Developmental Validation of the ANDE 6C System for Rapid DNA Analysis of Forensic Casework and DVI Samples

A developmental validation was performed to demonstrate reliability, reproducibility, and robustness of the ANDE Rapid DNA Identification System for processing of crime scene and disaster victim identification (DVI) samples. A total of 1705 samples were evaluated, including blood, oral epithelial samples from drinking containers, samples on FTA and untreated paper, semen, bone, and soft tissues. This study was conducted to address the FBI’s Quality Assurance Standards on developmental validation and to accumulate data from a sufficient number of unique donors and sample types to meet NDIS submission requirements for acceptance of the ANDE Expert System for casework use. To date, no Expert System has been approved for such samples, but the results of this study demonstrated that the automated Expert System performs similarly to conventional laboratory data analysis. Furthermore, Rapid DNA analysis demonstrated accuracy, precision, resolution, concordance, and reproducibility that were comparable to conventional processing along with appropriate species specificity, limit of detection, performance in the presence of inhibitors. No lane‐to‐lane or run‐to‐run contamination was observed, and the system correctly identified the presence of mixtures. Taken together, the ANDE instrument, I‐Chip consumable, FlexPlex chemistry (a 27‐locus STR assay compatible with all widely used global loci, including the CODIS core 20 loci), and automated Expert System successfully processed and interpreted more than 1200 unique samples with over 99.99% concordant CODIS alleles. This extensive developmental validation data provides support for broad use of the system by agencies and accredited forensic laboratories in single‐source suspect‐evidence comparisons, local database searches, and DVI.

Novel extraction chemistry and alternative amplification strategies for use with rootless hair shafts

Rootless hair shafts are often considered unsuitable for STR genotyping due to the known high failure rate. The same samples can be reliably processed with mitochondrial sequencing. However, the minimal discriminatory power of widely implemented control region mitochondrial sequencing techniques limits its utility in some forensic casework. In this research, multiple variables were tested to provide information on rootless hair shaft sample genotyping success. Results showed external decontamination procedures decreased drop-in alleles but also greatly reduced profile recovery. The novel InnoXtract^™ chemistry was comparable to automated EZ1 DNA Investigator extraction. With thoroughly decontaminated hairs, InnoTyper^® 21 amplification generated random match probabilities higher than STR chemistry in 71.875% of samples and 18.75% of samples benefitted from the use of InnoTyper^® 21 amplification compared with estimated mtDNA profile rarity. Compared with the capillary electrophoresis-based amplification chemistries tested, the ForenSeq™ DNA Signature Prep chemistry paired with massively parallel sequencing was the most discriminatory amplification strategy tested.

Review of direct PCR and Rapid DNA approaches to streamline sexual assault kit testing

Crime laboratories have been faced with large casework backlogs due to lengthy processing times, limited resources and scientists, and rising crime rates. Evidence related to sexual assault crimes, specifically sexual assault kits (SAKs), heavily contribute to the reported backlogs. Although more sensitive, faster chemistries and automated techniques have been implemented over the years, the traditional STR workflow remains relatively unchanged. Enhanced workflows such as direct PCR and Rapid DNA have the potential to streamline the processing of forensic evidence items including those commonly submitted in SAKs, but the FBI QAS guidelines restrict CODIS-approved labs from implementing these methods for forensic samples. Recent studies have shown decreased turnaround times and improved or comparable profiling success with both approaches. However, review of the literature shows a lack of in-depth research comparing traditional DNA workflows to faster and more sensitive direct PCR and/or Rapid DNA approaches for evidentiary samples, especially for SAKs. By providing the forensic science and criminal justice communities with the strengths and limitations of direct PCR and Rapid DNA methods, stakeholders and policy makers may be better informed.