Genetic tests help diagnose hundreds of diseases

by Aimee Keenan-Greene 

How do people react when the get the results of direct-to-consumer genetic testing? 

Researchers say knowing what diseases you are at risk for did not result in any measurable short-term changes in psychological health, diet or exercise behavior, or use of screening tests.  

The National Institute of Health says genetic testing is a type of medical test that identifies changes in chromosomes, genes, or proteins. Most of the time, testing is used to find changes that are associated with inherited disorders. The results of a genetic test can confirm or rule out a suspected genetic condition or help determine a person's chance of developing or passing on a genetic disorder. Several hundred genetic tests are currently in use, and more are being developed. 

The use of direct-to-consumer genomewide profiling to assess disease risk is controversial, and little has been known about the effect of this technology on the psychological and physical behavior of consumers. 

To see how people react scientists recruited subjects from health and technology companies who elected to purchase the Navigenics Health Compass, a commercially available test of uncertain clinical validity and utility, at a discounted rate.  

Subjects were asked to report any changes in symptoms of anxiety, intake of dietary fat, and exercise behavior after testing, as compared with baseline, along with any test-related distress and the use of health-screening tests. 

From a cohort of 3639 enrolled subjects, 2037 completed follow-up.  

The result, primary analyses showed no significant differences between baseline and follow-up in anxiety symptoms (P=0.80), dietary fat intake (P=0.89), or exercise behavior (P=0.61).  

Secondary analyses revealed test-related distress was positively correlated with the average estimated lifetime risk among all the assessed conditions (β=0.117, P<0.001).  

However, 90.3 percent of subjects who completed follow-up had scores indicating no test-related distress. There was no significant increase in the rate of use of screening tests associated with genomewide profiling, most of which are not considered appropriate for screening asymptomatic persons in any case. 

The study was funded by the National Institutes of Health and Scripps Health. 

The National Human Genome Research Institute says gene tests  look for signs of a disease or disorder in DNA or RNA taken from a person's blood, other body fluids like saliva, or tissues. These tests can look for large changes, such as a gene that has a section missing or added, or small changes, such as a missing, added, or altered chemical base (subunit) within the DNA strand. Gene tests may also detect genes with too many copies, individual genes that are too active, genes that are turned off, or genes that are lost entirely.  Some tests use DNA probes. A probe is a short string of DNA with base sequence complementary to (able to bind with) the sequence of an altered gene. These probes usually have fluorescent tags attached to them. During the test, a probe looks for its complement within a person's genome. If the altered gene is found, the complementary probe binds to it, and the fluorescent label can be used to identify the presence of the alteration. 

Another type of gene test relies on DNA or RNA sequencing. This test directly compares the base-by-base sequence of DNA or RNA in a patient's sample to a normal version of the DNA or RNA sequence.  

The Genetics and Public Policy Center says genetic testing can be done at many different times in one's life. Genetic tests can be used to determine whether a person will have a certain reaction towards a drug or medication. Prenatal genetic testing of a developing fetus during pregnancy can identify an alteration linked to current or future diseases. Genetic testing of newborn babies can identify a genetic disease or condition.  

The Human Genome Project was an international research effort to determine the sequence of the human genome.  The Project was coordinated by the National Institutes of Health and the U.S. Department of Energy.  The Human Genome Project formally began in 1990 and was completed in 2003, 2 years ahead of its original schedule. The work of the Human Genome Project has allowed researchers to begin to understand the blueprint for building a person. As researchers learn more about the functions of genes and proteins, this knowledge will have a major impact in the fields of medicine, biotechnology, and the life sciences. 

Before you get tested, its important to understand what you are looking for in your family tree. A family health history is the first step to outlining your inherited risks. InheritedHealth.com is the first social network that offers a secure place to collect, store and update your family health history with other family members. The proprietary risk analysis system uses entered health information to provide each family member with a personalized view of the hereditary diseases they are more like to develop, pass down to their children, and most importantly, ways to prevent these diseases. 

By providing individuals, their families, and their doctors, with the ability to access and share this critical information, Inherited Health helps everyone in the family take a proactive step in managing their health.

Inherited Health was founded in 2008 by Lee Essner (Founder and CEO) and Jordanna Joaquina (Co-Founder and Director of Genetics).

Inherited Health is an innovative online health resource that incorporates family social networking and disease risk assessment to facilitate life-saving conversations amongst families and their doctors.