The power of DNA is hard to understate, especially as technological advances continue to make DNA analysis more accurate and sensitive.
As a result, both public and private forensic labs have experienced much success. That success, however, has led to a greater number of cases than ever before—along with a greater number of samples per case. Even as automated and new techniques have shortened the processing time for DNA samples from months to days, laboratories are struggling to keep pace with the vastly increased demand.
To that end, in 2018, National Institutes of Justice (NIJ) commissioned a group of experts in forensic DNA analysis to research and write a new report—“National Best Practices for Improving DNA Laboratory Process Efficiency.” This just-released guide brings together a combination of innovative and practical concepts, recommendations, and best practices to assist DNA laboratories in increasing their productivity and capacity in a multitude of areas.
The scope of the report is too wide for one article, so Forensic will continue to summarize best practices in future publications. In this article, Forensic will focus specifically on recommendations for laboratory management and operations.
Screening evidence
The NIJ report lists four specific recommendations to save time in the lab.
The first, to decrease sample processing time in sexual assault kits, the report says DNA labs should adopt a Y-screening and/or direct-to-DNA approach for screening evidence samples. A direct to DNA approach allows laboratories to proceed directly to autosomal amplification without re-extraction.
On a related note, the report also recommends conducting traditional serological testing and sperm searchers only when necessary.
“The serology tests employed by forensic DNA laboratories are time-consuming and less sensitive than modern DNA typing kits,” reads the report. “In addition, if DNA typing is performed only on swabs that screen positive in serology tests, analysts may miss DNA profiles from body fluids not tested by a laboratory or samples collected for touch DNA. Rather than using traditional serology to determine which swabs should move forward to DNA analysis, we recommend using a Y-screening or direct to DNA approach, or a combination of both.”
Laboratories should also consider validating specific quantification cutoffs to determine when a sample should proceed directly to autosomal or Y-STR amplification, be re-extracted (e.g., when a differential protocol may yield a stronger male profile in the secondary fraction), or be terminated altogether, such as when the Y quantification value is undetermined or below a validated threshold.
Automation
To decrease time spent performing benchwork, the report says DNA labs should employ automated techniques in the DNA processing steps whenever possible. While that may sound pricey, robotic solutions come in all shapes and sizes. Even within the constraints of current budgets, laboratories can modify existing practices to operate more efficiently.
For example, something as simple as using vendor software or Excel worksheets to automate the creation of instrument-specific files and to track samples throughout the DNA workflow can increase both efficiency and quality.
Additionally, automation of sample preparation for quantitation, amplification and capillary electrophoresis will decrease time spent by analysts on routine tasks, freeing them for higher-level tasks, such as DNA interpretation and report writing.
The final time-saver recommendation according to the report is to employ batching at each step of the DNA process.
“Maintaining and building on these recommendations is essential for creating results that will endure,” concludes the report.
In future articles, Forensic will discuss recommendations/best practices for evidence submission, staffing and new technologies.