Genetic tests use a variety of laboratory techniques to determine if a person has a genetic condition or disease or is likely to get the disease. Individuals may wish to be tested if:

1. There is a family history of one specific disease.

2. They show symptoms of a genetic disorder,

3. They are concerned about passing on a genetic problem to their children.

Genetic tests include techniques to examine genes or markers near the genes. Direct testing for diseases such as MELAS and MERRF come from an analysis of an individual's specific genes. A technique called linkage analysis, or indirect testing, is used when the gene cannot be directly identified but can be located within a specific region of a chromosome. This testing requires additional DNA from an affected family member for comparison. Because each person's DNA is unique (except for identical twins), genetic tests also can be used for individual identification (DNA fingerprinting).