Association of Angiotensin Converting Enzyme Insertion/Deletion and Angiotensinogen T235 Polymorphisms with Risk of Essential Hypertension in Egyptian Patients

The effect of angiotensin converting enzyme gene insertion/deletion polymorphism on anthropometric and biochemical parameters among hypertension patients: A case-control study from Northwest Ethiopia

INTRODUCTION

The angiotensin-converting enzyme (ACE) gene polymorphism has recently been linked with altered anthropometric and biochemical parameters in hypertensive patients. However, these links are still poorly understood and there is scarce evidence on the topic. Therefore, this study aimed to assess the effect of ACE gene insertion/deletion (I/D) polymorphism on anthropometric and biochemical parameters among essential hypertension patients at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia.

MATERIALS AND METHODS

A case-control study with 64 cases and 64 controls was conducted from October 07, 2020, to June 02, 2021. The anthropometric measurements, biochemical parameters, and ACE gene polymorphism were determined using standard operating procedures, enzymatic colorimetric method, and polymerase chain reaction, respectively. A one-way analysis of variance was used to determine the association of genotypes with other study variables. P value < 0.05 was regarded as statistically significant.

RESULT

The systolic/diastolic blood pressure and blood glucose level (P-value<0.05) were significantly higher among study hypertensive patients with the DD genotype. However, anthropometric measures and lipid profiles of cases and controls were not associated with ACE gene polymorphism (P-value>0.05).

CONCLUSION

The DD genotype of the ACE gene polymorphism was found to have a significant association with high blood pressure and blood glucose levels in the study population. Advanced studies with a considerable sample size may be needed to utilize the ACE genotype as a biomarker for the early detection of hypertension-related complications.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphisms with risk of hypertension among the Ethiopian population

Introduction

Although the pathophysiological mechanism of hypertension is not fully elucidated yet, a large number of pieces of evidence have shown that genetic alterations in the renin-angiotensin-aldosterone system play a central role. However, the association of insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene with essential hypertension is controversial yet, and there is a limited number of publications among the Ethiopian population. Therefore, this study aimed to determine the association of ACE gene I/D polymorphism with the risk of hypertension among essential hypertension patients at the University of Gondar Comprehensive Specialized Hospital, Gondar, Ethiopia.

Materials and methods

A case-control study was conducted from October 07, 2020, to June 02, 2021, among hypertensive patients and normotensive control groups at the University of Gondar Comprehensive Specialized Hospital. A structured questionnaire was used to collect socio-demographic data and anthropometric measurements. Five milliliters of blood were drawn from each of the randomly selected 64 hypertensive and 64 normotensive participants for molecular test analysis. Genetic polymorphism of the ACE gene was identified using polymerase chain reaction (PCR) and electrophoresis. Data analysis was done using SPSS version 25.0 software. The strength of association between the genotype and hypertension was estimated through the calculation of adjusted odds ratio and 95% confidence intervals using logistic regression. P-value < 0.05 was considered statistically significant.

Result

The distribution of DD genotypes and D allele of the ACE gene were 48.4% and 63% in essential hypertensive patients, respectively, while it were 29.7% and 42.2% in control subjects respectively. The ACE DD genotype (p-value = 0.005) and D allele (p-value = 0.001) were more frequent among hypertensive patients as compared to controls.

Conclusion

The present study found that the DD genotype and D allele of the ACE gene has had a strong association with a high risk of hypertension in the study population.

The Association of Angiotensin-converting Enzyme I/D and Angiotensinogen M235T Polymorphism Genes with Essential Hypertension: A Meta-analysis

Objective:  Essential or primary hypertension in developing countries has become a major problem. Recent hypertension-related research has revealed susceptibility genes in genome-wide association studies. Several studies have associated angiotensin converting enzyme (ACE) I/D and angiotensinogen (AGT) M235T polymorphisms with essential hypertension, but results have been inconsistent. This meta-analysis aimed to clarify the association of AGT and ACE polymorphisms with the risk of primary hypertension. Methods: PubMed, Embase database, Medline, Goggle Scholar, Scopus.com, as well portal Garuda (www.garuda.ristekdikti.go.id) and Cochrane were used to retrieve all publications from 2006-2020 relating risk factors for hypertension with ACE I/D and AGT M235T polymorphisms. The meta-analysis was conducted from January –April 2020. All association studies were identified and data extracted from each study. Revman 5.3 software was used for meta-analysis to estimate odds ratios (OR) after extracting data and evaluating the quality of the enrolled studies. Results: A total of 27 studies (totaling 5,105 patients and 5196 controls) were identified. The overall effect suggested ACE I/D was significantly associated with primary hypertension (OR: 95%CI=1.51[1.29-1.77], p=0.004). There was no association between AGT M235T with risk of essential hypertension. Conclusion: This meta-analysis found significant association between ACE I/D gene polymorphisms with primary hypertension susceptibility. However, the AGT M235T gene had no association with the risk of primary hypertension. The Adrenoreceptor-beta/Renin Angiotensin System (ADRB/RAS) A allele should be considered a risk factor for essential hypertension.  

Hypertension in African Populations: Review and Computational Insights

Hypertension (HTN) is a persistent public health problem affecting approximately 1.3 billion individuals globally. Treatment-resistant hypertension (TRH) is defined as high blood pressure (BP) in a hypertensive patient that remains above goal despite use of ≥3 antihypertensive agents of different classes including a diuretic. Despite a plethora of treatment options available, only 31.0% of individuals have their HTN controlled. Interindividual genetic variability to drug response might explain this disappointing outcome because of genetic polymorphisms. Additionally, the poor knowledge of pathophysiological mechanisms underlying hypertensive disease and the long-term interaction of antihypertensive drugs with blood pressure control mechanisms further aggravates the problem. Furthermore, in Africa, there is a paucity of pharmacogenomic data on the treatment of resistant hypertension. Therefore, identification of genetic signals having the potential to predict the response of a drug for a given individual in an African population has been the subject of intensive investigation. In this review, we aim to systematically extract and discuss African evidence on the genetic variation, and pharmacogenomics towards the treatment of HTN. Furthermore, in silico methods are utilized to elucidate biological processes that will aid in identifying novel drug targets for the treatment of resistant hypertension in an African population. To provide an expanded view of genetic variants associated with the development of HTN, this study was performed using publicly available databases such as PubMed, Scopus, Web of Science, African Journal Online, PharmGKB searching for relevant papers between 1984 and 2020. A total of 2784 articles were reviewed, and only 42 studies were included following the inclusion criteria. Twenty studies reported associations with HTN and genes such as AGT (rs699), ACE (rs1799752), NOS3 (rs1799983), MTHFR (rs1801133), AGTR1 (rs5186), while twenty-two studies did not show any association within the African population. Thereafter, an in silico predictive approach was utilized to identify several genes including CLCNKB, CYPB11B2, SH2B2, STK9, and TBX5 which may act as potential drug targets because they are involved in pathways known to influence blood pressure. Next, co-expressed genes were identified as they are controlled by the same transcriptional regulatory program and may potentially be more effective as multiple drug targets in the treatment regimens for HTN. Genes belonging to the co-expressed gene cluster, ACE, AGT, AGTR1, AGTR2, and NOS3 as well as CSK and ADRG1 showed enrichment of G-protein-coupled receptor activity, the classical targets of drug discovery, which mediate cellular signaling processes. The latter is of importance, as the targeting of co-regulatory gene clusters will allow for the development of more effective HTN drug targets that could decrease the prevalence of both controlled and TRH.

Effects of angiotensin converting enzyme gene polymorphism on hypertension in Africa: A meta-analysis and systematic review

BACKGROUND

Hypertension is dramatically increasing in Africa with evidence of increased severity and resistance to treatment. Although angiotensin converting enzyme gene polymorphism is associated with higher prevalence of hypertension, the evidence is inconclusive on its influence on the emerging pattern in Africa. This meta-analysis is conducted to pool the available evidence to inform future research and interventions.

METHODS

Articles published through May 2018 were systematically searched in PubMed, Scopus and EMBASE databases. Studies were assessed for inclusion by two independent researchers. Six models were used to assess the effect of angiotensin converting enzyme deletion-insertion gene polymorphism. Heterogeneity and publication bias were tested and sensitivity analysis was carried out. Odds ratio and 95% confidence intervals were measured for pooled effect. Both random effect and fixed effect models were used, whilst the frequency of DD, II and DI genotypes were computed and compared.

RESULT

Patients with D allele were 1.49 times more likely to develop essential hypertension compared with patients who carry the I allele (OR:1.49; CI:1.07, 2.07). Similarly, patients who had homozygous co-dominance genotype DD (i.e., DD vs II) were at a 2.17 times higher risk of essential hypertension compared to the co-dominant genotype II (OR:2.17, CI:1.79, 3.18), dominant model (I.e., DD+ID vs II) (OR:1.48; CI:1.03, 2.12), and recessive model (OR:1.64; CI:1.03, 2.61). On subgroup analysis, participants from Sub-Saharan Africa were more genetically susceptible to hypertension compared to their North Africa counterparts. There was no publication bias found, but there was high to moderate heterogeneity.

CONCLUSION

ACE I/D polymorphism is associated with essential hypertension in Africa in the allele contrast model, as well as the dominant, recessive and homozygous codominance model. On subgroup analysis, ACE I/D was associated with essential hypertension in patients from Sub-Saharan Africa but not in North Africa. A future large scale study, which includes different ethnic groups, is recommended.

Genetic factors contributing to hypertension in African-based populations: A systematic review and meta-analysis

In a systematic review, the authors explored genetic association studies of essential hypertension in African populations. Studies reporting on the association of polymorphism(s) with hypertension in African populations were included. Appropriate studies were pooled using random effects model meta-analysis, under six potential inheritance models. In all, 46 polymorphisms in 33 genes were investigated for their association with hypertension or blood pressure levels. Meta-analysis was possible for three single nucleotide polymorphisms: rs4340, rs699, and rs5186. An association was found between rs5186, rs699, and hypertension under allele contrast and homozygous codominant models (odds ratio, 1.63 [95% confidence interval, 1.04-2.54] and 4.01 [95% confidence interval, 1.17-13.80] for rs5186, respectively; and 1.80 [95% confidence interval, 1.13-2.87] for rs699). Findings were mostly robust in sensitivity analyses. According to the systematic review, there is currently insufficient evidence on the specific polymorphisms that pose the risk of hypertension in African populations. Large-scale genetic studies are warranted to better understand susceptibility polymorphisms that may be specific to African populations.