Interpretation and reporting of mixed DNA profiles by seven forensic laboratories in the UK and Ireland.

In 2014, the UK Forensic Science Regulator (FSR) commissioned a collaborative trial to assess the methods used by forensic service providers (FSPs) in the UK and Ireland for analysis, interpretation and reporting of mixed DNA profiles. Five different mixed samples of varying complexity with supporting mock case circumstances were tested using SGMPlus™ and the newly introduced DNA-17(+) multiplexes and reported by participating laboratories. The results demonstrated a high degree of consistency in analytical methods and allele designations, but some variation in the statistical evaluation and reporting of results. Some of the differences noted were attributable to the major technology change to 17(+)-STR systems which had recently been implemented across the UK at that time. The FSR made recommendations based on the trial outcomes which were intended to produce a more consistent approach to mixtures analysis, interpretation and reporting. Four years later, the Association of Forensic Science Providers (AFSP) repeated the trial, with all major UK and Ireland FSPs (both public sector and private companies) again participating. This second trial used the same mixture set as the 2014 trial but was focussed on the methods for interpretation and evaluation. Since 2014, all UK and Ireland FSPs have implemented probabilistic statistical software using continuous models enabling statistical evaluation of more complex mixtures than was possible in 2014. The trial was therefore aimed at investigating the value of these improved capabilities and also to investigate if there appeared to be marked differences between the different software tools in use in the UK. The results demonstrate a high degree of concordance within and between FSPs and across different evaluation models, and will provide important support for the use of such models in evaluation of mixed DNA profiles.

Development of RapidHIT® ID using NGMSElect™ Express chemistry for the processing of reference samples within the UK criminal justice system.

The RapidHIT® ID is a new instrument which has been designed specifically for non-technical users in non-laboratory environments, for example police custody suites or border control. The development studies presented here were performed using the AmpFℓSTR® NGMSElect™ Express STR kit with single source reference samples. The system has been successfully optimised for extraction, PCR and electrophoresis. Once optimised studies on sensitivity, in terms of DNA input template, sample repeatability and instrument reproducibility have shown that the instrument is capable of producing robust profiles within an 85min, window, using mock reference buccal samples. This work has been carried out within the validation framework provided by the United Kingdom Forensic Science Regulator and is a key stage in the validation of the RapidHIT® ID for use in custody suites within the UK criminal justice system.

Development of enhanced sensitivity protocols on the RapidHIT™ 200 with a view to processing casework material.

The RapidHIT™ 200 device from IntegenX® provides a sample-to-profile platform that is capable of processing a variety of sample types. In this study we review the sensitivity of the 'Run Other' protocol for processing crime stain type samples containing various input quantities of DNA using the AmpFℓSTR® NGMSElect™ Express PCR Amplification Kit cartridges available from IntegenX®. The range of DNA inputs which achieved useable results were not as desired and therefore various enhancements to the instruments extraction processes were investigated. These studies showed an improvement in the range of DNA input templates that could by processed on the RapidHIT™ 200 by using the enhanced methods and resulted in three new run protocols.

Development and validation of the RapidHIT™ 200 utilising NGMSElect™ Express for the processing of buccal swabs.

The RapidHIT™ 200 System is a fully automated sample-to-DNA profile system designed to produce high quality DNA profiles within 2h. The use of RapidHIT™ 200 System within the United Kingdom Criminal Justice System (UKCJS) has required extensive development and validation of methods with a focus on AmpFℓSTR® NGMSElect™ Express PCR kit to comply with specific regulations for loading to the UK National DNA Database (NDNAD). These studies have been carried out using single source reference samples to simulate live reference samples taken from arrestees and victims for elimination. The studies have shown that the system is capable of generating high quality profile and has achieved the accreditations necessary to load to the NDNAD; a first for the UK.

UK and Irish Y-STR population data-A catalogue of variant alleles.

A total of 3128 Y-STR profiles from three UK and one Irish population have been analysed with the PowerPlex Y23 system and are reported here. Instances of haplotype sharing between apparently unrelated individuals were identified and further investigated with the use of the 5 additional markers within the Yfiler Plus kit, resulting in a reduction by 76% in the number of shared haplotypes. Furthermore, Yfiler Plus was also employed to verify locus deletions and duplications observed in Y23 genotypes while inconsistencies between the two kits were sequenced, revealing underlying Y23 primer binding site mutations in loci DYS392 and DYS576. Finally, the mechanism behind a previously reported population specific peak shift observed in DYS481 in South Asian samples has been evaluated and further investigated in a novel case of this phenomenon seen in a Black British individual featuring a different flanking region mutation.