Genetic Testing

Genetic testing involves the direct examination of the DNA molecule itself. A scientist scans a patient’s DNA sample for mutated sequences.
There are two major types of gene tests. In the first type, a researcher may design short pieces of DNA (“probes”) whose sequences are complementary to the mutated sequences. These probes will seek their complement among the base pairs of an individual’s genome. If the mutated sequence is present in the patient’s genome, the probe will bind to it and flag the mutation. In the second type, a researcher may conduct the gene test by comparing the sequence of DNA bases in a patient’s gene to disease in healthy individuals or their progeny.
Genetic testing is now used for:
• Carrier screening, or the identification of unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to manifest;
• Confirmational diagnosis of symptomatic individuals;
• Determining sex;
• Forensic/identity testing;
• Newborn screening;
• Prenatal diagnostic screening;
• Presymptomatic testing for estimating the risk of developing adult-onset cancers;
• Presymptomatic testing for predicting adult-onset disorders.
Some genetic tests are already available, although most of them are used in developed countries. The tests currently available can detect mutations associated with rare genetic disorders like cystic fibrosis, sickle cell anemia, and Huntington’s disease. Recently, tests have been developed to detect mutation for a handful of more complex conditions such as breast, ovarian, and colon cancers. However, gene tests may not detect every mutation associated with a particular condition because many are as yet undiscovered, and the ones they do detect may present different risks to different people and populations.