When Was DNA Testing Introduced?

The successes of DNA testing are often touted in the media---from resolving paternity disputes to overturning wrongful convictions. When it comes to studying its origins, however, the details are less highly publicized. Learn about the history behind what's been called "the most powerful crime-fighting tool we have at our disposal" and its evolution in both health care and forensics.

Early milestones

• Despite the first identification of the four human blood types in 1901-'02, it wasn't until the 1920s that scientists determined that blood type was genetically inherited. In the 1930s, serological tests were developed that could identify human blood by the presence of genetic material. In separate research, deoxyribonucleic acid ("DNA"), the chemical genetic building block, was first isolated in its pure state.

  By the 1950s, James Watson and Francis Crick were instrumental in "cracking" the genetic code. They revealed DNA's double-helix design and gained early insight into the significance of the sequencing of its four chemical base components.

  Further DNA testing throughout the '50s and '60s resulted in translating the DNA composition of proteins, and isolating a key DNA enzyme that could replicate DNA in a test tube. These milestones in genetic research and testing established procedural precedents that would later be used in modern DNA testing in the health and forensic sciences.

Testing for disease

• Equipped with the ability to identify the genetic traits of certain diseases, genetic DNA testing was introduced to the general population in the '60s. Newborns were genetically screened (by pricking the heel of their foot for a blood sample) for the metabolic disorder known as phenylketonuria ("PKU")---known to result in mental retardation without early treatment. PKU testing is recognized as the earliest genetic test performed nationwide. Testing for other genetically inherited diseases such as sickle cell anemia and Tay-Sachs disease began in the '70s.

Testing for justice

• The introduction of DNA testing has revolutionized the field of forensics, where scientific methods and tools are integrated for criminal and civil litigation. Dr. Alec J. Jeffreys, an English geneticist from Leicester University, developed a technique for examining the unique length variations for DNA repeat sequences in the mid-'80s. This technique made human identity tests possible when comparing a known DNA source with an unknown DNA source. Dr. Jeffreys called this technique "DNA fingerprinting" (also known as "DNA profiling" or "DNA typing").

First "fingerprints"

• In 1986, Dr. Jeffreys was asked to apply his DNA fingerprinting process to a rape-murder case in the English Midlands. A suspect had confessed to the crime and the police wanted to verify the confession with DNA evidence. After analysis, Dr. Jeffreys' DNA tests proved that the suspect did not commit the crimes. Soon thereafter, the first criminal conviction based on DNA evidence---the result of Dr. Jeffreys' innovation---was obtained for another criminal case in 1987.

Controversies

• The advantages gained by the prevalence of DNA testing in the health and forensic sciences are immeasurable. The negative consequences resulting from this technology are also substantial. They include but are not limited to the following: constitutional law violations, discrimination based on genetic history, and a lack of uniform regulation and compliance resulting in significant test inaccuracies.