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Abstract

Introduction:

Several studies show that the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been associated with hypertension in various populations. The present study sought to determine the association of the I/D gene polymorphism among Malay male essential hypertensive subjects in response to ACE inhibitors (enalapril and lisinopril).

Materials and methods:

A total of 72 patients with newly diagnosed hypertension and 72 healthy subjects were recruited in this study. Blood pressure was recorded from 0 to 24 weeks of treatment with enalapril or lisinopril. Genotyping of the I/D polymorphism was carried out using a standard PCR method.

Results:

Statistically significant association of the D allele of the ACE gene was observed between the case and control subjects (p < 0.01). There was a decrease in blood pressure in the patients carrying the DD genotype (SBP=18.5±8.1 mmHg, DBP=15.29±7.1 mmHg) rather than the ID (SBP=4.1±3.3 mmHg, DBP=9.1±3.5 mmHg) and II genotypes (SBP= 3.0±0.2 mmHg, DBP 0.11±6.1 mmHg) of the ACE gene.

Conclusion:

Patients carrying the DD genotype had higher blood pressure-lowering response when treated with ACE inhibitors enalapril or lisinopril than those carrying ID and II genotypes, suggesting that the D allele may be a possible genetic marker for essential hypertension among Malay male subjects.

Keywords

Hypertension I/D ACE polymorphism RAAS lisinopril enalapril

Introduction

High blood pressure (BP) or hypertension is the most common chronic condition, affecting 20%–30% of the adult population,¹ and it is a growing concern in Malaysia.² Most (90%–95%) hypertension is idiopathic and apparently primary or essential hypertension (EHT), and the remainder are said to be secondary hypertension that leads to renal and adrenal diseases.³ Evidence suggests that genes may contribute to 30% of the variation of BP; however, the gene-gene and gene-environment interactions are still remains unknown.^4,5 The renin-angiotensin system (RAS) regulates BP and fluid homeostasis.⁶ Angiotensin-converting enzyme (ACE) converts angiotensin I to the vasoactive angiotensin II and inactivates bradykinin. An insertion/deletion (I/D) polymorphism of the 187-bp Alu element in intron 16 of the ACE gene predicts approximately half of the inter-individual variability in serum ACE levels.⁷ Predicting the effect of a particular antihypertensive agent in an individual is a difficult task. To overcome this problem, researchers are currently considering which genes influence the response to various antihypertensive drugs.⁸ Some studies have investigated the effect of the ACE I/D polymorphism on BP response in patients with cardiovascular disease treated with ACE inhibitors (ACEIs).^9–14 Several studies have indicated that the D allele had a stronger BP-lowering effect,^15–17 while a few studies failed to show the association of I/D polymorphism in lowering the blood pressure.^18,19 The conflicting results made unclear to ability to predict whether the insertion or deletion allele of the I/D polymorphism of the ACE gene influences the response to ACEIs. Taking this into an account, we have evaluated the relationship between the I/D polymorphism of the ACE gene on the mean difference in systolic blood pressure (SBP) and diastolic blood pressure (DBP) among ACEIs in Malay male hypertensive subjects.

Material and methods

Study population

The study was conducted in conformity with the Universiti Putra Malaysia (UPM) declaration of ethical clearance from the National Medical Research Register, Malaysia (reference: NMRR-12-1062-12650). An additional approval letter was also obtained from Clinic Kesihatan Senawang, Seremaban, prior to recruiting subjects. This study was conducted in 72 EHT Malay men with a mean age of 47±11.3 years while visiting the clinic of non-communicable disease, Department of Hypertension, Seremban, Malaysia, with SBP more than 140 mmHg and/or DBP more than 90 mmHg. Subjects with a history of diabetes mellitus, renal failure, secondary form of hypertension and major infectious disease were excluded. A simple questionnaire was prepared both in Malay and English to obtain their socio-demographic and risk factors such as age and history of family disease. Informed consent was obtained from all the subjects. Each hypertensive patient received either enalapril or lisinopril (20 mg, once daily) for 24 weeks. During the follow-up period, BP was monitored once every four weeks. Following a 24-week period, 10 patients were withdrawn because they did not meet entry criteria or were no longer receiving either enalapril or lisinopril. Lipid profiles such as low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, total cholesterol (T. chl), fasting glucose (FBG) and body mass index (BMI) were measured from both groups of subjects. Seventy-two patients were assigned enalapril or lisinopril 20 mg once daily (20 mg/d). Prior to treatment initiation, all patients received advice with emphasis on lifestyle changes according to the clinical protocol including body weight control, alcohol moderation, sodium reduction, and increased consumption of fresh fruits and vegetable and low-fat dairy products.²⁰ The study also included 72 healthy volunteer controls recruited from the residents of Seremban and surrounding areas. BP was measured in all the study subjects using a sphygmomanometer at least three times at an interval of five minutes in accordance with the procedures recommended by the seventh Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VII) guidelines.²¹

Sample collection

Prior to receiving the ACEIs, 4–5 ml of blood samples of hypertensive subjects were collected from the peripheral blood leukocytes into an ethylenediaminetetraacetic acid (EDTA) tube (Becton Dickinson, NJ, USA) by a qualified phlebotomist. Plasma was separated from the blood by centrifugation method and stored at –20ºC for further analysis.

Genotyping of I/D polymorphism

Genomic DNA from peripheral blood was isolated with the QIAamp Blood DNA Mini Kit (QIAGEN, Germany). The purity of extracted DNA was checked using Biophotometer (Eppendorf, Germany). To determine the I/D polymorphism of the ACE gene, a flanking primer pair¹⁸ 5’ CTGGAGACCACTCCCATCCTTTCT-3’ and 5-GATGTGGCCATCACATTCGTC ACGAT-3’ (synthesized by Research Biolabs, Malaysia) was used to amplify the genotypes of the I/D polymorphism of the ACE gene by conventional polymerase chain reaction (PCR) technique. PCR amplification was performed with a 25 μl reaction mixture that contained 20 pmol of each primer, 0.4 mmol/l each deoxynucleotide triphosphate (dNTP), 2 mmol/l MgCl2, 1XTaq buffer and one unit of NEB Taq DNA polymerase (New England Biolabs, Beverly, MA, USA). The PCR cycling conditions were carried out on an iCycler machine (BioRad Laboratories, Hercules, CA, USA) with an initial denaturation step of five minutes at 94°C, followed by 30 cycles of denaturation at 94°C for 30 seconds, annealing at 58°C for one minute and extension at 72°C for two minutes, followed by a final extension for five minutes at 72°C before the storage of the samples at 4°C. PCR products were separated by agarose gel electrophoresis (Promega, Madison, WI, USA). DNA fragments were stained in ethidium bromide and visualized by Alpha Imager (Alpha Innotech, San Leandro, CA, USA) under ultraviolet (UV) light. The PCR fragments showed three genotypes: a 490 bp band (II), a 190 bp band (DD), and both a 490 and a 190 bp band (ID). Mistyping of ID heterozygotes as D homozygotes may occur. To increase the specificity of DD genotyping, PCR amplifications were also performed with an insertion-specific primer pair 5’-TGGGACCACAGCGCCCGCCACTAC-3’ and 5’-TCGCCAGCCCTCCCATGC CC-ATAA-3’ used in each sample that had the DD genotype.²² PCR conditions were performed with one minute of initial denaturation at 94°C, followed by 30 cycles of denaturation at 94°C for 30 seconds, annealing at 67°C for 45 seconds and extension at 72°C for two minutes. Under these conditions, the reaction showed the presence of an I allele at the 335 bp amplicon and no products in samples that were homozygous for the DD genotype. Identical results were obtained when genotyping was performed on two separate occasions.

Statistical analysis

All computations were carried out with the SPSS program, version 20. Results are expressed as mean±SD (standard deviation). Sample size was adequate for the present study determined by using standard statistical method at the ratio of 1:1 for case and control groups, at the significance level of 0.05 at power 80% on the basis of prevalence of minor alleles referred from previous studies.^23,24 Chi square (X²) goodness of fit was used to verify the agreement of observed genotype frequencies with those expected (Hardy-Weinberg equilibrium). Differences between genotype groups were tested with analysis of variance (ANOVA) using Bonferroni’s method for multiple comparisons between genotype classes. The multilinear stepwise regression was made to assess the factors responsible for the reduction of BP. P < 0.05 was considered statistically significant. Calculation of mean arterial pressure (MAP) is determined by the formula given below:

MAP = [(2 \times diastolic) + systolic] / 3

Where diastole counts twice as much as systole because two-thirds of the cardiac cycle is spent in diastole. The usual range of MAP is 70–110, and a MAP of about 60 is necessary to perfuse coronary arteries, brain and kidneys.

Results

A total of 72 hypertensive patients and 72 controls were recruited in our study. The D allele of the ACE I/D polymorphism was significantly associated with Malaysian Malay male hypertensive subjects. Our study results are well in accordance with other populations and differed from few ethnicities. Table 1 shows the list of populations with conflicting results in relation to the ACE I/D gene polymorphism. The mean age of hypertensives was 47.22±11.3 and that of normotensives was 46.92±12.7 years. Mean BMI, heart rate, different biochemical parameters and SBP and DBP of the study subjects are shown in Table 2.

Table 1.

Distribution of ACE I/D polymorphism in Asians and other populations.

Ethnicity	Allele frequency			References
	I	D	p value
Malaysian pooled	0.65	0.35	0.03^a
Malays	0.21	0.71	0.01^a
Chinese	0.63	0.37	0.04^a	Jayapalan et al., 2008²⁵
Indians	0.58	0.42	0.04^a
Malays	0.23	0.77	0.00^a	Current study
Asian Indians	0.36	0.64	0.04^a	Movvaa et al., 2007²⁶
Han Chinese	0.56	0.44	0.08^b	Ji et al., 2010²⁷
Southern China	0.32	0.68	0.03^b	Chang et al., 2007²⁸
Singaporeans	0.41	0.69	0.03^a	Jiang et al., 2009²⁹
Japanese	0.61	0.39	0.01^a	Mondry et al., 2005³⁰
Asian Indians	0.44	0.56	0.03^a	Das et al., 2009³¹
Indonesians	0.36	0.64	0.80^b	Rasyid et al., 2012³²
Europeans	0.47–0.58	0.37–0.48	0.09^b	Bleumink et al., 2005³³
Australians	0.42	0.58	0.000^a	Jones et al., 2008³⁴
Americans	0.51	0.49	0.07^a	Arnett et al., 2005¹⁴
Arabs	0.21–0.42	0.66–0.77	0.03^a	Bayoumi et al., 2006³⁵
Koreans	0.31	0.69	0.01^a	Bae et al., 2007³⁶
Mexican	0.65–0.79	0.35–0.45	0.07^b	Vargas-Alarcón et al., 2003³⁷
Indians	0.33	0.67	0.07^b	Das et al., 2008³¹
Bahraini	0.44	0.66	0.00^a	Al-Harbi et al., 2012³⁸
South Turkey	066	0.44	0.08^b	Acarturk et al., 2005³⁹

ACE: angiotensin-converting enzyme; I: insertion; D: deletion. ^ap < 0.05, ^bp > 0.05.

Table 2.

Demographic and clinical characteristics of the study population.

	Hypertensives	Normotensives	p value
Total	72	72	–
Age (years)	47.22±11.3	46.92±12.7	0.81
BMI (km/m²)	27.42 ± 2.7	21.60 ± 3.1	0.0001^a
HR (beats/min)	76.7 ± 8.1	75.8 ± 7.7	0.79
FBG (mg/dl)	92.54 ± 17.5	91.9 ± 14.3	0.75
LDL-C (mg/dl)	87.3±21.6	92.3±27.3	0.11
HDL-C (mg/dl)	42.4±6.1	38.3±6.2	0.08
TG (mg/dl)	166.1±30.3	169.9±20	0.78
TC (mg/dl)	149.8±31.9	150.2±28.4	0.81
SBP (mmHg)	152.0±13.0	120±13.3	0.0001^a
DBP (mmHg)	94.6±8.7	80.6±2.8	0.0001^a

Values in parenthesis indicate percentages. Mean ± SD for age, body mass index (BMI), systolic, heart rate (HR), fasting glucose (FBG), blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG). ^aSignificant difference at p < 0.05 from controls.

Genotypes of I/D polymorphism were determined by incubating the PCR product. The fragments were resolved on 2% agarose gel. Figure 1 shows the PCR product and gene polymorphisms. The absence/presence of a 287-bp Alu repeated sequence of I/D polymorphism represents the DD genotype (190 bp), whereas II indicates the homozygous (490 bp) and ID heterozygote genotypes (490 and 190 bp). Figure 2 shows the mistyping of ID heterozygotes of I/D polymorphism of the ACE gene.

Figure 1.

Detection of I/D polymorphism of the ACE gene in 2% agarose gel electrophoresis. Lanes 3, 7, 8 and 9 show homozygous II genotypes; lanes 1, 2, 4, 6 and 10 show heterozygous ID genotypes; lane 5 shows homozygous DD genotypes of I/D polymorphism. M represents a 100-bp DNA ladder. I: insertion; D: deletion; ACE: angiotensin-converting enzyme.

Figure 2.

Detection of mistyping of ID heterozygotes in 2% agarose gel electrophoresis. Lanes 1, 2, 4 and 5 show mistyping of ID heterozygotes as D homozygotes, which show the presence of the I allele (335 bp), whereas lanes 3, 6 and 7 show no products, which means there are confirmed homozygous DD genotypes of I/D polymorphism. M represents a 100-bp DNA ladder. I: insertion; D: deletion; ACE: angiotensin-converting enzyme.

The distribution of genotypes DD, ID and II in the controls and patients did differ significantly from that expected under Hardy-Weinberg equilibrium. In the total of 72 patients, the DD genotype was observed in 43 (59.42%), the ID genotype was observed in 25 (35.33%) and the II genotype in four (5.25%) of the case subjects. The observed genotypes in controls were 19 (26.41%) DD, 35 (49.96%) ID and 18 (23.65%) II genotypes. The allele frequencies in patients were found to be 0.77 and 0.27 for the D and I alleles, respectively, whereas 0.51 and 0.49 for D and I was observed in control subjects. We found significant associations of ACE genotypes (ID+DD) with EHT, as the observed difference in genotypes between the controls and patients was statistically significant: X² = 29.415, degree of freedom (df) = 1, p < 0.0001, odds ratio (OR) = 3.13 (1.9150–5.2868) at 95% confidence interval (CI). A statistically significant association of the D allele was observed between the case and control subjects: X² = 14.67, p = 0.00013 (Table 3). OR and relative risk adjusted for age in both genotypes and alleles. The observed changes in SBP and DBP were analyzed to determine their association with genotypes at the ACE gene locus. There was a statistically significant reduction in SBP in patients with II, ID and DD genotypes, 3±0.2 mmHg, 4.1±3.3 mmHg, 18.5±8.1 mmHg, respectively (p < 0.05) when treated with ACEI enalapril or lisinopril for 24 weeks. Similarly, there was a significant reduction in DBP genotypes, i.e. 0.11±6.1 mmHg, 9.1±3.5 mmHg and 15.29±7.1 mmHg, respectively (p = 0.06) when treated with ACEI enalapril or lisinopril. The decrease in SBP and DBP after 24 weeks of treatment of the patients carrying the DD genotype (SBP = 18.5±14.1 mmHg, DBP = 15.29±7.1 mmHg) was greater than the groups carrying ID (SBP = 4.1±3.3 mmHg, DBP = 9.1±3.5) and II genotypes (3± 0.2 mmHg, DBP = 0.11±6.1 mmHg. MAP before ACEI treatment in patients with three genotypes, i.e. DD, ID and II, were comparable (p < 0.05). In our study, the MAP in patients with DD genotypes (117.9±13.5 mmHg) was higher than the normal range of 70–110 mmHg and there was significantly greater reduction in MAP after treatment with enalapril or lisinopril as compared to patients with ID (p = 0.03) and II genotypes (p = 0.001) (Table 4). Allele frequencies of each polymorphism in the study population were in the Hardy-Weinberg equilibrium. Table 5 shows the changes of BP in response to lisinopril and enalapril drugs among I/D genotypes. Although two given BP-lowering drugs reduced MAP significantly, enalapril has a greater reduction level (II: 1.5±4.3, ID: 8.4 ± 3.7, DD: 16.4 ± 7.8) compared with lisinopril (II: 0.8± 4.3, ID: 7.5±3.5, DD: 14.2 ±13.1) (Table 5).

Table 3.

Genotypic and allelic frequencies of I/D polymorphism of the ACE gene among hypertensives and normotensives.

Genotypes	Hypertensives (HT) (%)	Normotensives (NT) (%)
DD (%)	43 (59.42%)	19 (26.41%)
ID (%)	25 (35.33%)	35 (49.96%)
II (%)	4 (5.25%)	18 (23.65%)
X ²
p value	0.0003^a
Alleles
D	111 (77.08%)	74 (51.3%)
I	33 (22.92%)	70 (48.61%)
X ²
p value	0.000^a
OR (95% CI) HT versus NT	3.18 (1.9150–5.2868)

Genotype frequencies are indicated as absolute values and percentages. Allele frequencies are indicated as fractions. I: insertion; D: deletion; ACE: angiotensin-converting enzyme; OR: odds ratio; CI: confidence interval. ^ap < 0.05 is considered to be significant.

Table 4.

Intergenotypic (I/D variant of the ACE gene) variations in systolic and diastolic blood pressure response when treated with ACE inhibitors (enalapril, lisinopril) in patients with essential hypertension.

BP (mmHg)	ACE I/D genotypes			p value
	II	ID	DD
SBPB	148.2±3.1	149.4±13.40	158.6±22	0.043^a
SBPA	145.2± 2.9	145.3±10.1	140.1±13.9	0.0002^a
SBPΔ	3± 0.2	4.1±3.3	18.5±8.1	0.0001^a
DBPB	96.21±13.2	94.7±10.9	97.6±9.2	0.05
DBPA	94.10±7.1	88.3±7.4	82.31±2.1	0.0001^a
DBPΔ	0.11±6.1	9.1±3.5	15.29±7.1	0.0001^a
MAPB	113.5±9.8	112.5±11.7	117.9±13.5	0.06
MAPA	111.1±5.7	107.3±8.3	101.6±6.0	0.0001^a
MAPΔ	2.4± 4.1	5.2± 3.4	16.3±7.5	0.0001^a
	p value
	II vs. DD		DD vs. ID	ID vs. II
SBPB	1.0		0.059	0.092
SBPA	0.019		0.0001	0.016
DBPB	0.22		1.00	0.11
DBPA	0.22		1.00	0.10
MAPB	0.012		0.72	1.0
MAPA	0.0001		0.001	0.03

I: insertion; D: deletion; ACE: angiotensin-converting enzyme; SBPA: systolic blood pressure after treatment; SBPB: systolic blood pressure before treatment; SBPΔ: average systolic blood pressure; DBPA: diastolic blood pressure after treatment; DBPB: diastolic blood pressure before treatment; DBPΔ: average diastolic blood pressure; MAPA: mean arterial pressure after treatment; MAPB: mean arterial pressure before treatment; MAPΔ: average mean arterial pressure. SBP, DBP, and MAP were compared with respect to genotypes with t-test of significance test at one degree of freedom adjusted for age. p < 0.05 is considered to be significant. ^aAnalysis of variance (ANOVA) using Bonferroni’s method for multiple comparisons between genotype classes.

Table 5.

I/D polymorphism and BP response to enalapril and lisinopril among hypertensive patients.

Enalapril					Lisinopril
BP (mmHg)	ACE I/D genotypes				ACE I/D genotypes
	II	ID	DD	p value	II	ID	DD	p value
SBPΔ	4.2± 0.3	7.1±4.2	19.7±9.2	0.0001^a	2.21±1.1	6.10±2.9	17.90±11.1	0.0001^a
DBPΔ	0.11±6.1	9.1±3.5	15.29±7.1	0.0001^a	0.13±5.92	8.13±3.8	12.94±4.6	0.0003^a
MAPΔ	1.5± 4.3	8.4± 3.7	16.4±7.8	0.0001^a	0.8±4.3	7.5±3.5	14.2±13.1	0.0001^a

I: insertion; D: deletion; BP: blood pressure; ACE: angiotensin-converting enzyme; SBPΔ: average systolic blood pressure; DBPΔ: average diastolic blood pressure; MAPΔ: average mean arterial pressure. ^ap < 0.01.

Discussion

Researchers are still investigating whether the ACE gene polymorphism helps in predicting the success of ACE inhibition among hypertensives and other complications. Taking that into an account and to the best of our knowledge, the current study is the first comprehensive report on the I/D polymorphism of the ACE gene in response to ACEIs among Malay male hypertensive subjects. Our results show that there was a significant association in carriers of genotype DD compared with the individuals with ID and II genotypes in lowering BP (p < 0.0001). Several studies have reported associations between essential hypertension and ACE (I/D) gene polymorphism such as in Taiwan,¹⁵ Turkey,⁴⁰ Malaysia⁴¹ and Chinese populations.⁴² However, studies reported the lack of association of the I/D gene polymorphism with EHT.^43,44 We have conducted this study in Malay male subjects to find an association between the I/D gene polymorphism and EHT. In our study, a co-dominant pattern of inheritance was seen in the study subjects as the genotype frequencies in both groups were all in accordance with the Hardy-Weinberg equilibrium. Results from our study have shown the distribution of I/D genotypes among patients in the order of DD>ID>II, which was similar to Malaysian⁴¹ and China⁴⁵ but quite different from the Tunisian.⁴⁶ The frequency of the D allele among controls in our study, which was 0.51, is lower than the study in the Malaysian population⁴¹ and approximately lower than in the Turkish population.⁴⁷ Multivariate logistic regression analysis (regressed for age) revealed that individuals with the D allele were at 1.8 times higher odds (3.18 (1.9150–5.2868) at 95% CI, X² = 24.415, p = 0.00013) of developing EHT. Our study showed a higher OR of 3.18 (95% CI, 1.9150–5.2868) compared to a recent meta-analysis indicated that D allele was associated with a 20% increase risk of hypertension (OR = 1.22, 95% CI, 1.10–1.29).¹¹ The relative risks for hypertension are 1.3 for subjects carrying the DD genotype and 1.28 for those having the D allele of the ACE (I/D) gene polymorphism. This study provides the normal distribution of the genotypes and alleles in I/D polymorphism among Malay male in Malaysian population and suggests that genetic factors play an important role in the etiology of hypertension among Malay male hypertensive subjects. Our study results are well in accordance with other studies.^16,17,48 ACEIs are recommended for managing cardiovascular diseases and renal diseases.^49–51 However, there is substantial variability in individual responses to these agents. For example, fewer than 50% of hypertensive patients achieve adequate BP control with ACEI monotherapy.⁵² An increasing number of studies have indicated that patients from different ethnic groups have different responses to ACEIs.⁵³ Heterogeneity in the individual BP response to ACEI therapy still represents an obstacle in the treatment of hypertension. Comparison of genotypes has shown a significant difference in the frequencies of ACE (I/D) gene polymorphisms that vary significantly by race.^15,41,47 Thus, it is possible that the ethnic diversity in genotypes contributes to the observed variability in ACEI responses among races. Arnett et al.¹⁴ reported the association of the D allele was associated with greater BP response in women patients with EHT treated with hydrochlorothiazide for four weeks. Milionis et al. found no relationship between the renin-angiotensin-aldosterone system (RAAS) gene polymorphisms and BP response to ACEIs among patients with hypertension and metabolic syndrome.⁵⁴ The inconsistency in results might be explained by the genetic and environmental heterogeneity among different ethnic groups, differences in ACE inhibitors⁵⁵ used and study sample size. The conflicting results among the various populations led us to determine the relationship between the ACE I/D gene polymorphism and BP response to an ACEIs enalapril and lisinopril in an appropriate sample size of 142 Malay male hypertensive subjects. Our study reported that the association of the D allele was associated with greater BP response in 72 newly diagnosed Malay male subjects and then treated with ACEI enalapril or lisinopril for 24 weeks. In our study, the MAP in patients with the DD genotype was higher than the normal range of 70–110 mmHg and there was significantly greater reduction in MAP after treatment with enalapril or lisinopril as compared to patients with the ID (p = 0.03) and II genotypes (p = 0.001). The present study has some limitations but, although our study sample was relatively small, the results show that the D allele has a strong association with EHT in response to ACEIs. However, further studies with larger sample sizes are recommended to confirm the association of the I/D polymorphism of the ACE gene.

Conclusion

Our study shows that individuals with the D allele of I/D polymorphism of the ACE gene were strongly associated with Malay male hypertensive subjects in blunting the BP response to ACEIs.

Footnotes

Acknowledgements

The authors gratefully like to extend their gratitude to all the volunteers participated in this study.

Conflict of interest

None declared.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

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