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Genetic Testing Definition
Genetic Testing – methods and procedures to determine the presence of a genetic disorder. The KARYOTYPE, which uses microphotographs to examine and depict an individual’s chromosomes, is one of the more common methods of genetic testing. Other methods include cytogenic analysis, AMNIOCENTESIS, and CHORIONIC VILLI SAMPLING (CVS). Some genetic testing methods are highly sophisticated and require specialized equipment and knowledge available only in research centers. Other methods, such as CVS, have become fairly commonplace.
Diagnostic genetic testing can identify the cause of symptoms resulting from GENEmutations and CHROMOSOMAL DISORDERS. This knowledge can be helpful when there are treatments and treatment choices for the resulting conditions, and in FAMILY PLANNING decisions. The matter of genetic testing to screen for the presence of GENETIC DISORDERS, particularly in people who do not have symptoms or apparent increased risk for conditions of genetic origin, remains an issue of intense ethical debate. Some such practices, such as testing for PHENYLKETONURIA (PKU) in newborns, have become standard in the United States. Others, such as those for the so-called CANCER genes (BRCA-1, BRCA-2, CA-125, and others), often raise more questions than answers because the consequence of having such genes remains uncertain.
Even when the outcome is certain, the knowledge of the genetic disorder may have little therapeutic value yet create distress for the individual. This is currently a significant issue with genetic testing for HUNTINGTON’S DISEASE, for example, a fatal neurodegenerative disorder for which there is no treatment or cure. People who carry the gene MUTATION for Huntington’s disease are certain to develop the disease in midlife. GENETIC COUNSELING is almost always a valuable and necessary component of genetic testing.