My-Forensic-Loci-queries (MyFLq) framework for analysis of forensic STR data generated by massive parallel sequencing

Forensic scientists are currently investigating how to transition from capillary electrophoresis (CE) to massive parallel sequencing (MPS) for analysis of forensic DNA profiles. MPS offers several advantages over CE such as virtually unlimited multiplexy of loci, combining both short tandem repeat (STR) and single nucleotide polymorphism (SNP) loci, small amplicons without constraints of size separation, more discrimination power, deep mixture resolution and sample multiplexing. We present our bioinformatic framework My-Forensic-Loci-queries (MyFLq) for analysis of MPS forensic data. For allele calling, the framework uses a MySQL reference allele database with automatically determined regions of interest (ROIs) by a generic maximal flanking algorithm which makes it possible to use any STR or SNP forensic locus. Python scripts were designed to automatically make allele calls starting from raw MPS data. We also present a method to assess the usefulness and overall performance of a forensic locus with respect to MPS, as well as methods to estimate whether an unknown allele, which sequence is not present in the MySQL database, is in fact a new allele or a sequencing error. The MyFLq framework was applied to an Illumina MiSeq dataset of a forensic Illumina amplicon library, generated from multilocus STR polymerase chain reaction (PCR) on both single contributor samples and multiple person DNA mixtures. Although the multilocus PCR was not yet optimized for MPS in terms of amplicon length or locus selection, the results show excellent results for most loci. The results show a high signal-to-noise ratio, correct allele calls, and a low limit of detection for minor DNA contributors in mixed DNA samples. Technically, forensic MPS affords great promise for routine implementation in forensic genomics. The method is also applicable to adjacent disciplines such as mitochondrial DNA research

DNA Authentication of St John’s Wort (Hypericum perforatum L.) Commercial Products Targeting the ITS Region

open access articleThere is considerable potential for the use of DNA barcoding methods to authenticate raw medicinal plant materials, but their application to testing commercial products has been controversial. A simple PCR test targeting species-specific sequences within the nuclear ribosomal internal transcribed spacer (ITS) region was adapted to screen commercial products for the presence of Hypericum perforatum L. material. DNA differing widely in amount and extent of fragmentation was detected in a number of product types. Two assays were designed to further analyse this DNA using a curated database of selected Hypericum ITS sequences: A qPCR assay based on a species-specific primer pair spanning the ITS1 and ITS2 regions, using synthetic DNA reference standards for DNA quantitation and a Next Generation Sequencing (NGS) assay separately targeting the ITS1 and ITS2 regions. The ability of the assays to detect H. perforatum DNA sequences in processed medicines was investigated. Out of twenty different matrices tested, both assays detected H. perforatum DNA in five samples with more than 103 ITS copies µL−1 DNA extract, whilst the qPCR assay was also able to detect lower levels of DNA in two further samples. The NGS assay confirmed that H. perforatum was the major species in all five positive samples, though trace contaminants were also detected

Evaluation of next generation mtGenome sequencing using the ion torrent Personal Genome Machine (PGM)

Insights into the human mitochondrial phylogeny have been primarily achieved by sequencing full mitochondrial genomes (mtGenomes). In forensic genetics (partial) mtGenome information can be used to assign haplotypes to their phylogenetic backgrounds, which may, in turn, have characteristic geographic distributions that would offer useful information in a forensic case. In addition and perhaps even more relevant in the forensic context, haplogroup-specific patterns of mutations form the basis for quality control of mtDNA sequences. The current method for establishing (partial) mtDNA haplotypes is Sanger-type sequencing (STS), which is laborious, time-consuming, and expensive. With the emergence of Next Generation Sequencing (NGS) technologies, the body of available mtDNA data can potentially be extended much more quickly and cost-efficiently. Customized chemistries, laboratory workflows and data analysis packages could support the community and increase the utility of mtDNA analysis in forensics. We have evaluated the performance of mtGenome sequencing using the Personal Genome Machine (PGM) and compared the resulting haplotypes directly with conventional Sanger-type sequencing. A total of 64 mtGenomes (>1 million bases) were established that yielded high concordance with the corresponding STS haplotypes (<0.02% differences). About two-thirds of the differences were observed in or around homopolymeric sequence stretches. In addition, the sequence alignment algorithm employed to align NGS reads played a significant role in the analysis of the data and the resulting mtDNA haplotypes. Further development of alignment software would be desirable to facilitate the application of NGS in mtDNA forensic genetics.This work leading to these results has received funding from the Austrian Science Fund (FWF) [P22880-B12] and [TRL397] and was financially supported from the European Union Seventh Framework Program (FP7/2007–2013) under grant agreement no. 285487 (EUROFORGEN-NoE). This work was further financially supported by the National Institute of Justice (NIJ) grant 2011-MU-MU-K402 and by the Foundation of Science and Technology Portugal (FCT) and Programa peracional Tema´ tico Factores de Competitividade (COMPETE), co-funded by the European Community Fund FEDER with the Project PTDC/CS-ANT/108558/2008 and also by the FCT fellowship SFRH/BD/63165/2009’’.http:// www.elsevier.com /locate/fsighb2014ay201

Biological Evidence Analysis in Cases of Sexual Assault

Sexual assault (SA) is a crime of violence against a person’s body resulting in a physical trauma, mental anguish, and suffering for victims generating expenses for government intended criminal investigation, medical care, and psychological attention. During the crime scene investigation, the identification and recovery of biological evidence (BE) are utmost important, since sometimes these are the only way to prove sexual contact and the perpetrator’s identity. The examiner, with the help of specific technologies and techniques, must be able to find evidence that otherwise could go unnoticed. Forensic laboratories identify biological evidence with systemized protocols and use molecular methods to generate DNA profiles based on the amplification and DNA sequencing. Before the arrival of the new-generation sequencers, the application of other markers (single nucleotide polymorphisms (SNPs), insertion-deletion of nucleotides (INDEL), or microhaplotypes (MHs)) was laborious, expensive, and not very informative for forensic purposes; however, now they are useful in this field. Next-generation sequencing (NGS) brought a new series of applications like epigenetics, microbiota, messenger RNA, and microRNA analysis and the inferences in the ancestry and phenotyping of individuals. In the end, the results obtained from such analyses and stored in databases are very useful for the identification of sexual aggressors

Genome-wide SNP typing of ancient DNA: Determination of hair and eye color of Bronze Age humans from their skeletal remains.

Objective A genome-wide high-throughput single nucleotide polymorphism (SNP) typing method was tested with respect of the applicability to ancient and degraded DNA. The results were compared to mini-sequencing data achieved through single base extension (SBE) typing. The SNPs chosen for the study allow to determine the hair colors and eye colors of humans. Material and methods The DNA samples were extracted from the skeletal remains of 59 human individuals dating back to the Late Bronze Age. The 3,000 years old bones had been discovered in the Lichtenstein Cave in Lower Saxony, Germany. The simultaneous typing of 24 SNPs for each of the ancient DNA samples was carried out using the 192.24 Dynamic Array (TM) by Fluidigm (R). Results Thirty-eight of the ancient samples (=64%) revealed full and reproducible SNP genotypes allowing hair and eye color phenotyping. In 10 samples (=17%) at least half of the SNPs were unambiguously determined, in 11 samples (=19%) the SNP typing failed. For 23 of the 59 individuals, a comparison of the SNP typing results with genotypes from an earlier performed SBE typing approach was possible. The comparison confirmed the full concordance of the results for 90% of the SNP typings. In the remaining 10% allelic dropouts were identified. Discussion The high genotyping success rate could be achieved by introducing modifications to the preamplification protocol mainly by increasing the DNA input and the amplification cycle number. The occurrence of allelic dropouts indicates that a further increase of DNA input to the preamplification step is desirable

Forensic DNA Technological Advancements as an Emerging Perspective on Medico-Legal Autopsy: A Mini Review

The importance of biological traces and evidences related to a criminal matter has been recognized for a long time. The examination of the expression of genetic polymorphism has been an integral part of the multidisciplinary field of medico-legal autopsy for over a century. Since the initial application of blood group antigens for personalization of a putative perpetrator in a murder case, the discipline of forensic genetics has evolved as a standard of forensic sciences. The real breakthrough, the application of molecular tools and processes for the in-vitro replication of genetic substances, has increasingly allowed the exploitation of advances of molecular genetics for both forensic and criminal investigations. Although there are certainly many more applications and scientific fields in the medico-legal arena, the relatively fast progress of genetics, which has accelerated recently with state-of-art technologies, can provide ever more relevant information in relation to a corpse or the cause and manner that resulted in the corpse for autopsy. This topic concerns the currently accepted forensic DNA technology, and the last section reviews commonly used markers for nuclear and mitochondrial DNA analysis as well as ongoing research. This review also focuses on the increasingly important non-human sources of DNA, and shortly covers the main aspects of animal forensic DNA examination

Fluorescent amplification for next generation sequencing (FA-NGS) library preparation.

BACKGROUND:Next generation sequencing (NGS) has become a universal practice in modern molecular biology. As the throughput of sequencing experiments increases, the preparation of conventional multiplexed libraries becomes more labor intensive. Conventional library preparation typically requires quality control (QC) testing for individual libraries such as amplification success evaluation and quantification, none of which occur until the end of the library preparation process. RESULTS:In this study, we address the need for a more streamlined high-throughput NGS workflow by tethering real-time quantitative PCR (qPCR) to conventional workflows to save time and implement single tube and single reagent QC. We modified two distinct library preparation workflows by replacing PCR and quantification with qPCR using SYBR Green I. qPCR enabled individual library quantification for pooling in a single tube without the need for additional reagents. Additionally, a melting curve analysis was implemented as an intermediate QC test to confirm successful amplification. Sequencing analysis showed comparable percent reads for each indexed library, demonstrating that pooling calculations based on qPCR allow for an even representation of sequencing reads. To aid the modified workflow, a software toolkit was developed and used to generate pooling instructions and analyze qPCR and melting curve data. CONCLUSIONS:We successfully applied fluorescent amplification for next generation sequencing (FA-NGS) library preparation to both plasmids and bacterial genomes. As a result of using qPCR for quantification and proceeding directly to library pooling, the modified library preparation workflow has fewer overall steps. Therefore, we speculate that the FA-NGS workflow has less risk of user error. The melting curve analysis provides the necessary QC test to identify and troubleshoot library failures prior to sequencing. While this study demonstrates the value of FA-NGS for plasmid or gDNA libraries, we speculate that its versatility could lead to successful application across other library types