An evaluation of the RapidHIT(®) system for reliably genotyping reference samples.

Short tandem repeat (STR) typing is used routinely for associating or excluding individuals with biological evidence left at a crime scene. Improvements have been made to reduce the turnaround time and labor involved with profile generation, but there is still some lag time between sample collection and interpretation of results. The RapidHIT(®) (IntegenX; Pleasanton, CA, USA) system is an automated instrument that is configured to perform DNA extraction, bead-based DNA normalization, amplification, electrophoresis of PCR amplicons, and data analysis of five reference swabs simultaneously.

Evaluation of a novel material, Diomics X-Swab™, for collection of DNA.

Success of DNA typing is related to the amount of target material recovered from an evidentiary item. Generally, the more DNA that is recovered, the better the chance is of obtaining a typing result that will be robust and reliable. One method of collecting stain materials is by swabbing.

A high volume extraction and purification method for recovering DNA from human bone.

DNA recovery, purity and overall extraction efficiency of a protocol employing a novel silica-based column, Hi-Flow(®) (Generon Ltd., Maidenhead, UK), were compared with that of a standard organic DNA extraction methodology. The quantities of DNA recovered by each method were compared by real-time PCR and quality of DNA by STR typing using the PowerPlex(®) ESI 17 Pro System (Promega Corporation, Madison, WI) on DNA from 10 human bone samples.

Utility of amplification enhancers in low copy number DNA analysis.

One parameter that impacts the robustness and reliability of forensic DNA analyses is the amount of template DNA used in the polymerase chain reaction (PCR). With short tandem repeat (STR) typing, low copy number (LCN) DNA samples can present exaggerated stochastic effects during the PCR that result in heterozygote peak height imbalance, allele drop out, and increased stutter. Despite these effects, there has been little progress toward decreasing the formation of stutter products and heterozygote peak imbalance effects during PCR.

Pressure cycling technology (PCT) reduces effects of inhibitors of the PCR.

A common problem in the analysis of forensic human DNA evidence, or for that matter any nucleic acid analysis, is the presence of contaminants or inhibitors. Contaminants may copurify with the DNA, inhibiting downstream PCR or they may present samples effectively as containing fewer templates than exist in the PCR, even when the actual amount of DNA is adequate. Typically, these challenged samples exhibit allele imbalance, allele dropout, and sequence-specific inhibition, leading to interpretational difficulties.