Explainer: Rapid DNA technology
The introduction of “Rapid DNA” technology will revolutionize the practice of forensics.
The U.S. Federal Bureau of Investigation (FBI) is currently running a “Rapid DNA” initiative to develop commercial instruments capable of producing a CODIS-compatible DNA profile within two hours and to integrate those instruments effectively within the existing CODIS structure to search unsolved crimes while an “arrestee” is in police custody during the booking process.
Rapid DNA describes a fully automated process of developing a “CODIS Core short tandem repeat (STR)” profile from a reference sample buccal swab, a relatively non-invasive way to collect DNA samples for testing from a person’s cheek. The “swab in – profile out” process consists of automated extraction, amplification, separation, detection and allele calling, without human intervention.
CODIS is the acronym for the “Combined DNA Index System” and is the generic term used to describe the FBI’s program of support for criminal justice DNA databases as well as the software used to run these databases.
Short tandem repeat (STR) analysis is a molecular biology method used to compare specific loci (or genetic indicators) on DNA from two or more samples. A short tandem repeat is a microsatellite, consisting of a unit of two to thirteen nucleotides repeated hundreds of times in a row on the DNA strand. STR analysis measures the exact number of repeating units. This method differs from restriction fragment length polymorphism analysis (RFLP) since STR analysis does not cut the DNA with restriction enzymes. Instead, probes are attached to desired regions on the DNA, and a polymerase chain reaction (PCR) is employed to discover the lengths of the short tandem repeats.
STR analysis is a tool in forensic analysis that evaluates specific STR regions found on nuclear DNA. The polymorphic, or variable, nature of the STR regions that are analyzed for forensic testing intensifies the discrimination between one DNA profile and another. Forensic science takes advantage of the population’s variability in STR lengths, enabling scientists to distinguish one DNA sample from another. For example, the likelihood that any two individuals, except identical twins, will have the same 13-loci DNA profile can be as high as one in one billion or greater.
Several manufacturers have developed prototype instruments for Rapid DNA analysis. Most notable is the RapidHIT™ Human DNA Identification System, developed by IntegenX, which claims to be the first fully automated sample-to-answer system for STR-based human identification. The self-contained human identification system produces standardized DNA profiles from buccal swabs and other human samples in 90 minutes or less. The RapidHIT System uses PCR and capillary electrophoresis (CE) sample extraction technologies.
Following commercial availability, the FBI will work with federal, state, and local CODIS laboratories and the Scientific Working Group on DNA Analysis Methods (SWGDAM) to test, evaluate, and validate the hands-free instruments for law enforcement use.
SWGDAM is comprised of dedicated forensic scientists, from international, federal, state and local forensic DNA laboratories as well as guests representing academia and other U.S. federal agencies. These forensic scientists serve as the DNA technical leaders or Combined DNA Index System (CODIS) administrators for their laboratories, and are able to offer the perspectives of practitioners in the areas of nuclear and mitochondrial DNA technologies. The responsibilities of SWGDAM are: to recommend revisions, as necessary, to the Quality Assurance Standards for Forensic DNA Testing Laboratories and the Quality Assurance Standards for DNA Databasing Laboratories; to serve as a forum to discuss, share, and evaluate forensic biology methods, protocols, training, and research to enhance forensic biology services; and to recommend and conduct research to develop and/or validate forensic biology methods.
SWGDAM will work with relevant authorities to approve and implement new Rapid DNA technologies. However, at this time, no Rapid DNA instruments or kits have been approved by the FBI for submission of samples to NDIS/CODIS.
Further, it is not known when law enforcement agencies will be able to search profiles developed by a Rapid DNA instrument in CODIS. There are a number of issues relating to the use of Rapid DNA analysis that will need to be addressed, such as the laboratory accreditation requirements of the DNA Identification Act of 1994, as well as compliance with the FBI Director’s Quality Assurance Standards.
In addition, the FBI is working on how to integrate Rapid DNA technology first into CODIS laboratory operations and then into police booking locations. Important issues relating to the validation and certification of the Rapid DNA analysis instruments must be resolved before implementing this new technology as part of the booking process. Guidelines for the use of this technology are being developed and training will also be needed for law enforcement and laboratory personnel to use the new technology in a manner that maintains the quality and integrity of CODIS and the National DNA Index System.