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The standard-of-care (SOC) diagnostic prenatal testing includes a combination of cytogenetic methods such as karyotyping, fluorescence in situ hybridization (FISH), and chromosomal microarray (CMA) using either direct or cultured amniocytes or chorionic villi sampling (CVS). However, each technology has its limitations: karyotyping has a low resolution (>5Mb), FISH is targeted, and CMA does not detect balanced structural variants (SVs) or decipher complex rearrangements in the genome. These limitations necessitate the use of multiple tests, either simultaneously or sequentially to reach a genetic diagnosis. This long-standing prenatal testing workflow demonstrates the need for an alternative technology that can provide high-resolution results in a cost and time-effective manner. Optical genome mapping (OGM) is an emerging technology that has demonstrated its ability to detect all classes of SVs, including copy number variations (CNVs) and balanced abnormalities in a single assay, but has not been evaluated in the prenatal setting. This retrospective validation study analyzed 114 samples (including replicates), representing 94 unique and well-characterized samples that were received in our laboratory for traditional cytogenetic analysis with karyotyping, FISH, and/or CMA. Samples comprised 84 cultured amniocytes, and 10 phenotypically normal and cytogenetically negative controls. Six samples were run in triplicate to evaluate intra-run, inter-run, and inter-instrument reproducibility. Clinically relevant SVs and CNVs were reported using the Bionano Access software with standardized and built-in filtration criteria and phenotype-specific analysis. OGM was 100% concordant in identifying the 101 aberrations that included 29 interstitial/terminal deletions, 28 duplications, 26 aneuploidies, 6 absence of heterozygosity (AOH), 3 triploid genomes, 4 Isochromosomes, 1 translocation, and revealed the identity of 3 marker chromosomes, and 1 chromosome with additional material not determined by karyotyping. Additionally, OGM detected 64 additional clinically reportable SVs in 43 samples. OGM demonstrated high technical and analytical robustness and a limit of detection of 5% allele fraction for interstitial deletions and duplications, and 10% allele fraction for translocation and aneuploidy. This study demonstrates that OGM has the potential to identify unique genomic abnormalities such as CNVs, AOHs, and several classes of SVs including complex structural rearrangements. OGM has a standardized laboratory workflow and reporting solution that can be adopted in routine clinical laboratories and demonstrates the potential to replace the current SOC methods for prenatal diagnostic testing. We recommend its use as a first-tier genetic diagnostic test in a prenatal setting.

The current standard-of-care cytogenetic techniques for the analysis of hematological malignancies include karyotyping, fluorescence in situ hybridization, and chromosomal microarray, which are labor intensive and time and cost prohibitive, and they often do not reveal the genetic complexity of the tumor, demonstrating the need for alternative technology for better characterization of these tumors. Herein, we report the results from our clinical validation study and demonstrate the utility of optical genome mapping (OGM), evaluated using 92 sample runs (including replicates) that included 69 well-characterized unique samples (59 hematological neoplasms and 10 controls). The technical performance (quality control metrics) resulted in 100% first-pass rate, with analytical performance (concordance) showing a sensitivity of 98.7%, a specificity of 100%, and an accuracy of 99.2%. OGM demonstrated robust technical, analytical performance, and interrun, intrarun, and interinstrument reproducibility. The limit of detection was determined to be at 5% allele fraction for aneuploidy, translocation, interstitial deletion, and duplication. OGM identified several additional structural variations, revealing the genomic architecture in these neoplasms that provides an opportunity for better tumor classification, prognostication, risk stratification, and therapy selection. Overall, OGM has outperformed the standard-of-care tests in this study and demonstrated its potential as a first-tier cytogenomic test for hematologic malignancies.

The standard-of-care (SOC) for genomic testing of myeloid cancers primarily relies on karyotyping/fluorescent in situ hybridization (FISH) (cytogenetic analysis) and targeted gene panels (usually ≤54 genes) that harbor hotspot pathogenic variants (molecular genetic analysis). Despite this combinatorial approach, ~50% of myeloid cancer genomes remain cytogenetically normal, and the limited sequencing variant profiles obtained from targeted panels are unable to resolve the molecular etiology of many myeloid tumors. In this study, we evaluated the performance and clinical utility of combinatorial use of optical genome mapping (OGM) and a 523-gene next-generation sequencing (NGS) panel for comprehensive genomic profiling of 30 myeloid tumors and compared it to SOC cytogenetic methods (karyotyping and FISH) and a 54-gene NGS panel. OGM and the 523-gene NGS panel had an analytical concordance of 100% with karyotyping, FISH, and the 54-gene panel, respectively. Importantly, the IPSS-R cytogenetic risk group changed from very good/good to very poor in 22% of MDS (2/9) cases based on comprehensive profiling (karyotyping, FISH, and 54-gene panel vs. OGM and 523-gene panel), while additionally identifying six compound heterozygous events of potential clinical relevance in six cases (6/30, 20%). This cost-effective approach of using OGM and a 523-gene NGS panel for comprehensive genomic profiling of myeloid cancers demonstrated increased yield of actionable targets that can potentially result in improved clinical outcomes.

PURPOSEThe recommended practice for individuals suspected of a genetic etiology for disorders including unexplained developmental delay/intellectual disability (DD/ID), autism spectrum disorders (ASD), and multiple congenital anomalies (MCA) involves a genetic testing workflow including chromosomal microarray (CMA), Fragile-X testing, karyotype analysis, and/or sequencing based gene panels. Since genomic imbalances are often found to be causative, CMA is recommended as first tier testing for many indications. Optical genome mapping (OGM) is an emerging next generation cytogenomic technique that can detect not only copy number variants (CNVs), triploidy and absence of heterozygosity (AOH) like CMA, but can also define the location of duplications, and detect other structural variants (SVs), including balanced rearrangements and repeat expansions/contractions. This study compares OGM to CMA for clinically reported genomic variants, some of which have additional structural characterization with fluorescencein situhybridization (FISH).METHODSOGM was performed on IRB approved, de-identified specimen from 55 individuals with unbalanced genomic abnormalities previously identified by CMA (61 clinically reported abnormalities). SVs identified by OGM were filtered by a control database to remove polymorphic variants and against an established gene list to prioritize clinically relevant findings before comparing with CMA and FISH results.RESULTSTOGM results showed 100% concordance with CMA findings for pathogenic variants and 98% concordant for all pathogenic/likely pathogenic/variants of uncertain significance (VUS), while also providing additional insight into the genomic structure of abnormalities that CMA was unable to provide.CONCLUSIONOGM demonstrates equivalent or superior performance to CMA and adds to an increasing body of evidence on the analytical validity and ability to detect clinically relevant abnormalities identified by CMA. Moreover, OGM identifies translocations, structures of duplications and complex CNVs intractable by CMA, yielding additional clinical utility.

7-Methylxanthine (7-MX, CAS No. 552-62-5, purity 99.46%) is the first orally administered drug candidate, which showed anti-myopic activity in different pre-clinical studies. In the present study, we investigated the

Structural variations (SVs) play a key role in the pathogenicity of hematological malignancies. Standard-of-care (SOC) methods such as karyotyping and fluorescencein situhybridization (FISH), employed globally for the past three decades have significant limitations in the resolution or the number of recurrent aberrations that can be simultaneously assessed, respectively. Next-generation sequencing (NGS) based technologies are now widely used to detect clinically significant sequence variants but are limited in their ability to accurately detect SVs. Optical genome mapping (OGM) is an emerging technology enabling the genome-wide detection of all classes of SVs at a significantly higher resolution than karyotyping and FISH. OGM neither requires cultured cells nor amplification of DNA and hence addresses the limitations of culture and amplification biases. This study reports the clinical validation of OGM as a laboratory developed test (LDT), according to CLIA guidelines, for genome-wide SV detection in different hematological malignancies. In total, 68 cases with hematological malignancies (of various subtypes), 27 controls and two cancer cell lines were used for this study. Ultra-high molecular weight DNA was extracted from the samples, fluorescently labeled, and run on the Bionano Genomics Saphyr system. A total of 207 datasets, including replicates, were generated and 100% could be analyzed successfully. Sample data were then analyzed using either disease specific or pan-cancer specific BED files to prioritize calls that are known to be diagnostically or prognostically relevant. Accuracy, precision, PPV and NPV were all 100% against standard of care results. Sensitivity, specificity, and reproducibility were 100%, 100% and 96%, respectively. Following the validation, 11 cases were run and analyzed using OGM at three additional sites. OGM found more clinically relevant SVs compared to SOC testing due to its ability to detect all classes of SVs at much higher resolution. The results of this validation study demonstrate OGM’s superiority over traditional SOC methods for the detection of SVs for the accurate diagnosis of various hematological malignancies.

The clinical performance of saliva compared with nasopharyngeal swabs (NPSs) has shown conflicting results in healthcare and community settings. In the present study, a total of 429 matched NPS and saliva sample pairs, collected in either healthcare or community setting, were evaluated. Phase-1 (protocol U) tested 240 matched NPS and saliva sample pairs; phase 2 (SalivaAll protocol) tested 189 matched NPS and saliva sample pairs, with an additional sample homogenization step before RNA extraction. A total of 85 saliva samples were evaluated with both protocols. In phase-1, 28.3% (68/240) samples tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from saliva, NPS, or both. The detection rate from saliva was lower compared with that from NPS samples (50.0% versus 89.7%). In phase-2, 50.2% (95/189) samples tested positive for SARS-CoV-2 from saliva, NPS, or both. The detection rate from saliva was higher compared with that from NPS samples (97.8% versus 78.9%). Of the 85 saliva samples evaluated with both protocols, the detection rate was 100% for samples tested with SalivaAll, and 36.7% with protocol U. The limit of detection with SalivaAll protocol was 20 to 60 copies/mL. The pooled testing approach demonstrated a 95% positive and 100% negative percentage agreement. This protocol for saliva samples results in higher sensitivity compared with NPS samples and breaks the barrier to using pooled saliva for SARS-CoV-2 testing.

Cytogenetic analysis for hematological malignancies most often includes karyotyping, fluorescence in situ hybridization, and rarely, chromosomal microarray (CMA). While considered the gold standard, karyotyping and FISH have significant limitations in resolution of structural variants (SVs). CMA has a much higher resolution, but cannot detect balanced SVs, and is less commonly used in the hematologic oncology setting. Optical genome mapping (OGM) can detect all classes of SVs at high resolution (duplications, deletions, inversions, insertions, translocations), and as such, detects many copy number variants (CNVs) and SVs that have not been previously described. Although these novel SVs will help better describe genetic contributions to disease, analysis, interpretation and curation can take considerable time. A streamlined workflow has been developed for use with Bionano VIA™ software for a comprehensive analysis of relevant SVs in a hematological malignancy genome. First, by employing disease-specific decision trees for variants published in guidelines for those conditions, the software automatically flags Tier 1A variants detected according to ACMG/AMP/CGC criteria. Second, the overall genome complexity is assessed by observing chromosomal abnormalities detected by OGM. Large events (>5Mb) are counted, and complex genomes are assigned if there are more than 3 or 5 events, depending on the cancer type. Third, calls are further refined by filtering on a pan-cancer specific list to capture those variants that are then manually classified as Tier 1B or 2 by the analyst. The Bionano VIA software allows case-specific and disease subtype-specific information to be added to various sections within the software, such as the Knowledgebase, Event Table, and Sample Info fields to facilitate autopopulation of reportable data and interpretations into a formatted report template. Bionano VIA software can also accommodate multiple platforms simultaneously (e.g., NGS panels) to provide users with a comprehensive view of genomic aberrations relevant to hematological malignancies. This workflow is intended to streamline analysis and automate reporting of oncology samples, which can be extremely complex and often require extensive research. Citation Format: Benjamin Clifford, Jen Hauenstien, Andy Wing Chun Pang, Rachel D. Burnside, Neil Miller, Alex Hastie, Alka Chaubey. Streamlined workflow for analyzing and reporting hematological malignancies in Bionano VIATM software [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2227.

Certain cancer treatments, such as the poly (ADP-ribos) polymerase (PARP) inhibitors, have been shown to be effective in killing cancer cells exhibiting genome instability signatures indicative of homologous recombination deficiency (HRD). Hence, these signatures are used as biomarkers to inform treatment decisions and prognosis. There are three measurements of HRD signatures commonly employed: loss of heterozygosity (HRD-LOH), telomeric allelic imbalance (TAI) and large-scale state transition (LST). It has been shown that combining all three scores can better determine the HRD phenotype, leading to a higher clinical impact. Yet current HRD signature tests, used to estimate HRD, have low negative predictive value, and one possible reason is that current genomic technologies lack sensitivity to capture the full extent of somatic genomic rearrangements. Here, optical genome mapping (OGM) was used to detect large structural variants (SVs) and calculate a HRD score. OGM captures high molecular weight DNA to call SVs by aligning these molecules to the public reference genome. OGM can comprehensively detect insertions and deletions >5kbp, inversions, interchromosomal translocations, plus large interstitial copy number variation (CNV) and aneusomies. Subsequently, an automated script was developed to compute the HRD score, which is the summation of the three HRD signatures: HRD-LOH, the number of regions with a loss >15 Mbp but shorter than the whole chromosome; TAI, the number of regions of gain and loss >10Mbp that extend to a subtelomere but do not cross the centromere; and LST, the number of chromosomal breakpoints whose SV size >10Mb but not the whole chromosome. We applied this script on 20 samples of solid tumors and myeloid neoplasms, and the automated scores are concordant with expertly curated scores, confirming the validity of the calculation. We believe that OGM data combined with this automated analysis of HRD signatures is much more sensitive and accurate for detection of HRD signatures and that this will enable more precise prediction of drug response for multiple tumor types. Citation Format: Andy Wing Chun Pang, Kelsea Chang, Nikhil Sahajpal, Daniel Saul, Ravindra Kolhe, Alka Chaubey, Alex Hastie. Application of optical genome mapping to identify samples with homologous recombination deficiency [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6539.

Hematological neoplasms are predominantly defined by chromosomal aberrations that include structural variations (SVs) and copy number variations (CNVs). The current standard-of-care (SOC) genetic testing for the detection of SVs and CNVs relies on a combination of traditional cytogenetic techniques that include karyotyping, fluorescence in situ hybridization (FISH), and chromosomal microarrays (CMA). These techniques are labor-intensive, time and cost-prohibitive, and often do not reveal the genetic complexity of the tumor. Optical genome mapping (OGM) is an emerging technology that can detect all classes of SVs in a single assay. We report the results from our clinical validation (in a CLIA setting) of the OGM technique for hematological neoplasms. The study included 92 sample runs (including replicates) using 69 well-characterized unique samples (59 hematological neoplasms and 10 controls). The technical (QC metrics and first-pass rate) and analytical performance [sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV)] were evaluated using the clinical samples. The reproducibility was evaluated by performing inter-run, intra-run, and inter-instrument comparisons using six samples run in triplicates. The limit of detection (LoD) for aneuploidy, translocation, interstitial deletion, and duplication was assessed. To confirm the LoD, samples at 12.5%, 10%, and 5% allele fractions (theoretical LoD range) were run in triplicates. The technical performance resulted in a 100% first-pass rate with all samples meeting the minimum QC metrics. The analytical performance showed a sensitivity of 98.7%, specificity of 100%, accuracy of 99.2%, PPV of 100%, and NPV of 98%, which included the detection of 61 aneuploidies, 34 deletions, 28 translocations, 11 duplications/amplifications, 15 insertions/additional material not identified with karyotyping, 12 marker chromosomes, and one each of ring chromosome, inversion and isochromosome. OGM demonstrated robust technical and analytical inter-run, intra-run, and inter-instrument reproducibility. The LoD was determined to be at 5% allele fraction for all the variant classes evaluated in the study. In addition, OGM demonstrated higher resolution to refine breakpoints, identify the additional genomic material, marker, and ring chromosomes. OGM identified several additional SVs, revealing the genomic architecture in these neoplasms that provides an opportunity for better tumor classification, prognostication, risk stratification, and therapy selection. This study is the first CLIA validation report for OGM for genome-wide structural variation detection in hematological neoplasms. Considering the technical and analytical advantages of OGM compared to the current SOC methods used for chromosomal characterization, we highly recommend OGM as a potential first-tier cytogenetic test for the evaluation of hematological neoplasms.

DNA copy number variants (CNVs) account for approximately 300 Mb of sequence variation in the normal human genome. Significant numbers of pathogenic CNVs contribute toward human genetic disorders. Recent studies suggest a higher diagnostic and clinical significance of low-pass genome sequencing (LP-GS) compared with chromosomal microarrays (CMAs). The performance metrics of the 5X LP-GS was compared with CMA to validate a low-cost and high-throughput method. LP-GS test performed on 409 samples (including 78 validation and 331 clinical) was evaluated using American College of Medical Genetics and Genomics guidelines. The CNV accuracy, precision, specificity, and sensitivity were calculated to be 100% for all previously characterized CNVs by CMA. Samples (n = 6) run at both approximately 30X GS and approximately 5X GS (LP-GS) average depth detected a concordance of 89.43% to 91.8% and 77.42% to 89.86% for overall single-nucleotide variants and insertions/deletions, respectively. In the 331 clinical samples, 17.2% each were classified as pathogenic/likely pathogenic and uncertain clinical significance. In addition, several cases with pathogenic CNVs were detected that were missed by CMA. This study demonstrates that LP-GS (5X GS) was able to reliably detect absence of heterozygosity, microdeletion/microduplication syndromes, and intragenic CNVs with higher coverage and resolution over the genome. Because of lower cost, higher resolution, and greater sensitivity of this test, our study in combination with other reports could be used in an evidence-based review by professional societies to recommend replacing CMAs.

Conventional cytogenetic analysis of products of conception (POC) is of limited utility because of failed cultures, as well as microbial and maternal cell contamination (MCC). Optical genome mapping (OGM) is an emerging technology that has the potential to replace conventional cytogenetic methods. The use of OGM precludes the requirement for culturing (and related microbial contamination). However, a high percentage of MCC impedes a definitive diagnosis, which can be addressed by an additional pre-analytical quality control step that includes histological assessment of H&E stained slides from formalin-fixed paraffin embedded (FFPE) tissue with macro-dissection for chorionic villi to enrich fetal tissue component for single nucleotide polymorphism microarray (SNPM) analysis. To improve the diagnostic yield, an integrated workflow was devised that included MCC characterization of POC tissue, followed by OGM for MCC-negative cases or SNPM with histological assessment for MCC-positive cases. A result was obtained in 93% (29/31) of cases with a diagnostic yield of 45.1% (14/31) with the proposed workflow, compared to 9.6% (3/31) and 6.4% (2/31) with routine workflow, respectively. The integrated workflow with these technologies demonstrates the clinical utility and higher diagnostic yield in evaluating POC specimens.

Conventional cytogenetic analysis of products of conception (POC) is of limited utility because of failed cultures, microbial and maternal cell contamination (MCC). Optical genome mapping (OGM) is an emerging technology that has the potential to replace conventional cytogenetic methods. The use of OGM precludes the requirement for culturing (and related microbial contamination). However, a high percentage of MCC impedes a definitive diagnosis, which can be addressed by an additional pre-analytical quality control step that includes histological assessment of H&E stained slides from FFPE tissue with macro-dissection for Chorionic villi to enrich fetal tissue component for Single nucleotide polymorphism (SNP) microarray analysis. An internal audit of POC cases subjected to karyotype-only analysis showed a low yield on clinically actionable information that contributed to patient care. To improve the diagnostic yield, an integrated workflow was devised that included MCC characterization of POC tissue, followed by OGM for MCC negative cases or SNPM with histological assessment for MCC positive cases. A result was obtained in 93% (29/31) cases with a diagnostic yield of 45.1% (14/31) with proposed workflow compared to 9.6% (3/31) and 6.4% (2/31) with routine workflow, respectively. The integrated workflow with these technologies demonstrates the clinical utility and higher diagnostic yield in evaluating POC specimens.

The standard-of-care (SOC) for genomic testing of myeloid cancers primarily relies on karyotyping and fluorescent in situ hydridization (FISH) (cytogenetic analysis) and targeted gene panels (≤54 genes) that harbor hotspot pathogenic variants (molecular genetic analysis). Both cytogenetic and molecular testing workup is necessary for the identification and detection of large structural variants (SVs) and small variants like single nucleotide variants (SNV) and indels, respectively. Despite this combinatorial approach, ∼50% of myeloid cancer genomes remain cytogenetically normal, and the limited sequencing variant profiles obtained from targeted panels are unable to resolve the genetic etiology of these myeloid tumors. In this study, we evaluated the performance and clinical utility of optical genome mapping (OGM) and a 523-gene next-generation sequencing (NGS) panel for comprehensive genomic profiling of 15 myeloid tumors and compared it to SOC cytogenetic methods (karyotyping and FISH) and a 54-gene NGS panel. OGM and the 523-gene NGS panel were found to have an analytical concordance of 100% with karyotyping, FISH, and the 54-gene panel, respectively. Additionally, OGM better characterized and resolved the structural variants previously reported by karyotyping in five cases, such as identifying the genomic content of marker and ring chromosomes. OGM also identified several additional translocations and eleven copy number variations (CNVs), of which the CNVs were validated/confirmed by the 523-gene panel. The 523-gene panel identified seven additional clinically relevant SNVs (two tier 1A variants and five tier 2C variants, as per the ACMG/AMP guidelines) in four cases. The simultaneous visualization of SVs and small NGS detected sequence variants (SNVs and small indels) from OGM and 523-gene NGS panel, respectively in the NxClinical software v6.1 identified two clinically relevant compound heterozygous events in two samples. This study demonstrates the higher sensitivity, resolution, accuracy, and ability to reveal cryptic and clinically relevant novel variants in myeloid cancers as compared to SOC methodologies. Our cost-effective approach of using OGM and a 523-gene NGS panel for comprehensive genomic profiling of myeloid cancers will not only increase the yield of actionable targets leading to improved clinical outcomes but also help resolve our ongoing conundrum of apparently genomically normal myeloid cancers by providing more answers.

BackgroundIn the current phase of COVID-19 pandemic, we are facing two serious public health challenges that include deficits in SARS-CoV-2 variant monitoring, and neglect of other co-circulating respiratory viruses. Additionally, accurate assessment of the evolution, extent and dynamics of the outbreak are required to understand the transmission of the virus amongst seemingly unrelated cases and provide critical epidemiological information. To address these challenges, we evaluated a new high-throughput next-generation sequencing (NGS), respiratory viral panel (RVP) that includes 40 viral pathogens with the aim of analyzing viral subtypes, mutational variants of SARS-CoV-2, model to understand the spread of the virus in the state of Georgia, USA, and to assess other circulating viruses in the same population.MethodsThis study evaluated a total of 522 samples that included 483 patient samples and 42 synthetic positive control material. The performance metrics were calculated for both clinical and reference control samples by comparing detection results with the RT-PCR assay. The limit of detection (LoD) studies were conducted as per the FDA guidelines. Inference and visualization of the phylogeny of the SARS-CoV-2 sequences were performed through the Nextstrain Command-Line Interface (CLI) tool, utilizing the associated augur and auspice toolkits.ResultsThe performance metrics calculated using both the clinical samples and the reference controls revealed a PPA, NPA and accuracy of 95.98%, 85.96% and 94.4%, respectively. The LoD was determined to be 10 copies/ml with all 25 replicates detected across two different runs. The clade for pangolin lineage B that contains certain distant variants, including P4715L in ORF1ab, Q57H in ORF 3a and, S84L in ORF8 covarying with the D614G spike protein mutation were the most prevalent, early in the pandemic, in Georgia, USA. In our analysis, isolates from the same county formed paraphyletic groups, which indicated virus transmission between counties.ConclusionThe study demonstrates the clinical and public health utility of the NGS-RVP to identify novel variants that can provide actionable information to prevent or mitigate emerging viral threats, models that provide insights into viral transmission patterns and predict transmission/ resurgence of regional outbreaks and provide critical information on co-circulating respiratory viruses that might be independent factors contributing to the global disease burden.

Background: Rolling-circle replication (RCR) is a novel technology that has not been applied to cell-free DNA (cfDNA) testing until recently. Given the cost and simplicity advantages of this technology compared to other platforms currently used in cfDNA analysis, an assessment of RCR in clinical laboratories was performed. Here, we present the first validation study from clinical laboratories utilizing RCR technology. Methods: 831 samples from spontaneously pregnant women carrying a singleton fetus, and 25 synthetic samples, were analyzed for the fetal risk of trisomy 21 (T21), trisomy 18 (T18) and trisomy 13 (T13), by three laboratories on three continents. All the screen-positive pregnancies were provided post-test genetic counseling and confirmatory diagnostic invasive testing (e.g., amniocentesis). The screen-negative pregnancies were routinely evaluated at birth for fetal aneuploidies, using newborn examinations, and any suspected aneuploidies would have been offered diagnostic testing or confirmed with karyotyping. Results: The study found rolling-circle replication to be a highly viable technology for the clinical assessment of fetal aneuploidies, with 100% sensitivity for T21 (95% CI: 82.35–100.00%), 100.00% sensitivity for T18 (71.51–100.00%), and 100.00% sensitivity for T13 analyses (66.37–100.00%). The specificities were &gt, 99% for each trisomy (99.7% (99.01–99.97%) for T21, 99.5% (98.62–99.85%) for T18, 99.7% (99.03–99.97%) for T13), along with a first-pass no-call rate of 0.93%. Conclusions: The study showed that using a rolling-circle replication-based cfDNA system for the evaluation of the common aneuploidies would provide greater accuracy and clinical utility compared to conventional biochemical screening, and it would provide comparable results to other reported cfDNA methodologies.

BackgroundRolling circle replication (RCR) is a novel technology that has not been applied to cell-free DNA (cfDNA) testing until recently. Given the cost and simplicity advantages of this technology compared to other platforms currently used in cfDNA analysis, an assessment of RCR in clinical laboratories was performed. Here, we present the first validation study from clinical laboratories utilizing RCR technology.Methods831 samples from spontaneously pregnant women carrying a singleton fetus and 25 synthetic samples were analyzed for the fetal risk of Trisomy 21, Trisomy 18 and Trisomy 13 by three laboratories on three continents. All women who provided the samples were followed to birth, where evaluation for fetal aneuploidies was performed using newborn examinations and any suspected aneuploidies were confirmed with karyotyping.ResultsThe study found rolling circle replication to be a highly viable technology for clinical assessment of fetal aneuploidies with 100% sensitivity for T21 (95% CI:82.35% - 100.00%); 100.00% sensitivity for T18 (71.51% - 100.00%) and 100.00% sensitivity for T13 analyses (66.37% - 100.00%). The specificities were >99% for each trisomies [99.7% (99.01% - 99.97%) for T21; 99.5% (98.62% - 99.85%) for T18; 99.7% (99.03% - 99.97%) for T13], along with a first pass no-call rate of 0.93%.ConclusionsThe study showed that using a rolling circle replication-based cfDNA system for the evaluation of the common aneuploidies would provide greater accuracy and clinical utility compared to conventional biochemical screening and comparable results to other reported cfDNA methodologies.

Background Copy-neutral absence of heterozygosity (CN-AOH) observed on a single chromosome or part of a chromosome may be indicative of uniparental disomy (UPD) and may require additional testing when such chromosomes or chromosome regions are known to harbor imprinted genes. Case presentation Here we report 2 cases of neonates that presented to clinic with hypotonia, poor oral skills including inability to feed by mouth, weak cry, no response to noxious stimulation and vertical plantar creases (case 1) and hypotonia and respiratory distress (case 2). A preliminary chromosome analysis showed normal karyotypes in both cases while the high-resolution single nucleotide polymorphism (SNP) microarray showed copy neutral absence of heterozygosity involving chromosome 15 distal long arm. In case 1, the CN-AOH involved a 28.7 Mb block from genomic coordinates 73703619_102429049. In case 2, the CN-AOH involved a 15.3 Mb block from genomic coordinates 54729197_70057534. In both cases, methylation-specific PCR did not detect an unmethylated allele for the SNRPN gene suggesting either a deletion of paternal allele or maternal UPD for chromosome 15. Since microarray analysis did not show any copy number alterations on chromosome 15, a microdeletion was ruled out. Conclusions Based on our cases, we suggest that CN-AOH on chromosome 15, even if it does not involve the critical region of 15q12q13, should warrant additional studies for diagnosis of Prader–Willi/Angelman syndromes.