James P. Ross, BS, Demris A. Lee, MSFS, Jeanne M. Willard, MFS, Richard E. Wilson, MS, Michael Marino, MS and Mitchell Holland, PhD
The Armed Forces DNA Identification Laboratory, Office of the Armed Forces Medical Examiner, Armed Forces Institute of Pathology, Rockville, MD 20850

× Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø × Ø

The forensic DNA community continues to move towards short tandem repeat (STR) analysis as a means of DNA identification. STR loci provide several advantages over other PCR-based methods of analysis, such as increased sensitivity and greater discriminatory power. Many new STR multiplex systems (AmpFISTR (ABI) and GenePrint™ [Promega]) are being developed and some are currently commerically available. The combination of two or three STR multiplex systems (i.e. 6-12 loci) offer levels of discrimination comparable to restriction fragment length polymorphism (RFLP) markers with decreased analsysis time and increased sensitivity.

Polyacrylamide slab gel formats have long been the standard method for analysis of amplified DNA fragments. Formats of this type can resolve DNA fragments which differ in length by as little as a single base pair. While these systems allow for precise allele designations, they are somewhat limited by the fact that they are not fully automatable. With increased pressure to analyze more samples in less time, there is a need to move towards detection methods which are more amenable to automation. Capillary electrophoresis (CE) is a proven DNA separation method which integrates automation and fluorescent detection into a system which can analyze approximately 50 samples per day. These systems offer the precision of slab gels with the potential for integration into an automated, high-throughput analytical system. Future systems which feature a capillary array format will be capable of analyzing greater than 1000-5000 samples per day on a single instrument.

Through the course of this study a variety of multiplex systems, including ABI’s AmpFlSTR Blue (D3S1358, vWA, FGA), Green (D5S818, D13S317, D7S820) and Yellow II (D8S1179, D21S11, D18S51) as well as the Promega GenePrint™ PowerPlex™ system (vWA, TH01, TPOX, CSF1PO, D5, D13, D7, D16) will be evaluated on both the ABI 373A DNA Sequencer and the ABI Prism™ 310 Genetic Analyzer. Areas such as precision and reproducibility will be determined and compared for both instruments. In addition, non-probative routine casework samples will be analyzed to determine the reliability of the CE with forensic casework specimens.