Autosomal Short Tandem Repeat Typing Research Articles

Separation mixed semen of two individuals using magnetic beads coupled ABH blood group antibody.

In sexual assault cases, one of the most common samples collected is a mixed semen stain, which is often found on the vagina, female underwear, or bed sheets. However, it is usually difficult to identify the perpetrator based on this sample alone. One technique that has been developed to address this issue is magnetic bead-based separation. This method involves using modified magnetic microspheres to capture and enrich specific target cells, in this case, sperm cells. In this study, we utilized magnetic beads coupled with ABH blood group antibody to isolate sperm cells from an individual of a single ABO blood type. Subsequently, polymerase chain reaction amplification and capillary electrophoresis were employed to perform the genotyping the short tandem repeat (STR) loci. This approach allows for the identification of different individuals in a mixed seminal stain sample from two individuals, by first separating sperm cells based on ABH antigen differences and subsequently utilizing autosomal STR typing on the enriched single blood group cells.

Biological kinship in 750 year old human remains from Central Argentina with signs of interpersonal violence.

Human skeletal remains of an adult male (20-24years old) and a juvenile (4-8years old), dated to 750 ± 85 14C years BP, were found on the southern margin of Mar Chiquita Lagoon (Córdoba, Argentina). Both individuals show signs of being victims of interpersonal violence, with arrowheads associated with the remains and perimortem lesions on the juvenile, as well as an unusual form of burial, with the juvenile partially overlapped with the adult. The aim of this work is to study a possible kin relationship between these two individuals through ancient DNA analysis. Biological kinship was evaluated by autosomal and Y-chromosome STR (short tandem repeat) typing, PCR-APLP for SNP determination and hypervariable region I sequencing of the mitochondrial DNA. Genetic analyses indicated that these individuals shared the same Y-chromosomal haplotype but different mitochondrial lineages. The likelihood ratio based on autosomal loci indicates that the genetic profiles of the human remains would be more likely to be that indicating a father-son bond. The paleogenetic approach combined with forensic genetic methods applied to this study allowed us to confirm a hypothesis that originated in bioarchaeological evidence. This study constitutes a unique case in Argentina of kinship determination based on DNA profiles of human remains in an archaeological context of interpersonal violence. It is important to highlight the contribution made by these studies to address topics usually hidden in bioarchaeological studies, such as community organization, cultural customs and mortuary practices.

Large-scale identification of human bone remains via SNP microarray analysis with reference SNP database

Single nucleotide polymorphisms (SNPs) are valuable markers complementary to conventional forensic short tandem repeat (STR) markers in genetic typing, with potential advantages in challenging forensic casework. With the advent of high-throughput technologies, such as microarrays and massively parallel sequencing, the use of SNP typing has now expanded to large-scale forensic applications. Herein, a forensic case is presented to demonstrate the usefulness of SNP typing in identifying large-scale human bone remains with reference database construction. A total of 402 bone remains were recovered from an island in the Jeju Province of Korea where a massive disaster occurred in 1948. The first phase of the identification process was accomplished via conventional DNA typing methods including autosomal and Y-chromosomal STR typing, and mitochondrial DNA sequencing, which resulted in the identification of 74 of 402 remains. The second phase of the identification involved the remaining 327 unidentified remains using SNP typing as a supplementary tool based on Affymetrix resequencing array. The SNP markers of 782 family members were also analyzed and a reference database was constructed for comparison. An additional 51 bone remains were identified in the second phase. SNP data obtained from the supplementary genotyping yielded additional genetic information as well as contributed to kinship testing to determine the second degrees of relationship. In addition SNPs are useful in discriminating ambiguous relationship when only STR data are available. A software program developed for SNP typing system enabled efficient kinship analysis for large-scale forensic identification. The results and the casework are described and discussed.

Impact of DNA degradation on massively parallel sequencing-based autosomal STR, iiSNP, and mitochondrial DNA typing systems.

Biological samples, including skeletal remains exposed to environmental insults for extended periods of time, exhibit increasing levels of DNA damage and fragmentation. Human forensic identification methods typically use a combination of mitochondrial (mt) DNA sequencing and short tandem repeat (STR) analysis, which target segments of DNA ranging from 80 to 500base pairs (bps). Larger templates are often unavailable as skeletal samples age and the associated DNA degrades. Single-nucleotide polymorphism (SNP) loci target shorter templates and may serve as a solution to the problem. Recently developed assays for STR and SNP analysis using a massively parallel sequencing approach, such as the ForenSeq kit (Verogen, San Diego, CA), offer a means for generating results from degraded samples as they target templates down to 60 to 170bps. We performed a modeling study that demonstrates that SNPs can increase the significance of an identification when analyzing DNA down to an average size of 100bps for input amounts between 0.375 and 1ng of nuclear DNA. Observations from this study were then compared with human skeletal material results (n = 14, ninth to eighteenth centuries), which further demonstrated the utility of the ForenSeq kit for degraded samples. The robustness of the Promega PowerSeq™ Mito System was also tested with human skeletal remains (n = 70, ninth to eighteenth centuries), resulting in successful coverage of 99.29% of the mtDNA control region at 50× coverage or more. This was accompanied by modifications to a mainstream DNA extraction technique for skeletal remains that improved recovery of shorter templates.

Use of the LUS in sequence allele designations to facilitate probabilistic genotyping of NGS-based STR typing results

Some of the expected advantages of next generation sequencing (NGS) for short tandem repeat (STR) typing include enhanced mixture detection and genotype resolution via sequence variation among non-homologous alleles of the same length. However, at the same time that NGS methods for forensic DNA typing have advanced in recent years, many caseworking laboratories have implemented or are transitioning to probabilistic genotyping to assist the interpretation of complex autosomal STR typing results. Current probabilistic software programs are designed for length-based data, and were not intended to accommodate sequence strings as the product input. Yet to leverage the benefits of NGS for enhanced genotyping and mixture deconvolution, the sequence variation among same-length products must be utilized in some form.Here, we propose use of the longest uninterrupted stretch (LUS) in allele designations as a simple method to represent sequence variation within the STR repeat regions and facilitate – in the nearterm – probabilistic interpretation of NGS-based typing results. An examination of published population data indicated that a reference LUS region is straightforward to define for most autosomal STR loci, and that using repeat unit plus LUS length as the allele designator can represent greater than 80% of the alleles detected by sequencing. A proof of concept study performed using a freely available probabilistic software demonstrated that the LUS length can be used in allele designations when a program does not require alleles to be integers, and that utilizing sequence information improves interpretation of both single-source and mixed contributor STR typing results as compared to using repeat unit information alone. The LUS concept for allele designation maintains the repeat-based allele nomenclature that will permit backward compatibility to extant STR databases, and the LUS lengths themselves will be concordant regardless of the NGS assay or analysis tools employed. Further, these biologically based, easy-to-derive designations uphold clear relationships between parent alleles and their stutter products, enabling analysis in fully continuous probabilistic programs that model stutter while avoiding the algorithmic complexities that come with string based searches. Though using repeat unit plus LUS length as the allele designator does not capture variation that occurs outside of the core repeat regions, this straightforward approach would permit the large majority of known STR sequence variation to be used for mixture deconvolution and, in turn, result in more informative mixture statistics in the near term. Ultimately, the method could bridge the gap from current length-based probabilistic systems to facilitate broader adoption of NGS by forensic DNA testing laboratories.

Prediction of autosomal STR typing success in ancient and Second World War bone samples

Human-specific quantitative PCR (qPCR) has been developed for forensic use in the last 10 years and is the preferred DNA quantification technique since it is very accurate, sensitive, objective, time-effective and automatable. The amount of information that can be gleaned from a single quantification reaction using commercially available quantification kits has increased from the quantity of nuclear DNA to the amount of male DNA, presence of inhibitors and, most recently, to the degree of DNA degradation. In skeletal remains samples from disaster victims, missing persons and war conflict victims, the DNA is usually degraded. Therefore the new commercial qPCR kits able to assess the degree of degradation are potentially able to predict the success of downstream short tandem repeat (STR) typing. The goal of this study was to verify the quantification step using the PowerQuant kit with regard to its suitability as a screening method for autosomal STR typing success on ancient and Second World War (WWII) skeletal remains. We analysed 60 skeletons excavated from five archaeological sites and four WWII mass graves from Slovenia. The bones were cleaned, surface contamination was removed and the bones ground to a powder. Genomic DNA was obtained from 0.5g of bone powder after total demineralization. The DNA was purified using a Biorobot EZ1 device. Following PowerQuant quantification, DNA samples were subjected to autosomal STR amplification using the NGM kit. Up to 2.51ng DNA/g of powder were extracted. No inhibition was detected in any of bones analysed. 82% of the WWII bones gave full profiles while 73% of the ancient bones gave profiles not suitable for interpretation. Four bone extracts yielded no detectable amplification or zero quantification results and no profiles were obtained from any of them. Full or useful partial profiles were produced only from bone extracts where short autosomal (Auto) and long degradation (Deg) PowerQuant targets were detected. It is concluded that STR typing of old bones after quantification with the PowerQuant should be performed only when both Auto and Deg targets are detected simultaneously with no respect to [Auto]/[Deg] ratio. Prediction of STR typing success could be made according to successful amplification of Deg fragment. The PowerQuant kit is capable of identifying bone DNA samples that will not yield useful STR profiles using the NGM kit, and it can be used as a predictor of autosomal STR typing success of bone extracts obtained from ancient and WWII skeletal remains.

Genetic diversity between two Igbo men from Owerri senatorial province as determined by autosomal short tandem repeats, Y-chromosomal short tandem repeats and mitochondrial DNA typing methods

Background: Human identification has recently been optimized following the completion of human genome sequence, by using DNA markers that exhibit the highest possible variation. However, in developing countries such as Nigeria, the application of DNA typing for identification of human subjects either for forensic or medical purposes is inadequate due to the absence of national forensic DNA laboratories and lack of the legislative framework. Materials and Methods: In this study, two male subjects of Igbo origin provided their blood, hair and buccal samples for DNA analysis. DNA was extracted, purified, quantified with human quantifiler™ polymerase chain reaction reaction mix. Hyper-variable segment 1 of the D-loop mitochondrial DNA (mtDNA HVS-1) was amplified, purified and fragments sequenced and analyzed with ABI Genetic Analyzer. A multiplex AmpFlSTR Identifiler kit amplified 15 STR plus amelogenin loci of the nuclear DNA and 16 STR of the Y-chromosome. GeneMapper ID software version 3.2 was used for the analysis of autosomal and Y-chromosome AmpFlSTR. Results: Result show that the mtDNA lineage of UMBACK subject belongs to L3e2b while ELAMBIA is assigned to L3f1b1 haplogroup. Based on the allelic frequency database, both subjects displayed uniqueness in random match probability for the autosomal allelic short-tandem repeat (STR). Based upon a mutation rate of 0.003 for Y-DNA STR markers, the two individuals most likely shared a common paternal ancestor 96 generations ago. Both subjects were assigned to E1b1a haplogroup with a 100% probability, which is consistent with the haplogroup associated with Igbo people in Nigeria. Conclusion: As expected, well-established forensic genetic tools comprising of mtDNA, autosomal and Y-chromsomomal STR typing methods were all found to distinguish two selected Nigerian Igbo individuals with a very high power of discrimination.

An Unusual Case0020in Paternity Testing

We introduce a case of disputed parentage with 2 presumptive related fathers, although using multiple genetic systems, neither of the 2 fathers may be excluded. Nineteen autosomal short tandem repeat typing and 12 X-chromosome markers could not clarify the case. We can conclude that forensic autosomic short tandem repeats included in commercial kits are not sufficient to definitively discriminate parent-offspring with related putative fathers in forensic laboratories, and supplementary investigations should be available for selected cases.

Performance of the Human Quantifiler, the Investigator Quantiplex and the Investigator ESSplex Plus kit for quantification and nuclear DNA typing of old skeletal remains

Aim. We tested the performance of two real-time polymerase chain reaction (PCR) human quantification kits (Human Quantifiler (Applied Biosystems) and Investigator Quantiplex kit (Qiagen)) and forensic identification short tandem repeat (STR) Investigator ESSplex Plus (Qiagen) kit on approximately 70 years old skeletal remains. Methods. We analysed 54 bones and teeth excavated from Second World War mass graves in Slovenia. Genomic DNA was obtained from 0.5 g of bone or tooth powder after total demineralization. The DNA was purified in a Biorobot EZ1 (Qiagen) device. The same extract was used for quantification and STR typing with all three kits using the amplification conditions recommended by the manufacturers. Results. In almost two thirds of the samples the results of quantification were up to 6 times higher using the Human Quantifiler than using the Investigator Quantiplex kit, because of the degradation of DNA in old skeletal remains and amplification of shorter DNA fragment with the Human Quantifiler kit. The autosomal STR typing with the Investigator ESSplex Plus kit was successful in 52 out of the 54 samples, which represent a 96% success rate. Conclusion. The commercially available Investigator ESSplex Plus kit can be used for STR typing of old skeletal remains with the DNA extraction method optimised in our laboratory and without any changes to the manufacturers' PCR amplification protocols. The Human Quantifiler kit and Investigator Quantiplex kit together can be used for estimation of the degree of DNA degradation in compromised old bone samples.

A Comparative Analysis of the AmpFlSTR Identifiler and PowerPlex 16 Autosomal Short Tandem Repeat (STR) Amplification Kits on the Skeletal Remains Excavated from Second World War Mass Graves in Slovenia

Aim. This paper describes a comparative study of two different amplification kits for autosomal STR typing of skeletal remains excavated from Second World War mass graves in Slovenia. We analyzed 92 bones and teeth and compared the genetic profiles obtained using the AmpFlSTR IdentifilerTM Amplification Kit (Applied Biosystems) and the PowerPlex 16 System (Promega). Methods. We cleaned the bones and teeth, removed surface contamination and ground them into a powder using liquid nitrogen. Prior to deoksiribo nucleic acid (DNA) isolation with Biorobot EZ1 (Qiagen), 0.5g bone or tooth powder was decalcified. The nuclear DNA of the samples was quantified using the real-time polymerase chain reaction (PCR) method. The amplification protocols for both kits were optimised for old skeletal remains. Results. We extracted 0.4 to 100 ng DNA/g of powder from the bones and teeth. Both amplification kits showed very similar efficiency on the 70 year old bones and teeth, since DNA typing was successful in 81 out of the 92 bones and teeth with both amplification kits, which represent an 88% success rate. Conclusions. The comparative study indicated that the commercially available Identifiler and PowerPlex 16 PCR amplification kits are reliable for short tandem repeat (STR) typing of World War II skeletal remains with the DNA extraction method and PCR amplification conditions optimised in our laboratory, since very often complete STR profiles of autosomal DNA were obtained with both kits.

Long-term room temperature preservation of corpse soft tissue: an approach for tissue sample storage

BackgroundDisaster victim identification (DVI) represents one of the most difficult challenges in forensic sciences, and subsequent DNA typing is essential. Collected samples for DNA-based human identification are usually stored at low temperature to halt the degradation processes of human remains. We have developed a simple and reliable procedure for soft tissue storage and preservation for DNA extraction. It ensures high quality DNA suitable for PCR-based DNA typing after at least 1 year of room temperature storage.MethodsFragments of human psoas muscle were exposed to three different environmental conditions for diverse time periods at room temperature. Storage conditions included: (a) a preserving medium consisting of solid sodium chloride (salt), (b) no additional substances and (c) garden soil. DNA was extracted with proteinase K/SDS followed by organic solvent treatment and concentration by centrifugal filter devices. Quantification was carried out by real-time PCR using commercial kits. Short tandem repeat (STR) typing profiles were analysed with 'expert software'.ResultsDNA quantities recovered from samples stored in salt were similar up to the complete storage time and underscored the effectiveness of the preservation method. It was possible to reliably and accurately type different genetic systems including autosomal STRs and mitochondrial and Y-chromosome haplogroups. Autosomal STR typing quality was evaluated by expert software, denoting high quality profiles from DNA samples obtained from corpse tissue stored in salt for up to 365 days.ConclusionsThe procedure proposed herein is a cost efficient alternative for storage of human remains in challenging environmental areas, such as mass disaster locations, mass graves and exhumations. This technique should be considered as an additional method for sample storage when preservation of DNA integrity is required for PCR-based DNA typing.

Real-time forensic DNA analysis at a crime scene using a portable microchip analyzer

An integrated lab-on-a-chip system has been developed and successfully utilized for real-time forensic short tandem repeat (STR) analysis. The microdevice comprises a 160-nL polymerase chain reaction reactor with an on-chip heater and a temperature sensor for thermal cycling, microvalves for fluidic manipulation, a co-injector for sizing standard injection, and a 7-cm-long separation channel for capillary electrophoretic analysis. A 9-plex autosomal STR typing system consisting of amelogenin and eight combined DNA index system (CODIS) core STR loci has been constructed and optimized for this real-time human identification study. Reproducible STR profiles of control DNA samples are obtained in 2 h and 30 min with ≤0.8 bp allele typing accuracy. The minimal amount of DNA required for a complete DNA profile is 100 copies. To critically evaluate the capabilities of our portable microsystem as well as its compatibility with crime scene investigation processes, real-time STR analyses were carried out at a mock crime scene prepared by the Palm Beach County Sheriff's Office (PBSO). Blood stain sample collection, DNA extraction, and STR analyses on the portable microsystem were conducted in the field, and a successful “mock” CODIS hit was generated on the suspect's sample within 6 h. This demonstration of on-site STR analysis establishes the feasibility of real-time DNA typing to identify the contributor of probative biological evidence at a crime scene and for real-time human identification.

Mutations or exclusion: an unusual case in paternity testing

In an immigration case with the scope of family reunification, the DNA extracted from the saliva samples of the male child, the alleged mother and the putative father was typed with 22 autosomal short tandem repeat (STR) systems. In seven STR systems, the alleged mother could be excluded from maternity, and the case then had to be regarded as a deficiency case. Taking this fact into consideration, only two exclusions were found for the putative father, and the question arose whether there was an exclusion of the putative father or the existence of two mutations. Autosomal STR typing could not clarify the case, but the application of eight Y-chromosomal markers showed that the alleged father could be excluded from paternity.