G-protein beta3 subunit variant C825T is a risk factor for hypertension in Japanese females--a prospective cohort study over 5 years

Association between G-protein β3 subunit gene and isolated systolic blood pressure elevation of greater than 130 mmHg: A large-scale cross-sectional study in the Japanese population

AIM

To investigate whether GNB3 C825T single nucleotide polymorphism (SNP) contributes to systolic blood pressure (SBP) ≥ 130 mmHg in a large-scale cross-sectional study among the Japanese population with diastolic blood pressure (DBP) < 85 mmHg.

METHODS

We analyzed 11008 Japanese subjects, including 2797 cases (SBP ≥ 130 and DBP < 85 mmHg) who were not taking anti-hypertensive medication and 8211 controls (SBP < 130 and DBP < 85 mmHg), all of whom enrolled in the genome banking project of the 21^st Century COE (Center of Excellence) Program at Jichi Medical University. Subjects were divided into four groups according to gender (male and female) and age (≤ 49 years and ≥ 50 years). GNB3 gene polymorphism was determined using the TaqMan probe method. We compared the frequencies of alleles and genotypes between cases and controls by chi-squared test. The strength of the associations was estimated by odds ratios (ORs) and 95%CI by using logistic regression analysis. The ORs were adjusted for age and body mass index.

RESULTS

Allele and genotype distributions significantly differed between cases and controls only in males aged ≤ 49 years. Compared to the CC genotype, a significant OR was obtained in the TT genotype among males aged ≤ 49 years.

CONCLUSION

This study indicates that the TT genotype of the GNB3 C825T SNP may contribute to SBP elevation of greater than 130 mmHg compared to the CC genotype in Japanese males aged ≤ 49 years.

The C825T polymorphism of the G-protein β3 subunit gene and its association with hypertension and stroke: an updated meta-analysis

OBJECTIVE

Several epidemiological studies have evaluated the association between the GNB3 C825T polymorphism and hypertension or stroke. The results of these studies were inconsistent; therefore, we performed a meta-analysis to clarify these discrepancies.

METHODS

We systematically searched the PubMed, Embase, Web of Science, CNKI, and CBM databases, and manually searched reference lists of relevant papers, meeting abstracts, and relevant journals. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for dominant, recessive, and allelic models. A fixed or random effects model was separately adopted depending on study heterogeneity. Subgroup and sensitivity analyses were performed to detect study heterogeneity and examine result stability, respectively. Publication bias was tested using funnel plots, the Egger's regression test, and Begg's test.

RESULTS

We screened 66 studies regarding hypertension and eight concerning stroke. A combined analysis showed that only the allelic model found a marginal association with hypertension (OR = 1.07, 95% CI = 1.01-1.13) and female gender (OR = 1.11, 95% CI = 0.99-1.24). However, no comparison models found an association with stroke (allelic model: OR = 1.11, 95% CI = 0.94-1.32; dominant model: OR = 1.16, 95% CI = 0.92-1.48; and recessive model: OR = 1.05, 95% CI = 0.97-1.14). Sensitivity analysis suggested that all models did not yield a relationship to hypertension or stroke among Asians. Besides, there was a lack of statistical association with hypertension in Caucasians, which maybe due to a small sample size. When we restricted the included studies to normal populations according to the Hardy-Weinberg equilibrium, no association was found.

CONCLUSIONS

There was no evidence indicating that the 825T allele or TT genotype was associated with hypertension or stroke in Asians or hypertension in Caucasians. However, further studies regarding Africans and other ethnicities are needed to identify further correlations.

A two-stage matched case-control study on multiple hypertensive candidate genes in Han Chinese

BACKGROUND

Hypertension affects about 1/3 of adults worldwide, ~3.8 million in Taiwan, 160 million in China, and 1 billion worldwide. It is a major risk factor leading to stroke, cardiovascular disease, and end-stage renal disease. In each year, more than 13.5 million deaths are due to hypertension-related diseases worldwide.

METHODS

We performed a two-stage association study of hypertension using genotype data of single-nucleotide polymorphisms (SNPs) from 992 young-onset hypertensive cases and 992 matched controls of Han Chinese in Taiwan. A total of 238 SNPs of 36 highly replicated hypertension candidate genes with functional importance were investigated. Association analysis was carried out using conditional logistic regression.

RESULTS

We identified two SNPs that were strongly associated with hypertension in both the first and the second stages. The first SNP (rs2301339) is located at guanine nucleotide-binding protein β3 subunit (GNB3) and the other one (rs17254521) is located at insulin receptor (INSR).

CONCLUSIONS

SNP rs2301339 is perfectly linked in linkage disequilibrium (LD) with C825T (rs5443) which has been associated with hypertension in Caucasian, but inconsistent in Asian populations. However, we found that in our sample this SNP has an opposite effect with the previous findings. In summary, this study identified one novel SNP in GNB3 and one novel SNP in INSR that are strongly associated with young-onset hypertension. Due to relatively small sample size, the results should still be interpreted with caution and need to be replicated in other studies.

Association between the G protein β3 subunit C825T polymorphism and the occurrence of cardiovascular disease in hypertensives: The Nord-Trøndelag Health Study (HUNT)

BACKGROUND

Several studies examining the C825T polymorphism of the G protein β3 subunit (GNB3) have shown inconsistent results regarding susceptibility to hypertension. With twice the length of earlier studies, the aim of our study was to further investigate this association with a cross-sectional design over an 11.5-year follow-up period in a Norwegian population.

METHODS

Two randomized selected population samples from the Nord-Trøndelag Health Study 1995-1997 (HUNT 2) were genotyped. One sample included individuals reporting use of antihypertensive medication (n = 969), and the other did not report use of antihypertensive medication, cardiovascular disease (CVD), or diabetes (n = 1,867). Of those genotyped, 2,254 participants (79.5%) also attended HUNT 1 in 1984-1986.

RESULTS

There was no significant higher prevalence of hypertension (blood pressure ≥140/90 mm Hg and/or antihypertensive medication) in T-allele carriers than in C allele carriers. However, TT homozygous men with treated hypertension showed statistical significant association with self-reported CVD compared to the CC genotype (odds ratio (OR) 3.19, P = 0.001). No statistical significant association between hypertension and the C825T polymorphism was found during the follow-up.

CONCLUSIONS

No association was found between the C285T polymorphism of the GNB3 and hypertension. However, CVD was more common among treated hypertensive men with the TT genotype compared to men with the CC genotype. Thus, further studies are needed to explore whether this finding could be caused by other mechanisms than elevated blood pressure.

The G-protein beta3 subunit 825 TT genotype is associated with epigastric pain syndrome-like dyspepsia

Background

Although familial clustering of functional dyspepsia (FD) has been reported, the role of genetics in the susceptibility to FD is still not well understood. Several reports indicate an association between FD and G-protein β3 (GNB3) subunit gene polymorphism (C825T); however, these studies had small sample sizes and the findings are inconclusive. In the present study we clarified the association between GNB3 gene polymorphism and dyspepsia in a large population of Japanese subjects who visited a hospital for annual health check-up.

Methods

Subjects with significant upper gastrointestinal findings were excluded. Subjects with dyspeptic symptoms were divided into either a postprandial distress syndrome (PDS) group or an epigastric pain syndrome (EPS) group according to the Rome III criteria. The presence of the GNB3 C825T polymorphism was then evaluated and logistic regression analysis was used to test all variables.

Results

The GNB3 genotype distribution in subjects without dyspepsia was 191 CC (25.1%), 368 TC (48.4%), and 202 TT (26.5%) and 17 CC (25.0%), 29 TC (42.6%), and 22 TT (32.4%) in subjects with dyspepsia. No significant correlation was found between the GNB3 825TT genotype and dyspepsia. However, the TT genotype was significantly associated with subjects with EPS-like symptoms (odds ratio (OR) = 2.00, 95% confidence interval (CI); 1.07-3.76) compared to the CT/CC genotype adjusted for gender and age. No significant correlation was found between GNB3 polymorphism and PDS-like symptoms (OR = 0.68, 95% CI; 0.31-1.51). With the exclusion of subjects with both EPS- and PDS-like symptoms, only the TT genotype was significantly associated with EPS-like symptoms (OR = 2.73, 95% CI; 1.23-5.91).

Conclusion

The homozygous GNB3 825T allele influences the susceptibility to EPS-like dyspepsia.