subject: Genetic Testing [print this page] Genetic Testing Genetic Testing
Genetic testing is when doctors look at a person's DNA (genetic information) to see if they or their children are likely to have medical problems in the future. Before doctors could test for genes that might give trouble, they had to understand what genes are and how they work. This knowledge was gained starting in the early 1950s, when the nature of the DNA molecule was first understood. By the late 1980s, devices existed that allow doctors to sequence DNA cheaply and quickly enough to make genetic testing possible. The popularity and usefulness of genetic testing grew during the 1990s. Today it is a common procedure.
Genetic testing can be classified into the following categories:
Carrier identification. Some diseases, called genetic diseases, are passed by their parents to their children. In some cases the parents may not have the disease themselves: a person must have two copies of a defective gene (DNA segment) to get the disease, and often a person has one copy. The person with one copy is called a carrier. If both parents have the defective gene, however, then the chances are high that at least some of their children will get two copies and therefore have the disease.
Prenatal diagnosis. This is when DNA taken from a developing fetus is tested, usually to see if there is mental retardation or some other severe birth defect. Parents sometimes choose abortion if the test shows that their developing fetus is likely to be born with severe mental retardation.
Newborn screening. Newborn screening is when newborn babies are tested to see if they have genetic disorders that can be better treated if treatment starts at once. Newborn screening can test for dozens of disorders, many involving the body's ability to produce certain substances that are vital to life. If caught early, sickness and death can sometimes be prevented.
Late-onset disorders. Genetic tests are also available for diseases that affect people later in life, such as heart disease, colon cancer, certain kinds of breast cancer, and some other cancers. These tests do not prove that a person is going to have a certain disease, but a positive result means that the person is more likely than other people to get that disease.
