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Health
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Tuesday, May 13, 2008, 11:38 AM
Questions with genetic code By Dr. Dawn Brezina | Daily Times Columnist Everywhere we turn we see something about genetics and health. Genetic engineering, genetic remodeling, genetic predisposition to different illnesses, such as breast cancer or Alzheimer's Disease, in vitro fertilization. There are even genetic tests which predict if the individual is at high risk for developing drug or alcohol excess. Practically every medical specialty has carved out a piece of the "genetic club" that is specific to that particular specialty. The human genetic code was "cracked," that is, completely sequenced, in 2001. Since that time the field of genetics has exploded. In many ways, this has created more questions than answers. If a person tests "positive" for a serious medical illness, what do they do then? Does everyone who tests positive get that illness? Indiscriminant testing can result in serious difficulties. Genes carry the information of life: how tall you are, facial structure, skin color, temperament and probably a host of more subtle characteristics. Every human cell has about 25,000 genes. Some of these characteristics include tendency to develop illness, such as cancer, diabetes, blindness, alcoholism, dementia and many more. Genes are the unit of information, and they are made up of DNA; DNA is a chemical compound composed of repeating smaller units of information. One of the complicating issues with respect to genetic testing is the superimposed issue of environment: other factors have had an influence, too. The person may have the bladder cancer gene, but did they smoke? In some cases the gene will never be activated unless an additional factor (like smoking) is present. These are called multifactorial diseases. In some cases there are several genes coding for the same illness. Perhaps a person has two genes for lung cancer -- in that case, the disease may occur with or without an outside smoking. This is unifactorial disease: the genetic predisposition was sufficient to cause disease. The hope is to create treatments -- particularly for cancer -- that are genetically specific for the individual's cancer. It is hoped that this type of targeted treatment would be more effective and cause fewer side effects. Some genetically engineered treatments are currently in use. People who have serious illnesses that run in their family may want to be tested to see if they are genetic carriers of disease before they have children. Some people have a strong family history of cancer and may want to know if they are at risk. In some cases, a very high risk of cancer combined with a positive genetic test may be sufficient evidence to prompt careful surveillance and follow-up or even preemptive surgery to prevent future problems.
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