Genetic Testing and Screening

Current research from the human genome project has identified numerous genes that are responsible for genetic disorders impacting society. This knowledge provides us with opportunities to test children and adults to predetermine genetic disorders/diseases and make educated decisions about options available. The U.S. Congress' Office of Technology Assessment (OTA) defines genetic testing as "the use of specific assays to determine the genetic status of individuals already suspected to be at high risk for a particular inherited condition." In contrast, genetic screening is defined as the systematic search of populations for persons with latent, early, or asymptomatic disease and is distinguished from genetic testing by its target population (McCarrick, 1997).

The impact that this information could have on society is overwhelming. Once genetically at-risk individuals are identified, they could enter special prevention programs that would provide treatments and information to improve their quality of life (Eng, 1997). A stumbling block in advancing genetic screening technology and implementation is that the majority of inherited diseases are caused by mutations scattered along the length of their respected genes. This has created a challenge for researchers to develop methods that look at a 'big picture' instead of focusing on only one area.

Technical Aspects

Applying this technology is the new challenge facing society. Tests have been developed for numerous disorders and their evaluation is critical to their effectiveness. An evaluation of any screening test depends on three factors, specifically the prior probability of having the condition, the sensitivity of the test, and the specificity of the test (Warmuth, et al. 1997).

Prenatal Testing

Genetic screening and testing have found increasing usage in prenatal care. The tests are performed on pregnant women to provide information on the health of the fetus. In the case that an actual fetal disability is revealed, the mother is confronted with an array of complex decisions, such as to continue the pregnancy and prepare for the birth, fetal surgery or organ donation, or to end the pregnancy with an abortion. There has also been discussion into testing parents who participate in an in vitro fertilization program and are at genetic risk. Testing of preimplanted embryos might ensure that only embryos free of genetic diseases or problems be placed into the uterus.

The majority of prenatal tests involve obtaining a sample of either amnionic fluid, chorion, fetal blood or mother's blood. Not all techniques are invasive though and one example is fetal ultrasound (sonography). This technique is composed of ultilizing sound waves by placement of a transducer, either on the woman's abdomen or inserted vaginally, to obtain a picture of the fetus on a television-like screen.