Genetic Predisposition Testing for Coronary Heart Disease

What Exactly is the Relationship Between Heart Disease and Genes?

Heart disease is often a family matter – there exists certain features of family history that indicate genetic heart disorder – these include: sudden cardiac death, heart failure at a young age, palpitations or abnormal rhythm at a young age, fainting or seizures and more than one relative with the same type of heart disease.

There are many different forms of heart disease. The most common cause of heart disease is narrowing or blockage of the coronary arteries, the blood vessels that supply blood to the heart itself. This is called Coronary Artery Disease (CAD) and happens slowly over time. It’s the major reason people have heart attacks.

Four chambers that sustain life

The heart is the pumping organ of the body that works tirelessly throughout life and follows the principle of “all or none law”. It classifies oxygenated blood (goes to the organs) and deoxygenated blood (goes to lungs). The heart is therefore called a vital organ. It is an evolution marvel as far as anatomy and functionality is concerned.

Cardiovascular disease

Cardiovascular diseases include a range of conditions that affect the normal functioning of the heart such as myocardial infarction (MI), acute coronary syndrome (ACS), congenital heart disease (CHD), disease of vasculature etc. Most of these diseases are heritable and are passed on from generation to generation, though the contribution of industrialisation and life-style changes cannot be ignored. Studies have confirmed that exercise and diet control can reduce the chances of developing heart disease; however only the thorough understanding of the genes and the role they play can protect a large section of population from this menace.

Heart disease can and is preventable. Our diets plays a very important role along side our genes. There are many charities and organisations that are here to help people in South Africa, providing all the assistance they need. For more information why not visit the Heart and Stroke Disease Foundation of South Africa?

Defective Genes: Getting into the Heart of them

• apoE gene: APOE is responsible for the transportation of the lipids to the cells and tissues, and have high affinity binding with the LDL receptor. This polymorphic gene has three alleles ε2, ε3, and ε4 that encodes 3 isoforms of proteins E2, E3 and E4 with different functions. While E2 isoform is responsible for lower LDL levels, E4 is associated with higher LDL Levels. A 40% higher risk for development of CHD was observed in E4 carriers in a recent meta-analysis. Thus establishing a link between CHD and apoE gene.
• ABCA1 gene: Mutation of ABCA1 gene leads to an increased level of cellular cholesterol, and low HDLc levels in plasma, thereby increasing the risk of CHD several-folds. ABCA1 gene is responsible for the encoding of protein which regulates the efflux of cholesterol and other phospholipids into an apolipoprotein transporter.
• Familial defective ApoB100 gene: The defective ApoB100 gene leads to alteration in the binding capacity of LDL to LDL receptor. This leads to an increased level of LDL in plasma, thereby leading to premature atherosclerosis.
• HPA-2 Met: The variation of this gene leads to quicker clotting of the blood, sometimes even in the coronary artery. Smoking and stress are believed to intensify this process.

Hypertension and Cardiovascular disease- How they are linked through gene?

Renin-angiotensin system (RAS) is responsible for the monitoring of the blood pressure, blood flow and some significant cardiovascular functions. Polymorphism of angiotensinogen gene, M235T and angiotensin II type 1 receptor gene, A1166C, are linked with hypertension and to coronary artery disease through epistatic interaction with D/I polymorphism of angiotensin converting enzyme gene.

Indirect Genetic Predisposition

Sometimes apart from the direct link to genetic causes, there is also indirect genetic predisposition. For example, genes that predispose into unhealthy behavior, such as smoking and alcohol consumption, greatly increase the risk of cardiovascular disease (CVD). Diabetes, a known genetic disease, significantly increases the risk of the patient to develop CVD.

Managing the Menace

Prevention of cardiovascular disease at an individual level requires co-operation of body and mind. Exercise, diet control, smoking cessation and stress management are the first steps towards a healthy life for patients with CVD. A scientific approach to screening of the high-risk population through genetic assessment of high-risk groups and aggressive therapy of hypertension and diabetes, which are predisposing factors to development of CVD.