Abstract

Hypertension also known as high blood pressure is one of the most common non-communicable disease afflicting the adult population in the world especially in African countries. It is an important public health problem causing morbidity, mortality and cost to society. Globally, hypertension prevalence among adults aged 18 years and older was reported to affect about one billion people with an annual death of approximately 7.1 million people. The angiotensin converting enzyme (ACE) gene, the key gene in Renin-angiotensin-aldosterone system (RAAS). Studies have demonstrated that ACE Insertion (I)/Deletion (D) polymorphism is associated with hypertension while other studies show that it is not associated with the disease. This study, therefore, sought to assess the association of ACE gene polymorphism with Hypertension in Buea Municipality, South West Cameroon. Demographic data was obtain by administering a structured questionnaire. Systolic and diastolic blood pressures (SBP and DBP) were measured in different individuals, using mercury sphygmomanometer and venous blood collected by venipuncture. Genomic DNA was extracted from peripheral blood by the phenol Chloroform technique with standard buffers. Angiotensin converting enzyme (ACE) gene amplification was then carried out by PCR using predesigned primers. Microsoft Excel and SPSS version 20 was used for statistical analysis. Results from the studies shows that the SBP, DBP, FBS, Weight and BMI were all between their normal references ranges indicating that the parameters were not a risk factor of hypertension in the population. The frequency of the genotypes II and ID were 37.5% and 62 .5% in hypertensive and 40% and 60% for non-hypertensive respectively, whereas for allele frequencies of the D and I alleles were 61.5% and 38.5% for hypertensive and 62.5% and 37.5% for non-hypertensive respectively. The results of the study show that there was absence of the DD genotype with no significance difference in the genotype and allele frequency distribution between the hypertensive and non-hypertensive hence no association of ACE polymorphism with hypertension in the Buea Municipality.

1.1 Introduction

Hypertension also known as high blood pressure is one of the most common non-communicable disease afflicting the adult population in the world especially in African countries. It is an important public health problem causing morbidity, mortality and cost to society. Globally, hypertension prevalence among adults aged 18 years and older was reported to affect about one billion people with an annual death of approximately 7.1 million people. Africa records the highest prevalence at 29.6% (Ajonina et al., 2018). According to Kearney et al, 75% of death in sub-Saharan Africa (SSA) by 2020 will be attributed to hypertension. The average global prevalence of hypertension has declined slightly during the past two decades; meanwhile there is an increasing trend in the middle and low-income countries. However, about two-thirds of patients with hypertension are now living in developing countries. In Cameroon, the prevalence of hypertension spans from 5.7% in rural settings (Tabi et al., 2016) through 21.9% in semiurban (Atashili et al., 2010) to 47.5% in urban milieu (Dzudie et al., 2012) with a national average survey of 31.0% (Kingue et al., 2015). Hypertension is a well-known risk factor for various cardiovascular, peripheral vascular and renal events in our body. The cause of essential hypertension is multifactorial; genetic factors also a part of it (Watt et al., 1992). Genetic factors are responsible for about 30-60% of the familial aggregation of blood pressure and the transmission of cultural factors being responsible for the remaining (stress, diet, physical activity) (Ward, 1990). Elevated blood pressure (BP) is a precursor to excessive morbidity and premature mortality. Blood pressure is mainly regulated by Renin-angiotensin system (RAS) which also acts as a key regulator of electrolyte balance. The angiotensin converting enzyme (ACE) gene is the key gene in RAS. ACE insertion/deletion (ACE I/D) polymorphism is one of the well described polymorphism of the RAS. The ACE genotypes include the presence (I allele) or absence (D allele) of a 287 bp Alu repeat sequence in intron 16, resulting in 3 genotypes (D/D and I/I homozygote, and I/D heterozygote). Studies have demonstrated that ACE Insertion (I)/Deletion (D) polymorphism are associated with common diseases like hypertension, diabetic nephropathy, coronary heart disease and tuberculosis (Mulder et al., 2003). There are very limited studies available in Cameroonian, su bjects regarding association of ACE polymorphism with hypertension. The present study therefore aimed at exploring the association of ACE polymorphism with hypertensive patients in Buea municipality.

1.2 Rationale

Hypertension is a major health problem with high prevalence in the Africa and a leading cause of Morbidity and mortality. The angiotensin converting enzyme (ACE) gene, the key gene in Renin-angiotensin-aldosterone system (RAAS) which is mainly regulated by blood pressure and also acts as a key regulator of electrolyte balance is said to control the manifestation of hypertension. Studies have demonstrated that ACE Insertion (I)/Deletion (D) polymorphism is associated with hypertension while other studies show that it is not associated with the disease. This therefore implies that the association of this gene with hypertension is based on geographical location and ethnic groups. This study, therefore, sought to assess the association of ACE gene polymorphism with Hypertension in Buea Municipality, South West Cameroon.

1.3 Hypothesis

H1: Angiotensin converting enzymes polymorphism is associated with hypertension in individuals from the Buea Regional Hospital.

1.4 Objectives

1.4.1 General objective

To investigate the prevalence association of Angiotensin converting enzyme gene polymorphism in individuals from the Buea Regional Hospital.

1.4.2 Specific objectives

1. Identify risk factors for hypertension in Buea southwest Cameroon.
2. To determine the prevalence of Hypertension in the Buea Regional Hospital

• To identify the genotypes of Angiotensin converting enzymes responsible for Hypertension in individuals from the Buea Regional Hospital.