Sample Tracking Programs

Managing large amounts of data becomes a problem for many laboratories as they scale up their efforts. Computer databases are often developed to aid in tracking samples and results obtained. Sample tubes can be bar-coded and tracked through the analysis process. An example of efforts in this area is the Overlord System developed at the Forensic Science Service (FSS; Hopwood et al. 1997). The FSS Overlord program is a laboratory information management system (LIMS) and aids sample tracking as well as overall control of the different robotic stations. LIMS systems are rather expensive and are typically used only by laboratories with very high sample volumes.

Commercial LIMS systems, such as the Crime Fighter B.E.A.S.T. (computerized Bar-coded Evidence Analysis, Statistics, and Tracking LIMS) from Porter Lee Corporation (Schaumburg, IL), are being used in a growing number of forensic laboratories to provide electronic case files and automated sample tracking capabilities. A LIMS manufacturer typically sets up their software and customizes it to accommodate protocols and processes within each customer laboratory.

The Armed Forces DNA Identification Laboratory (AFDIL, Rockville, MD) has worked in conjunction with Future Technologies Inc. (Fairfax, VA) to develop LISA, which stands for Laboratory Information Systems Applications. LISA contains a number of sub-systems that permit case accessioning and the ability to electronically track the life cycle of each evidence and reference sample. There are additional modules such as MFIMS (Mass Fatality Incident Management System) and ASAP (AFDIL Statistical Application Program) that manage victim and family reference data as well as easing the tedious process of reporting results.

STaCS™ (Sample Tracking and Control System) is a system co-developed by forensic DNA scientists at the Royal Canadian Mounted Police (RCMP) and Anjura Technology Corporation (Ottawa, Ontario) that integrates robotic sample processing with custom LIMS software. STaCS monitors instrument performance and can provide a variety of operational information reports to help make the process of DNA typing more efficient. This system has been set-up in several DNA databasing laboratories including the Florida Department of Law Enforcement (Tallahassee, FL) and the FBI Laboratory (Quantico, VA).

Fully integrated systems with robotic liquid handling are especially useful for DNA databasing of convicted offender samples, which are usually more uniform in nature (i.e., are all bloodstains or buccal swabs), single-source samples, and relatively concentrated in amount. In one laboratory, over 17 000 DNA samples were processed in a 20 month period using robotics and LIMS with an overall typing success-rate of 99.99% (Parson and Steinlechner 2001). While automation is being developed and implemented to robotically process and track samples through the steps of DNA extraction, quantitation, PCR amplification, and sample setup prior to electrophoretic separation, separate computer programs commonly referred to as 'expert systems' are being constructed to enable automatic interpretation of STR alleles from the resulting electropherograms.

EXPERT SYSTEMS FOR STR DATA INTERPRETATION

One of the highest labor efforts in the process of typing STRs is the data interpretation stage. For many high-throughput laboratories, data assessment and interpretation of STRs represents approximately 50% or more of the resource requirement to deliver final results for samples. In many cases, more time is actually spent evaluating the STR profiles than preparing and collecting the data on the sample. In order to reduce this resource requirement, software has been designed and implemented to replace the traditional manual assessment. Two of the first applications used operationally include STRess® developed by the Forensic Science Service in England and TrueAllele® developed by Mark Perlin of Cybergenetics (Pittsburg, PA).

Expert systems have conventionally been considered and designed to translate the electropherogram signal into a genotype compatible with a database. As these expert systems are developed and implemented, bottlenecks will shift to other areas in the DNA typing process and thus permit development of expert systems that can solve ever more complex and diverse problems. As will be discussed below, the Forensic Science Service has developed computer systems that perform a variety of roles within the convicted offender and crime stain analyses processes.

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