|
Second of two parts by Steve Kemp, Thermo Fisher Scientific, and Richard Pinchiin, iForensic, Forensic Science Service Ltd.
By 2000, the FSS had encountered a need to develop the automation systems to increase capacity – demand had increased to in the region of 300,000 samples per annum, and there was a need to extend automated processing beyond buccal swabs to other sample types such as chewing gum, cigarette butts and other samples types that are common in forensic DNA profiling. The new technologies that were developed included modified chemistries for various stages of the process, as well as improved automation that was able to handle samples in a more efficient and effective manner. With the extended sample types that needed to be processed, the LIMS also needed modifications to the batch and sample management approach. This included the capability to control the positioning of samples within a batch and ensure reference samples and unknown (casework) samples were always kept separate.. Additionally, there were requirements to separate certain samples from each other within a batch for quality assurance purposes, or to collate other samples together because of their type. These ‘batching rules’ were developed and held in the LIMS taking it to a new height of full process control.
To complement this development the FSS recognized that automating the DNA profiling process would bring numerous benefits including improved speed and efficiency. The DNA profiling process not only included the technical elements but also the interpretation of the resulting profiles. To maximize these benefits the FSS simultaneously embarked on a programme to develop expert DNA profile interpretation systems with the aim of reducing the interpretation workload, leaving the highly skilled staff to focus on those cases requiring expert human interpretation. In 2005 the FSS implemented FSS-i3, a DNA expert system suite containing i-STRess (a core DNA interpretation tool), i-ntegrity (an application that provides a full within-batch comparison of profiles that can highlight potential contamination events), and i-stream (a tool for the analysis of simple, mixed DNA profiles; in many labs these results are discarded despite containing useful information as the interpretation is deemed to be “difficult”). The benefits this delivered were: improved consistency of allele designation, significant reduction in the time required to interpret a batch of DNA data, increased load rate of DNA profiles to the NDNAD, reduction in the unit cost of DNA analysis, fast resolution of two-person mixtures, and release of staff resource to undertake more highly valued examinations. FSS-i3 continues to be upgraded, delivering improvements on the baseline benefits.
The FRVs were used in a pilot with a UK Police Force in 2005. This pilot only included DNA samples collected from burglaries and vehicle crimes and ran for 19 days. In total 92 DNA samples were processed, the fastest within 7 hrs. Of these 92 samples, 51% were searched against the NDNAD, and 65% of them resulted in a match.
The FSS has recently launched a new rapid, laboratory based sub-24hr turn round time DNA profiling service. This is available to police forces across the country and enables the express processing of priority DNA submissions. As with the more routine automated DNA analysis and the FRV, this new rapid process also requires a LIM system that can handle the same data fields and management information but based on a DNA line utilizing different technology and file formats.
LIMS deployed within the FSS are highly functional solutions, designed to support complex processes that need to adapt to meet the changing needs of the business. For FSS, customization has been an essential part of implementation process. The selection of a LIMS platform that provides a development environment that supports standard rather than proprietary languages with the capability of using “extensions” was key. The FSS is currently using Thermo Scientific’s Nautilus LIMS™ for this purpose.
Large amounts of data may be easily entered into Nautilus LIMS both automatically or manually. The user interface is based on a Microsoft Windows Explorer format allowing manual entry for processes such as sample login to be quick and intuitive. Data can be automatically entered into the system by importing and exporting files using the mapping and parsing functionality included with the software, this is particularly useful for integrating the LIMS with an automated robotics system, reducing the possibility of transcription errors and file corruption.
In addition to the data repository and report generation functions, the LIMS plays an important role in control and validation. Calibration of instrumentation can be monitored from within the system and scheduled, with the ability to prevent work being performed on out of service robotic instrumentation. The validation of consumables such as reagents can be stored within the system which can then regulate certain batches of reagents for use in the process. The security aspect of the LIMS software plays a regulatory role, controlling the access and data available to operators. This enables distinct working practices to be reflected in the system.
The UK National DNA Database (NDNAD) currently holds over 4 million DNA profiles. Approximately 12,000 subject samples and approximately 1,000 scenes of crime samples are added weekly. There have been several legislative changes since the introduction of the NDNAD that have allowed for its expansion and have enhanced the power of DNA in detecting crime. The current chance of a profile obtained from a crime scene matching against an individual’s profile already on the NDNAD is approximately 45%. As the FSS has responded to their customers’ demands for fast, cost-efficient DNA processing it now has the capacity to process in excess of 1,000,000 forensic DNA samples per annum, making it the world’s largest DNA capacity of a single forensic DNA provider.
About the authors: Mr. Kemp is Channels Manager, Thermo Fisher Scientific
Mr. Pinchin is Head of US Operations, iForensic, Forensic Science Service Ltd.
|
