Types of genetic tests

Predictive testing detects genetic abnormalities that increase a person's risk of developing disorders later in life. Tests for the so-called breast cancer genes, BRCA1 and BRCA2, are good examples -- they identify women who have a very high chance of getting breast and ovarian cancer.

Presymptomatic testing determines whether a person will develop a genetic disorder before any signs or symptoms appear. It is typically performed in individuals known to be at high risk for a particular genetic disease such as Huntington's.

Diagnostic testing helps confirm a diagnosis when a person is displaying signs or experiencing symptoms of a genetic disease. For example, children displaying significant developmental delays might be tested for Fragile X Syndrome.

Carrier testing determines whether an individual carries a genetic mutation that is linked to a particular disease. Although carriers remain disease-free, they can pass the gene on to their children. A child who inherits two genes -- one from each parent -- can develop the disease.

Prenatal testing helps identify genetic abnormalities before a baby is born.

-- Valerie Ulene