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Abstract

Introduction:

The renin-angiotensin system (RAS) has been considered to play an important role in the regulation of blood pressure. This study aimed to investigate the correlation between RAS gene polymorphisms and essential hypertension (EH) in the Chinese Yi ethnic group.

Materials and methods:

A total of 244 EH subjects and 185 normotensive individuals from the Chinese Yi ethnic group were genotyped for AGT M235T (rs699), AT1R A1166C (rs5186), ACE I/D (rs4340) and ACE G2350A (rs4343) polymorphisms by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method.

Results:

Significant differences in the allele and genotype frequency of ACE G2350A were observed between the EH cases and controls (p=0.001, 0.002). After being grouped by gender, significant differences in the allele and genotype frequency of ACE G2350A and AT1R A1166C were observed between females of the EH cases and controls (ACE G2350A: p=0.000, 0.002; AT1R A1166C: p=0.008, 0.011). After excluding the influence of multifactorial interactions, the ACE G2350A polymorphism is significantly associated with the pathogenesis of EH in the Chinese Yi ethnic group (odds ratio (OR)=1.656, 95% confidence interval (CI) 1.807–2.524, p=0.019).

Conclusions:

The RAS-related ACE G2350A polymorphism is associated with the pathogenesis of EH in the Chinese Yi ethnic group.

Keywords

Essential hypertension genetic polymorphism Chinese Yi ethnic group

Introduction

Hypertension is a common disease that affects approximately 22% of the world’s population.¹ There are hundreds of millions of hypertension patients in China currently, and the vast majority of these patients have essential hypertension (EH). The prevalence of hypertension is quite different among the various ethnic groups in China. The most recent World Health Organization reported that the prevalence of hypertension was 19.8% in Chinese adults aged 18 years and over.¹ In contrast, the prevalence of hypertension in the rural Yi ethnic group, which has a lower morbidity rate, was only 3.19%.² In addition to the differences in geographical distribution, living habits, economy and culture among different ethnic groups, the differences in genetic background may be the major factor affects the prevalence of EH. This study focused on the Yi ethnic group to provide valuable information on the genetic mechanism of EH.

The etiology of EH has attracted the attention of the researchers in recent years and nearly 150 candidate genes have been studied. Of these genes, the renin-angiotensin system (RAS) has been considered to play an important role in the regulation of blood pressure, the maintenance of salt and water balance and the remodeling of cardiovascular tissue.³ In this system, the angiotensinogen (AGT) gene, the angiotensin II type 1 receptor (AT1R) gene and the angiotensin-converting enzyme (ACE) gene are considered to be important candidate genes for EH. Previous studies found that polymorphisms in RAS genes (i.e. AGT M235T (rs699), AT1R A1166C (rs5186), ACE I/D (rs4340), and ACE G2350A (rs4343)) were associated with the pathogenesis of EH.^4–7 However, the results of the studies that investigated different populations were not consistent.^8–11

We conducted a case-control study that included 244 EH subjects and 185 normotensive individuals from the Chinese Yi ethnic group. The correlations between the RAS-related AGT M235T, AT1R A1166C, ACE I/D, ACE G2350A polymorphisms and EH were investigated comprehensively and systematically in the Chinese Yi ethnic group. The present study will help elucidate the genetic mechanism of EH and facilitate the prevention and early diagnosis of EH.

Materials and methods

Study subjects

This study was approved by the ethics committee of Kunming Medical University. All of the tested individuals gave informed consent for this survey and examinations. All subjects in the study were from the Shuanghe Yi Village, which is in Jinning County, Kunming Prefecture, Yunnan Province, China. All subjects were local Yi. Due to the backward economy and the inconvenience of communication in this region, this village has a relatively isolated population with a homogenous genetic background. The right arm blood pressure was measured three times with a mercury sphygmomanometer in a sitting position; the mean of three readings was used for the statistical analysis. Hypertension was defined as systolic blood pressure ⩾140 mm Hg or diastolic blood pressure ⩾90 mm Hg (1 mm Hg=0.133 kPa) or the use of antihypertensive medication during the previous two weeks. Subjects with secondary hypertension, diabetes, liver and kidney dysfunction, coronary heart disease, and other cardiovascular disorders were excluded. The normotensive controls had a systolic blood pressure <140 mm Hg and a diastolic blood pressure <90 mm Hg. Subjects with a history of hypertension, diabetes, or liver, kidney and heart disease were excluded from this group.

Determination indicators and methods

For all subjects, disease history was collected; meanwhile, systolic blood pressure, diastolic blood pressure, height, weight, and waist and hip circumference were measured. Also measured were the body mass index (BMI)=weight/height² (kg/m²) and the waist-hip ratio (WHR)=waist circumference (cm)/hip circumference (cm). Smoking and drinking habits of participants were surveyed. Fasting venous blood was collected from each of the tested individuals to examine liver and kidney function, total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglycerides (TG), serum uric acid (SUA) and other parameters.

Genomic DNA extraction

A volume of 2 ml of venous blood was collected from all the subjects in ethylene diamine tetraacetic acid (EDTA) tubes. Then leukapheresis was performed. After hemolysis with hypotonic solution, genomic DNA was isolated by phenol-chloroform extraction. The genomic DNA was dissolved in TE buffer (Tris-EDTA buffer) and stored at 4°C.

Polymorphism analysis

AGT M235T

The polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method was used for polymorphism analysis. For primer sequences, PCR reaction conditions, restriction enzymes and digestion conditions, please see the relevant report by Ishigami et al.¹² The PCR product was 163 bp, and two fragments of 140 bp and 23 bp were generated after restriction digestion, but only the 140 bp fragment was revealed in electrophoresis. If no mutation was present at this site, then the amplified fragment length would not change. There are two alleles for this polymorphism site: allele M (163 bp) and allele T (140 bp).

AT1R A1166C

The PCR-RFLP method was used for polymorphism analysis. For primer sequences, PCR reaction conditions, restriction enzymes and digestion conditions, please see the relevant report by Katsuya et al.¹³ The amplified PCR product was 360 bp, and two fragments of 220 bp and 140 bp were generated after restriction digestion. If no mutations were present at this site, then the amplified fragment length would not change. There are two alleles for this polymorphism site: allele A (360 bp) and allele C (140 bp and 220 bp).

ACE I/D

The PCR method was used for polymorphism analysis. For primer sequences and PCR reaction conditions, please see the relevant report by Rigat et al.¹⁴ PCR amplified fragments of two different lengths generated two alleles: allele I (insertion, 490 bp) and allele D (deletion, 190 bp).

ACE G2350A

The PCR-RFLP method was used for polymorphism analysis. For primer sequences, PCR reaction conditions, restriction enzymes and digestion conditions, please see the relevant report by Vasudevan et al.¹⁵ The amplified PCR product was 122 bp, and two fragments of 100 bp and 22 bp were generated after restriction digestion. But only the 100 bp fragment was revealed in electrophoresis. If no mutations were present at this site, the amplified fragment length would not change. There are two alleles for this polymorphism site: allele G (122 bp) and allele A (100 bp).

Statistical analysis

SHEsis software was used for the Hardy-Weinberg equilibrium test and the chi-square test of the genotype and allele frequencies.¹⁶ PLINK software was used for genotype dominant and recessive mode analysis for all four sites. SPSS16.0 software was used for the logistic regression analysis of the multifactorial interaction influence, and the odds ratio (OR) value and 95% confidence interval (CI) were calculated. Continuous variables were represented as means±standard deviation (SD). Student’s t test was used to compare measured data between groups. The χ² test was used to compare counted data between groups. PS software was used for conclusion accuracy analysis.¹⁷

Results

The present study included a total of 244 EH patients (92 males, 152 females) and 185 normotensive controls (70 males, 115 females). The average age of the EH group was 59.281±12.828 years, and the average age of the control group was 61.148±13.491 years. A comparison of the clinical and biochemical parameters is presented in Table 1. The BMI, WHR, TC, LDL-C, TG and SUA values and the smoking and alcohol consumption proportions of the EH group were significantly higher than those of the control group (p<0. 05).

Table 1.

Clinical and biochemical presentation of essential hypertension (EH) cases and controls.

Parameters	Control (n=185)	EH (n=244)	t/χ2	p
Gender (M/F)	70/115	92/152	0.001	0.978
Age (years)	59.281±12.828	61.148±13.491	1.449	0.148
BMI (kg/m²)	20.633±2.677	21.702±3.081	3.766	0.000
WHR	0.845±0.067	0.862±0.083	2.34	0.020
TC (mmol/l)	5.102±0.944	5.304±0.895	2.255	0.025
HDL-C (mmol/l)	1.542±0.356	1.476±0.343	−1.967	0.050
LDL-C (mmol/l)	2.613±0.769	2.834±0.786	2.912	0.004
TG (mmol/l)	1.227±0.734	1.587±1.221	3.55	0.000
SUA (μmol/l)	247.773±73.465	267.135±78.413	2.602	0.010
Smoking (yes/no)	66/119	116/128	6.065	0.014
Drinking (yes/no)	46/139	98/146	11.044	0.001

BMI: body mass index; HDL-C: high density lipoprotein cholesterol; LDL-C: low density lipoprotein cholesterol; TC: total cholesterol; TG: triglyceride; SUA: serum uric acid; WHR: waist-hip ratio.

Analysis revealed that the genotype distribution of the four studied polymorphisms was consistent with Hardy-Weinberg equilibrium in both the EH and control groups.

ACE G2350A polymorphism

The A allele frequencies of the EH group and the control group were 29.1% and 19.5%, respectively; the difference between these values was statistically significant (χ²=10.444, p=0.001). The AA, GA and GG genotype frequencies of the EH group and the control group were 10.7%, 36.9%, 52.5% and 5.9%, 27.0%, 67.0%, respectively; this difference also reached statistical significance (χ²=9.641, p=0.008). After being grouped by gender, the A allele frequencies among females in the EH group and the control group were 28.6% and 15.7%, respectively. The AA, GA and GG genotype frequencies were 10.5%, 36.2%, 53.3% and 3.5%, 24.3%, 72.2%, respectively. All of these differences were statistically significant (χ²=12.417, p=0.000; χ²=11.093, p=0.004). The A allele, which has a lower frequency in the population, is assumed to be a mutant gene. Under dominant mode, individuals carrying this mutation are more susceptible to EH (AA+GA vs GG, p=0.002). Under recessive mode, the difference is not significant (AA vs AG+GG). Therefore, we propose that if the A allele is associated with the pathogenesis of EH, it may function in dominant mode. In males, neither the allele frequency nor the genotype frequency of this site exhibited a significant difference between the two groups (Table 2 and Table 3).

Table 2.

Distributions of allele frequencies in essential hypertension (EH) cases and controls stratified gender wise.

SNPs	Allele	Minor allele	Minor allele control (n, %)	Minor allele EH (n, %)	OR (95% CI)	χ²	p
AT1R A1166C	A/C	C	8 (2.2%)	22 (4.5%)	0.468 (0.206–1.064)	3.433	0.064
Male			6 (4.3%)	7 (3.8%)	1.132 (0.372–3.447)	0.048	0.827
Female			2 (0.9%)	15 (4.9%)	0.169 (0.038–0.747)	7.019	0.008
AGT M235T	M/T	M	97 (26.2%)	106 (21.7%)	0.781 (0.569–1.071)	2.354	0.125
Male			33 (23.6%)	42 (22.8%)	0.959 (0.570–1.614)	0.025	0.875
Female			64 (27.8%)	64 (21.1%)	0.692 (0.464–1.031)	3.296	0.069
ACE I/D	I/D	D	133 (35.9%)	188 (38.5%)	1.117 (0.844–1.477)	0.598	0.440
Male			57 (40.7%)	69 (37.5%)	0.874 (0.557–1.371)	0.346	0.557
Female			76 (33.0%)	119 (39.1%)	1.303 (0.911–1.865)	2.103	0.147
ACE G2350A	G/A	A	72 (19.5%)	142 (29.1%)	1.699 (1.230–2.347)	10.444	0.001
Male			36 (25.7%)	55 (29.9%)	1.232 (0.752–2.017)	0.687	0.407
Female			36 (15.7%)	87 (28.6%)	2.161 (1.400–3.335)	12.417	0.000

ACE: angiotensin-converting enzyme; AGT: angiotensinogen; AT1R: angiotensin II type 1 receptor; CI: confidence interval; OR: odds ratio; SNP: single nucleotide polymorphism.

According to the principle of Bonferroni correction, p<0.013 (alpha value 0.05/4) was defined as statistically significant.

Table 3.

Statistical analysis of genotype frequencies by dominant and recessive genetic model in controls and essential hypertension (EH) cases.

SNPs	Genotype	Control (n, %)	EH (n, %)	χ²	p	Model type	p	OR	95% CI
AT1R A1166C	CC	0 (0.0%)	1 (0.4%)	3.383	0.184	Dominant (CC+AC/AA)	0.081	/	/
AT1R A1166C	AC	8 (4.3%)	20 (8.2%)			Recessive (CC/AC+AA)	N/A	/	/
	AA	177 (95.7%)	223 (91.4%)
Male	CC	0 (0.0%)	0 (0.0%)	0.050	0.823	Dominant (CC+AC/AA)	0.823	/	/
	AC	6 (8.6%)	7 (7.6%)			Recessive (CC/AC+AA)	N/A	/	/
	AA	64 (91.4%)	85 (92.4%)
Female	CC	0 (0.0%)	1 (0.7%)	6.555	0.038	Dominant (CC+AC/AA)	0.011	5.296	1.228–22.842
	AC	2 (1.7%)	13 (8.6%)			Recessive (CC/AC+AA)	N/A	/	/
	AA	113 (98.3%)	138 (90.8%)
AGT M235T	MMMTTT	13 (7.0%)71 (38.4%)101 (54.6%)	14 (5.7%)78 (32.0%)152 (62.3%)	2.581	0.275	Dominant (MM+MT/TT)Recessive (MM/MT+TT)	0.1080.586	//	//
Male	MM	2 (2.9%)	5 (5.4%)	1.191	0.551	Dominant (MM+MT/TT)	0.603	/	/
	MT	29 (41.4%)	32 (34.8%)			Recessive (MM/MT+TT)	0.682	/	/
	TT	39 (55.7%)	55 (59.8%)
Female	MM	11 (9.6%)	9 (5.9%)	3.017	0.221	Dominant (MM+MT/TT)	0.103	/	/
	MT	42 (36.5%)	46 (30.3%)			Recessive (MM/MT+TT)	0.263	/	/
	TT	62 (53.9%)	97 (63.8%)
ACE I/D	DD	30 (16.2%)	41 (16.8%)	0.949	0.622	Dominant (DD+ID/II)	0.342	/	/
	ID	73 (39.5%)	106 (43.4%)			Recessive (DD/ID+II)	0.871	/	/
	II	82 (44.3%)	97 (39.8%)
Male	DD	16 (22.9%)	14 (15.2%)	2.032	0.362	Dominant (DD+ID/II)	0.877	/	/
	ID	25 (35.7%)	41 (44.6%)			Recessive (DD/ID+II)	0.215	/	/
	II	29 (41.4%)	37 (40.2%)
Female	DD	14 (12.2%)	27 (17.8%)	2.025	0.363	Dominant (DD+ID/II)	0.279	/	/
	ID	48 (41.7%)	65 (42.8%)			Recessive (DD/ID+II)	0.210	/	/
	II	53 (46.1%)	60 (39.5%)
ACE G2350A	AA	11 (5.9%)	26 (10.7%)	9.641	0.008	Dominant (AA+GA/GG)	0.002	1.842	1.239–2.738
ACE G2350A	GA	50 (27.0%)	90 (36.9%)			Recessive (AA/GA+GG)	0.085	/	/
	GG	124 (67.0%)	128 (52.5%)
Male	AA	7 (10.0%)	10 (10.9%)	0.933	0.627	Dominant (AA+GA/GG)	0.344	/	/
	GA	22 (31.4%)	35 (38.0%)			Recessive (AA/GA+GG)	0.858	/	/
	GG	41 (58.6%)	47 (51.1%)
Female	AA	4 (3.5%)	16 (10.5%)	11.093	0.004	Dominant (AA+GA/GG)	0.002	2.274	1.355–3.815
	GA	28 (24.3%)	55 (36.2%)			Recessive (AA/GA+GG)	0.030	3.265	1.061–10.046
	GG	83 (72.2%)	81 (53.3%)

ACE: angiotensin-converting enzyme; AGT: angiotensinogen; AT1R: angiotensin II type 1 receptor; CI: confidence interval; OR: odds ratio; SNP: single nucleotide polymorphism.

According to the principle of Bonferroni correction, p<0.013 (alpha value 0.05/4) was defined as statically significant. The chi-square test revealed no significant differences, and the OR values were not calculated.

AT1R A1166C polymorphism

No significant differences in the allele frequency and genotype frequency were observed between the two groups. After being grouped by gender, however, the C allele frequency among females in the EH group was higher than that of the control group (4.9% and 0.9%, respectively). This difference was statistically significant (χ²=7.019, p=0.008). The CC, AC and AA gene frequencies of the EH group and the control group were 0.7%, 8.6%, 90.8% and 0%, 1.7%, 98.3%, respectively (χ²=6.555, p=0.038). The C allele, which has a lower frequency in the population, is assumed to be a mutant gene. Under dominant mode, individuals carrying this mutation are more susceptible to EH (CC+AC vs AA, p=0.011). Under recessive mode, this difference is not significant (CC vs AC+AA). Therefore, we suggest that if the C allele is associated with the pathogenesis of EH, it may function in dominant mode. Among females, the p value for the comparison of the genotype frequency of this site between the two groups was slightly higher than the corrected critical value (Bonferroni correction p=0.013); however, under dominant mode, the p value was smaller than this critical value. Therefore, we suggest that among Yi females, a significant difference in the genotype frequency of this site exists between the EH group and the control group. In contrast, among males, neither the allele frequency nor the genotype frequency of this site exhibited a significant difference between the two groups (Table 2 and Table 3).

AGT M235T polymorphism

No significant differences in allele frequency or genotype frequency were observed between the two groups. No significant differences in allele frequency or genotype frequency were observed between the two groups among individuals of either gender (Table 2 and Table 3).

ACE I/D polymorphism

Genetic power test

We performed a study with 488 experimental subjects and 370 control subjects. The probability of exposure among controls is 0.195. If the true probability of exposure among cases is 0.291, we will be able to reject the null hypothesis that the exposure rates for case and controls are equal with probability (power) 0.901. The Type I error probability associated with this test of this null hypothesis is 0.05. We used an uncorrected chi-squared statistic to evaluate this null hypothesis.

Multivariate logistic regression analysis

We used BMI, WHR, TC, HDL-C, LDL-C, TG, SUA, drinking, smoking and ACE G2350A (AA+GA vs GG), AT1R A1166C (CC+AC vs AA), which exhibited differences in the univariate analysis, as the independent variables and EH as the dependent variable to perform a multivariate logistic regression analysis. The results demonstrated that under the influence of multifactorial interactions, the genetic factor that had a significant impact on the pathogenesis of EH in the Yi ethnic group was the ACE G2350A polymorphism. The risk of being affected by EH for individuals with a genotype of AA/GA was 1.656 times higher than that of individuals with a genotype of GG (OR=1.656, 95% CI 1.807-2.524, p=0.019). No significant correlation was observed between the AT1R A1166C polymorphism and EH occurrence in the Yi ethnic group (OR=1.910, 95% CI 0.800-4.558, p=0.145). In addition, TG levels (OR=1.544, 95% CI 1.086-2.196, p=0.016) and drinking (OR=1.806, 95% CI 1.050-3.109, p=0.033) also impacted the occurrence of EH in the Yi ethnic group.

Discussion

ACE is an important component of the RAS because this enzyme can convert angiotensin I (Ang I) to angiotensin II (Ang II), which exhibits a strong vasoconstrictor activity.¹⁸ The G2350A (rs4343) polymorphism, which is located in an exon, is related to the plasma ACE concentration.¹⁹ ACE can increase vascular tension and increase blood pressure through Ang II.²⁰ A study of the Emirati population in 2003 demonstrated that the G2350A polymorphism could increase the risk of EH.²¹ Subsequent studies in south Indian, Malaysia and Pakistan also found that the polymorphism at this site was associated with blood pressure variability and EH.^15,22,23 Studies in the Chinese Han population demonstrated that the polymorphism at this site was not associated with EH.²⁴ To date, no reports on the correlation between the polymorphism at this site and EH are available for other Chinese ethnic groups. Our study found significant association of ACE G2350A polymorphism with EH in the Chinese Yi ethnic group and that the 2350A allele can increase the risk of EH. The present study demonstrates that the 2350A allele frequency of EH patients in the Yi ethnic group is 0.291, which is slightly higher than that of the Pakistani population (0.226)²³ and similar to those of the Indian, Malaysian and Emirati populations (0.342, 0.343, and 0.258, respectively).^9,15,21 This frequency is significantly lower than that of the Chinese Han population (0.550).²⁵

Ang II in the RAS increases blood pressure by binding to its receptor (i.e. angiotensin II receptor (ATR)). AT1R A1166C was one of the first polymorphic loci to be associated with EH.⁷ Subsequently, a large number of related studies were conducted in different populations; however, the results were inconsistent.^26–28 The results of our study demonstrated that no significant differences in the AT1R A1166C polymorphism existed between the EH group and the control group. However, after we grouped the patients by gender, among females, significant differences in both the allele frequency and the genotype frequency of this site were observed between the EH group and the control group, indicating the association of A1166C polymorphism with the occurrence of EH in Yi females. A possible explanation for this finding is that the A1166C polymorphism affects the binding between AT1R and Ang II, thereby affecting the ability of Ang II to act as a vasoconstrictor and increase blood pressure. Thus, this effect changes the risk of EH occurrence. Based on our study, the 1166C allele frequency in the Yi ethnic group is 0.045, which is similar to that of the Taiwanese population (0.038)²⁹ and lower than those of the Japanese (0.087),³⁰ Caucasian (0.398)³¹ and Ukrainian (0.513)²⁶ populations.

It is worth noting that in our results, after being grouped by gender, the ACE G2350A and AT1R A1166C polymorphisms were associated with the occurrence of EH in females but not in males. Studies in south Indian also demonstrated the existence of gender-based differences in RAS gene polymorphism.³² This difference may occur due to the regulation of RAS activity by estrogen and variations in the sensitivity of different alleles to estrogen. Clinically, the prevalence of hypertension in post-menopausal females was found to be much higher than that of pre-menopausal females; estrogen deficiency was the main reason for this difference. Estrogen can reduce the conversion of Ang I to Ang II by reducing ACE activity. Estrogen can also reduce the expression and concentration of AT1R, thereby affecting the RAS.³³ In addition, previous studies revealed the existence of gender-based differences in the regulation of pulse pressure by the RAS; in different sexes, different pathways were used by the RAS to increase or decrease blood pressure.³⁴ This finding suggests that the gender-based differences in the RAS may be related to the regulation of blood pressure and the pathogenesis of hypertension.

We mentioned above that the Yi ethnic group had a lower EH prevalence than other Chinese ethnic groups; the prevalence of EH in this group was much lower than the national average. Multivariate analysis revealed that among the four polymorphic sites studied here, only the ACE G2350A polymorphism was associated with EH occurrence in the Yi ethnic group. We speculate that the Yi ethnic group carries less pathogenic genes for EH, leading to a lower EH prevalence and the detection of a smaller proportion of positive sites in our study.

The comparison of clinical and biochemical parameters revealed significant differences in TG and SUA between the EH group and the control group, indicating that dyslipidemia and increased SUA may affect blood pressure in the Yi ethnic group to a certain degree. A number of studies demonstrated that different components of the RAS were up-regulated in hypertension and atherosclerosis patients. In addition, the accumulation of lipids in the blood vessels can enhance the expression of RAS components.³⁵ Recent studies revealed that SUA is strongly associated with blood pressure in new and recent onset essential hypertension. The UA may play a role in the pathogenesis of hypertension.³⁶ The mechanism by which SUA increases blood pressure remains unclear. High levels of SUA may activate the RAS or induce high SUA-related insulin resistance, then lead to high blood pressure.

It is noted that the sample size in our study is small, although the probability (power) of the chi-squared test is 0.901. However, we believe that the positive associations which we observed in our survey are convincing. Because the samples came from a genetic similar or genetically homogeneous population, the disease gene spectrum of hypertension may be narrow in this population. A few disease gene mutations responded for the hypertension in Yi people. So the statistical power is still high. Further surveys with a larger sample size and through the whole gene will be valuable for confirming these positive associations and finding the functional mutations which could potentially link with these positive associations.

Footnotes

Acknowledgements

The authors gratefully acknowledge all of the patients and controls who participated in this study.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by grants from the National Natural Science Foundation of China (grant no. 81160164 and 81060074); the Yunnan Applied Basic Research Projects (grant no. 2008CD117); the Yunnan Applied Basic Research Projects-Joint Special Project (grant no. 2014FZ004); and the Research Foundation of the Department of Education of Yunnan Province (grant no. 2014C038Y).

References

World Health Organization. Global status report on noncommunicable diseases 2014, http://www.who.int/nmh/publications/ncd-status-report-2014/en/ (2014, accessed 28 May 2015).

Wang

Wei

. Prevalence and risk factors of essential hypertension in Yi people in Sichuan Province China. Chin J Public Health 2010; 26: 472–473.

Kato

Sugiyama

Morita

. Angiotensinogen gene and essential hypertension in the Japanese: Extensive association study and meta-analysis on six reported studies. J Hypertens 1999; 17: 757–763.

Jeunemaitre

Soubrier

Kotelevtsev

. Molecular basis of human hypertension: Role of angiotensinogen. Cell 1992; 71: 169–180.

Caulfield

Lavender

Farrall

. Linkage of the angiotensinogen gene to essential hypertension. N Engl J Med 1994; 330: 1629–1633.

Duru

Farrow

Wang

. Frequency of a deletion polymorphism in the gene for angiotensin converting enzyme is increased in African-Americans with hypertension. Am J Hypertens 1994; 7: 759–762.

Bonnardeaux

Davies

Jeunemaitre

. Angiotensin Ⅱ type 1 receptor gene polymorphisms in human essential hypertension. Hypertension 1994; 24: 63–69.

Kooffreh

Anumudu

Duke

. Angiotensin II type 1 receptor A1166C gene polymorphism and essential hypertension in Calabar and Uyo cities, Nigeria. Indian J Hum Genet 2013; 19: 213–218.

Vamsi

Swapna

Reddy

. Risk of angiotensin-converting enzyme (ACE) gene I/D and g.2350G>A polymorphisms in causing susceptibility to essential hypertension. Asian Biomed (Res Rev News) 2012; 6: 255–264.

10.

Ashavaid

Shalia

Nair

. ACE and AT1R gene polymorphisms and hypertension in Indian population. J Clin Lab Anal 2000; 14: 230–237.

11.

Thomas

Tomlinson

Chan

. Renin-angiotensin system gene polymorphisms, blood pressure, dyslipidemia, and diabetes in Hang Kong Chinese: A significant association of the ACE insertion/deletion polymorphism with type 2 diabetes. Diabetes Care 2001; 24: 356–361.

12.

Ishigami

Umemura

Iwamoto

. Molecular variant of angiotensinogen gene is associated with coronary atherosclerosis. Circulation 1995; 91: 951–954.

13.

Katsuya

Koike

Yee

. Association of angiotensinogen gene T235 variant with increased risk of coronary heart disease. Lancet 1995; 345: 1600–1603.

14.

Rigat

Hubert

Corvol

. PCR detection of the insertion/deletion polymorphism of the human angiotensin converting enzyme gene (DCP1)(dipeptidyl carboxypeptidase 1). Nucleic Acids Res 1992; 20: 1433.

15.

Vasudevan

Ismail

Stanslas

. Association of G2350A Polymorphism of angiotensin converting enzyme gene with essential hypertension and type 2 diabetes mellitus in Malaysian subjects. J Biol Sci 2008; 8: 1045–1050.

16.

Zhang

. A partition-ligation-combination subdivision EM algorithm for haplotype inference with multiallelic markers: Update of the SHEsis (http://analysis.bio-x.cn). Cell Res 2009; 19: 519–523.

17.

Dupont

Plummer

Jr.

Power and sample size calculations for studies involving linear regression. Control Clin Trials 1998; 19: 589–601.

18.

Moore

Dicker

O’Brien

. Renin gene polymorphisms and haplotypes, blood pressure, and responses to renin-angiotensin system inhibition. Hypertension 2007; 50: 340–347.

19.

Zhu

Bouzekri

Southam

. Linkage and association analysis of angiotensin I-converting enzyme (ACE)-gene polymorphisms with ACE concentration and blood pressure. Am J Hum Genet 2001; 68: 1139–1148.

20.

Hackam

Spence

Garg

. Role of renin-angiotensin system blockade in atherosclerotic renal artery stenosis and renovascular hypertension. Hypertension 2007; 50: 998–1003.

21.

Mahmood

Saboohi

Ali

. Association of the angiotensin-converting enzyme (ACE) gene G2350A dimorphism with essential hypertension. J Hum Hypertens 2003; 17: 719–723.

22.

Singh

Jajodia

Kaur

. Renin angiotensin system gene polymorphisms in response to antihypertensive drugs and visit-to-visit blood pressure variability in essential hypertensive patients. Curr Pharmacogenomics Person Med 2014; 12: 227–235.

23.

Alvi

Hasnain

ACE I/D and G2350A polymorphisms in Pakistani hypertensive population of Punjab. Clin Exp Hypertens 2009; 31: 471–480.

24.

Pan

Zhu

Liu

. Angiotensin-converting enzyme gene 2350 G/A polymorphism is associated with left ventricular hypertrophy but not essential hypertension. Hypertens Res 2007; 30: 31–37.

25.

Niu

Hou

. Haplotype-based association of the renin angiotensin-aldosterone system genes polymorphisms with essential hypertension among Han Chinese: The Fangshan study. Hypertens 2009; 27: 1384–1391.

26.

Kaidashev

Rasin

Savchenko

. Polymorphism of the angiotensin Ⅱ type 1 receptor in patients with essential hypertension in Ukrainian population. Tsitol Genet 2005; 39: 51–55.

27.

Shahin

Irshaid

Saleh

AA.

The A(1166)C polymorphism of the AT1R gene is associated with an early onset of hypertension and high waist circumference in Jordanian males attending the Jordan University Hospital. Clin Exp Hypertens 2014; 36: 333–339.

28.

Patnaik

Pati

Swain

. Aldosterone synthase C-344T, angiotensin II type 1 receptor A1166C and 11-β hydroxysteroid dehydrogenase G534A gene polymorphisms and essential hypertension in the population of Odisha, India. J Genet 2014; 93: 799–808.

29.

Tsai

Fallin

Chiang

. Angiotensinogen gene haplotype and hypertension: Interaction with ACE gene I allele. Hypertension 2003; 41: 9–15.

30.

Sugimoto

Katsuya

Ohkubo

. Association between angiotensin II type 1 receptor gene polymorphism and essential hypertension: The Ohasama study. Hypertens Res 2004; 27: 551–556.

31.

Wang

Zee

Morris

BJ.

Association of angiotensin II type 1 receptor gene polymorphism with essential hypertension. Clin Genet 1997; 51: 31–34.

32.

Singh

Jajodia

Kaur

. Gender specific association of RAS gene polymorphism with essential hypertension – a case control study. Biomed Res Int. Epub 17 April 2014. DOI: 10.1155/2014/538053.

33.

Kuroski

Bold

ML.

Estrogen, natriuretic peptides and the renin–angiotensin system. Cardiovasc Res 1999; 41: 524–531.

34.

Hilliard

Sampson

Brown

. The “his and hers” of the renin-angiotensin system. Curr Hypertens Rep 2013; 15: 71–79.

35.

Singh

Mehta

JL.

Interactions between the renin-angiotensin system and dyslipidemia: Relevance in the therapy of hypertension and coronary heart disease. Arch Intern Med 2003; 163: 1296–1304.

36.

Anand

Padma

Prasad

. Serum uric acid in new and recent onset primary hypertension. J Pharm Bioallied Sci 2015; 7: S4–S8.

Correlation between renin-angiotensin system gene polymorphisms and essential hypertension in the Chinese Yi ethnic group

Abstract

Introduction:

Materials and methods:

Results:

Conclusions:

Keywords

Introduction

Materials and methods

Study subjects

Determination indicators and methods

Genomic DNA extraction

Polymorphism analysis

AGT M235T

AT1R A1166C

ACE I/D

ACE G2350A

Statistical analysis

Results

ACE G2350A polymorphism

AT1R A1166C polymorphism

AGT M235T polymorphism

ACE I/D polymorphism

Genetic power test

Multivariate logistic regression analysis

Discussion

Footnotes

Acknowledgements

Declaration of Conflicting Interests

Funding

References