Reference DNA Samples Research Articles

Development and Evaluation of a Semi-Nested PCR Method Based on the 18S ribosomal RNA Gene for the Detection of Babesia aktasi Infections in Goats.

We developed and evaluated a semi-nested PCR assay for the detection of Babesia aktasi infection in goats based on the sequence of the B. aktasi 18S ribosomal RNA gene. Following in silico screening, the specificity of the primers was assessed using reference DNA samples, including B. ovis, B. motasi, B. crassa, B. venatorum, B. divergens, B. capreoli, Theileria ovis, and T. annulata. To determine the sensitivity of the method, blood infected with 2% parasitemia of B. aktasi was diluted to 10-fold serial dilutions. The method specifically amplified a 438 bp fragment of B. aktasi DNA, but did not demonstrate cross-amplification with the other hemoparasites tested. The sensitivity assay indicated that this PCR method was able to detect infection at a dilution of 10-8 of 2% parasitemia (0.074 parasites/200 µL). Ninety-seven blood samples collected from goats were used to analyze for B. aktasi, and the infection was detected in 18.5% of the goats. Additionally, the method was also applied to 44 field DNA samples that were detected to be positive for B. aktasi by reverse line blotting (RLB), and showed 84.1% agreement. The findings revealed that newly developed semi-nested PCR can detect B. aktasi infections in goats with high sensitivity and specificity.

Use of the EmsB microsatellite-based next generation sequencing for genotyping of Echinococcus granulosus sensu lato in hydatid cyst tissue samples from animals and humans.

Echinococcus granulosus (Batsch, 1786), a cestode of the Teniidae family, causes human cystic echinococcosis (CE) also known as hydatid disease. Echinococcus granulosus sensu lato includes the G1, G3, G4, G5, G6/7 and G8/10 genotypes which are known to cause human CE. This study aimed to differentiate genotypes of E. granulosus s.l. complex by employing EmsB, a tandemly repeated multilocus microsatellite, using next-generation sequencing (MIC-NGS). Human and animal histopathology-confirmed hydatid cyst tissue samples and reference DNA samples of E. granulosus G1, G3, G4, G5, G6/7 and G10 underwent MIC-NGS assay with custom primers amplifying a 151 bp EmsB DNA fragment. NGS data were analysed using online Galaxy analysis pipeline, a phylogenetic tree was constructed by MEGA software, and haplotype networking was performed with PopArt 1.7. All sixty samples (49 from animals and 11 from humans) included were successfully identified and genotyped with a 100 % success rate. The study showed improved discrimination power to distinguish all study samples including closely related E. granulosus s.s. genotypes G1-G3. The maximum likelihood tree reaffirmed the monophyly of E. granulosus s.l. The median-joining haplotype networking revealed 12 distinct haplotypes. In conclusion, MIC-NGS assay was shown to be sensitive, specific and simple to apply to clinical samples offering a powerful discriminatory tool for the genotyping of E. granulosus s.l.

Abstract 6423: KRAS mutation detection by Sanger sequencing using the SeqStudio Flex capillary electrophoresis instrument

Abstract The detection of mutations in the KRAS gene highly associated with cancer is one of the most widely used Sanger sequencing capillary electrophoresis (CE) applications in molecular diagnostics. In addition to their traditional role in cancer diagnostic, KRAS mutations have recently gained additional relevance as pharmacogenomics (PGx) markers for a significant number of new oncology therapeutics. KRAS mutation detection assays are used as companion diagnostics (CDx) for these cancer treatments. Analysis by Sanger Sequencing of KRAS mutations is cost effective and lends itself for use in resource limited healthcare settings. While there are currently no commercial kits for targeted sequencing of the KRAS mutation hotspots available, the online Applied Biosystems Primer Designer™ Tool (thermofisher.com) allows standardization of the PCR primer design between labs and repeat orders of the KRAS assays by using these commercially available assay ID numbers. Here we demonstrate the use of Primer Designer KRAS mutation detections assays for mutation in codon 12, 13 and 61 totaling to 8 allele variants. The data was generated on the SeqStudio Flex CE instrument using reference standard DNA as well as DNA extracted from FFPE solid tumor samples. We show accuracy of variant call (OPA 100% (64/64)) and concordance (OPA 98.3% (59/60)) in a side-by-side comparison of the SeqStudio Flex with the legacy Model 3500 Genetic Analyzer instrument using a set of commercially available (Horizon Discovery) KRAS reference DNA samples. Primary solid tumor samples are processed to Fresh Frozen Paraffin Embedded samples (FFPE) for further disease marker evaluation. These samples are stable for long term at ambient temperatures and provide the opportunity to evaluate prospective biomarkers at large scale to understand their potential utility. Discovery Life Sciences has generated a large-scale biorepository of human biospecimen, including FFPE, plasma/sera, buffy coat, and PBMCs. Archival FFPE samples from oncology indications associated with KRAS mutations, such as non-small cell lung cancer and colorectal cancer, were analyzed and identified samples with KRAS mutations, demonstrating the potential diagnostic utility of these assays. Finally, cell-free (cf) DNA from double spun plasma from relevant indications was also successfully evaluated for KRAS mutations, highlighting the potential for these assays in liquid biopsy studies. The study demonstrates the robustness of the Primer Designer KRAS mutation detection sequencing assays using reference standard DNA as well as DNA derived from FFPE DNA and cfDNA from patient derived tumor samples. For Research Use Only. Not for use in diagnostic procedures. Citation Format: Achim Karger, Ami Patel, Kaylee Tseng, Camila Ornelas, Mary Napier, Rod Beck, Kerri Collwell, Shawn Fahl, Carole Bornarth. KRAS mutation detection by Sanger sequencing using the SeqStudio Flex capillary electrophoresis instrument [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6423.

Genotyping of European Toxoplasma gondii strains by a new high-resolution next-generation sequencing-based method

PurposeA new high-resolution next-generation sequencing (NGS)-based method was established to type closely related European type II Toxoplasma gondii strains.MethodsT. gondii field isolates were collected from different parts of Europe and assessed by whole genome sequencing (WGS). In comparison to ME49 (a type II reference strain), highly polymorphic regions (HPRs) were identified, showing a considerable number of single nucleotide polymorphisms (SNPs). After confirmation by Sanger sequencing, 18 HPRs were used to design a primer panel for multiplex PCR to establish a multilocus Ion AmpliSeq typing method. Toxoplasma gondii isolates and T. gondii present in clinical samples were typed with the new method. The sensitivity of the method was tested with serially diluted reference DNA samples.ResultsAmong type II specimens, the method could differentiate the same number of haplotypes as the reference standard, microsatellite (MS) typing. Passages of the same isolates and specimens originating from abortion outbreaks were identified as identical. In addition, seven different genotypes, two atypical and two recombinant specimens were clearly distinguished from each other by the method. Furthermore, almost all SNPs detected by the Ion AmpliSeq method corresponded to those expected based on WGS. By testing serially diluted DNA samples, the method exhibited a similar analytical sensitivity as MS typing.ConclusionThe new method can distinguish different T. gondii genotypes and detect intra-genotype variability among European type II T. gondii strains. Furthermore, with WGS data additional target regions can be added to the method to potentially increase typing resolution.

Validation and benchmarking of targeted panel sequencing for cancer genomic profiling.

To validate a large next-generation sequencing (NGS) panel for comprehensive genomic profiling and improve patient access to more effective precision oncology treatment strategies. OncoPanScan was designed by targeting 825 cancer-related genes to detect a broad range of genomic alterations. A practical validation strategy was used to evaluate the assay's analytical performance, involving 97 tumor specimens with 25 paired blood specimens, 10 engineered cell lines, and 121 artificial reference DNA samples. Overall, 1107 libraries were prepared and the sequencing failure rate was 0.18%. Across alteration classes, sensitivity ranged from 0.938 to more than 0.999, specificity ranged from 0.889 to more than 0.999, positive predictive value ranged from 0.867 to more than 0.999, repeatability ranged from 0.908 to more than 0.999, and reproducibility ranged from 0.832 to more than 0.999. The limit of detection for variants was established based on variant frequency, while for tumor mutation burden and microsatellite instability, it was based on tumor content, resulting in a minimum requirement of 20% tumor content. Benchmarking variant calls against validated NGS assays revealed that variations in the dry-bench processes were the primary cause of discordances. This study presents a detailed validation framework and empirical recommendations for large panel validation and elucidates the sources of discordant alteration calls by comparing with "gold standard measures."

The case of Pfc. Charles McAllister

In 2004, the remains of two First World War US soldiers from France were delivered to the US Government for identification and burial. One set of remains was identified and buried, and the other went into a cold-case status. In 2019, the second individual was identified using multiple lines of evidence. The possible individuals that could be associated with the remains were reduced based on material evidence recovered with the remains and the spatiotemporal historical context of the remains. The First World War personnel records then offered sufficient biometric criteria to narrow the possible individuals associated with the second recovered individual to one person, Pfc. Charles McAllister. A family reference DNA sample from a direct matrilineal descendant of the individual added statistical weight to the identification, although the mtDNA was not a decisive or necessary factor in the identification. Due to bureaucratic reasons, the legal identification of Pfc. Charles McAllister is still pending.

Applying Unique Molecular Indices with an Extensive All-in-One Forensic SNP Panel for Improved Genotype Accuracy and Sensitivity

One of the major challenges in forensic genetics is being able to detect very small amounts of DNA. Massively parallel sequencing (MPS) enables sensitive detection; however, genotype errors may exist and could interfere with the interpretation. Common errors in MPS-based analysis are often induced during PCR or sequencing. Unique molecular indices (UMIs) are short random nucleotide sequences ligated to each template molecule prior to amplification. Applying UMIs can improve the limit of detection by enabling accurate counting of initial template molecules and removal of erroneous data. In this study, we applied the FORCE panel, which includes ~5500 SNPs, with a QIAseq Targeted DNA Custom Panel (Qiagen), including UMIs. Our main objective was to investigate whether UMIs can enhance the sensitivity and accuracy of forensic genotyping and to evaluate the overall assay performance. We analyzed the data both with and without the UMI information, and the results showed that both genotype accuracy and sensitivity were improved when applying UMIs. The results showed very high genotype accuracies (>99%) for both reference DNA and challenging samples, down to 125 pg. To conclude, we show successful assay performance for several forensic applications and improvements in forensic genotyping when applying UMIs.

DNA extraction procedures and validation parameters of a real-time PCR method to control milk containing only A2 β-casein

Bovine milk mainly contains two types of β-casein: A1 and A2 variants. In recent years, a new variety of cows’ milk has emerged in dairy sector called “A2 milk”. This novel product is characterised by the absence of A1 β-casein, which has been associated with possible gastrointestinal discomfort due to β-casomorphin-7 (BCM-7) release during gastrointestinal digestion. In this context, methods to verify A1 allele absence in A2 milk are required as a quality control in the A2 milk commercialisation. Therefore, the aim of the present study was to develop a locked nucleic acid (LNA) probe-based duplex real-time PCR (qPCR) assay for A1 allele detection in A2 milk samples. Firstly, four DNA isolation methods from milk somatic cells were optimised and evaluated. Results suggests that the commercial kit NucleoSpin Tissue was the most suitable method in terms of DNA quality and amplificability for downstream applications. Then, optimisation and validation of the qPCR assay were carried out. For both A1 and A2 alleles, the absolute limits of detection of this qPCR assay were 7.3 DNA copies/reaction (2 x 10 −5 ng DNA) and 30.4 DNA copies/reaction (0.1 ng DNA) at a 95% confidence level with synthetic reference DNA samples and heterozygous genotyped DNA sample, respectively. The relative limits of detection were 2% (15 copies) and 5% (152 copies) for A1 allele in A2 samples at a 95% confidence with synthetic reference and genotyped DNA samples, respectively. The qPCR assay was robust, with intra- and inter-assay variability below 4.3%, and specific, differentiating between A1 and A2 alleles with 100% genotyping accuracy. In conclusion, this cost-effective and fast method could be used to discriminate A1 allele in A2 samples and, consequently, to verify A1 allele absence in “A2 milk” by screening commercial product on the market. • The LNA duplex qPCR assay developed could be used to verify A1 allele absence in “A2 milk”. • LNA probes reliably discriminated between A1 and A2 alleles. • The relative limits of detection reach up to 2% (15 copies) for A1 allele in A2 samples at a 95% confidence. • Milk is a challenging matrix for DNA isolation due to the presence of PCR inhibitors that leads to low DNA yield.

P-552 Analysis of the genomewide BAF profiles of selected SNPs allows reliable aneuploidy detection in preimplantation embryos, independent of haplotyping

Abstract Study question Can we reliably detect aneuploidy in trophectoderm samples using SNP array data, independent of haplotyping? Summary answer We identified all chromosomes with meiotic copy number gains and non-mosaic copy number losses larger than 5Mb that had been detected with Karyomapping. What is known already Currently, generic methods such as Karyomapping (Vitrolife) and OnePGT (Agilent), are commonly used for preimplantation genetic testing of monogenic disorders (PGT-M). The genome-wide approach has the advantage that also aneuploidy can be detected by visualizing the haplotypes, the raw B-allele frequency (BAF) and the copynumber (CN) or Log2 ratio (Log2R) values. However, these haplotyping methods have considerable shortcomings for PGT-A including the need of reference DNA samples from both sides of the family and the long time required to access all haplotype information. We aimed to circumvent these shortcomings with our own proprietary method. Study design, size, duration We retrospectively re-analyzed the available raw SNP array data from 359 embryos with trophectoderm biopsy between September 1 2015 and December 31 2017 that were diagnosed with Karyomapping (Vitrolife) as being not genetically transferable. The local ethical committee approved this study under number B.U.N. 143201731745. Written informed consent was available. We intended to identify anomalies >5Mb that are detectable by haplotyping. Participants/materials, setting, methods SNPs were categorized based on the parental SNP genotypes. Next, the BAF values for each category of SNPs (cBAF) were extracted from the raw SNP array data and visualized on genomewide plots. The obtained cBAF plots were analyzed for the presence of aneuploidy together with raw BAF and Log2R SNP data. The results from the interpretation of these profiles were compared with the findings previously obtained with Karyomapping (Log2R, raw BAF and haplotype profiles). Main results and the role of chance A low level maternal contamination was observed in 5 embryos by analysis of cBAF profiles that had not been detected using Karyomapping. In five other embryos, an abnormal ploidy was observed with both methods. In the remaining 8027 chromosomes from 349 embryos, all 70 chromosomes with both parental homolog (BPH) anomalies larger than 5Mb detected with Karyomapping were identified by analysis of cBAF profiles. In 68 chromosomes the type (segmental or whole chromosome) and the copy number (+1 or + 2 copies) of the detected BPH anomaly was identical with both methods. All 93 chromosomes with a copy number loss larger than 5Mb detected with Karyomapping were identified by analysis of cBAF profiles. For 92 out of 93 chromosomes the type of non-mosaic copy number loss was identical (segmental or whole chromosome). Out of 17 single parental homolog (SPH) copy number gains interpreted as non-mosaic by Karyomapping, 16 were interpreted as non-mosaic based on cBAF profiles. In one instance, the SPH copy number detected with Karyomapping was interpreted as a mosaic SPH trisomy using cBAF. Two chromosomes with mosaic anomalies and one chromosome without diagnosis with Karyomapping were interpreted as non-mosaic anomalies using cBAF. Limitations, reasons for caution In case of consanguinity aneuploidy may be more difficult to detect. The limit of detection for the size of segmental anomalies remains to be determined. Wider implications of the findings By analyzing the cBAF profiles we were able to detect all types of chromosome anomaly that are detectable by haplotyping. We were able to identify meiotic BPH copy number gains and determine the parent of origin for all anomalies without haplotyping and hence without the need for DNA from familymembers. Trial registration number not applicable

Abstract 6201: Cross-platform comparisons for DNA methylation sequencing

Abstract Introduction: Accurate, reproducible, and cost-effective NGS platform is essential to identify malignancy-related abnormal DNA methylation changes and translate them into clinical applications including cancer detection, prognosis, and surveillance. In this study we evaluated the performances by the MGISEQ-2000 sequencer in DNA methylation sequencing, using Illumina’s NovaSeq6000 as a benchmark. Materials and Methods: We performed both genome-wide methylation profiling and targeted methylation sequencing on reference DNA and clinical DNA samples. To minimize non-platform discrepancies, we prepared 2 libraries, one for NovaSeq600 and the other for MGISEQ-2000, from each DNA sample using the same experimental protocol except the last step, when we used indexed primers whose sequences and chemical modification are compatible with either NovaSeq600 or MGISEQ-2000 to amplify the corresponding library. We conducted standardized analyses on MGISEQ-2000’s reads quality, sequence bias, genome alignment and coverage, regional depth, limits of detection (LOD), etc. We compared methylation levels at CpG sites, and measurements of methylation haplotypes to assess the consistency in mapping and quantifying genome-wide and regional methylation by MGISEQ-2000 and between the 2 platforms. Furthermore, we analyzed inter-platform variations in classifying normal and malignant plasma DNA samples using targeted methylation sequencing data from either platform exclusively. Results: We prepared and sequenced libraries from over 100 DNA samples of normal or malignant tissue or blood samples for comparison, in addition to reference DNA. Overall, MGISEQ-2000 displayed high level of consistency, and little-to-no sequence bias in methylation sequencing. At genome-wide, regional, and individual-CpG levels, MGISEQ-2000 demonstrated high degree of concordance with NovaSeq6000 in quantifying DNA methylation, as the inter-platform Pearson correlation coefficients were consistently above 0.90 or higher for both targeted sequencing and whole-genome bisulfite sequencing, regardless of whether average methylation level (AMF) or methylation haplotype-specific metrics such as Methylation Haplotype Load (MHL) were used to quantify methylation. Additionally, MGISEQ-2000 is as sensitive as NovaSeq6000 at detecting spik-in methylation controls, as both reached an LOD of 0.1%. Lastly, MGISEQ-2000 produced similar results in classifying normal and malignant samples as NovaSeq6000, suggesting it had minimal distortion on the NovaSeq6000-based classifier. Conclusions: MGISEQ-2000 demonstrated comparable data quality, methylation-calling accuracy, and consistency as NovaSeq6000 in DNA methylation sequencing, supporting its application in future investigation on DNA methylation as cancer biomarkers. Citation Format: Mingyang Su, Jin Sun, Jianhua Ma, Jun Xia, Chengcheng Ma, Wei Li, Zhixi Su, Qiye He, Rui Liu. Cross-platform comparisons for DNA methylation sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6201.

Development and evaluation of ActSeq: A targeted next-generation sequencing panel for clinical oncology use.

PurposeThe demand for high-throughput genetic profiling of somatic mutations in cancer tissues is growing. We sought to establish a targeted next generation sequencing (NGS) panel test for clinical oncology practice.MethodsCustomized probes were designed to capture exonic regions of 141 genes selected for the panel, which was aimed for the detection of clinically actionable genetic variations in cancer, including KRAS, NRAS, BRAF, ALK, ROS1, KIT and EGFR. The size of entire targeted regions is 0.8 Mb. Library preparation used NEBNext Ultra II FS kit coupled with target enrichment. Paired-end sequencing was run on Illumina NextSeq 500 at a read length of 150 nt. A bioinformatics workflow focusing on single nucleotide variant and short insertions and deletions (SNV/indel) discovery was established using open source, in-house and commercial software tools. Standard reference DNA samples were used in testing the sensitivity and precision and limit of detection in variant calling.ResultsThe general performance of the panel was observed in pilot runs. Average total reads per sample ranged from 30 million to 48 million, 73% ~82% unique reads. All runs had more than 99% average mapping rate. Mean target coverage ranged from 727x to 879x. Depth of coverage at 50x or more reached 87% of targeted region and 60% of targeted region received 500x or more coverage depth. Using OncoSpan HD827 DNA, which bears 144 variants (SNV/indel) from 80 genes that are within the targeted region on the panel, our somatic variant calling pipeline reached 97% sensitivity and 100% precision respectively, with near 48 million reads. High concordance with orthogonal approaches in variant detection was further verified with 7 cancer cell lines and 45 clinical specimens.ConclusionWe developed a NGS panel with a focus on clinically actionable gene mutations and validated the performance in library construction, sequencing and variant calling. High concordance with reference materials and orthogonal mutation detection was observed.

Dreading Yet Hoping: Traumatic Loss Impacted by Reference DNA Sample Collection for Families of Missing People.

The trauma of having a family member missing is commonly described as an ambiguous loss where the finality of the loss is not realized, as is experienced with a death. There is uncertainty due to the trauma of the absence and subsequent police investigation, leading to physical and emotional impacts for the aftercare of those left behind. There are 850 unidentified human remains and 2,600 long-term missing persons cases in Australia. The Australian Federal Police (AFP) National DNA Program for Unidentified and Missing Persons aims to scientifically link these cases using modern DNA techniques and databases. A DNA-led identification effort may assist to provide answers to Australian families searching for missing relatives, but may also contribute to the trauma experienced by these families. A literature review demonstrated empirical research for the development of scientific best practices for the collection of reference DNA samples for forensic purposes, but minimal evidence about the impact of reference DNA sample collection on kin when attempting to identify the deceased remains of missing people in non-mass casualty situations. The aim of this study was to develop an academically robust understanding of the unique impact of reference DNA sample collection on families of missing persons and support pathways tailored to the experience. This study involved 26 Australian families of long-term missing (ranging from 1 to 20+ years) people in Australia anonymously completing a mixed-methods online survey about their experiences of providing reference DNA samples to aid missing persons investigations. Respondents were representative of a range of ages, genders and relationships to the missing individual. The thematic analysis of the survey results identified the provision of a reference DNA sample: (1) resembles an overt act of hope as families perceive their sample assists the investigation, whilst also being traumatic, triggered by the prospect of scientifically matching their missing family member to a set of unknown human remains; (2) can cause immediate interpersonal impacts and ongoing impacts to families' wellbeing; and (3) can be improved by considering the environment where the sample is collected, professionalism of the police officer collecting the sample, timeliness of the provision of the sample, level of support provided during and after sample collection, and effective communication of forensic procedures and processes as they relate to the missing persons investigation. The study concludes that the complexity associated with provision of family reference samples requires the development and implementation of best practice guidelines, including psycho-education strategies to be used by practitioners to minimize the vicarious trauma for relatives already traumatized by the loss of their missing family member. These guidelines would support the objectives of the AFP Program and benefit all routine missing persons investigations.

Consistency and reproducibility of large panel next-generation sequencing: Multi-laboratory assessment of somatic mutation detection on reference materials with mismatch repair and proofreading deficiency

IntroductionClinical precision oncology increasingly relies on accurate genome-wide profiling using large panel next generation sequencing; however, difficulties in accurate and consistent detection of somatic mutation from individual platforms and pipelines remain an open question. ObjectivesTo obtain paired tumor–normal reference materials that can be effectively constructed and interchangeable with clinical samples, and evaluate the performance of 56 panels under routine testing conditions based on the reference samples. MethodsGenes involved in mismatch repair and DNA proofreading were knocked down using the CRISPR-Cas9 technology to accumulate somatic mutations in a defined GM12878 cell line. They were used as reference materials to comprehensively evaluate the reproducibility and accuracy of detection results of oncopanels and explore the potential influencing factors. ResultsIn total, 14 paired tumor–normal reference DNA samples from engineered cell lines were prepared, and a reference dataset comprising 168 somatic mutations in a high-confidence region of 1.8 Mb were generated. For mutations with an allele frequency (AF) of more than 5% in reference samples, 56 panels collectively reported 1306 errors, including 729 false negatives (FNs), 179 false positives (FPs) and 398 reproducibility errors. The performance metric varied among panels with precision and recall ranging from 0.773 to 1 and 0.683 to 1, respectively. Incorrect and inadequate filtering accounted for a large proportion of false discovery (including FNs and FPs), while low-quality detection, cross-contamination and other sequencing errors during the wet bench process were other sources of FNs and FPs. In addition, low AF (<5%) considerably influenced the reproducibility and comparability among panels. ConclusionsThis study provided an integrated practice for developing reference standard to assess oncopanels in detecting somatic mutations and quantitatively revealed the source of detection errors. It will promote optimization, validation, and quality control among laboratories with potential applicability in clinical use.

ECNano: A cost-effective workflow for target enrichment sequencing and accurate variant calling on 4800 clinically significant genes using a single MinION flowcell

BackgroundThe application of long-read sequencing using the Oxford Nanopore Technologies (ONT) MinION sequencer is getting more diverse in the medical field. Having a high sequencing error of ONT and limited throughput from a single MinION flowcell, however, limits its applicability for accurate variant detection. Medical exome sequencing (MES) targets clinically significant exon regions, allowing rapid and comprehensive screening of pathogenic variants. By applying MES with MinION sequencing, the technology can achieve a more uniform capture of the target regions, shorter turnaround time, and lower sequencing cost per sample.MethodWe introduced a cost-effective optimized workflow, ECNano, comprising a wet-lab protocol and bioinformatics analysis, for accurate variant detection at 4800 clinically important genes and regions using a single MinION flowcell. The ECNano wet-lab protocol was optimized to perform long-read target enrichment and ONT library preparation to stably generate high-quality MES data with adequate coverage. The subsequent variant-calling workflow, Clair-ensemble, adopted a fast RNN-based variant caller, Clair, and was optimized for target enrichment data. To evaluate its performance and practicality, ECNano was tested on both reference DNA samples and patient samples.ResultsECNano achieved deep on-target depth of coverage (DoC) at average > 100× and > 98% uniformity using one MinION flowcell. For accurate ONT variant calling, the generated reads sufficiently covered 98.9% of pathogenic positions listed in ClinVar, with 98.96% having at least 30× DoC. ECNano obtained an average read length of 1000 bp. The long reads of ECNano also covered the adjacent splice sites well, with 98.5% of positions having ≥ 30× DoC. Clair-ensemble achieved > 99% recall and accuracy for SNV calling. The whole workflow from wet-lab protocol to variant detection was completed within three days.ConclusionWe presented ECNano, an out-of-the-box workflow comprising (1) a wet-lab protocol for ONT target enrichment sequencing and (2) a downstream variant detection workflow, Clair-ensemble. The workflow is cost-effective, with a short turnaround time for high accuracy variant calling in 4800 clinically significant genes and regions using a single MinION flowcell. The long-read exon captured data has potential for further development, promoting the application of long-read sequencing in personalized disease treatment and risk prediction.

On Taking DNA Reference Samples - Comment to the Judgment of the European Court of Human Rights of 14 April 2020 in the Case of Dragan Petrović v. Serbia, Application no. 75229/10

The comment deals with the evaluation of (not only) Serbian law concerning taking body samples for DNA examinations. The authors share the arguments of the dissenting opinion from the judgment in question that the phrase “other medical procedures” was at that stage sufficient for such a procedure. A comparative analysis of the Polish law is also conducted.

The FORCE Panel: An All-in-One SNP Marker Set for Confirming Investigative Genetic Genealogy Leads and for General Forensic Applications.

The FORensic Capture Enrichment (FORCE) panel is an all-in-one SNP panel for forensic applications. This panel of 5422 markers encompasses common, forensically relevant SNPs (identity, ancestry, phenotype, X- and Y-chromosomal SNPs), a novel set of 3931 autosomal SNPs for extended kinship analysis, and no clinically relevant/disease markers. The FORCE panel was developed as a custom hybridization capture assay utilizing ~20,000 baits to target the selected SNPs. Five non-probative, previously identified World War II (WWII) cases were used to assess the kinship panel. Each case included one bone sample and associated family reference DNA samples. Additionally, seven reference quality samples, two 200-year-old bone samples, and four control DNAs were processed for kit performance and concordance assessments. SNP recovery after capture resulted in a mean of ~99% SNPs exceeding 10X coverage for reference and control samples, and 44.4% SNPs for bone samples. The WWII case results showed that the FORCE panel could predict first to fifth degree relationships with strong statistical support (likelihood ratios over 10,000 and posterior probabilities over 99.99%). To conclude, SNPs will be important for further advances in forensic DNA analysis. The FORCE panel shows promising results and demonstrates the utility of a 5000 SNP panel for forensic applications.

Streamlining the decision-making process for international DNA kinship matching using Worldwide allele frequencies and tailored cutoff log10LR thresholds

The identification of human remains belonging to missing persons is one of the main challenges for forensic genetics. Although other means of identification can be applied to missing person investigations, DNA is often extremely valuable to further support or refute potential associations. When reference DNA samples cannot be collected from personal items belonging to a missing person, a direct DNA identification cannot be carried out. However, identifications can be made indirectly using DNA from the missing person’s relatives. The ranking of likelihood ratio (LR) values, which measure the fit of a missing person for any given pedigree, is often the first step in selecting candidates in a DNA database. Although implementing DNA kinship matching in a national environment is feasible, many challenges need to be resolved before applying this method to an international configuration. In this study, we present an innovative and intuitive method to perform international DNA kinship matching and facilitate the comparison of DNA profiles when the ancestry is unknown or unsure and/or when different marker sets are used. This straightforward method, which is based on calculations performed with the DNA matching software BONAPARTE, Worldwide allele frequencies and tailored cutoff log10LR thresholds, allows for the classification of potential candidates according to the strength of the DNA evidence and the predicted proportion of adventitious matches. This is a powerful method for streamlining the decision-making process in missing person investigations and DVI processes, especially when there are low numbers of overlapping typed STRs. Intuitive interpretation tables and a decision tree will help strengthen international data comparison for the identification of reported missing individuals discovered outside their national borders.

Performance assessment of DNA sequencing platforms in the ABRF Next-Generation Sequencing Study.

Assessing the reproducibility, accuracy and utility of massively parallel DNA sequencing platforms remains an ongoing challenge. Here the Association of Biomolecular Resource Facilities (ABRF) Next-Generation Sequencing Study benchmarks the performance of a set of sequencing instruments (HiSeq/NovaSeq/paired-end 2 × 250-bp chemistry, Ion S5/Proton, PacBio circular consensus sequencing (CCS), Oxford Nanopore Technologies PromethION/MinION, BGISEQ-500/MGISEQ-2000 and GS111) on human and bacterial reference DNA samples. Among short-read instruments, HiSeq 4000 and X10 provided the most consistent, highest genome coverage, while BGI/MGISEQ provided the lowest sequencing error rates. The long-read instrument PacBio CCS had the highest reference-based mapping rate and lowest non-mapping rate. The two long-read platforms PacBio CCS and PromethION/MinION showed the best sequence mapping in repeat-rich areas and across homopolymers. NovaSeq 6000 using 2 × 250-bp read chemistry was the most robust instrument for capturing known insertion/deletion events. This study serves as a benchmark for current genomics technologies, as well as a resource to inform experimental design and next-generation sequencing variant calling.

What is she doing here? Klinefelter syndrome in forensic casework

In this case report, we describe a sexual assault incident in which the male victim’s seminal fluid contained no sperm cells, as indicated by sperm cell staining and microscopic screening, and DNA profiling results from the non-sperm cell fraction showed a major/minor DNA mixture that could be interpreted as female and male. DNA profiling of a sample from a disposable drinking cup used by the victim at the crime scene provided a single source profile, and showed a 2:1 imbalance between the heights of the X and Y chromosomes, respectively. The victim’s DNA reference sample showed a similar imbalance of the X and Y chromosomes. These observations suggested that the victim might suffer from Klinefelter syndrome, a genetic disorder related to the sex chromosomes.Here, we describe the first reported use of the QIAGEN Investigator® Argus X-12 kit for characterization of X-chromosomal STR loci to potentially identify a case of Klinefelter syndrome. This commercially available kit is primarily used in forensic laboratories to investigate kinship relations and for paternity testing in alleged father/daughter cases. Results of the X chromosome DNA profiling from the victim’s disposable drinking cup and reference samples revealed two alleles at various X-chromosomal STR loci. Moreover, this kit can also amplify a Y chromosome specific sequence (AMEL-Y), and the results indicated that this sample actually originated from a male. Evidence of two X chromosomes in the victim's DNA suggested that he was likely to have Klinefelter syndrome. In this case report, we propose the use of the QIAGEN Investigator® Argus X-12 kit as a practical forensic tool for the detection of potential genetic syndromes related to the sex chromosomes, which can affect test results and, at times, make them difficult to interpret. We also aim to increase awareness within the forensic science community regarding the existence of genetic anomalies, which should be considered when analyzing DNA profiles.

Abstract 4315: NGS-based reference materials for fusion and somatic variant detection in myeloid cancers

Abstract The large range of genetic aberrations and genes involved Myeloid malignancies, clonal diseases of hematopoietic progenitor cells which can lead to accumulation of immature blast cells in the bone marrow and peripheral blood, make Next Generation Sequencing (NGS) assays a cost effective and sensitive way to determine genetic changes. Understanding the genetic changes which lead to the clonal proliferation can aid in both determining prognosis and therapy selection. Consequently, there are an increasing number of NGS-based oncology tests available for somatic mutation detection in patients with hematological malignancies. However, reference materials that contain the relevant genetic blood cancer mutations are lacking. We designed a purified RNA reference material that contains nine RNA fusions two different ETV6-ABL1 transcripts, including BCR-ABL1, MYST3-CREBBP, RUNX1-RUNX1T1, and PML-RARα which are important in myeloid cancers. Conversely, a purified DNA reference material was designed to include 23 somatic variants included two FLT3 internal tandem duplications. The biosynthetic RNA or DNA constructs were mixed with either total RNA or purified genomic DNA from GM24385 reference human cell line. Digital PCR was used to quantify the variant sequences to determine the abundance of the fusion RNAs and the allele frequencies of the somatic mutations. NGS testing on a variety of targeted NGS assays was then performed to show compatibility. The Seraseq Myeloid RNA Mix was tested by digital PCR to confirm that each of the nine fusions in the reference samples are present at approximately 100 fusion copies per nanogram of total RNA. The FusionPlex Myeloid Kit for Illumina (ArcherDx) as well as the Oncomine Myeloid Panel (Thermo Fisher) showed positive detection for all fusions present in the reference samples. In addition, the Seraseq Myeloid DNA Mix was also tested by digital PCR to confirm the variant allele frequencies were on target at the 5%, 10% or 15% VAF. While, dPCR allele specific assays could not be obtained for CEBPA mutations, NGS testing of the reference samples by VariantPlex Core Myeloid Kit for Illumina (ArcherDx) and Oncomine Myeloid Panel (Thermo Fisher) confirmed the presence of these mutations at the expected levels, as well as all of the other variants in the DNA reference samples. In conclusion, SeraCare has developed highly multiplexed RNA and DNA-based reference materials for evaluating Myelogenous disorders by NGS. The reference materials allow monitoring of a broad range of somatic mutations and gene fusions which can aid optimization and verification of detection limits for NGS-based Myeloid disease assay testing, and provide laboratories greater assurance in their ability to correctly detect and quantify various types of genetic events in diseased patient samples. Citation Format: Farol Lovell Tomson, Praveena Kamineni, Catherine Huang, Jessica Dickens, Dan Brudzewsky, Omoshile Clement, Ram Santhanam, Bharathi Anekella. NGS-based reference materials for fusion and somatic variant detection in myeloid cancers [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4315.