Genetics, environment, and life habits

By Noralyn Onto Dudt

The advent of Molecular Biology and the Human Genome Project has dramatically increased our understanding of the mechanisms of human disease. As the underlying molecular causes for many diseases have been elucidated, it is now clear that the mechanism of a disease is influenced by genetics, environment, and life habits.

For example, even though the causes of Parkinson disease are still a mystery, it is believed that about 15% of people may have a genetic mutation that puts them at risk. Head injuries or exposure to certain environmental toxins may play a role as well.

Similarly, research studies indicate that 15 to 20 % of those with AMD ( age-related macular degeneration) have at least one first-degree relative ( like a sibling or parent) who suffers from it.

Another example is when  people may pick up a virus or a bacteria but only a few of them  may contract a certain disease. Research shows that genetics play a role: some genes are switched off in some,  thereby preventing a pathway for the bacteria to interact with cells. In others, the gene may be missing. However,  there  are also cases where a gene (DNA) is switch on to  fight or to block an invader.

When a bacterium succeeds in invading a body, the bacterium produces a variety of toxins that simulate white blood cells ( the soldiers of the body) to produce small proteins (  cytokines) that perpetuate the inflammatory cycle. The immune system is then  tricked into responding and it can go into overdrive causing a variety of symptoms.

The environment ( air pollution, polluted water, toxic fumes, etc.) is also a factor as well as one's life habits (sedentary lifestyle, unhealthy diet, smoking, excessive workload that produces stress).  Whereas genetics cannot be prevented, the role of environment and life habits can be managed or modified. For example, current evidence suggests that exercise may reduce the risk of certain common malignancies.  It makes biological sense, since exercise reduces body fat, and obesity is an important cancer risk factor.  In addition, exercise lowers levels of insulin and various growth factors that appear to stimulate the runaway growth of cancer cells.

It is important to note that while certain vitamins can reduce risk of some type of cancer, these same vitamins may also increase the risk of another. Folic acid, a B vitamin may help reduce the risk of colon cancer at least in women, but a 2007 study found that very high doses of folic acid can increase the risk of prostate cancer in men.  Obviously, this study emphasizes that moderation is key.

In Clinical Medicine, the human genome gives important clues in understanding human diseases in terms of human biology and pathology. As a result,  medicine has been revolutionized in improving diagnosis, prognosis, treatments, and prevention.

Taking all that into account, knowing our genetic background is indeed helpful. When we have a grandparent, a parent, an uncle or an aunt who have had the same type of cancer, coronary (heart) illness, etc., we can easily assume that we maybe predisposed to that disease as well. And in recognizing that susceptibility, taking the path  to creating  our environment and changing our life habits would greatly diminish that genetic predisposition. It will not cost much but it will require some discipline: a  better environment,  a  healthier diet, a habit of daily exercise, and quitting a habit such as smoking that puts the lung and heart at risk.