C825T polymorphism of the GNB3 gene codifying the G-protein beta3-subunit and cardiovascular risk

Hypertension is a common disorder of multifactorial origin that constitutes a major risk factor for cardiovascular events such as stroke and myocardial infarction. The subunits of the heterotrimeric G proteins are attractive candidate gene products for both susceptibility to essential hypertension and interindividual variation in blood pressure. A polymorphism (825C/T) in exon 10 of the GNB3 gene, that encodes for the beta3 subunit, has recently been described. The 825T allele is associated with alternative splicing of the gene and formation of a truncated but functionally active beta3 subunit. Carriers of the 825T allele appear to have an increased risk for hypertension, obesity, insulin-resistance and left ventricular hypertrophy. Moreover, 825T allele carriers respond with a stronger decrease in blood pressure to therapy with a thiazide diuretic and with clonidine. GNB3 825T allele may be regarded as a potential genetic marker for a better definition of the risk profile of hypertensive subjects, but further studies are needed to precisely define the impact of T allele on the prognosis of such patients.     

温州地区汉族人群G蛋白β3亚基C825T基因多态性与肥胖的相关性研究

目的研究温州地区汉族人群G蛋白β3亚基（GNB3）C825T等位基因多态性与超重及单纯性肥胖的相关性。方法超重及单纯性肥胖组为肥胖专科门诊中随机选取161例超重或单纯性肥胖患者，并于温州市中心血站随机选取313名体重正常健康献血者为对照组，PCR-RFLP检测基因型。结果（1）温州地区汉族人群GNB3 825T等位基因频率为0．428，与其他人种的基因频率显著不同。（2）超重及单纯性肥胖组的TT基因型携带者显著增加（P〈0．01），TT／CT导致肥胖的比数比（OR值）为2．9（95％可信区间1．8-4．7，P〈0．01）；TT／CC致肥胖的OR值为2．7（95％CI 1．5—4．7，P〈0．01）；TT基因型分布按体重指数（BMI，kg／m^2）分组后，正常体重（18≤BMI〈23）、超重（23≤BMI〈25）、Ⅰ度肥胖（25≤BMI〈30）和Ⅱ度肥胖（BMI≥30）4组均显著高于低体重（BMI〈18组，P〈0．05或P〈0．01）；Ⅰ度肥胖、Ⅱ度肥胖组高于正常体重组（均P〈0．05）；Ⅱ度肥胖组高于超重组（P〈0．01）。（3）同组男女间比较GNB3 C825T基因型和T等位基因频率分布差别无统计学意义。结论GNB3 C825T等位基因频率分布存在种族差异，温州地区汉族人群GNB3 825T等位基因频率为0．428，GNB3 825T等位基因与超重及单纯性肥胖呈正相关。GNB3 825T基因型可作为早期预测单纯性肥胖的遗传学指标之一。     

GNB3基因C825T多态性与新疆和田地区维吾尔族自然长寿老人的相关性研究

目的 探讨GNB3基因C825T多态性与新疆和田地区维吾尔族老人长寿的关系.方法 采用聚合酶链反应-限制性片段长度多态法(PCR-RFLP)和直接测序法检测百岁组(年龄不小于100岁)65例和长寿组(90-99岁)100例老人GNB3基因825位点的基因型,对照组112例(年龄不超过70岁自然死亡人群)作为对照组.结果 百岁组和对照组GNB3 825C/T的基因型和等位基因频率分布差异均具有统计学意义(P=0.0021,P<0.0001).其中百岁组CC基因型的频率为60.0%,对照组为36.6%(OR 2.60;95%CI 1.39-4.89).结论 本研究初步表明,新疆和田地区维吾尔族人GNB3基因C825T多态性与个体寿命密切相关,但同时也应考虑长寿是年龄依赖的多种因素影响的结果.     

Effects of the C825T polymorphism of the GNB3 gene on body adiposity and blood pressure in fertile and menopausal women: a population-based study

OBJECTIVES: The 825T allele of the GNB3 gene is implicated in adipose distribution, predisposing to obesity and hypertension. Menopause is also considered a condition leading to excess adiposity and hypertension. The aim of the present study was to clarify whether the effects of menopause on body weight and blood pressure are influenced by the C825T polymorphism of the GNB3 gene. METHODS: The study involved 1339 subjects (43% men) aged 18-95 years, genotyped at the GNB3 825 locus, undergoing, in an epidemiological population-based frame, questionnaire, anthropometrics and blood examinations. RESULTS: Mean skinfold thickness (MST), truncal obesity and excess subcutaneous adiposity (MST greater than median) were higher in women than in men. A significant interaction was detected between menopausal status and the C825T polymorphism (Pint > 0.0001). MST, truncal obesity and excess subcutaneous adiposity were lower in CC fertile than menopausal women, but were comparable in TT fertile and menopausal women. In a multivariate logistic model for excess subcutaneous adiposity, the relative risk of menopause was 4.12 (95% confidence interval 2.35-7.22) in CC women but was insignificant in the other two genotypes. In fertile women only, higher systolic blood pressure (SBP) was detected in TT than in CC genotypes. CONCLUSION: An interaction exists between the C825T polymorphism and menopause in controlling body adiposity and blood pressure in women. Adiposity and SBP are higher in menopausal than in fertile women, provided they have the CC genotype. TT fertile women show the same adiposity as those in menopause. Men have the same excess adiposity as menopausal women, independent of the GNB3 genotype.     

GNB3基因C825T多态性与中国高血压患者服用坎地沙坦酯或坎地沙坦酯／氢氯噻嗪复方制剂降压疗效的相关性研究

目的探讨GNB3C825T基因多态性与坎地沙坦酯及复方坎地沙坦酯（坎地沙坦酯＋氢氯噻嗪）降压疗效的相关性。方法62名原发性高血压患者随机分组，分别给予坎地沙坦酯片及坎地沙坦酯＋氢氯噻嗪片治疗8周，定期随访取得血压下降数据。采用聚合酶链式反应．限制性片断长度多态性（PCR-RFLP）方法检测GNB3基因型。利用协方差分析各基因型与两药物降压疗效的关系。结果服用坎地沙坦酯／氢氯噻嗪复方的病人血压下降值明显高于单独服用坎地沙坦酯的病人血压下降值（P〈0．05）。GNB3825T等位基因在入选的高血压病人中频率为45．16％。与多数国人报道结果一致。协方差分析结果显示服用两种药后收缩压和舒张压的下降幅度在GNB3C825T各基因型高血压患者问比较均无统计学差异（P〉0．05）。结论GNB3C825T基因多态性可能与坎地沙坦酯及坎地沙坦酯＋氢氯噻嗪降压疗效不相关。     

The GNB3 C825T polymorphism and essential hypertension: a meta-analysis of 34 studies including 14,094 cases and 17,760 controls

OBJECTIVES: The C825T single nucleotide polymorphism of the G-protein beta3 (GNB3) has been implicated in susceptibility to essential hypertension, through the expression of an alternatively spliced truncated variant. In an effort to clarify earlier inconclusive results, we performed a meta-analysis of population-based case-control genetic association studies. METHODS: Random-effects methods were applied on summary data in order to combine the results of the individual studies. RESULTS: We identified in total 34 studies, including 14,094 hypertensive cases and 17,760 controls. The TT versus CC + CT contrast yielded an overall odds ratio (OR) of 1.08 [95% confidence interval (CI): 1.01, 1.15], the contrast of TT + CT versus CC, an OR of 1.17 (95% CI: 1.06, 1.29), whereas that of the T allele versus C allele yielded a non-significant OR of 1.05 (95% CI: 0.98, 1.13). There was moderate evidence for a publication bias in the latter two contrasts, which was eliminated after excluding studies not in Hardy-Weinberg equilibrium and those performed on non-normal populations (those with a diagnosis of diabetes, obesity and myocardial infarction). Subgroup analyses revealed that non-significant estimates arose from studies on Asian populations, as opposed to the Caucasian ones. Furthermore, the frequency of the T allele was lower in Caucasians and these populations were found to inhabit higher latitudes. CONCLUSIONS: The findings are in agreement with a recently proposed causal model for systolic blood pressure, which correlates it with the T allele and the absolute latitude. Further studies are needed in order to fully address questions about the aetiological mechanism of the particular association, as well as to study the effect in populations of African descent.     

乙型肝炎肝硬化肝气郁结证与5-HTTLPR重复序列、TPH A218C、GNB3 C825T基因多态性相关性分析

目的:通过分子生物学检测,分析乙型肝炎肝硬化肝气郁结证与候选基因多态性的关联。方法:将96例乙型肝炎肝硬化患者辨证分为肝气郁结证组20例、兼肝气郁结证组24例和非肝气郁结证组52例,筛选与人体情绪调节相关的基因位点五羟色胺转运体启动子区(5-HTTLPR)重复序列、色氨酸羟化酶(TPH)A218C、G蛋白β3亚单位(GNB3)C825T位点,观察其基因多态性与肝气郁结证的相关性,为肝气郁结证的基因特征研究提供依据。结果:5-HTTLPR的S等位基因或L等位基因在各组间分布差异均无显著性意义(P0.05),TPH A218C中肝气郁结证组患者CC基因型占45.00%(9/20)、C等位基因频率占67.50%(27/40),明显高于非肝气郁结证组的14.0%(7/50)和43.00%(43/100),差异有显著性意义(P0.05或0.01),而GNB3 C825T中的CC基因型和C等位基因在肝气郁结证组患者中的出现频率分别为15.00%(3/20)、42.50%(17/40),明显低于非肝气郁结证组的44.00%(22/50)和66.00%(66/100),差异有显著性意义(P0.05)。结论:TPHA218C的CC基因型、C等位基因及GNB3 C825T T等位基因可能是乙型肝炎肝硬化肝气郁结证的易感基因,TPH A218C的A等位基因及GNB3C825T的CC基因型、C等位基因可能是其保护基因;5-HTTLPR基因多态性与该证的发生可能无相关性。     

Studies of the association of the GNB3 825C>T polymorphism with components of the metabolic syndrome in white Danes

Aims/hypothesis The 825C>T polymorphism in the gene encoding the G protein β3 subunit (GNB3) causes enhanced G protein activation and increased in vitro cell proliferation. This polymorphism is also repeatedly associated with an increased risk of hypertension and has been studied in relation to obesity with divergent results. Only a few association studies have investigated whether this polymorphism is related to type 2 diabetes or the metabolic syndrome. We estimated the impact of the GNB3 825C>T polymorphism in relatively large-scale association studies of common phenotypes of the metabolic syndrome. Materials and methods The GNB3 825C>T polymorphism was genotyped in 7,518 white Danish subjects using mass spectrometry analysis of PCR products. Case–control studies were undertaken for obesity, hypertension, type 2 diabetes and the metabolic syndrome, and a meta-analysis including data from the present study and previous studies of hypertension was performed. Quantitative trait studies of metabolic variables were carried out in 4,387 glucose-tolerant subjects. Results We observed minor differences in 825C>T genotype distributions for type 2 diabetes (CC/CT/TT 49/41/10% (control) vs 46/46/9% (cases), respectively, p=0.007); however, after correction for multiple testing, these were not statistically significant. No association was found with hypertension, obesity or the metabolic syndrome. Curiously, the T allele was associated with nominally lower systolic and diastolic blood pressure levels—a finding in contrast with most previous studies–but not with other metabolic variables. Meta-analysis demonstrated a high degree of heterogeneity between study populations of different ethnic origin. Although there was a tendency towards an increased risk of hypertension among 825T allele carriers, this was not statistically significant. Conclusions/interpretation The present study suggests no major involvement of the GNB3 825C>T polymorphism in components of the metabolic syndrome.     

G蛋白β_3亚单位基因C825T多态性影响缬沙坦的降压疗效

目的探讨G蛋白β3亚单位基因C825T多态性与缬沙坦的降压疗效的关系。方法采用聚合酶链反应限制片段长度多态性方法检测147例健康人(对照组)和321例高血压病患者(高血压组)的G蛋白β3亚单位C825T多态性,其中102例高血压病患者口服缬沙坦4周。结果高血压组G蛋白β3亚单位C825T多态性中基因型频率(CC28.7%、CT 52.0%、TT 19.3%)、等位基因频率(C 54.7%、T 45.3%)与对照组基因型频率(CC 27.2%、CT 46.9%、TT25.9%)、等位基因频率(C 50.7%、T 49.3%)比较无显著性差异;缬沙坦对CT[(18.29±11.17)mm Hg,1 mm Hg=0.133 kPa]、TT[(25.63±22.68)mm Hg]、CT+TT[(19.25±13.20)mm Hg]基因型患者降低收缩压的作用强于CC基因型[(11.33±9.15)mm Hg,P<0.05];对CT[(15.03±9.35)mm Hg]、CT+TT[(14.50±9.23)mm Hg]基因型患者降低舒张压的作用强于CC基因型[(8.81±5.60)mm Hg,P<0.05]。结论G蛋白β3亚单位基因C825T多态性与缬沙坦的降压疗效相关,而与原发性高血压无关。     

GNB3 C825T polymorphism and response to interferon-alfa/ribavirin treatment in patients with hepatitis C virus genotype 1 (HCV-1) infection

BACKGROUND/AIMS: The outcome of infection with the hepatitis C virus (HCV) has been shown to be influenced by genetic host factors. The G protein beta3 subunit (GNB3) C825T polymorphism has been shown to determine immune cell functions in vitro. We investigated the association of GNB3 genotypes with treatment response in HCV-infected patients. METHODS: We genotyped 1781 HCV-free blood donors and 232 HCV-infected patients treated with interferon-alfa/ribavirin. Sustained virologic response (SVR) was defined by undetectable HCV-RNA 24 weeks after discontinuation of therapy. Non-response (NR) was defined by positive HCV-RNA at the end of at least 24 weeks of treatment. GNB3 genotypes were determined by DNA restriction enzyme analyses. RESULTS: Genotype distribution was not significantly different in healthy controls and HCV-infected patients. Only in HCV genotype 1-infected patients a significant correlation between GNB3 CC genotype and NR could be observed (6 TT, 42 TC, 54 CC) versus SVR (11 TT, 25 TC, 19 CC) patients (P = 0.004). In a logistic regression analysis including biochemical and virologic characteristics, only GNB3 CC genotype was significantly associated with NR (OR 4.9; 95% CI = 1.4-16.5; P = 0.011). CONCLUSIONS: The GNB3 825 CC genotype is associated with NR in HCV-1-infected patients.     

The human G-protein beta3 subunit C825T polymorphism is associated with coronary artery vasoconstriction.

AIMS: Abnormal coronary vasomotion plays a role in the clinical expression of coronary artery disease. We hypothesized that the functional C825T polymorphism located in the ubiquitous G-protein beta3 subunit, implicated in the cellular signal transduction of many receptors, could modify artery coronary vasomotion. We assessed the potential association of the pertussis toxin-sensitive G protein beta3 subunit (GNB3) gene C825T polymorphism on coronary vasomotion in humans. METHODS AND RESULTS: We examined the response of angiographically normal human coronary arteries (n=131) after intravenous injection of methylergonovine maleate, a vasoconstrictor, followed by injection of isosorbide dinitrate, a vasodilator, according to GNB3 genotypes. Coronary vasomotion was assessed with quantitative coronary angiography. Subjects bearing at least one T allele had greater susceptibility to vasoconstriction in response to methylergonovine maleate than CC subjects, whereas vasodilation in response to isosorbide dinitrate did not differ among the different genotypes. CONCLUSION: The C825T polymorphism of the G-protein beta3 subunit may be a genetic determinant of coronary artery vasomotion in humans.     

Interaction between GNB3 C825T and ACE I/D polymorphisms in essential hypertension in Koreans

Essential hypertension (EH) is considered a typical polygenic disease, so the evaluation of gene-gene interactions rather than the determination of single gene effects is crucial to understanding any genetic influences. The G-protein beta3-subunit (GNB3) 825T allele, associated with enhanced G-protein signalling, is a strong candidate for interactions with polymorphisms, such as insertion/deletion (I/D) polymorphism of angiotensin I-converting enzyme (ACE) gene. We investigated whether there is an association between GNB3 C825T and ACE I/D polymorphisms for the development of EH. We carried out a case-control study of 688 hypertensive and 924 normotensive subjects recruited from South Korea. The GNB3 C825T and ACE I/D genotypes were determined by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism methods, respectively. The distributions of alleles and genotypes for the GNB3 C825T and ACE I/D polymorphisms were not found to be significantly associated with hypertensive status in either males or females. Logistic regression analysis indicated that the GNB3 825T allele carriers were positively associated with EH in males (odds ratio (OR) for TT/CT, 1.459; 95% confidence interval (CI), 1.048-2.033, P=0.0255). In analysis of gene-gene interaction, we found that there was a significant interaction between the GNB3 825T and ACE D alleles (P<0.05). OR for EH was significantly higher in 825T allele carriers with ACE D allele (OR, 1.490; 95% CI, 1.117-1.987, P=0.0067). A significant interaction between the GNB3 825T and the ACE D alleles may contribute to the predisposing effect for the development of EH in Koreans.     

Lack of an Association of GNB3 C825T Polymorphism and Blood Pressure in Patients with Rheumatoid Arthritis

G-protein beta 3 subunit (GNB3) C825T (rs5443) single nucleotide polymorphism (SNP) has been implicated as a risk factor for essential hypertension in the general population. The effects of this SNP may be more prominent in subjects with endothelial dysfunction (ED). Rheumatoid arthritis (RA) is associated with ED and has a high prevalence of hypertension. Thus far, this SNP has not been studied in RA patients. We genotyped 383 RA patients and 432 controls. GNB3 C825T was identified using real-time polymerase chain reaction (PCR) and melting curve analysis. There were no differences in the frequencies of the GNB3 C825T genotype and alleles between RA and controls. Within RA patients, prevalence of hypertension did not differ across genotypes. The TT versus CC+CT contrast yielded an adjusted odds ratio (OR) of 0.92 (95% CI: 0.49 to 1.76, p = 0.813), the contrast of TT+CT versus CC an adjusted OR of 2.17 (95% CI: 0.885 to 5.30, p = 0.091), whereas that of the T allele versus C allele an adjusted OR of 1.11 (95% CI: 0.76 to 1.61, p = 0.604). Systolic and diastolic blood pressure levels were not significantly different across the three genotypic groups. No significant interaction was observed between GNB3 825C/T polymorphism and serum endothelin levels. Data from the present study suggest that the T825 variant of the G protein β3 subunit gene is unlikely to constitute major susceptibility loci for essential hypertension in Caucasian RA patients. Further larger studies are required to confirm our findings and assess the interaction of rs5443 with environmental factors.     

Interaction of the ACE D allele and the GNB3 825T allele in myocardial infarction

In polygenetic disorders, such as ischemic heart disease, the investigation of gene-gene interactions rather than determination of single gene effects is crucial to better understand the contribution of genetic factors. The 825T allele of the G-protein ss(3)-subunit gene (GNB3) associated with enhanced G-protein signaling is a candidate to interact with the angiotensin-converting enzyme (ACE) deletion/insertion (D/I) polymorphism to increase the risk for myocardial infarction (MI). The ACE D:/I variant affects the renin-angiotensin system hormones that activate G-protein-coupled receptors. Genotyping at the ACE and GNB3 loci was performed on 585 patients with coronary artery disease with (n=270) or without (n=315) previous MI. Logistic regression analysis demonstrated a significant interaction between the ACE D: allele and the GNB3 825T allele (P<0.001). The odds ratio for MI, associated with the 825T allele, was not increased in the presence of the ACE II genotype (OR 0.5; P=0.09) but was significantly higher in 825T allele carriers with the ACE DI genotype (OR 1.9; P=0.01) and further increased in individuals with the ACE DD genotype (OR 2.4; P=0.02). The highest odds ratio was found in homozygous 825T allele carriers with the ACE DD genotype (OR 7.5; P=0.006). Our data suggest a significant interaction of the GNB3 825T allele with the ACE D allele in MI. These hypothesis-generating data may justify larger prospective studies.     

Homozygous 825T Allele of the GNB3 Protein Influences the Susceptibility of Japanese to Dyspepsia

The role of genetics in the susceptibility to functional dyspepsia (FD) is not well established. Recently, two different associations were reported between FD and G-protein beta3 (GNB3) subunit gene polymorphism. We aim to clarify the association between GNB3 protein C825T polymorphism and dyspepsia in the Japanese population. Eight-nine dyspeptics and 94 nondyspeptic subjects enrolled in this study. All subjects underwent gastroscopy and patients with significant upper gastrointestinal findings were excluded. Other diseases were also excluded by face-to-face history and physical examination. GNB3 protein C825T polymorphisms were determined by polymerase chain reaction-restriction fragment-length polymorphism. H. pylori infection status was examined by histology or antibody against H. pylori. Nonsignificant correlation was found between GNB3 protein homozygous 825T and unexplained dyspepsia (OR = 1.65, 95% CI: 0.87–3.13). However, among H. pylori-negative subjects, homozygous GNB3 protein 825T significantly increased the risk of dyspepsia (16.7% versus 40.5%; CC versus TT; OR = 5.10, 95% CI: 1.21–21.43, CC versus others; OR = 3.40, 95% CI: 1.16–9.93, respectively). This significant association remained after logistic regression analysis with adjustment for sex and age (CC versus TT; OR = 5.73, 95% CI: 1.27–25.82, CC versus others; OR = 3.08, 95% CI: 1.02–9.25). No significant correlation was found between GNB3 polymorphism and any dyspeptic symptoms. Our data suggest that the homozygous 825T allele of GNB3 protein is associated with dyspepsia in the H. pylori-negative Japanese population. The role of genetics in the development of dyspepsia needs further evaluation.     

The GNB3 C825T polymorphism affects response to HCV therapy with pegylated interferon in HCV/HIV co-infected but not in HCV mono-infected patients

BACKGROUND/AIMS: Response to HCV treatment with pegylated interferon-alpha is variable but might at least in part depend on genetic host factors. The G protein beta3 unit (GNB3) C825T polymorphism has been shown to affect treatment response in HCV mono-infection. Here, we analyzed the impact of the GNB3 genotype in the context of HCV/HIV co-infection. METHODS: HIV/HCV co-infected (n=112) and HCV mono-infected patients (n=150), receiving therapy with pegylated IFN-alpha/ribavirin, were enrolled into this study. Furthermore, we analyzed 220 healthy and 92 HIV mono-infected patients. GNB3 genotype was defined and correlated with respect to treatment response. RESULTS: GNB3 genotype distribution differed significantly between HIV/HCV co-infected patients and HIV-positive/HCV-negative (p=0.0002) or healthy controls (p=0.03). Patients with a GNB3 CC genotype had significantly lower SVR rates as compared to carriers of a non-CC genotype (52% versus 77%; p=0.018). In a logistic regression analysis the GNB3 genotype and the HCV genotype were significantly associated with response to treatment (p=0.018). In contrast to HIV/HCV co-infected patients, GNB3 genotype did not affect response to treatment in HCV mono-infected patients. CONCLUSIONS: The GNB3 825 CC genotype is associated with poor SVR rates in HIV/HCV co-infected patients. This underlines the impact of genetic host factors for treatment response.     

GNB3 gene C825T and ACE gene I/D polymorphisms in essential hypertension in a Kazakh genetic isolate

The Kazakh inhabitants living in Barkol pasture of northeast China belong to a genetic isolate characterized by ethnically homogeneous and a communal pastoral lifestyle. To investigate whether the polymorphisms in the G-protein beta-3 subunit (GNB3) gene and angiotensin-converting enzyme (ACE) gene are associated with essential hypertension (EH), we carried out a case-control study of 290 hypertensive subjects and 244 normotensive (NT) controls randomly selected from Kazakh populations of Barkol. A previous medical history of diabetes and hypertension, and body mass index (BMI) was recorded. Plasma glucose, triglyceride, and cholesterol were measured. The insertion/deletion (I/D) polymorphism of the ACE gene and the C825T polymorphism of the GNB3 gene were determined by the polymerase chain reaction (PCR) technique. The distributions of genotypes and alleles for the two polymorphisms did not differ significantly between the case and control populations, and odds ratio of EH related to the ACE gene D allele and GNB3 gene T allele was not significantly different from 1.0. Logistic regression analysis shows the variation at the GNB3 and ACE did not have any statistically significant synergistic effect on blood pressure (BP). Stratification of NT and untreated hypertensives according to I/D polymorphism of ACE gene and C825T polymorphism of GNB3 gene disclosed no significant difference across genotypes with respect to BMI, glucose, triglyceride, cholesterol, systolic and diastolic BP. In conclusion, the polymorphisms in the GNB3 gene and ACE gene, solely or combined, did not confer a significantly increased risk for the development of EH in the Kazakh isolate of northeast China.