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The extraction of DNA is a fairly standard procedure routinely undertaken in biological academic and research settings. In a forensic DNA context, DNA extraction is the crucial first step toward the generation of DNA profiles used to support convictions or exonerations in the criminal justice system. However, it is often complicated by the additional challenge of yielding sufficient quantities of clean DNA that is free from environmental inhibitors, from a wide spectrum of sample types which may contain limited quantities of biological material. While improvements in methods and technology over the decades have sped up and simplified the process of DNA extraction, several issues remain to be fully addressed—such as the incomplete separation of spermic DNA from sperm‐epithelial cell mixtures, increasing demands for ever‐faster DNA results, or even on‐scene DNA processing, and processing of difficult samples such as skeletal remains or samples contaminated by Chemical, Biological, or Radiological (CBR) agents. These challenges are often compounded by high work volumes and limited quantities of starting material. As such, this review focuses on recent trends and developments in four areas of forensic DNA extraction: (a) analysis of sexual assault evidence which often represents a significant portion of a forensic DNA laboratory's casework, (b) use of portable rapid DNA instruments which has gained much traction among law enforcement in recent times, (c) DNA extraction from difficult and CBR‐contaminated samples which, albeit rare, would be essential in a DNA laboratory's toolbox in the event of an incident, and (d) bypassing DNA extraction altogether. This article is categorized under:Forensic Biology > Forensic DNA Technologies [ABSTRACT FROM AUTHOR]

The standard forensic DNA analysis workflow typically encompasses DNA extraction, quantification, STR-PCR amplification, and CE detection. A direct PCR amplification method eliminates the extraction and quantification steps, shortening the turnaround time for DNA profiling. However, a limitation to the direct PCR amplification method lies in its inability to allow for additional PCR amplification on the same sample. We found that replicate PCR amplifications can be afforded with the following modification to the direct PCR amplification method: after sample collection, the microFLOQ™ Direct swabs were incubated in low TE buffer prior to PCR amplification of the lysate. With replicate amplifications, the impact of stochastic effects during STR-PCR amplification on DNA profile interpretation would be reduced. Additionally, adjustments can be made to template volumes in subsequent amplifications, preventing oversaturated PCR reactions. Our results showed that this modified direct amplification method gave comparable median peak heights, allele recovery and intra-locus peak-height-ratio to those of the standard workflow, while maintaining the advantage of minimal evidence consumption. [ABSTRACT FROM AUTHOR]

Sexual assault examination often requires serological saliva/semen testing and differential organic DNA extraction. However, some tests are time-consuming (e.g. microscopic sperm identification) or do not necessarily correlate with the detection of male DNA (e.g. Semenogelin and PSA testing). Additionally, conventional differential organic DNA extraction utilises phenol/chloroform, is laborious, and requires multiple manual tube-to-tube transfer steps. The present study evaluated a modification of the differential DNA extraction workflow, incorporating semi-automation in the form of Promega Maxwell-16 DNA Extraction System. This modified workflow gave comparable results to organic method in terms of sensitivity, sperm DNA recovery and robustness. In addition, the modified extraction workflow significantly reduced the processing time of sexual assault evidences by 15 h. [ABSTRACT FROM AUTHOR]

Urine samples are commonly analysed in cases with suspected illicit drug consumption. In events of alleged sample mishandling, urine sample source identification may be necessary. A simple DNA extraction procedure suitable for STR typing of urine samples was established on the Promega Maxwell® 16 paramagnetic silica bead platform. A small sample volume of 1.7mL was used. Samples were stored at room temperature, 4°C and -20°C for 100days to investigate the influence of storage temperature and time on extracted DNA quantity and success rate of STR typing. Samples stored at room temperature exhibited a faster decline in DNA yield with time and lower typing success rates as compared to those at 4°C and -20°C. This trend can likely be attributed to DNA degradation. In conclusion, this study presents a quick and effective DNA extraction protocol from a small urine volume stored for up to 100days at 4°C and -20°C. [ABSTRACT FROM AUTHOR]