease was significantly less in homozygous CC subjects, greater nocturnal BP decline in this genotype appears to be beneficial in the circadian BP rhythm.

Public response to the Tokai nuclear accident

This article discusses the influence of the September 30, 1999 nuclear accident in Tokai village (Japan) on the public's attitudes toward nuclear power in Japan. The data used in this report were taken from the results of two surveys conducted mainly to measure the attitudes of the Japanese public with regard to the use of nuclear power in Japan. The first survey was done before the accident in District 23 in Tokyo and also in Osaka and Nagoya. The second survey, which took place after the accident in District 23 in Tokyo and in Osaka and Nagoya, also included residents in a number of other cities of various sizes throughout Japan. The results of the two surveys showed that (1) acceptability of and trust in nuclear power operation had decreased, (2) perceived accident likelihood and public interest had significantly increased, and (3) there had been neither significant nor even a small change in the public's self-rated knowledge about nuclear power or their distrust of the government. The results also showed that the ratio of nuclear power generation opponents to total respondents had considerably increased (7% to 23%) whereas nuclear power generation supporters had moderately decreased (1% to 12%).

Endothelin-1 gene variant associates with blood pressure in obese Japanese subjects: the Ohasama Study

A recent report based on the results of 2 epidemiological studies, the Etude Cas-Temoin de l'Infarctus Myocarde (ECTIM) and the Glasgow Heart Scan Study, revealed that a G/T polymorphism with an amino acid substitution (Lys-->Asn) at codon 198 in exon 5 of the endothelin-1 gene (ET-1) is associated with blood pressure in overweight people. They suggested that G/T polymorphism of ET-1 strongly interacted with body mass index (BMI) in the determination of BP levels. To examine interaction among G/T polymorphism of ET-1, BMI, and BP, we performed an association study in a general Japanese population. Subjects (n=1250) were recruited from Ohasama, a cohort in a rural community of northern Japan. DNA was extracted from buffy coat of participants, and G/T polymorphism of ET-1 was determined by the TaqMan probe polymerase chain reaction method, a powerful tool for semiautomatic genotype determination of a large number of samples. Frequency of T (Asn 198) allele in Japanese (27%) was slightly but significantly higher than in whites (24%). Baseline characteristics (age, BMI, systolic and diastolic BP, and antihypertensive treatment) of all subjects were not significantly different according to the genotype of G/T polymorphism. However, in obese subjects (> or =25 kg/m(2)) diastolic BPs were significantly associated with G/T polymorphism of ET-1. After adjustment for confounding factors, significant association remained; for overweight subjects, diastolic BP level in those with T allele (GT + TT) was 1.8 mm Hg (P=0.04) higher than in those with GG genotype. That similar results were obtained from subjects of different races suggests that the Lys198Asn polymorphism of ET-1 is involved in determination of BP levels in obese subjects.

Association analyses between genetic polymorphisms of endothelial nitric oxide synthase gene and hypertension in Japanese: The Suita Study

OBJECTIVES

Endothelium-derived nitric oxide plays a key role in the regulation of vascular tone. Recently, endothelial nitric oxide synthase (eNOS) gene polymorphisms were reported to be associated with hypertension or coronary spasm. We investigated the association between the eNOS gene polymorphisms and hypertension in a large population-based sample of 4055 Japanese.

DESIGN AND METHODS

We investigated two polymorphisms of the eNOS gene, Glu298Asp polymorphism of exon 7 and T(-786)C polymorphism of the promoter region. The genotype distribution in hypertensive subjects was compared to that in the other subjects. The influence of the genotype on blood pressure values was analyzed in the subjects not taking hypertensive medication. The promoter activities of the eNOS gene with the (-786)T or (-786)C allele were measured by a luciferase reporter gene assay.

RESULTS

There was significant linkage disequilibrium between the two polymorphisms (P < 0.0001). The genotype distribution of the Glu298Asp or T(-786)C polymorphism did not differ between the hypertensive and the other subjects. No significant differences in the blood pressure of subjects not taking hypertensive medication were observed among the three genotypes of Glu298Asp or T(-786)C polymorphisms. No significant differences in the promoter activity were observed between bovine endothelial cells transfected with the (-786)T and (-786)C alleles.

CONCLUSIONS

Our data suggested that these polymorphisms of the eNOS gene are unlikely to be major factors in the susceptibility to hypertension in the Japanese population studied.

Association of sodium channel gamma-subunit promoter variant with blood pressure

The SCNN1G gene, located on human chromosome 16p12, encodes the gamma subunit of the amiloride-sensitive epithelial sodium channel, and mutations in SCNN1G can result in Liddle's syndrome or pseudohypoaldosteronism type I. We identified sequence variations in the promoter region of SCNN1G and examined the association between this polymorphism and blood pressure in a large cohort (n=4075) representing the general population in Japan. We found T(-1290)C, T(-501)G, G(-173)A, and G(-104)T polymorphisms in the promoter region of SCNN1G and confirmed the existence of T387C and T474C polymorphisms in exon 3 and the C1947G polymorphism in exon 13. Because the genotypes of the T(-1290)C, T(-501)G, G(-104)T, and T474C polymorphisms were in tight linkage disequilibrium, we selected the T474C and G(-173)A polymorphisms for an association study. The G(-173)A polymorphism of SCNN1G had a significant effect on systolic pressure (P=0.0050) and pulse pressure (P=0.0050). The AA genotype was associated with an 11 mm Hg drop in systolic pressure and an 8 mm Hg drop in pulse pressure and with a higher prevalence of hypotension (P=0.0195). A transient transfection assay using MDCK cells and human renal epithelial cells indicated that the promoter activity of the G(-173) allele was higher than that of the A(-173) allele. Although the effects of the A(-173) allele were recessive and although the AA genotype was found in just 0.7% of our study population, we observed that this variation of human SCNN1G had significant effects on blood pressure.

The aldehyde dehydrogenase 2 gene is a risk factor for hypertension in Japanese but does not alter the sensitivity to pressor effects of alcohol: the Suita study

Excessive alcohol consumption is a potent risk factor for high blood pressure. About half of Japanese show an extremely high sensitivity to alcohol, which is due to a genetic deficiency in an isoenzyme of aldehydede-hydrogenase with a low Km (ALDH2). It is possible that the effects of alcohol consumption on blood pressure differ according to the ALDH2 genotype. The purpose of the present study was to assess the influence of the ALDH2 genotype on the pressor effects of alcohol. The influence of the ALDH2 genotype on blood pressure was investigated in a large cohort (4,000 subjects) representing the general population in Japan. The genotype was determined by the TaqMan method. The genotype was significantly associated with alcohol consumption, gamma-GTP level, and HDL cholesterol level in both males and females. The odds ratio for the presence of hypertension for the Glu/Glu genotype in comparison to other genotypes was 1.67 (p< 0.0001, odds ratio=1.37-2.08, 95% confidence interval) among males. In contrast, the ALDH2 genotype had no significant effects on blood pressure among females. To investigate whether the ALDH2 genotype affected the sensitivity to the pressor effects of alcohol, we analyzed the effects of the ALDH2 genotype (Lys/Lys+Lys/Glu=0, Glu/Glu=1) and the level of alcohol consumption on blood pressure values after adjusting for age and BMI (residuals after adjusting for age and BMI). Among males, while the level of alcohol consumption significantly affected systolic, diastolic and pulse pressure, no significant interaction was observed between the ALDH2 genotype and the level of alcohol consumption in determining blood pressure levels. These results suggest that the Glu/Glu genotype is a potent risk factor for hypertension among males mainly through its association with the level of alcohol consumption, and that the ALDH2 genotype does not affect the sensitivity to the pressor effects of alcohol.

Effects of antihypertensive drugs and gene variants in the renin-angiotensin system

Many genes and environmental factors are involved in the pathogenesis of hypertension, but the exact cause of essential hypertension has not yet been clarified. Gene polymorphism of the renin-angiotensin system (RAS) is one of the candidates. In the current study, we examined whether there was a correlation between the gene polymorphisms in RAS and either the choice of antihypertensive drugs or their efficacy. Subjects with essential hypertension (n=299) were recruited from among the outpatients of Osaka University Hospital and provided their informed consent for genetic analysis. Physicians freely chose the antihypertensive drugs and adjusted its dose until the patient's blood pressure was well controlled. The efficacy of each antihypertensive drug was estimated using the following formula: ABP=BP 1 (before treatment) - BP 2 (after treatment)/BP 1 x 100 (%). Gene variants in RAS were determined using PCR or PCR-RFLP (restriction fragment of polymorphism). The gene polymorphisms of RAS were not associated with delta SBP or ADBP. However, the mean ASBP in subjects with a deletion homozygote of the angiotensin converting enzyme gene (ACE/DD) was significantly lower (p<0.05) than that in patients with an insertion I allele of the ACE gene. The gene polymorphisms of RAS did not significantly affect the choice of antihypertensive drugs. Even though gene polymorphism in the renin angiotensin system was not a major factor in the antihypertensive therapy, the determination of genotype might be of help in the management of essential hypertension.

Low potentiality of angiotensin-converting enzyme gene insertion/deletion polymorphism as a useful predictive marker for carotid atherogenesis in a large general population of a Japanese city: the Suita study

BACKGROUND AND PURPOSE

Some previous studies, almost all western, have investigated whether there is a relationship between the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) and carotid atherosclerosis. The results, however, have not been consistently positive. Further, there have been few investigations based on a large, general population. Therefore, the present study aimed to clarify whether ACE gene deletion polymorphism was associated with carotid atherosclerosis in a large Japanese general population with a more homogeneous genetic background than Caucasian populations.

METHODS

Subjects aged 30 to 86 years were randomly selected from Suita City, located in Osaka, the second largest urban area of Japan, and included 1894 men and 2137 women. With the aid of high-resolution ultrasonography, carotid atherosclerosis was evaluated using our atherosclerotic indexes of intimal-medial thickness (IMT), plaque number (PN), plaque score (PS), and percentage of stenosis of the carotid artery assessed using high-resolution B-mode ultrasonography. ACE gene I/D polymorphism was detected by polymerase chain reaction.

RESULTS

There were no significant differences among the ACE genotypes for age and conventional cardiovascular risk factors, except for systolic blood pressure (SBP) and the percentage of hypertension in men. The values of IMT, PN, and PS as carotid atherosclerotic indexes were not significantly different among genotypes for either sex. After adjusting for age, body mass index, smoking habit, high-density lipoprotein cholesterol, triglycerides, presence of hypertension, presence of diabetes mellitus, and presence of hyperlipidemia, the estimated ORs for the presence of IMT >/=1.10 mm (defined as thickened IMT), according to ACE genotype (DD versus II, DD+ID versus II, and DD versus ID+II), for men were 0.80 (95% CI 0.60 to 1.23), 0.89 (0.62 to 1.29), and 0.89 (0.70 to 1.28), respectively. On the other hand, the ORs for women after the same adjustment were 0.92 (95% CI 0.58 to 1.35), 0.93 (0.59 to 1.45), and 0.91 (0.59 to 1.27), respectively.

CONCLUSIONS

Our present data suggest that ACE I/D polymorphism is not potentially a useful predictive marker for carotid atherogenesis when investigated in a large and homogeneous general Japanese population of 4031 subjects, a finding similar to that in a Caucasian population study, the Perth Carotid Ultrasound Disease Assessment Study, an Australian study based on a general population using 1111 subjects.

Lack of correlation between Mbo I restriction fragment length polymorphism of renin gene and essential hypertension in Japanese

Predisposition to essential hypertension is associated with gene polymorphisms of the renin angiotensin system (RAS). Gene polymorphisms of the angiotensinogen and angiotensin converting enzyme genes are known to be risk factors for hypertension, while few studies concerning the renin gene polymorphism have been published. In the present investigation, we carried out a case control study using a Japanese population to examine the genetic influence of the renin gene on the predisposition to hypertension. Patients (n=235) recruited from outpatients at Osaka University Hospital and diagnosed with essential hypertension or receiving long-term antihypertensive medication participated in the study. Normotensive control subjects (n=510) without a history of hypertension and without diabetes mellitus were recruited from the same population, and were sex-matched with experimental subjects. A polymorphism in intron 9 of the human renin gene was determined as the Mbo I restriction fragment length polymorphism (Mbo I-RFLP). There was no significant association between Mbo I-RFLP of the renin gene and predisposition to essential hypertension in Japanese (p>0.05, chi2=2.1). These results suggest that the Mbo I (+) allele of the renin gene does not increase the risk for hypertension in Japanese.

[Genetic polymorphisms of the renin-angiotensin system]

Essential hypertension is a multifactorial disease which is evoked by multiple environmental and genetic factors. Recent progress in molecular biology enables us a comprehensive understanding of the molecular pathogenesis of this disease. The genes of renin-angiotensin system such as renin, angiotensinogen, angiotensin-converting enzyme and angiotensin receptors genes are all reported as positive linkage to hypertension. Now ongoing progress of the human genome project will further accelerate the molecular studies on the rennin-angiotensin system and hypertension.

Lack of association between genetic polymorphism of CYP11B2 and hypertension in Japanese: the Suita Study

Aldosterone synthase (CYP11B2) is a key enzyme in the biosynthesis of aldosterone. Recently, a polymorphism in the 5'-flanking region of the CYP11B2 gene [T(-344)C] has been reported to be associated with blood pressure and plasma aldosterone levels. We investigated the association between this polymorphism and hypertension in a large population-based sample of 4,000 Japanese. The genotype distribution in hypertensive subjects (n=1,535) was compared to that in normotensive subjects (n=2,514). In subjects not receiving antihypertensive medication, the influence of the genotype on blood pressure values adjusted for clinical covariates was analyzed. All analyses were performed separately for men and women. The genotype distribution did not differ between hypertensive and normotensive subjects in either men (frequency of C allele: 30.3% vs. 31.4%, p=0.48) or women (31.5% vs. 31.7%, p=0.93). There were no significant differences in systolic blood pressure, diastolic blood pressure, or pulse pressure among the three genotypes in either men or women who had not received hypertensive medication. Our data suggest that the T(-344)C polymorphism of CYP11B2 is unlikely to influence blood pressure status in the Japanese population.

A common mutation of low-density lipoprotein receptor gene is associated with essential hypertension among Japanese

Candidate genes offer one approach to the identification of the genetic susceptibility to hypertension. A common gene variant of the low-density lipoprotein (LDL) receptor gene (LDLR) that affects plasma LDL metabolism within the normolipidaemic range, may be such a candidate gene. A common mutation of LDLR, C1773T, was associated with lipid metabolism such that the T1773 allele increased plasma LDL levels in a Caucasian population. The present study examined whether C1773T/LDLR was associated with essential hypertension in a Japanese population. Subjects with essential hypertension (EHT, n = 300) with a family history of hypertension, and controls (NT, n = 310, sex- and age-matched with EHT) were recruited from among out-patients at Osaka University Hospital. A C1773T substitution at codon 570 in LDLR was determined using PCR-Hinc II-RFLP. It was revealed that the C1773 allele was significantly more frequent (0.89) among hypertensive patients (chi2 = 9.58, P < 0.01) than normotensives (0.83), the calculated odds ratio being 1.7 (95% CI: 1.2-2.4). The effect of the T1773 allele on increasing cholesterol was significant in normotensives without antihyperlipidaemic medication, but not in hypertensives. After adjustments of confounding factors, the estimated odds ratio for hypertension in the subjects with C1773 homozygote increased to 2.1 (95% CI: 1.3-3.5), suggesting that this polymorphism is an independent risk factor for hypertension. Our results show that the C1773 mutant of LDLR increases susceptibility to hypertension, but not via hypercholesterolaemia.

T+31C polymorphism of angiotensinogen gene and essential hypertension

A common variant at codon 235 of the angiotensinogen gene with methionine to threonine amino acid substitution (AGT M235T) has been reported as a genetic risk for essential hypertension. However, the frequency of AGT T235 was heterogeneous among races, and a positive association between AGT M235T and hypertension was not settled. To examine the association in a general population of Japanese (n=4013), we introduced the TaqMan polymerase chain reaction method and examined the relation between hypertension and T+31C polymorphism, which was in absolute linkage disequilibrium with AGT M235T. The C+31 allele of AGT was significantly associated with the positive family history of hypertension (FH) but not with the presence of hypertension or blood pressure. The subjects with CC tended to have hypertensive relatives, especially a hypertensive father or siblings, and its statistical significance was stronger in men. Adjustment of confounding factor did not alter the results of simple association study, suggesting that this positive association with FH is independent and significant. Our findings revealed that the TaqMan polymerase chain reaction method is a powerful tool for genetic association study with a large number of subjects and that AGT T+31C is significantly associated with paternal FH.

Symposium on the etiology of hypertension--summarizing studies in 20th century. 1. Hypertension and genes

Under classical strategy, scientists have tried first to find a physiological phenomenon specific for essential hypertension, then to identify the protein underlying the physiological abnormality, and finally to clarify the causative gene which encoded the protein. On the other hand, under the reverse genetic approach, the correlation between hypertension and genetic abnormality is identified first, and then the pathogenesis is clarified-in reverse order. Therefore, it is not extraordinary for unexpected results to be obtained in the correlation between a gene and a disease, suggesting that this approach has a possibility to be a breakthrough in the chaos of hypertension research.

Nine polymorphisms of angiotensinogen gene in the susceptibility to essential hypertension

Even if the importance of angiotensinogen (AGT) gene has been known in gene targeting animals and humans genetic studies, its precise mechanism and the interaction among AGT gene variants, plasma AGT concentration and risk for hypertension remain uncertain. We examined whether AGT gene variants predispose to hypertension via an increase of plasma AGT concentration. Plasma AGT concentration was estimated from plasma angiotensin I which was cleaved by an excess amount of human renin and measured by RIA. Using 9 AGT gene variants which included new polymorphisms (G-152A and T+31C), we examined the association with hypertension and with plasma concentration by a case-control study. Haplotype analysis revealed that G-6A, T+31C and M235T polymorphisms were in absolute linkage disequilibrium and were associated with hypertension but not with plasma AGT level. On the other hand, -1074t;T235 haplotype was associated with an increase of AGT level but not with hypertension. In the haplotype analysis, only H3 haplotype frequency, which contained G-6, T+31 and M235 alleles, was significantly increased in normotensive subjects, suggesting that this haplotype is associated with a hypotensive effect. According to combined haplotype analysis of diallele and microsatellite markers, it remains a possibility that M235T, T+31C, G-6A, A-20C and G-1074T polymorphisms may play an important role in increased risk for essential hypertension. Our results suggest that the positive association between AGT polymorphism and hypertension is not simply explained by an increase of plasma AGT concentration.

Dynamic contrast-enhanced MR imaging of the water fraction of normal bone marrow and diffuse bone marrow disease

PURPOSE

To clarify the contrast-enhancement pattern of the normal hematopoietic element by isolating the signal of the water fraction in vertebral bone marrow and to investigate whether this approach can be used to characterize bone marrow pathology in several diffuse bone marrow diseases.

METHODS

Two groups were examined: 30 normal healthy volunteers and 19 patients with primary diffuse bone marrow disease (aplastic anemia [n=8], myelodysplastic syndrome (MDS) [n=5], chronic myelogenic leukemia (CML) [n=4], polycythemia vera [n=2]). Isolation of the signal of hematopoietic tissue was done by the chemical-shift misregistration effect. Twenty consecutive T1-weighted midsagittal lumbar vertebral images were obtained immediately after the intravenous administration of Gd-DTPA of 0.1 mmol/kg body weight, and the pattern of the time-intensity curve, the peak contrast-enhancement (CE) ratio, and the washout rate (%/min) of bone marrow in normal volunteers were compared with those in patients suffering from primary diffuse bone marrow disease.

RESULTS

The pattern of the time-intensity curve of patients with aplastic anemia showed a low peak value followed by a slow washout. However, the pattern of time-intensity curves in patients with MDS, CML, and polycythemia vera was similar to that of normal volunteers. The peak CE ratio of the water fraction in normal marrow ranged from 0.45 to 1.26 (mean +/- S.D.: 0.87 +/- 0.18). Patients with aplastic anemia showed an abnormally lower peak CE ratio of the water fraction (mean +/- S.D.: 0.34 +/- 0.19, p<0.0001). On the other hand, the peak CE ratio of the water fraction in patients with MDS was significantly higher than that of normal volunteers (mean +/- S.D. 1.35 +/- 0.39, p<0.05). In contrast, the peak CE ratio of patients with CML or polycythemia vera did not differ significantly from that of normal volunteers. The mean washout rate of patients with aplastic anemia was significantly lower than that of normal volunteers (mean +/- S.D.: 3.50 +/- 2.51%/min vs. 7.13 +/- 1.74%/min, p<0.01). However, there was no significant difference in the washout rate among patients with MDS, CML, polycythemia vera, and normal volunteers.

CONCLUSION

Dynamic contrast-enhanced MR imaging of the water fraction provides additional valuable qualitative information about structural changes of the hematopoietic element.

Deletion polymorphism of angiotensin-converting enzyme gene is associated with postprandial hyperglycaemia in individuals undergoing general check-up

1. Deletion polymorphism, DD, of the angiotensin-converting enzyme (ACE) gene is reported to be related to cardiovascular disease, which is frequently based on insulin resistance. 2. To clarify the relationship between the ACE genotype DD and plasma glucose increases after an oral glucose load, we performed 75 g oral glucose tolerance test (OGTT) in 301 nondiabetic men (age range 30-60 years) undergoing general check-up. 3. Insertion/deletion (I/D) polymorphism of the ACE gene was explored using a polymerase chain reaction. The frequency of the II, ID and DD genotypes was 0.43, 0.43 and 0.14, respectively. 4. There were no differences in baseline clinical characteristics between subjects with each ACE genotype. 5. The mean (+/- SEM) plasma glucose level at 60 min of the OGTT was significantly higher in subjects with the DD genotype (170.8 +/- 6.9 mg/dL) than in subjects with either the II or ID genotype (mean value for two groups 156.6 +/- 2.7 mg/dL; P < 0.05). Moreover, the mean percentage change of plasma glucose after 60 min of the OGTT, a marker of plasma glucose increase, was significantly higher in individuals with the DD genotype than in individuals with either the II or ID genotypes. 6. In contrast, the mean fasting plasma glucose level, the plasma glucose level at 120 min, the glucose response area and the fasting insulin level were not different between individuals with the DD genotype and individuals with other genotypes. 7. In conclusion, subjects with the DD genotype showed transiently higher levels of plasma glucose after an oral glucose load than subjects with other genotypes. Further studies are required to determine whether the association between ACE genotype and postprandial hyperglycaemia influences the incidence of cardiovascular disease and diabetes mellitus.

Japanese individuals do not harbor the T594M mutation but do have the P592S mutation in the C-terminus of the beta-subunit of the epithelial sodium channel: the Ohasama study

OBJECTIVE

To assess the implications of polymorphisms of the amiloride-sensitive epithelial sodium channel in essential hypertension in the Japanese population by determining the incidence of the T594M mutation in the , subunit of the epithelial sodium channel, and by screening the C-terminus of the epithelial sodium channel.

METHODS

Single-strand confirmational polymorphism (SSCP) analysis using two sets of primers which cover the last two-thirds of the last exon coding the B epithelial sodium channel and modification of a specific enzyme restriction site (NlaIII) for the T594M mutation were performed on 803 Japanese subjects. They were randomly selected from the study participants representative of a general population of Ohasama, Japan, who measured their home blood pressure. Polymerase chain reaction (PCR) products presenting a shift in SSCP gel, as well as controls, were directly sequenced by autoanalyser to identify the mutation.

RESULTS

SSCP analysis identified altered migration in five subjects. Four SSCP variants found by sequencing were heterogeneous for the P592S (CCT to TCT) mutation conserving the PY motif, although it was not significantly associated with either home or casual blood pressure values. The resting polymorphism was at codon Thr 594, leading to no change in the amino acid sequence (ACG to ACA). None of the PCR products were modified by NlaIII, indicating the absence of the T594M mutation.

CONCLUSIONS

The epithelial sodium channel variants at the C-terminus are not involved in the common form of essential hypertension in Japanese.

Deletion allele of angiotensin-converting enzyme gene increases risk of essential hypertension in Japanese men : the Suita Study

BACKGROUND

The Framingham Study recently revealed that the homozygous deletion polymorphism of the angiotensin-converting enzyme gene (ACE DD) is associated with increased risk for essential hypertension in a male-specific manner. However, this association has not been confirmed in races other than whites.

METHODS AND RESULTS

Using a large number of Japanese subjects (n=5014) that were randomly selected from the general population (the Suita Study), we examined the association between ACE DD and hypertension. The frequency of DD (17.1%) in hypertensive men was significantly higher (P<0.0015) than that (11.8%) in other mildly hypertensive or normotensive men, and the estimated odds prevalence for hypertension (DD vs II) was 1.75 (95% CI 1.21 to 2.53). In contrast, no significant association was confirmed in women (OR 1.17, 95% CI 0.79 to 1.72).

CONCLUSIONS

Despite the lower frequency of the DD genotype in Japanese than in whites, the ACE gene polymorphism was associated with increased risk for hypertension, suggesting that this polymorphism is a mild but certain genetic risk factor for essential hypertension in men.

Genetic analysis of essential hypertension in Japanese populations

The reverse genetic approach, which examines genetic factors underlying the root of pathogenesis first, is a powerful tool to clarify the genetic cause of essential hypertension. Using the rat cross model, studies of the genetically hypertensive inbred rat model indicated several candidate loci on the rat chromosome responsible for blood pressure, but failed to identify the exact causal gene. Moreover, it was not certain that the rat data really reflect the human case. Thus, we shifted our focus to human genetics and carried out case control studies using the candidate gene approach. We mainly focused on gene components of the renin-angiotensin system as candidates, finding that angiotensinogen gene polymorphisms are genetic predisposing factors for hypertension. However, the results obtained from case-control studies using Japanese subjects were not consistent, suggesting that there was a problem in control sampling. In our recent study, we recruited more than 5,000 residents of an urban community as a general population and examined the association between genetic factors and their health status. Our results indicate that angiotensin-converting enzyme gene polymorphism is a male-specific genetic risk for essential hypertension. In light of our previous investigations, we present a discussion concerning the design of future studies of the genetics of hypertension.

Association of polymorphism in the promoter region of the apolipoprotein E gene with diastolic blood pressure in normotensive Japanese

The epsilon4 allele of apolipoprotein E (APOE) is reported to be a genetic risk factor of atherosclerosis through hyperlipidemia and late-onset Alzheimer's dementia. A recent report showed that a genetic variant (A -491T) in the promoter region of the APOE gene increases the risk of Alzheimer's disease. In the present study, we examined whether these APOE polymorphisms were genetically involved in essential hypertension. Japanese hypertensives (n=180) with a family history of hypertension and normotensive controls (n=195, sex and age matched with hypertensives) were recruited from the outpatients of Osaka University Hospital, and an informed consent to participate in the study was obtained from each person. APOE polymorphisms were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The frequencies of the A -491 allele in hypertensives and normotensives were 0.98 and 0.97, respectively, and the TT/-491 genotype was not found in either group. No significant differences between hypertensives and normotensives were observed in allele frequencies in either APOE polymorphism; however, the mean diastolic blood pressure in normotensive subjects with AA/-491 was significantly higher than in the subjects with AT/-491 (p < 0.01). These results suggest that the presence of the APOE promoter polymorphism is not a major risk factor for hypertension but that it does have some minor effect on basal blood pressure variation.

Gene polymorphism of the renin-angiotensin system associates with risk for lacunar infarction. The Ohasama study

The polymorphism of the angiotensin-converting enzyme gene is considered to be associated with increased risk for stroke, but there is a diversity in the results obtained. The genetic involvement of the renin-angiotensin system in stroke also remains unclear. To predict the genetic risk of lacunar infarction, we conducted an association study in an Ohasama population, which is the cohort in a rural region of northern Japan. A total of 134 subjects without major neurological, cardiovascular, or metabolic disorders were recruited. Using brain magnetic resonance imaging, the number of lacunae in each of four brain regions were calculated, and periventricular hyperintensity was classified into five grades. We used the following four candidate gene polymorphisms: angiotensin converting enzyme (ACE)/Insertion(I)-Deletion(D), angiotensinogen (AGT)/M235T, angiotensin II type 1 receptor (AT1)/ A1166C, type 2 receptor (AT2)/C3123A, to examine the association between polymorphisms and the severity of lacunar infarction. AGT/M235T was significantly associated with the number of lacunae in the brain stem, the basal ganglia (P < .05), and whole brain (P < .005) regions. The AT1 polymorphism was also significantly associated with the number of lacunae in the basal ganglia and whole brain regions (P < .05), and with periventricular hyperintensity grade (P < .005) in the younger population. However, ACE and AT2 polymorphisms failed to show an association with either the number of lacunae or the PVH grade. We concluded that AGT and AT1 polymorphisms are independent genetic risk factors for lacunar infarction.

Human G-protein beta3 subunit variant is associated with serum potassium and total cholesterol levels but not with blood pressure

The activity of a sodium-proton exchanger is enhanced in the patients with essential hypertension and regulated via G-protein, which is a signal transducer between receptors and intracellular effectors. A recent study has revealed that a novel variant (C825T) in exon 10 of the gene encoding the beta3 subunit of heterotrimetric G proteins (GNB3) is a genetic factor predisposing to hypertension in Caucasians. We examined the association between GNB3/ C825T and blood pressure, lipids, electrolytes, and other parameters in a Japanese population. Subjects (n = 352) were selected from the Ohasama Study, the population of which is regarded as from a rural community in Japan. To obtain precise clinical measurements, 24-h ambulatory blood pressure monitoring (ABPM), brain magnetic resonance imaging (MRI), and carotid ultrasonography (CUS) were conducted in this population. In addition, we recruited 762 subjects from outpatients at the Osaka University Medical School to carry out the association study between hypertension and GNB3. The GNB3 genotype distribution did not differ significantly between normotensives and hypertensives in either of the two studies. The T825 allele of GNB3 was not associated with the presence of hypertension, blood pressure level, the number of brain lacunae or carotid wall thickness. However, the serum potassium and total cholesterol levels were significantly higher in subjects with the T allele (P < .005). The T825 allele of GNB3 is associated with increased serum potassium and total cholesterol levels but not with blood pressure in a Japanese population.

Human prostacyclin synthase gene and hypertension : the Suita Study

BACKGROUND

Prostacyclin (prostaglandin I(2)) is a strong vasodilator that inhibits the growth of vascular smooth muscle cells and is also the most potent endogenous inhibitor of platelet aggregation. Therefore, it has been considered to play an important roles in cardiovascular disease. On the basis of the hypothesis that variations of the prostacyclin synthase gene may also play an important role in human cardiovascular disease, we performed a screening for variations in the human prostacyclin synthase gene.

METHODS AND RESULTS

We have detected a repeat polymorphism in the promoter region of the human prostacyclin synthase gene. The number of 9-bp (CCGCCAGCC) repeats in the promoter region, which encodes a tandem repeat of Sp1 transcriptional binding sites, varied between 3 and 7 in Japanese subjects. Luciferase reporter analysis indicated that the alleles of 3 and 4 repeats (R3 and R4, respectively) had less promoter activity in cultured human umbilical vein endothelial cells. We then investigated the possible association of this repeat polymorphism with blood pressure in a large population-based sample (the Suita Study), which consisted of 4971 Japanese participants. Multivariate models indicated that participants with the R3R3, R3R4, or R4R4 genotype (SS genotype, n=80) had significantly higher systolic pressure (P=0.0133) and pulse pressure (P=0.0005). The odds ratio of hypertension (140/90 mm Hg) for the SS genotype was 1.942 (95% confidence interval 3.20 to 1.19, P=0.0084).

CONCLUSIONS

Repeat polymorphism of the human prostacyclin synthase gene seems to be a risk factor for higher pulse pressure and is consequently a risk factor for systolic hypertension in the Japanese population.

Pharmacogenetic analysis of the effect of angiotensin-converting enzyme inhibitor on restenosis after percutaneous transluminal coronary angioplasty

Angiotensin-converting enzyme (ACE) inhibitors are reported to prevent neointimal formation after balloon injury in animal models, but in most prospective studies in humans, ACE inhibitors failed to prevent restenosis after percutaneous transluminal coronary angioplasty (PTCA). The ACE genotype assigned by an insertion/deletion (I/D) polymorphism is known to affect the potency of ACE inhibitors in several renal diseases. The authors attempted to clarify whether the effect of ACE inhibitors on restenosis might be modified by the ACE genotype. A total of 126 patients was randomly and prospectively assigned to the control group and the imidapril group. In the imidapril group, patients received 5 mg imidapril daily, starting 1 day before PTCA and continuing for 3 to 6 months. Forty-six control (65 vessels) and 32 imidapril patients (43 vessels) completed the study. The minimal lumen diameter before and after the procedure did not differ significantly among the groups with the three genotypes (II, ID, and DD) in both the control and imidapril groups. Late luminal loss during the follow-up period was not related to the ACE genotype in the control group but was significantly related in the imidapril group (II, 0.63+/- 0.19 mm; ID + DD, 1.12+/-0.14 mm, p<0.05). Furthermore, in the II genotype, imidapril significantly reduced late loss and restenosis rate as defined by most of the frequently used definitions. In conclusion the ACE I/D polymorphism may influence the effect of ACE inhibitors in preventing restenosis after PTCA.

[Genetic analysis of candidate gene polymorphisms in elderly hypertension]

Recent developments in molecular biological techniques allowed us to examine the genetic risk factors responsible for essential hypertension. The candidate gene approach revealed that several gene polymorphisms increase the relative risk for hypertension. Most genetic studies, however, examined only young subjects but not elderly ones. To examine the importance of gene polymorphisms in elderly hypertension, we carried out a case-control study and compared the odds ratio for hypertension between young (< 60) and elderly (> or = 60) subjects. The participants of this study were recruited from the outpatients of Osaka University Medical School with informed consent. We examined the following polymorphisms as candidates: the angiotensinogen (AGT/M235T), angiotensin converting enzyme (ACE I/D), angiotensin II type 1 (AT1/A1166C) and type 2 (AT2/C3123A) receptors, alpha-adducin (adducin/Gly460Trp), methylenetetrahydrofolate reductase (MTHHR/C677T), and apolipoprotein (apoE/epsilon 4, apoE/T-491A). In young subjects, the AGT/T235 allele significantly increased the odds ratio for hypertension but not in elderly subjects. In young males, the AT2/A3123 allele was also associated with hypertension but not in females or in elderly subjects. Other associations between polymorphism and hypertension did not reach a significant level. To sum up, it was revealed that some polymorphisms increase the susceptibility for hypertension but others do not, which suggests that there is heterogeneity in the genetic involvement of polymorphism due to aging.

[Gene loci and polymorphisms of angiotensin II receptor]

The gene encoding angiotensin II type 1 receptor (AT1) is mapped on 3q21-q25 region, and a polymorphism, A1166C, is located at 3'untranslated region (UTR). A1166C is associated with increased risk for hypertension, aortic stiffness, left ventricular hypertrophy and diabetic nephropathy, and synergistically increases the risk for ischemic heart disease with DD polymorphism of angiotensin converting enzyme gene. However, these results were still in controversy. On the other hand, the gene encoding angiotensin II type 2 receptor (AT2) gene is mapped on Xq22-q23 region, and a polymorphism, C3123A, is identified at 3'UTR of AT2 gene. However, any significant association with C3123A has not been obtained in case control studies yet.

Intact PTH-producing hepatocellular carcinoma treated by transcatheter arterial embolization

We report a case of hepatocellular carcinoma with hypercalcemia. There was no evidence of bone metastasis or increase in parathyroid hormone-related protein. The serum level of intact parathyroid hormone (intact PTH) was very high, and the results of the hepatic venous sampling suggested that the tumor produced intact PTH. Transcatheter arterial chemoembolization effectively controlled the humoral hypercalcemia.

Methylenetetrahydrofolate reductase gene polymorphism: relation to blood pressure and cerebrovascular disease

Hyperhomocysteinemia is reported to be associated with an increase in the incidence of ischemic heart disease and cerebrovascular disease. Genetic aberrations in methylenetetrahydrofolate reductase (MTHFR) may account for reduced enzyme activity and elevated plasma homocysteine level. A recent report revealed that a common mutation (677C to T; Ala to Val) in the MTHFR gene is associated with decreased specific MTHFR activity and with increased risk for coronary artery disease in the homozygous state (Val/Val). In the present study, we investigated whether the MTHFR gene is a genetic risk factor for cerebrovascular disease (CVD). To undertake a case-control study, we selected the patients with cerebral infarction (n = 48) or cerebral hemorrhage (n = 35) and examined the association between MTHFR gene polymorphism and CVD. The genotype distribution of the MTHFR gene was not significantly different between cases and controls. Because the possibility of matching the morbidity of the effects of hypertension, the lack of association could not be excluded in the first study; however, we also examined whether the MTHFR mutation was associated with any clinical risk factor for CVD or with hypertension. It turned out that the subjects with the Val allele of the MTHFR gene had significantly lower blood pressure than the subjects with other genotypes in the general population (P = .02), and that the frequency of the Val/Val genotype in hypertensive subjects (n = 173) was significantly lower than in control subjects (n = 184) (P = .03). From these results, we conclude that the Val/Val homozygous state of the MTHFR gene increased the risk of thrombosis, but reduced the blood pressure, which resulted in the lack of increased risk for CVD.

Bronchial arterial angio-CT: evaluation of intradural and oesophageal enhancement before bronchial arterial infusion

Ultrafast CT combined with bronchial angiography (BA angio-CT) demonstrated a supply from the bronchial arteries to the oesophagus and spinal cord which is not identified on conventional bronchial arteriography using a digital subtraction technique. 20 patients with bronchial carcinoma and one with lung metastasis were examined using BA angio-CT, before bronchial artery infusion. 20 ml of non-ionic iodinated contrast medium (300 mgI ml-1) was injected into the bronchial artery, and ultrafast CT of the whole mediastinum was commenced when 10 ml had been injected. The 6 mm single slice mode was used and 40 images were obtained. Intradural and oesophageal enhancement was evaluated on BA angio-CT, and compared with the findings on digital subtraction angiography (DSA) of the bronchial arteries. BA angio-CT clearly showed intradural enhancement in eight patients. Marked spinal cord enhancement was demonstrated in three, and a coaxial catheter technique was used to avoid infusing the intercostal branch of the intercostobronchial trunk. Oesophageal enhancement was demonstrated in 18 patients on BA angio-CT. In contrast, no enhancement of these structures was seen on bronchial arterial DSA. In conclusion, BA angio-CT enabled precise evaluation of intradural and oesophageal enhancement.

Association between angiotensin II receptor gene polymorphism and serum angiotensin converting enzyme (SACE) activity in patients with sarcoidosis

BACKGROUND

Serum angiotensin converting enzyme (SACE) is considered to reflect disease activity in sarcoidosis. SACE activity is increased in many patients with active sarcoid lesions. The mechanism for the increased SACE activity in this disease has not been clarified. ACE insertion/deletion (I/D) gene polymorphism has been reported to have an association with SACE levels in sarcoidosis, but no evidence of an association between angiotensin II receptor gene polymorphism and SACE in this disease has been found. A study of the association of angiotensin II receptor gene polymorphisms with sarcoidosis was therefore undertaken.

METHODS

ACE (I/D), angiotensin II type 1 receptor (AGTR1), and angiotensin II type 2 receptor (AGTR2) gene polymorphisms were investigated by polymerase chain reaction (PCR) and SACE levels were measured in three groups of patients: those with sarcoidosis or tuberculosis and normal controls.

RESULTS

There was no difference in allele frequency of AGTR1 and AGTR2 polymorphism among the three groups. Neither AGTR1 nor AGTR2 polymorphisms were associated with sarcoidosis. SACE activity was higher in patients with sarcoidosis with the AGTR1 A/C genotype than in others. However, this tendency was not detected in patients with tuberculosis.

CONCLUSIONS

The AGTR1 allele C is associated with high activity of SACE in patients with sarcoidosis. It is another predisposing factor for high levels of SACE in patients with sarcoidosis and is considered to be an independent factor from the ACE D allele for high levels of SACE in sarcoidosis. This fact could be one of the explanations for the increased SACE activity in sarcoidosis.

No association between alpha-adducin 460 polymorphism and essential hypertension in a Japanese population

Many unknown genetic factors are involved in the pathogenesis of hypertension. Recently, the reverse genetic approach revealed that some genetic variants, such as angiotensinogen, lipoprotein lipase, and alpha-adducin gene polymorphisms, increase the risk for hypertension. Both in rat and human, the genetic predisposition to hypertension was confirmed only for angiotensinogen and alpha-adducin genes. Adducin is a membrane cytoskeletal protein, which is thought to regulate sodium transport. Abnormalities of membrane sodium transport in the kidney play an important role in hypertension. A recent report by Cusi et al showed that the Trp allele of alpha-adducin polymorphism (Gly 460 Trp) is associated with an increased risk of hypertension in whites, which led us to carry out a case-control study to examine whether the same association is observed in the Japanese population. We recruited 170 hypertensive and 194 normotensive Japanese subjects and compared the genotype distribution of alpha-adducin 460 polymorphism between cases and controls and between whites and Japanese. Trp allele frequency of controls in the Japanese subjects was twice as high as in the whites. However, no association was observed between alpha-adducin polymorphism and hypertension. Furthermore, alpha-adducin 460 polymorphism was not associated with any clinical characteristics. Accordingly, we concluded that alpha-adducin 460 polymorphism is not a major genetic risk for hypertension in Japanese people.

Angiotensin II type 1 receptor gene polymorphism is associated with increase of left ventricular mass but not with hypertension

A genetic epidemiologic approach is useful to elucidate the genes responsible for hypertension. Genetic analyses of the components of the renin-angiotensin system have succeeded in showing an association between their polymorphism and hypertension. Recently, two types of angiotensin II receptor were cloned and characterized. To examine the genetic contribution of angiotensin II type 1 receptor (AT1) and type 2 receptor (AT2) genes in human essential hypertension, a case-control study was performed in Japanese subjects. The study comprised 321 subjects with hypertension who satisfied the criteria for essential hypertension, together with 215 age and sex matched controls. The significance of the differences in genotype distribution between hypertensive and normotensive subjects was examined by chi2 analysis. Neither AT1 nor AT2 gene variants were associated with human essential hypertension in the Japanese subjects. However, the AT1 receptor gene polymorphism was associated with left ventricular mass index in normotensive subjects. The study results suggest that gene polymorphisms of both angiotensin II receptors are not directly involved in the increase of genetic risk for hypertension, but that the AT1 receptor gene might contribute genetically to the increase of left ventricular mass.

A novel vascular modulator, hepatocyte growth factor (HGF), as a potential index of the severity of hypertension

HGF (hepatocyte growth factor), a member of endothelium-specific growth factors, might contribute to protection and/or repair of vascular endothelial cells injured by high blood pressure (BP). If so, serum HGF level might be elevated in response to endothelial cell damage. To test this hypothesis, we measured serum levels of HGF in hypertensive and normotensive patients. Serum HGF concentration in hypertensive patients without any complication was significantly higher than normal subjects (p < 0.001). Serum HGF concentration showed a significant positive correlation with BP (p < 0.01). Interestingly, serum HGF concentration in hypertensive patients with complications was significantly higher than that in hypertensive patients without complication and normotensive subjects (p < 0.01). Of importance, hypertensive patients treated with antihypertensive drugs showed the same level of serum HGF concentration as normotensive subjects (p < 0.001). The present study demonstrated that serum concentration of HGF is significantly elevated dependent on the severity of hypertension, suggesting that HGF may be a new index of the severity of hypertension.