Publications by authors named "James W Schumm"
Background: The generation of short tandem repeat profiles, also referred to as 'DNA typing,' is not currently performed outside the laboratory because the process requires highly skilled technical operators and a controlled laboratory environment and infrastructure with several specialized instruments. The goal of this work was to develop a fully integrated system for the automated generation of short tandem repeat profiles from buccal swab samples, to improve forensic laboratory process flow as well as to enable short tandem repeat profile generation to be performed in police stations and in field-forward military, intelligence, and homeland security settings.
Results: An integrated system was developed consisting of an injection-molded microfluidic BioChipSet cassette, a ruggedized instrument, and expert system software.
Different national and international agencies have selected specific STR sets for forensic database use. To enhance database comparison across national and international borders, a 27-locus multiplex system was developed comprising all 15 STR loci of the European standard set, the current 13 STR loci of the CODIS core, the proposed 22 STR loci of the expanded CODIS core, 4 additional commonly used STR loci, and the amelogenin locus. Development required iterative primer design to resolve primer-related artifacts, amplicon sizing, and locus-to-locus balance issues.
View Article and Find Full Text PDFWith the recent expansion of DNA database laws in many states, there is a critical need for the rapid and simple collection of DNA samples and streamlined processing for downstream applications. The Buccal DNA Collector was developed to address the need for a reliable, practical alternative to blood collection that is compatible with high-throughput operations. The collection area consists of filter paper that is placed against the inside of the cheek, and the sample is taken by swiping the cheek several times while pulling the device out of the mouth.
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- The PowerPlex 16 BIO system includes 13 CODIS loci, two additional pentanucleotide loci, and the Amelogenin sex-identifying locus, optimized for specific imaging systems.
- Extensive validation studies involving seven labs confirmed the system's reliability, with one minor discordance in a single sample and consistent results across nonprobative casework.
- The system showed robust performance with minimal DNA input, although higher temperatures could degrade larger DNA fragments and some cross-reactivity was noted with primate DNA.
Accurate human-specific DNA quantification is essential for forensic casework analysis. In this work, we describe a microplate-based quantification assay that utilizes the PCR amplification of human-specific TH01 primers. This method enables the reliable quantification of human DNA samples from 0.
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- A nine-locus STR multiplex system called GenePrint PowerPlex 2.1, developed by Promega, was tested alongside the Penta D locus to improve human identification accuracy.
- The system incorporates highly variable DNA loci and can work with the previously established PowerPlex 1.1 system, sharing some loci for quality control.
- Validation studies across seven laboratories confirmed the PowerPlex 2.1/Penta D system's efficiency, reproducibility, and reliability for forensic DNA testing, aligning with FBI quality assurance standards.
Article Synopsis
- - The NCSBI found discrepancies in DNA analysis of the D16S539 locus compared to other loci when outsourcing to TBTG, highlighting issues like allele drop out and imbalances in sister alleles.
- - A review of the differing lab techniques revealed that variations in DNA extraction and amplification methods could be causing the discrepancies, but the exact cause was unclear at first.
- - Further experiments identified a point mutation in the D16S539 primer-binding site that affects African-American populations, prompting Promega to create a new degenerate primer for more accurate detection of alleles in future tests.