Expert Systems

Expert Systems

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Expert systems are designed to provide laboratories with a tool for expediting data interpretation, which is currently performed solely by the DNA analyst. Expert systems have been developed to streamline this process, limiting the analyst’s involvement.

Accredited laboratories and National DNA Index System (NDIS) participants must use approved expert systems as outlined in the FBI’s National DNA Index System DNA Data Acceptance Standards Operation Procedures and comply with Standard 12 of the Quality Assurance Standards.22

Click here to read the definition of expert systems in the FBI's "NDIS DNA Data Acceptance Standards Operation Procedures"

Expert systems are software programs that have user-defined rules, which can serve as a quality check of the data including:

Peak height, shape and area assessment 23
Control assessment
Ladder assessment
Threshold
Heterozygosity
Percent contribution for mixtures

Two of the first programs used for automated genotyping in the forensic community are STRess^® (Forensic Science Service) and TrueAllele^® (Cybergenetics). Forensic Science Services has developed a software suite, of which STRess is one component.

Expert Systems Comparison
Manufacturer	Software Program	Features
Applied Biosystems	GeneMapper^® ID	Uses a method referred to as Process Component-Based Quality Values (PQVs) to establish criteria for evaluating data and assigning genotypes24,25 Can only be used on data generated from Applied Biosystems platforms Does not require data optimization
Forensic Science Service^®	FSS-i³(Available through the Promega corportation)	Performs data optimization and assesses the quality of the data26 Consists of three software programs Can analyze and interpret single source DNA profiles, resolve two person DNA mixtures and check batches of data for potential contamination.
Cybergenetics	TrueAllele^®	Performs data optimization and assesses the quality of the data

Prior to using the software, some manufacturers perform an optimization process using the laboratory’s output data. The optimization process is an effort to "train" the software and verify its use for that laboratory.27

Other software programs have been developed but are not commercially available at this time. Additionally, the National Institute of Health (Bethesda, MD) has designed a software program called OSIRIS. Some of the work of OSIRIS was initiated during the tragic events of September 11, 2001.

Many of these expert systems have captured the needs of the forensic community and will help in reducing the backlog by reducing the amount of analyst evaluation time. They have been designed to evaluate the data in much the same manner as a human analyst, but remove subjectivity.

The National Institute of Justice’s Expert Systems Testbed Project, or NEST Project, was introduced in June 2005. An Implementation Team and the Project Team Advisors convened in Washington, DC in May 2005 to determine the focus and direction of the NEST Project.

Click here to read more about the NEST Project at htt://www.forensics.marshall.edu.

The primary goal of the NEST Project is to conduct a thorough evaluation of the commercially available software programs and report the results back to the forensic community to help in each laboratory’s informed decision in its choice of software to purchase. The goal of this project is to document the purchasing process for each of the individual software packages, the vendor optimization of the analysis parameters, the customer service and training provided by the vendors, and the utility of the software.28

Expert systems will have the most utility for single source interpretation and offender sample processing, but have also been designed for mixed DNA samples.29 As with any new technology implemented by the forensic science community, the software will require validation by the individual user laboratories.

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