Unravelling the Secrets of Genetic Testing

Genetic testing is a powerful tool used to uncover the secrets of our DNA. It can be used to diagnose genetic disorders, identify inherited diseases, and even detect predispositions to certain conditions. Polymerase chain reaction (PCR) is a common technique for making numerous copies of short sections of DNA from a very small sample of genetic material. Doctors order exome and genome sequencing for people with complex medical histories.

Large-scale genomic testing is also used in research to learn more about the genetic causes of conditions. Large-scale genetic testing can yield results unrelated to the reason the test was requested in the first place (secondary findings). Some examples of secondary findings are genes associated with a predisposition to cancer or rare heart disease when looking for a genetic diagnosis that would explain a child's developmental disabilities. With respect to genetic testing and information in general, United States legislation called the Genetic Information Non-Discrimination Act prohibits group health plans and health insurers from denying coverage to a healthy person or charging higher premiums based solely on a genetic predisposition to develop a disease in the future.

Both the American Academy of Pediatrics (AAP) and the American College of Medical Genetics and Genomics (ACMG) advise against the use of direct-to-consumer genetics and in household kits because of the accuracy, interpretation and monitoring of the content of the tests. Direct-to-consumer genetic testing (DTC) (also called in-home genetic testing) is a type of genetic test that the consumer can access directly without having to go to a health professional. The physical risks associated with most genetic tests are very small, especially where only a blood sample or a buccal swab (a procedure in which samples of cells are taken from the inner surface of the cheek) is required. The first forms of genetic testing, which began in the 1950s, consisted of counting the number of chromosomes per cell.

A genetics professional can explain in detail the benefits, risks, and limitations of a particular test. Genetic testing can also include measuring the results of genetic changes, such as analyzing RNA as a result of gene expression, or through biochemical analysis to measure the production of specific proteins. Abnormalities in these substances may indicate that there are changes in the DNA that underlie a genetic disorder. In general, there are three categories of genetic tests available: cytogenetic tests, biochemical tests, and molecular tests to detect abnormalities in chromosomal structure, protein function, and DNA sequence, respectively. Many of the risks associated with genetic testing have to do with the emotional, social, or financial consequences of test results.

Genetic testing is done with a sample of blood, hair, skin, amniotic fluid (the fluid that surrounds the fetus during pregnancy), or other tissue. Many biochemical genetic diseases are known as “congenital errors of metabolism”, since they are present from birth and alter a key metabolic pathway. The Genetic Testing Registry is available at the National Center for Biotechnology and Information of the National Library of Medicine. Encourage patients and their families to share information and even offer them help to explain the results, to family members, or to refer them to genetic counseling. Some possible future ethical issues related to genetic testing were considered in the sci-fi film Gattaca, the novel Next and the sci-fi anime series Mobile Suit Gundam Seed.