Gene Testing and the Human Genome Project

2 http://www.ornl.gov/hgmis/medicine/genetest.html

What is gene testing? How does it work? Gene tests (also called DNA-based tests), the newest and most sophi- sticated of the techniques used to test for genetic disorders, involve direct examination of the DNA mole-cule itself. Other genetic tests include biochemical tests for such gene products as enzymes and other proteins and for microscopic examination of stained or fluores-cent chromosomes.

Genetic tests are used for several reasons, including: 1. carrier screening, which involves identifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to be expressed; 2. prenatal diagnostic testing; 3. newborn screening; 4. presymptomatic testing for predicting adult-onset disorders such as Huntington's disease; 5. presymptomatic testing for estimating the risk of developing adult-onset cancers and Alzheimer's disease; 6. confirmational diagnosis of a symptomatic individual; and 7. forensic/identity testing.