Genetics

Nature vs. Nurture

The influential role of genetics on disease has often been a controversial topic. The human genome project which began in 1990 attempted to sequence all the genes in the human body. A common goal of the project included identifying genetic variants that could potentially increase the likelihood of developing disease. The many ethical issues and potential outcomes surrounding this topic stirred much debate in the media and even contributed to the making of the Hollywood movie Gattaca. The field of genetics and the many directions it can take has also played a role in agriculture. The first genetically modified food was introduced on the market in 1996. The long-term consequences of genetically modified foods are a growing concern. The introduction of foreign genes into food plants may have unexpected and negative impacts on human health. Today many products used daily are genetically modified, in particular soybean, corn, canola, rice and cotton seed oil.

Genetics can definitely play a role in health however, it is important to note the difference between genetic disorders and genetic tendencies. Genetic disorders are the result of abnormal genes, chromosomes or DNA mutations. These alterations can be present before birth, can be inherited from parents and can occur later in life. Cystic fibrosis, Tay Sach’s disease, Down’s Syndrome, Klinefelter syndrome and Turner syndrome are all examples of disorders that are present from birth. These DNA modifications inevitably have an effect on growth and development.

Certain human viruses and bacteria have the ability to alter human DNA. In order to replicate, these particular microorganisms are absorbed and reproduced inside human cells. In some cases, these foreign invaders can insert their DNA into ours. For example, the herpes virus can remain inside the cell and interfere with the cell’s normal processes long after the initial infection. The portion of the herpes viral genome that is left over can reactivate the virus later in life causing painful Shingles. In cases like these, genes have a direct impact on the presence of a disease.

Genetic tendencies, on the other hand, do not guarantee that you will acquire the disease. Many people have a family health history with a chronic disease or health condition, such as heart disease, diabetes, high blood pressure or high cholesterol. Having a family member with this condition suggests a higher risk for developing that disease, although genetics is not the only factor that needs to be considered. Lifestyle, environment, behaviour and diet all play a key role in health and disease. Genes are very susceptible to the environment. Ultraviolet light, nuclear radiation, heavy metals and certain chemicals can damage DNA. There have also been correlations made between microwaves and mobile phone use with genetic damage.

Genetic disorders are often confused with genetic tendencies. While it is true that inheritance can play a role in the risk of developing a disease, the presence of environmental and lifestyle factors contribute significantly to determining whether you will actually develop the disease in the future.

References:

  1. http://www.cdc.gov/genomics/public/index.htm
  2. http://www.geneticsofpregnancy.com/Encyclopedia/The_risk_of_transmitting_common_diseases.aspx?pid=28&cid=49
  3. http://www.csa.com/discoveryguides/gmfood/overview.php
  4. Virella, G. Microbiology and Infectious Disease. 3rd edit. Williams & Wilkins. Baltimore, Maryland, 1997.