Genetic tests use a variety of laboratory techniques to determine if a person has a genetic condition. Individuals may get tested if there is a family history of one specific disease or if they are concerned about passing on a genetic problem to their children (1). Infact, in a study published recently, doctors revealed that they can determine if a child is born of incest without testing the DNA of parents. This breakthrough was made while analyzing the DNA of disabled children to figure out which genes trigger various disabilities.

Genetic tests include techniques to examine genes or markers near the genes (1). Direct testing for diseases such as cystic fibrosis and sickle cell anemia come from an analysis of an individual's specific genes. A technique called linkage analysis, or indirect testing, is used when the gene cannot be directly identified but can be located within a specific region of a chromosome. This testing requires additional DNA from an affected family member for comparison. Genetic tests can be used for individual identification ("DNA fingerprinting"), because each person’s gene is unique, with the exception of identical twins.

Genetic testing is a complex process, and the results depend both on reliable laboratory procedures and accurate interpretation of results (1). Tests vary in sensitivity and their ability to detect mutations. Interpretation of test results is often complex even for trained physicians and other health care specialists. When interpreting the results of any genetic test, one must take into account the probability of false positive or false negative test results (1). Special training is required to analyze and convey information about genetic testing to affected individuals and their families.

Types of Genetic inheritances

Every cell within the human body contains DNA, made up of four chemicals including adenine, guanine, thymine and cytosine. Every human being inherits DNA from both his parents. Abnormalities within the inherited DNA results in genetic inheritance disorders, of which there are four types.

Monogenetic Inheritance

A single gene triggers the genetic disorder, which causes proteins within cellular structures to function improperly (2). Examples of monogenetic inheritance disorders are Huntington's disease and Marfan syndrome. Cystic fibrosis, a chronic genetic disorder that produces life-threatening lung infections also has links to monogenetic inheritance.

Complex Inheritance

Environmental influences in combination with multiple genetic mutations define disorders that result from complex genetic inheritance. High blood pressure is one example of a disorder linked to complex inheritance (2). Obesity is another prime example according to the University of Texas. While obesity does have genetic links, overeating, an environmental influence, also plays a large role, making the genetic disorder more complex.

Merits of Genetic testing

Genetic testing has potential benefits whether the results are positive or negative for a gene mutation. Test results can provide a sense of relief from uncertainty and help people make informed decisions about managing their health care (1,3). For example, a negative result can eliminate the need for unnecessary checkups and screening tests in some cases. A positive result can direct a person toward available prevention, monitoring, and treatment options (1). Some test results can also help people make decisions about having children.

Ethical Issues in Genetic Testing, Legal, and Social

Information from genetic testing can affect the lives of individuals and their families. In addition to personal and family issues, genetic disease or susceptibility may have implications for employment and insurance (1). Critical issues include privacy, informed consent, and confidentiality.

 Individuals have the right to maintain privacy. Some genetic tests are required or strongly encouraged for developing fetuses and newborn babies (1). If an infant is found to be a carrier or likely to develop or be affected by an inherited disease, these findings may affect the future employability or insurability of the individual.

To perform genetic testing, one must give consent. One must have knowledge of the risks, benefits, effectiveness, and alternatives to testing in order to understand the implications of genetic testing.

Genetic information is sensitive and access should be limited to those authorized to receive it. Future access to a person's genetic information also should be limited.

With respect to genetic testing, legislation in the U.S called the Genetic Information Nondiscrimination Act prohibits group health plans and health insurers from denying coverage to a healthy individual or charging higher premiums because of a genetic predisposition to developing a disease in the future. The legislation also prevents employers from using genetic information while making important decisions.

Shortcomings of Genetic testing

Current gene tests do not provide a convincing answer for people at risk for inherited breast or colon cancer. Shared environmental exposures could play a big role rather than inherited susceptibility. Identifying mutations remains a great challenge (3). Many of the genes contain many thousands of bases. Searching through long stretches of DNA is difficult. A positive test does not guarantee that disease is imminent and a negative test only evaluates the more common mutations and cannot completely rule it out. One person with a given gene may develop a disease, while another person remains healthy. Predictive tests deal in probabilities, not certainties. Last but not least, test information is not always supported by diagnostics and therapies.

About the Author

Born in Redwood City, California, Varun Mohan is raised in Sunnyvale, CA. He is currently a sophomore at The Harker School, who enjoys problem solving in math and science. While he is not solving problems, he reads fiction and listens to western classical music. Besides, he loves to play water polo and viola, and is part of Harker's water polo team and orchestra.

Citations

1.Human Genome Project Information[homepage on the Internet]. Washington D.C:  Human Genome Program; 2010 [Updated Sep 2010; cited 2011 Oct 29]. Available from: http://www.ornl.gov/sci/techresources/Human_Genome/medicine/genetest.shtml

2.Inheritance Patterns[homepage on the Internet]. Burlington, VT: Gene Primer; 2010[Updated Apr 2010; cited 2011 Oct 20]. Available from

http://www.uvm.edu/~cgep/Education/Inheritance2.html

3.Health and Wellness[homepage on the Internet]. Charlotte, NC. Potential Benefits; 2008[Updates Sep 2008; cited 2011 Oct 29]. Available from

http://impact-study.co.uk/public/geneticsandcancer/genetictesting/positiveandnegativeaspects