Continual Improvement of the Reliability of Next-Generation Sequencing-Based ctDNA Analysis: A Long-Term Comparison of ctDNA Detection in China.

BACKGROUND: Since circulating tumor DNA (ctDNA) sequencing is increasingly being applied in clinical management of patients with cancer, its testing accuracy has become a matter of serious concern. To address this issue, a long-term ctDNA analysis proficiency testing (PT) scheme for next-generation sequencing (NGS) was launched in China in 2018, serving as an educational tool for assessing and improving the testing quality of NGS-based ctDNA detection. METHODS: Feedback from participating laboratories across 23 different PT samples containing different variants with varying variant allele frequency was collected between 2018 and 2021. To further show the landscape of changing conditions in accuracy and reliability of NGS-based ctDNA testing, performance was analyzed by evaluating the cfDNA extraction kits, testing panels, target enrichment strategies, and sequencing platforms. RESULTS: During the 4 years, 2745 results reported from 504 laboratories were evaluated. Only 66.3% of results from laboratories were entirely in concordance with the expected results. Nonetheless, along with an increasing number of participating laboratories, the number of errors occurring in laboratories, and the proportion of laboratories that experienced errors both showed a significant downward trend. No obvious differences in the error rates were found regarding the kit manufacturers or sequencing platform. Moreover, the individual performances of the laboratories improved when they participated in more PT scheme rounds. CONCLUSIONS: These data demonstrated that the performance of individual Chinese laboratories for NGS-based ctDNA analysis continuously improved over time with participation in PT schemes. However, further care must also be taken in standardized operations and validations.

Preparation of multiplexed control materials for cancer mutation analysis by genome editing in GM12878 cells.

BACKGROUND: Quality control materials are necessary for assay development, test validation, and proficiency testing in cancer mutation analysis. Most of the existing controls for somatic mutations only harbor a single variant and are derived from unstable cell lines. This study aimed to establish a method to create stable multianalyte controls in a defined background by genome editing in GM12878 cells, which also can be applied for the reference of next-generation sequencing. METHODS: GM12878 cells were electroporated with a donor plasmid containing a mutant DNA sequence and a Cas9/sgRNA expressing vector. The genome-edited GM12878 cell was validated with Sanger sequencing, amplification refractory mutation system (ARMS), and next-generation sequencing (NGS). RESULTS: We have successfully generated a mutant GM12878 cell line harboring the defined variants including single-nucleotide variants (SNVs), small insertions and deletions (indels), and structural variants (SVs). The introduction of intended mutations in GM12878 cell line was confirmed by both ARMS and sequencing methods. CONCLUSIONS: We developed a method for the preparation of the multiplexed controls for reference mutations in cancer gene by genome editing in GM12878 cells. This methodology can be used to generate other stable cancer reference materials with an unlimited supply.

From Somatic Variants Toward Precision Oncology: An Investigation of Reporting Practice for Next-Generation Sequencing-Based Circulating Tumor DNA Analysis.

BACKGROUND: With the accelerated development of next-generation sequencing (NGS), identified variants, and targeted therapies, clinicians who confront the complicated and multifarious genetic information may not effectively incorporate NGS-based circulating tumor DNA (ctDNA) analysis into routine patient care. Consequently, standardized ctDNA testing reports are of vital importance. In an effort to guarantee high-quality reporting performance, we conducted an investigation of the current detection and reporting practices for NGS-based ctDNA analysis. MATERIALS AND METHODS: A set of simulated ctDNA samples with known variants at known allelic frequencies and a corresponding case scenario were distributed to 66 genetic testing laboratories for ctDNA analysis. Written reports were collected to evaluate the detection accuracy, reporting integrity, and information sufficiency using 21 predefined criteria. RESULTS: Current reporting practices for NGS-based ctDNA analysis were found to be far from satisfactory, especially regarding testing interpretation and methodological details. Only 42.4% of laboratories reported the results in complete concordance with the expected results. Moreover, 74.2% of reports only listed aberrations with direct and well-known treatment consequences for the tumor type in question. Genetic aberrations for which experimental agents and/or drug access programs are available may thus be overlooked. Furthermore, methodological details for the interpretation of results were missing from the majority of reports (87.9%). CONCLUSION: This proof-of-principle study suggests that the capacity for accurate identification of variants, rational interpretation of genotypes, comprehensive recommendation of potential medications, and detailed description of methodologies need to be further improved before ctDNA analysis can be formally implemented in the clinic. IMPLICATIONS FOR PRACTICE: Accurate, comprehensive, and standardized clinical sequencing reports can help to translate complex genetic information into patient-centered clinical decisions, thereby shepherding precision oncology into daily practice. However, standards, guidelines, and quality requirements for clinical reports of next-generation sequencing (NGS)-based circulating tumor DNA (ctDNA) analysis are currently absent. By using a set of simulated clinical ctDNA samples and a corresponding case scenario, current practices were evaluated to identify deficiencies in clinical sequencing reports of ctDNA analysis. The recommendations provided here may serve as a roadmap for the improved implementation of NGS-based ctDNA analysis in the clinic.

RCasFISH: CRISPR/dCas9-Mediated in Situ Imaging of mRNA Transcripts in Fixed Cells and Tissues.

Effective characterization and imaging of endogenous RNA transcripts have important value in the diagnosis, treatment, and prognosis of diseases. Traditional qRT-PCR as a liquid-based RNA detection method might lead to false-negative results due to the admixture of too many nontarget cells. Also, many in situ RNA imaging methods were hindered by long turnaround time and insufficient signals. Here, we describe and evaluate a CRISPR/dCas9-MS2-based RNA fluorescence in situ hybridization assay (RCasFISH) for in situ amplified imaging and quantification of RNA transcripts in fixed cells as well as formalin-fixed, paraffin-embedded (FFPE) tissue sections at a single-molecular level in individual cells. Compared to single molecular FISH (smFISH), RCasFISH yields brighter dot signals and a better signal-to-noise ratio (SNR) with lower costs and less than 1.5 h of hybridization. In addition, by using human epidermal growth factor receptor 2 (HER2) as a model, we quantified individual HER2 mRNA molecules in clinical breast cancer FFPE tissue sections and demonstrated its potential to resolve FISH-equivocal cases. Therefore, RCasFISH may provide a new approach for gene expression studies in basic research and hold the potential for molecular diagnostic applications.

The miR-21 potential of serving as a biomarker for liver diseases in clinical practice.

The role of miR-21 in the pathogenesis of various liver diseases, together with the possibility of detecting microRNA in the circulation, makes miR-21 a potential biomarker for noninvasive detection. In this review, we summarize the potential utility of extracellular miR-21 in the clinical management of hepatic disease patients and compared it with the current clinical practice. MiR-21 shows screening and prognostic value for liver cancer. In liver cirrhosis, miR-21 may serve as a biomarker for the differentiating diagnosis and prognosis. MiR-21 is also a potential biomarker for the severity of hepatitis. We elucidate the disease condition under which miR-21 testing can reach the expected performance. Though miR-21 is a key regulator of liver diseases, microRNAs coordinate with each other in the complex regulatory network. As a result, the performance of miR-21 is better when combined with other microRNAs or classical biomarkers under certain clinical circumstances.

Utilizing CRISPR/Cas9 technology to prepare lymphoblastoid cell lines harboring genetic mutations for generating quality control materials in genetic testing.

BACKGROUND: To meet the requirements of the rapidly progressing genetic testing technologies in clinical laboratories, assuring the quality of genetic tests by utilizing appropriate quality control materials is of paramount importance. The CRISPR/Cas9 technology was used to prepare quality control materials because genome-edited human cell lines are one of the major resources for quality control materials. METHODS: In this study, in vitro transcribed sgRNA were transfected into a Cas9-expressing lymphoblastoid cell line (LCL)-by electroporation-to simulate the SEA-type deletion observed in α-thalassemia. The edited positive cell line was screened and identified by polymerase chain reaction (PCR) followed by Sanger sequencing. The whole-genome sequencing was also performed to show evidence of predicted mutation. RESULTS: The results showed that electroporation of the in vitro transcribed gRNAs into stable Cas9-expressing LCL was a more efficient gene-editing technique as compared to plasmid-mediated transfection, and that the positive rates could reach up to 35.9%. The predominance of indel sizes relative to the predicted deletion length was clustered between 10 and 0 bp. The results of whole-genome sequencing also demonstrated the existence of SEA-type deletion of α-thalassemia. CONCLUSIONS: Gene-editing based on Cas9-expressing LCL by electroporation of sgRNA was a more efficient approach to introduce mutations for generating quality control materials for genetic testing. The edited lymphoblastoid cell lines were feasible to serve as quality control materials in genetic testing.

Accuracy of analysis of cfDNA for detection of single nucleotide variants and copy number variants in breast cancer.

BACKGROUND: Gene variants are dependable and sensitive biomarkers for target-specific therapies in breast cancer (BC). However, detection of mutations within tissues has many limitations. Plasma circulating free DNA (cfDNA) has been reported in many studies as an alternative tool for detection of mutations. But the diagnostic accuracy of cfDNA for most mutations in BC needs to be reviewed. This study was designed to perform comparative assessment of the diagnostic performance of cfDNA and DNA extracted from tissues for detection of single nucleotide variants (SNV) and copy number variants (CNV). METHODS: True-positive (TP), false-positive (FP), false-negative (FN), and true-negative (TN) values were extracted from each selected study. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated. Subgroup analysis and single study omitted analysis were performed to quantify and explain the study heterogeneity. RESULTS: Twenty eligible studies that involved 1055 cases were included in this meta-analysis. SNV studies in early breast cancer (EBC) subgroup are not suitable for meta-analysis owing to high heterogeneity. However, in advanced breast cancer (ABC) subgroup, the pooled sensitivity and specificity of detection of SNVs were 0.78 (0.71-0.84) and 0.92 (0.87-0.95), respectively. The summary receiver operative curve (SROC) exhibited an area under the curve (AUC) of 0.91(0.88-0.93). The pooled results of studies involving subgroups of PIK3CA, TP53, and ESR1 indicate that the diagnostic value of different genes is different, such as AUC for PIK3CA and TP53 were reported to be 0.96 (0.94-0.98) and 0.94 (0.91-0.95), respectively, and ESR1 had the lowest diagnostic value of 0.80 (0.76-0.83). Owing to the low sensitivity and AUC in the cases of CNV, there is no value for cfDNA-based detection of CNV based on insufficient amount of CNV data. CONCLUSION: This meta-analysis suggests that the detection of gene mutations in cfDNA have adequate diagnostic accuracy and can be used as an alternative to the tumor tissue for detection of SNV but not for CNV in BC yet.

Clinician-friendly reports of molecular measurable residual disease monitoring in acute promyelocytic leukemia.

Molecular measurable residual disease (MRD) monitoring based on real-time quantitative reverse transcription PCR (RT-qPCR) plays an important role in acute promyelocytic leukemia (APL) management, but the performance status of clinical reports is unknown. This study focuses on the specific elements in molecular MRD monitoring report and their impact on clinical decision-making. The participating laboratories were asked to submit real and formal clinical reports for mock samples panel with APL clinical case. The MRD-specific elements were analyzed and summarized. The significance of longitudinal MRD monitoring curve and the missing MRD-specific elements for clinical decision-making were assessed. MRD-specific elements were significantly missing in clinical reports. The element "testing results" existed great inconsistencies in the written form of testing items and data. The longitudinal MRD monitoring curve of false-negative or false-positive MRD result was obviously different from all-correct. It not only identified MRD time point of tissue sampling relative to treatment and ensured the reliability of the negative MRD results, but also gave MRD diagnosis, clinical interpretation, and further recommendation. Clinician-friendly reports with MRD-specific elements can better serve clinical practice. The correctly intuitive results and clinically important MRD-specific elements can provide a good description of the reliability and clinical significance of MRD results.

The applications of CRISPR/Cas system in molecular detection.

The Streptococcus pyogenes CRISPR/Cas system has found widespread applications as a gene-editing and regulatory tool for the simultaneous delivery of the Cas9 protein and guide RNAs into the cell, thus making the recognition of specific DNA sequences possible. The recent study that shows that Cas9 can also bind to and cleave RNA in an RNA-programmable manner is suggestive of potential utility of this system as a universal nucleic-acid recognition tool. To increase the signal intensity of the CRISPR/Cas system, a signal amplification technique has to be exploited appropriately; this requirement is also a challenge for the detection of DNA or RNA. Furthermore, the CRISPR/Cas system may be used to detect point mutations or single-nucleotide variants because of the specificity of the recognition between the target sequence and the CRISPR/Cas system. These lines of evidence make this technique capable of detecting pathogens during infection via analysis of their DNA or RNA. Thus, here we summarize applications of the CRISPR/Cas system to the recognition and detection of DNA and RNA molecules as well as the signal amplification. We also describe its potential ability to detect mutations and single-nucleotide variants. Finally, we sum up its applications to testing for pathogens and potential barriers for its implementation.

A novel cell line generated using the CRISPR/Cas9 technology as universal quality control material for KRAS G12V mutation testing.

BACKGROUND: KRAS mutations are the key indicator for EGFR monoclonal antibody-targeted therapy and acquired drug resistance, and their accurate detection is critical to the clinical decision-making of colorectal cancer. However, no proper quality control material is available for the current detection methods, particularly next-generation sequencing (NGS). The ideal quality control material for NGS needs to provide both the tumor mutation gene and the matched background genomic DNA, which is uncataloged in public databases, to accurately distinguish germline polymorphisms and somatic mutations. METHODS: We developed a novel KRAS G12V mutant cell line using the clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) technique to make up for the deficiencies in existing quality control material and further validated the feasibility of the cell line as quality control material by amplification refractory mutation system (ARMS), Sanger sequencing, digital PCR (dPCR), and NGS. RESULTS: We verified that the edited cell line specifically had the G12V mutation, and the validation results presented a high consistency among the four methods of detection. The three cell lines screened contained the G12V mutation and the mutation allele fractions of G12V-1, G12V-2, and G12V-3 were 52.01%, 82.06%, and 17.29%, respectively. CONCLUSION: The novel KRAS G12V cell line generated using the CRISPR/Cas9 gene editing system is suitable as a quality control material for all current detection methods and provides a new direction in the development of quality control material.

Synthetic Circulating Cell-free DNA as Quality Control Materials for Somatic Mutation Detection in Liquid Biopsy for Cancer.

BACKGROUND: Detection of somatic genomic alterations in tumor-derived cell-free DNA (cfDNA) in the plasma is challenging owing to the low concentrations of cfDNA, variable detection methods, and complex workflows. Moreover, no proper quality control materials are available currently. METHODS: We developed a set of synthetic cfDNA quality control materials (SCQCMs) containing spike-in cfDNA on the basis of micrococcal nuclease digestion carrying somatic mutations as simulated cfDNA and matched genomic DNA as genetic background to emulate paired tumor-normal samples in real clinical tests. Site-directed mutagenesis DNA that contained 1500-2000 bases with single-nucleotide variants or indels and genomic DNA from CRISPR/Cas9 edited cells with EML4-ALK rearrangements was fragmented, quantified, and added into micrococcal nuclease-digested DNA derived from HEK293T cells. To prove their suitability, the SCQCMs were compared with patient-derived plasma samples and validated in a collaborative study that encompassed 11 laboratories. RESULTS: The results of SCQCM analysis by next-generation sequencing showed strong agreement with those of patient-derived plasma samples, including the size profile of cfDNA and the quality control metrics of the sequencing data. More than 95% of laboratories correctly detected the SCQCMs with EGFR T790M, L858R, KRAS G12D, and a deletion in exon 19, as well as with EML4-ALK variant 2. CONCLUSIONS: The SCQCMs were successfully applied in a broad range of settings, methodologies, and informatics techniques. We conclude that SCQCMs can be used as optimal quality controls in test performance assessments for circulating tumor DNA somatic mutation detection.

Enhancing the quality of panel-based tumor mutation burden assessment: a comprehensive study of real-world and in-silico outcomes.

Targeted panel-based tumor mutation burden (TMB) assays are widely employed to guide immunotherapy for patients with solid tumors. However, the accuracy and consistency of this method can be compromised due to the variability in technical details across different laboratories, particularly in terms of panel size, somatic mutation detection and TMB calculation rules. Currently, systematic evaluations of the impact of these technical factors on existing assays and best practice recommendations remain lacking. We assessed the performance of 50 participating panel-based TMB assays involving 38 unique methods using cell line samples. In silico experiments utilizing TCGA MC3 datasets were performed to further dissect the impact of technical factors. Here we show that the panel sizes beyond 1.04 Mb and 389 genes are necessary for the basic discrete accuracy, as determined by over 40,000 synthetic panels. The somatic mutation detection should maintain a reciprocal gap of recall and precision less than 0.179 for reliable psTMB calculation results. The inclusion of synonymous, nonsense and hotspot mutations could enhance the accuracy of panel-based TMB assay. A 5% variant allele frequency cut-off is suitable for TMB assays using tumor samples with at least 20% tumor purity. In conclusion, this multicenter study elucidates the major technical factors as sources of variability in panel-based TMB assays and proposed comprehensive recommendations for the enhancement of accuracy and consistency. These findings will assist clinical laboratories in optimizing the methodological details through bioinformatic experiments to enhance the reliability of panel-based methods.

A novel method for the preparation of reproducible, stable, and non-infectious quality control materials for Chlamydia trachomatis nucleic acid detection.

Chlamydia trachomatis (CT) is a significant sexually transmitted pathogen known to evoke severe complications, including infertility. Nucleic acid amplification tests (NAATs) are recommended by the World Health Organization to detect CT infection. Furthermore, the establishment of methods, performance validation, internal quality control, and external quality assessment for CT NAATs necessitate the utilization of quality control materials (QCs). QCs are specimens or solutions that are analyzed for quality control purposes in a test system. In this study, we established a novel cell line that stably integrates CT amplification target sequences for producing QCs for CT NAATs. Utilizing clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 technology, we integrated the CT plasmid-mediated sequence (comprising the full length of the cryptic plasmid and the major outer membrane protein gene, 9,136 bp) into the MUC4 gene of HEK293T cells. Positive clones were screened through flow cytometric sorting, single-cell culture, and PCR-based identification, followed by the establishment of stable cell lines. These cells were then processed using optimized cell preservation procedures to prepare QCs. The sequence insertion copy number was confirmed by real-time quantitative PCR. This novel CT QCs demonstrate excellent clinical applicability, non-infectiousness, quantifiability, and stability. With an integrated sequence exceeding 9 kb in length, it offers exceptional flexibility for adapting to new kit developments. Furthermore, maintaining a well-defined copy number and stable shelf life, the QCs closely aligns with the quality control requirements of CT NAATs. This study presents an innovative method for preparing QCs for CT nucleic acid detection, making a valuable contribution to improving the performance of CT NAATs.IMPORTANCEUntreated CT infections impose significant burdens on individuals and communities, underscoring the importance of early and accurate testing via CT NAATs for disease control. QCs are instrumental in identifying testing process issues. Hence, we developed a cell line integrating CT-amplified target sequences as readily accessible non-infectious QCs. These QCs boast several advantages: the integration of over 9 kb of CT sequence allows for broad applicability, allowing flexible adaptation to the development of new kits. Confirming the CT sequence copy number provides a reliable basis for QC concentration preparation and kit detection limit evaluation. Optimized preservation protocol enhances QC stability during storage, facilitating convenient shipment to clinical laboratories at ambient temperatures. In summary, our novel CT QCs offer a powerful tool for improving CT NAAT performance and present a fresh perspective on QC preparation for detecting nucleic acids from intracellular parasitic pathogens.

Analysis of Clinical Laboratory Detecting Challenging Variants from Exome Sequencing Using Simulated Patient-Parent Trio Sample: Pilot Study for Neurodevelopmental Disorder de Novo Variants.

To date, there has been no systematic analysis for the clinical laboratory in detecting technically challenging variants using the trio-based exome sequencing (ES) approach. Here, we present an interlaboratory pilot proficiency testing study that used synthetic patient-parent specimens to assess the detection of challenging variants with de novo dominant inheritance modes for neurodevelopmental disorders using various trio-based ES. In total, 27 clinical laboratories that performed diagnostic exome analyses participated in the survey. One of the 26 challenging variants was identified by all laboratories, whereas all 26 variants were identified by only nine laboratories. The lack of identification of mosaic variants was often due to the bioinformatics analysis that excluded the variant. For missing intended heterozygous variants, probable root causes were related to the technical bioinformatics pipeline and variant interpretation and reporting. For each missing variant, there may be more than one probable reason from the different laboratories. There was considerable variation in interlaboratory performance for detecting challenging variants using trio-based ES. This finding may have important implications for the design and validation of tests for different variant types in clinical laboratories, especially for technically challenging variants, and necessary workflow modification can potentially improve trio-based ES performance.

Quartet DNA reference materials and datasets for comprehensively evaluating germline variant calling performance.

BACKGROUND: Genomic DNA reference materials are widely recognized as essential for ensuring data quality in omics research. However, relying solely on reference datasets to evaluate the accuracy of variant calling results is incomplete, as they are limited to benchmark regions. Therefore, it is important to develop DNA reference materials that enable the assessment of variant detection performance across the entire genome. RESULTS: We established a DNA reference material suite from four immortalized cell lines derived from a family of parents and monozygotic twins. Comprehensive reference datasets of 4.2 million small variants and 15,000 structural variants were integrated and certified for evaluating the reliability of germline variant calls inside the benchmark regions. Importantly, the genetic built-in-truth of the Quartet family design enables estimation of the precision of variant calls outside the benchmark regions. Using the Quartet reference materials along with study samples, batch effects are objectively monitored and alleviated by training a machine learning model with the Quartet reference datasets to remove potential artifact calls. Moreover, the matched RNA and protein reference materials and datasets from the Quartet project enables cross-omics validation of variant calls from multiomics data. CONCLUSIONS: The Quartet DNA reference materials and reference datasets provide a unique resource for objectively assessing the quality of germline variant calls throughout the whole-genome regions and improving the reliability of large-scale genomic profiling.

Development of a Novel Reference Material for Tumor Mutational Burden Measurement Based on CRISPR/Cas9 Technology.

As a biomarker that affects treatment decisions of immune checkpoint inhibitors, the accuracy, reliability, and comparability of tumor mutational burden (TMB) estimation is of paramount importance. To improve the consistency and reliability of these tests, qualified reference materials providing ground-truth data are crucial. In this study, we developed a set of formalin-fixed and paraffin-embedded (FFPE) samples with different TMB values as the novel reference materials for TMB estimation. By introducing several clinically relevant variants in MutS Homolog 2 (MSH2) gene and DNA polymerase epsilon (POLE) gene into human cell lines using CRISPR/Cas9 technology, we first constructed four typical cell lines which verified with hypermutator or ultramutator phenotype. Followed by cell mixing and paraffin embedding, the novel FFPE samples were prepared. It was confirmed that our novel FFPE samples have sufficient quantity of cells, high reproducibility, and they can provide matched wild type sample as the genetic background. The double-platform whole exome sequencing validation showed that our FFPE samples were also highly flexible as they containing different TMB values spanning a clinically relevant range (2.0-106.1 mut/Mb). Without limitations on production and TMB values, our novel FFPE samples based on CRISPR/Cas9 editing are suitable as candidate reference materials. From a practical point of view, these samples can be used for the validation, verification, internal quality control, and proficiency testing of TMB assessment.

Reprogramming of Human B Cells from Secreting IgG to IgM by Genome Editing.

B lymphocytes are activated and regulated by their interactions with T cells, a process that results in one-way class switching of immunoglobulins (ig) from IgM to IgG, IgE, or IgA. In this study, we show the application of clustered regularly interspaced short palindromic repeat-Cas9-induced nonhomologous end joining in B cells to achieve reverse-directional Ig class switching. By electroporating Cas9 and guide RNA and a Cµ encoding donor into cells, we engineered IgG-secreting human B cell lines to switch to express IgM antibody. This approach offers a new potential path for the production of IgM antibodies.

Adaptation of ACMG-ClinGen Technical Standards for Copy Number Variant Interpretation Concordance.

This study aimed to evaluate inter-laboratory classification concordance for copy number variants (CNVs) with a semiquantitative point-based scoring metric recommended by the American College of Medical Genetics and Genomics (ACMG) and Clinical Genome Resources (ClinGen). A total of 234 CNVs distributed by the National Center of Clinical Laboratories (NCCLs), and 72 CNVs submitted by different laboratories, were distributed to nine clinical laboratories performing routine clinical CNV testing in China and independently classified across laboratories. The overall inter-laboratory complete classification concordance rate of the 234 distributed CNVs increased from 18% (41/234) to 76% (177/234) using the scoring metric compared to the laboratory's previous method. The overall inter-laboratory complete classification concordance rate of the 72 submitted CNVs was 65% (47/72) using the scoring metrics. The 82 variants that initially did not reach complete concordance classification and 1 additional CNV deletion were reviewed; 34 reached complete agreement, and the overall post-review complete concordance rate was 85% (260/306). Additionally, the overall percentage of classification discordance possibly impacting medical management [i.e., pathogenic (P) or likely pathogenic (LP) vs. variant of uncertain significance (VUS)] was 11% (35/306). The causes of initial and final discordance in the classification were identified. The ACMG-ClinGen framework has promoted consistency in interpreting the clinical significance of CNVs. Continuous training among laboratories, further criteria and additional clarification of the standards, sharing classifications and supporting evidence through public database, and ongoing work for dosage sensitive genes/regions curation will be beneficial for harmonization of CNVs classification.

Delivery of microRNA-21-sponge and pre-microRNA-122 by MS2 virus-like particles to therapeutically target hepatocellular carcinoma cells.

MicroRNAs are related to the development of hepatocellular carcinoma and can serve as potential therapeutic targets. Therapeutic strategies increasing tumor-suppressive microRNAs and reducing oncogenic microRNAs have been developed. Herein, the effects of simultaneously altering two microRNAs using MS2 virus-like particles were studied. The sequences of microRNA-21-sponge and pre-microRNA-122 were connected and cloned into a virus-like particle expression vector. Virus-like particles containing microRNA-21-sponge and pre-microRNA-122 sequences were prepared and crosslinked with a cell-specific peptide targeting hepatocellular carcinoma cells. Delivery effects were studied using RT-qPCR and functional assays to investigate the level of target mRNAs, cell toxicity, and the effects of proliferation, invasion, and migration. Virus-like particles delivered miR-21-sponge into cells, with the Ct value reaching 10 at most. The linked pre-miR-122 was processed into mature miR-122. The mRNA targets of miR-21 were derepressed as predicted and upregulated 1.2-2.8-fold, and the expression of proteins was elevated correspondingly. Proliferation, migration, and invasion of HCC cells were inhibited by miR-21-sponge. Simultaneous delivery of miR-21-sponge and miR-122 further decreased proliferation, migration, and invasion by up to 34%, 63%, and 65%, respectively. And the combination promoted the apoptosis of HCC cells. In conclusion, delivering miR-21-sponge and miR-122 using virus-like particles modified by cell-specific peptides is an effective and convenient strategy to correct microRNA dysregulation in hepatocellular carcinoma cells and is a promising therapeutic strategy for hepatocellular carcinoma.

External Quality Assessment for Molecular Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Clinical Laboratories.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a huge threat to public health. Viral nucleic acid testing is the diagnostic gold standard and can play an important role in the prevention and control of this infection. In this study, bacteriophage MS2 virus-like particles encapsulating specific RNA sequences of SARS-CoV-2 and other coronaviruses were prepared by genetic engineering. The assessment panel, consisting of four positive samples with concentrations of 2.8, 3.5, 4.2, and 4.9 log10 copies/mL and five negative samples with other human coronaviruses, was prepared and distributed to evaluate the accuracy of routine viral RNA detection. Results of 931 panels from 844 laboratories were collected. The overall percentage agreement, positive percentage agreement (PPA), and negative percentage agreement, defined as the percentage of agreement between the correct results and total results submitted for all, positive, and negative samples were 96.8% (8109/8379), 93.9% (3497/3724), and 99.1% (4612/4655), respectively. For samples with concentrations of 4.9 and 4.2 log10 copies/mL, the PPAs were >95%. However, for 3.5 and 2.8 log10 copies/mL, the PPAs were 94.6% (881/931) and 84.9% (790/931), respectively. For all negative samples, the negative percentage agreement values were >95%. Thus, most laboratories can reliably detect SARS-CoV-2. However, further improvement and optimization are required to ensure the accuracy of detection in panel members with lower concentrations of viral RNA.