In this age of healthy living, much emphasis has been placed on advocating an active lifestyle, nutritionally balanced diet, and adequate daily exercise to mitigate the risk of developing health complications. One of the major illnesses that everyone hopes to avoid is heart disease.
The human heart is a muscle that pumps blood in our body 24/7 without a break. In order to accomplish this enormous feat, the heart needs a constant supply of nutrient and oxygen. When interrupted, the heart becomes damaged, leading to heart diseases. Risk factors for heart diseases come in several forms such as smoking, fat-rich diet, and lack of physical activity. However, even when these external factors are kept relatively similar, individuals with at least one biological parent with incidence of heart disease are 40-60% more likely to develop heart complications compared to those whose parents did not suffer from heart diseases . This intriguing result suggests genetics is an important risk factor for cardiac ailment.
Genetic cause of heart diseases #1: high cholesterol
Jonathan Cornall is an active runner. He maintains a healthy lifestyle and does not fit the prototypical profile of a person who is at risk of developing heart diseases. However, one day, during his routine jog he experienced pain in the chest, which persisted, thereafter, whenever he exercised.
Troubled by this, Jonathan visited his family physician who diagnosed him with high blood pressure caused by abnormally high cholesterol. When cholesterol is present chronically at elevated levels, it blocks the flow of blood to the heart, leading to painful episodes in the chest. But why would Jonathan suffer from heart diseases when he exercises regularly, eats healthy, and never smokes?
The answer lies in his genes. It turns out that Jonathan most likely has a mutation in one of the proteins – LDLR, apoB, or PCSK9, that are crucial for the breakdown of cholesterol, to prevent its build-up in the blood . Such mutations lead to heart disease and occur in 1:5000 people. It is highly heritable because it is autosomal dominant, which means a single copy from one of the parents is sufficient to cause the disease in the offspring. Due to this unfortunate genetic mutation, Jonathan had to undergo heart bypass surgery to circumvent the obstruction of blood flow into his heart and needs to manage his blood cholesterol for the rest of his life with medications and strict diet to manage his heart disease.
Genetic cause of heart diseases #2: irregular heartbeat
Our heart’s ability to deliver oxygen and nutrient to our body parts is vital to our well-being, especially for professional athletes who require their hearts to perform at an elevated pace in the heat of competition. As a result, any little defect in an athlete’s heart poses a significant threat to their performance, career, and most importantly, life.
For example, Arian Foster, who is a top running back for Houston Texan in NFL, was unable to return to a game in 2012 because of a sudden episode of irregular heartbeat. Although this irregular heartbeat can be the result of dehydration and stress, it can also be genetically inherited and long QT syndrome is a prime example. Patients suffering from this form of irregular heartbeat have genetic mutations in their protein channel genes (KCNQ1, KCNH2, and SCN5A) that interfere with the rhythmic cues for normal heartbeat . This disruption often leads to an increased heart rate, fainting, and sudden heart attacks, particularly threatening for athletes. As these mutations correspond to 70-80% of clinical prognosis for irregular heart rates in patients, careful monitoring and intervention is needed to manage this heart condition. In some people, these symptoms may also be triggered by certain medications that affect heart rate. Patients with undiagnosed long QT syndrome may experience irregular heart beat when taking antibiotics such as Telavancin, antidepressants or other drugs.
Genetic predisposition to heart disease can be the unpleasant reality that some people have to face. However, proper genetic screening and analysis of family history can guide medical counseling and disease preventive treatment. Estimating an individual’s risk for heart disease can be used to strategize a medically detailed approach to manage the disease. For example, genetic mutations that lead to abnormally high cholesterol can be controlled by cholesterol lowering medication to maintain blood pressure and reduce incidences of blockage. In severe cases of Long QT syndrome, cardiac device implantation can be used to correct the inherited irregular heartbeat. In combination with lifestyle changes to minimize threats from environmental factors, risk of heart diseases can be controlled despite a genetic predisposition.
If you have a family history of heart disease, find out what GeneYouIn can do for you to manage your risk of developing heart diseases through our genetic tests.
- Familial transmission of coronary heart disease: a cohort study of 80,214 Swedish adoptees linked to their biological and adoptive parents. Am Heart J. 2011.
- Monogenic hypercholesterolemia: new insights in pathogenesis and treatment. J Clin Invest. 2003.
- Genetic testing in cardiovascular medicine: current landscape and future horizons. Curr Opin Cardiol. 2013.