Abstract: The study of geographically and/or linguistically isolated populations could represent a potential area of interaction between population and forensic genetics. These investigations may be useful to evaluate the suitability of loci which have been selected using forensic criteria for bio-anthropological studies. At the same time, they give us an opportunity to evaluate the efficiency of forensic tools for parentage testing in groups with peculiar allele frequency profiles. Within the frame of a long-term project concerning Italian linguistic isolates, we studied 15 microsatellite loci (Identifiler kit) comprising the CODIS panel in 11 populations from the north-eastern Italian Alps (Veneto, Trentino and Friuli Venezia Giulia regions). All our analyses of inter-population differentiation highlight the genetic distinctiveness of most Alpine populations comparing them either to each other or with large and non-isolated Italian populations. Interestingly, we brought to light some aspects of population genetic structure which cannot be detected using unilinear polymorphisms. In fact, the analysis of genotypic disequilibrium between loci detected signals of population substructure when all the individuals of Alpine populations are pooled in a single group. Furthermore, despite the relatively low number of loci analyzed, genetic differentiation among Alpine populations was detected at individual level using a Bayesian method to cluster multilocus genotypes. Among the various populations studied, the four linguistic minorities (Fassa Valley, Luserna, Sappada and Sauris) showed the most pronounced diversity and signatures of a peculiar genetic ancestry. Finally, we show that database replacement may affect estimates of probability of paternity even when the local database is replaced by another based on populations which share a common genetic background but which differ in their demographic history. These findings point to the importance of considering the demographic and cultural profile of populations in forensic applications, even in a context of substantial genetic homogeneity such as that of European populations.

The new book, "A Companion to Forensic Anthropology," edited by Dr. Dennis Dirkmaat, chair of the Applied Forensic Sciences Department and the Master of Science program in Anthropology at Mercyhurst University, Erie, Pa., presents the most comprehensive assessment of the philosophy, goals, and practice of forensic anthropology today, with chapters by renowned international scholars and experts.

Abstract: DNA barcoding was adopted in our laboratory for the identification of tobacco (Nicotiana spp.) in moassel samples seized from “hookah bars”. As recommended by the CBOL Plant Working Group, we used a 2-locus combination of rbcL and matK as the plant barcode. As previously reported rbcL routinely produced high quality bi-directional reads but had a lower discriminating power than matK. It was much more difficult obtaining high quality bi-directional reads with matK possibly because of poor sample quality. DNA barcoding successfully identified tobacco in over 60 commercial tobacco moassel products. On the other hand, negative results (no amplification) or the identification of non-tobacco species were obtained from herbal moassel products. Our study clearly demonstrates the practical utility of DNA barcoding beyond taxonomy.

A protocol for the simultaneous amplification of 25 STR loci plus amelogenin has been recently published . We applied a slightly modified method to a sample of 100 unrelated subjects living in Tuscany, Italy; 23 loci (plus amelogenin) were successfully genotyped in a single multiplex.

Abstract: Ideally for use in forensic analyses, genetic markers on the same chromosome should be more than 50 Mb in physical distance to ensure full recombination and thus independent inheritance. The forensic community has given attention to two STR markers, D12S391 and vWA, that are 6.3 megabases (Mb) apart on chromosome 12. Recent studies have shown no significant linkage disequilibrium between vWA and D12S391 in U.S. and worldwide populations, although genetic linkage has been identified. It is important to evaluate the impact of linkage effects on kinship analysis. In this study, we aimed to determine a more precise measurement of the recombination frequency between vWA and D12S391 based on a larger number of informative meiosis than has been studied previously. We estimated the recombination frequency (?) to 0.089 (95% CI 0.044–0.158). Using pedigrees simulated under specific kinship scenarios where recombination was expected to affect the likelihood ratio (LR), we evaluated the impact on LR values of including or ignoring linkage between vWA and D12S391. For all pedigree scenarios considered, on average, LR values ignoring linkage were slightly underestimated than when linkage was considered. However, in the incest scenario considered, LR values could be overestimated up to 25–30 times when linkage was ignored. We demonstrate that the effect of ignoring linkage in the likelihood ratio calculation can be considerable. These results suggest that linkage should be considered during kinship analysis when vWA and D12S391 are tested for pedigrees where a recombination could impact the LR value.

Abstract: In the forensic examination of DNA mixtures, the question of how to set the total number of contributors (N) presents a topic of ongoing interest. Part of the discussion gravitates around issues of bias, in particular when assessments of the number of contributors are not made prior to considering the genotypic configuration of potential donors. Further complication may stem from the observation that, in some cases, there may be numbers of contributors that are incompatible with the set of alleles seen in the profile of a mixed crime stain, given the genotype of a potential contributor. In such situations, procedures that take a single and fixed number contributors as their output can lead to inferential impasses. Assessing the number of contributors within a probabilistic framework can help avoiding such complication. Using elements of decision theory, this paper analyses two strategies for inference on the number of contributors. One procedure is deterministic and focuses on the minimum number of contributors required to ‘explain’ an observed set of alleles. The other procedure is probabilistic using Bayes’ theorem and provides a probability distribution for a set of numbers of contributors, based on the set of observed alleles as well as their respective rates of occurrence. The discussion concentrates on mixed stains of varying quality (i.e., different numbers of loci for which genotyping information is available). A so-called qualitative interpretation is pursued since quantitative information such as peak area and height data are not taken into account. The competing procedures are compared using a standard scoring rule that penalizes the degree of divergence between a given agreed value for N, that is the number of contributors, and the actual value taken by N. Using only modest assumptions and a discussion with reference to a casework example, this paper reports on analyses using simulation techniques and graphical models (i.e., Bayesian networks) to point out that setting the number of contributors to a mixed crime stain in probabilistic terms is, for the conditions assumed in this study, preferable to a decision policy that uses categoric assumptions about N.

Abstract: A new amplification system for ABO and STR genotyping in a single reaction has been successfully developed. Two types of information can be obtained from a biological sample at one time. One is the classical information of ABO blood group typing for screening suspects and the other is STR information for individual identification. The system allows for the simultaneous detection of 15 autosomal STR loci (containing all CODIS STR loci as well as Penta D and Penta E), six ABO genotypes (O/O, B/B, A/A, A/O, A/B, and B/O) and the gender-determining locus Amelogenin. Primers are designed so that the amplicons are distributed ranging from 75bp to 500bp within a four-dye fluorescent design, leaving a fourth dye for the internal size standard. With 30 cycles, the results showed that the optimal amount of DNA template for this multiplex ranges from 250pg to 2ng and the lowest detection threshold is 125pg (as low as 63pg for ABO loci). For the DNA template outside the optimal detection range, we could adjust the number of cycles to obtain the robust profiles. Mixture studies showed that over 83% of minor alleles were detected at 1:9 ratios. The full profiles were still observed when 4ng of degraded DNA was digested by DNase I and 1ng undegraded DNA was added to 40?M haematin. Polymerase chain reaction (PCR)-based conditions including the concentrations of primers, magnesium and the Taq polymerase as well as volume, cycle numbers and annealing temperature were examined and optimised. In addition, the system was validated by 364 bloodstain samples and 32 common casework samples. According to the Chinese National Standards and Scientific Working Group on DNA Analysis Methods (SWGDAM) guidelines, our system demonstrates good detection performance and is an ideal tool for forensic DNA typing with potential application.

A new quantum mechanical-based biosensor designed by a team at University of California, Santa Barbara offers tremendous potential for detecting biomolecules at ultra-low concentrations, from instant point-of-care disease diagnostics, to detection of trace substances for forensics and security.

Abstract: We explore the applicability of second generation sequencing (SGS) to sequence multiplexed forensic STR amplicons, both in a single contributor sample as in multiple-person mixtures with different ratios. We compare the results of a commercial STR profiling kit (Applied Biosystems AmpFlSTR® Profiler Plus®), analyzed both with capillary electrophoresis and with Roche GS FLX sequencing. An easy to use open-source software pipeline is provided, chaining together the different steps needed to start the analysis from a GS FLX FASTA file, resulting in a FASTA file containing the called and quantified alleles present in the data. Sequencing of multiplexed STR amplicons using Roche GS FLX titanium technology is technically feasible but the technology is not ideal for this purpose. The fraction of full length reads is small and the homopolymer sequencing error rate is high. The pipeline compresses the homopolymers to a single base to avoid false results caused by these homopolymers. The qualitative and quantitative results from the SGS STR analysis pipeline are comparable to the electrophoresis method. Additionally, the SGS method provides extra information and is able to call allele subtypes based on STR sequences in a database. In mixed samples, all alleles were reported from individuals that contributed at least 10% to the mixture.

In order to accurately identify skulls as male or female, forensic anthropologists need to have a good understanding of how the characteristics of male and female skulls differ between populations. A new study from North Carolina State University shows that these differences can be significant, even between populations that are geographically close to one another.