by Alicia M Prater PhD

Created on: October 04, 2007   Last Updated: January 14, 2009

Hypertension is defined as a sustained increased in arterial pressure, in other words, high blood pressure. The current guidelines place anyone with a consistent blood pressure of 140/90 or higher in the category of hypertensive, which currently includes 31% of adults over the age of 20 years in the United States according to the Centers for Disease Control and Prevention (CDC). Having family members with hypertension increases a person's risk of developing the disorder themselves.

Essential hypertension (90-95% of cases) is compatible with living a long life, it is the complications that are life threatening. Complications of chronically high blood pressure include stroke, kidney disease or renal failure, and weakening of the blood vessels in a process called arteriosclerosis, possibly resulting in an aneurysm. Prevention and treatment include reducing sodium intake, exercising for weight maintenance to reduce obesity, and the use of pharmaceutical diuretics to reduce water retention.

The contribution of genetics and environment to the development of hypertension is generally accepted to be 50/50. Environmental factors include diet, such as high sodium intake and high cholesterol; smoking; obesity; and other diseases, such as diabetes. Genetic factors include severe genetic mutations in the renin or ACE (angiotensin converting enzyme) genes or more subtle mutations that may have an effect on blood pressure regulation over the long term.

Some people are born with slight mutations in genes that are responsible for producing proteins involved with blood pressure regulation. Over time, regular increases in blood pressure due to extra proteins/receptors will weaken the system's feedback system and the individual could develop hypertension. A genetic predisposition combined with environmental contributors (high salt diet, smoking, physical trauma to the kidney) almost always results in the disease. Also affecting blood pressure is the amount of water and metabolic byproducts filtered from the blood. Thus, physical defects in the kidney, or a weakening of the renal system due to other factors, can contribute to the development of the disease as well.

There is not one single mutation or one single gene that contributes to hypertension so genetic screening is a far off possibility. There are several genes with several mutations in each that have been identified as candidates. These include precursor proteins, such as angiotensinogen; receptors, such as the angiotensin receptors; and enzymes, such as renin and ACE, which are also drug targets for treating hypertension. There is also not one single environmental factor involved in the development of the disease. Some factors influence different mutations to a greater extent. The disease is therefore referred to as being polygenic and multifactorial in research settings.

As we age, our bodies do not work as efficiently. In certain populations it is nearly impossible to find non-hypertensive (normotensive) individuals. This may be due to genetic predisposition or to common environmental factors, but is probably a combination of the two. In a general sense, as we age, our kidneys do not function as they should and, over time, blood pressure is not regulated as efficiently, resulting in a consistent increase in cardiovascular pressure, or hypertension.

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