Molecular Diagnostic Laboratories Research Articles

Development and validation of automated methods for COVID-19 PCR Master Mix preparation

Polymerase chain reaction (PCR)-based assays were widely deployed during the SARS-CoV-2 pandemic for population-scale testing. High-throughput molecular diagnostic laboratories required a high degree of process automation to cope with huge testing demands, fast turnaround times, and quality requirements. However, process developers and optimizers often neglected the critical step of preparing a PCR Master Mix. The construction of PCR Master Mix depends on operator skill during the manual pipetting of reagents. Manual procedures introduce variation, inconsistency, wastage, and potentially risks data integrity. To address this, we developed a liquid-handler-based solution for automated, traceable, and compliant PCR Master Mix preparation. Here, we show that a fully automated PCR Master Mix protocol can replace manual pipetting, even in a diagnostic environment, without affecting accuracy or precision. Ultimately, this method eliminated operator-induced wastage and improved the consistency of the quality of results.

Performance of a Rapid Digital PCR Test for the Detection of Non-Small Cell Lung Cancer (NSCLC) Variants.

Next-generation sequencing is widely used for comprehensive molecular profiling for many cancers including lung cancer. However, the complex workflows and long turnaround times limit its access and utility. ChromaCode's High Definition PCR Non-Small Cell Lung Cancer Panel (HDPCR™ NSCLC Panel) is a low-cost, rapid turnaround, digital polymerase chain reaction assay that is designed to detect variants in nine NSCLC genes listed in National Comprehensive Cancer Network guidelines. This assay uses TaqMan® probe limiting chemistry and proprietary analysis software to enable multi-target detection within a single-color channel. We compared the performance of the HDPCR™ NSCLC Panel against an in-house, laboratory-developed, targeted next-generation sequencing panel used in the Molecular Diagnostics Laboratory at the University of Minnesota Medical Center to detect biomarkers for NSCLC. The overall accuracy of the HDPCR panel was 99.48% (95% confidence interval 99.01-99.76) with a sensitivity of 95.35% (95% confidence interval 88.52-98.72) and a specificity of 99.69% (95% confidence interval 99.29-99.90). The HDPCR wet lab workflow was 4 h, and the time to generate variant calls from raw data using the ChromaCode Cloud was 2 minutes. We demonstrated that the HDPCR™ NSCLC Panel provides timely, comprehensive, and sensitive mutation detection in NSCLC samples with results in less than 24 h.

Variant classification changes over time in the clinical molecular diagnostic laboratory setting

BackgroundVariant classification in the setting of germline genetic testing is necessary for patients and their families to receive proper care. Variants are classified as pathogenic (P), likely pathogenic (LP), uncertain...

Validation of Nanopore long-read sequencing to resolve RPGR ORF15 genotypes in individuals with X-linked retinitis pigmentosa.

X-linked retinitis pigmentosa (XLRP) is characterized by progressive vision loss leading to legal blindness in males and a broad severity spectrum in carrier females. Pathogenic alterations of the retinitis pigmentosa GTPase regulator gene (RPGR) are responsible for over 70% of XLRP cases. In the retina, the RPGRORF15 transcript includes a terminal exon, called ORF15, that is altered in the large majority of RPGR-XLRP cases. Unfortunately, due to its highly repetitive sequence, ORF15 represents a considerable challenge in terms of sequencing for molecular diagnostic laboratories. However, in a recent preliminary work Yahya et al. reported a long-read sequencing approach seeming promising. Here, the aim of the study was to validate and integrate this new sequencing strategy in a routine screening workflow. For that purpose, we performed a masked test on 52 genomic DNA samples from male and female individuals carrying 32 different pathogenic ORF15 variations including 20 located in the highly repetitive region of the exon. For the latter, we have obtained a detection rate of 80-85% in males and 60-80% in females after bioinformatic analyses. These numbers raised to 100% for both status after adding a complementary visual inspection of ORF15 long-reads. In accordance with these results, and considering the frequency of ORF15 pathogenic variations in XLRP, we suggest that a long-read screening of ORF15 should be systematically considered before any other sequencing approach in subjects with a diagnosis compatible with XLRP.

The clinical application and laboratory management of molecular genetic diagnosis in children's hospital

AbstractBackgroundMolecular diagnostic technology is the foundation of precision medicine, which has the advantages of good specificity, high sensitivity, strong targeting, rapiddiagnosis, etc. It has a wide range of applications in the field of pediatrics. However, molecular diagnostic technology is characterized by complicated experimental operation, high difficulty in data analysis and interpretation, in consistent standards among laboratories, and difficult standardization of technical processes. Enhancing the application value of molecular diagnostic technology in pediatrics and promoting the high‐quality development of the discipline requires careful consideration by relevant management and professionals.MethodsThis study firstly outlines the development history of molecular diagnostic technology. Then, it analyzes the application of molecular diagnostic technology in the field of pediatrics. Finally, it explores the countermeasures for the management of molecular diagnostic laboratories.ResultsThis study highlights the importance of molecular diagnostic technology in providing information and decision‐making basis for disease prevention, prediction,diagnosis, treatment and regression. It has a wide range of applications in the molecular diagnosis of pediatric hereditary diseases, malignant tumors and infectious diseases. In addition, the countermeasures for the management of molecular diagnostic laboratories are proposed from the five aspects of laboratory, personnel team construction, standardized management,multidisciplinary cross‐discipline, research and translation, safety managementand ethical supervision, and management upgrading and modernization.ConclusionsMolecular diagnostic technology, as the basis of precision medicine, has become one of the important frontier fields in the development of contemporary pediatric medicine. Enhanced laboratory capacity in molecular diagnostic techniques can improve outcomes in the prevention, prediction, diagnosis, treatment, prognosis and research of pediatricdiseases, and lay the groundwork for child healthcare.

Nationwide Real-World Data of Microsatellite Instability and/or Mismatch Repair Deficiency in Cancer: Prevalence and Testing Patterns.

Determination of microsatellite instability (MSI)/mismatch repair (MMR) status in cancer has several clinical implications. Our aim was to integrate MSI/MMR status from patients tested in Greece to assess the prevalence of MSI-high (MSI-H)/deficient MMR (dMMR) per tumor type, testing patterns over time and concordance between MSI and MMR status. We retrospectively recorded MSI/MMR testing data of patients with diverse tumor types performed in pathology and molecular diagnostics laboratories across Greece. Overall, 18 of 22 pathology and/or molecular diagnostics laboratories accepted our invitation to participate. In the 18 laboratories located across the country, 7916 tumor samples were evaluated for MSI/MMR status. MSI/MMR testing significantly increased in patients with colorectal cancer (CRC) and other tumor types overtime (p < 0.05). The highest prevalence was reported in endometrial cancer (47 of 225 patients, 20.9%). MSI-H/dMMR was observed in most tumor types, even in low proportions. Among 904 tumors assessed both for MSI and MMR status, 21 had discordant results (overall discordance rate, 2.3%). We reported MSI-H/dMMR prevalence rates in patients with diverse cancers, while demonstrating increasing referral patterns from medical oncologists in the country overtime. The anticipated high rate of concordance between MSI and MMR status in paired analysis was confirmed.

When False-Positives Arise: Troubleshooting a SARS-Coronavirus-2 (SARS-CoV-2) Detection Assay on a Semi-Automated Platform.

During the COVID-19 pandemic, many molecular diagnostic laboratories performed high-throughput SARS-CoV-2 testing often with implementation of automated workflows. In parallel, vaccination campaigns resulted increasingly in specimens from fully vaccinated patients, with resultant clinical inquiries regarding positive results in this patient population. This prompted a quality improvement initiative to investigate the semi-automated testing workflow for false-positive results. The troubleshooting workflow is described and procedural improvements are outlined that serve as a resource for other molecular diagnostic laboratories that need to overcome testing anomalies in a semi-automated environment. This workflow utilized the MagMax-96 Viral RNA kit and the CDC 2019-nCoV RT-qPCR Panel on the Agilent Bravo Liquid-Handler (Bravo). Screening of the environment, personnel, and the mechanical performance of instrumentation using low Ct checkerboard challenges was executed to identify sources of cross-contamination. Evaluation of the assay and reporting design was conducted. Specimen contamination was observed during the viral extraction process on the Bravo. Changes to the program reduced plate contamination by 50% and importantly revealed consistent hallmarks of contaminated samples. We adjusted the reporting algorithm using these indicators of false positives. False positives that were identified made up 0.11% of the 45 000+ tests conducted over the following 8 months. These adjustments provided confident and quality results while maintaining turnaround time for patients and pandemic-related public health initiatives. This corrected false-positive rate is concordant with previously published studies from diagnostic laboratories utilizing automated systems and may be considered a laboratory performance standard for this type of testing.

Development and evaluation of three automated media pooling and molecular diagnostic systems for the detection of SARS-CoV-2.

Pooled testing combined with molecular diagnostics for the detection of SARS-CoV-2 is a promising method that can increase testing capacities and save costs. However, pooled testing is also associated with the risks of decreased test sensitivity and specificity. To perform reliable pooled testing, we developed and validated three automated media pooling and molecular diagnostic systems. These pooling systems (geneLEAD-PS, Panther-PS, and Biomek-PS) comprised existing automated molecular detection platforms, corresponding automated media pooling devices, and laboratory information management systems. Analytical sensitivity analysis and mock sample evaluation were performed, and the obtained data were used to determine the sizes of the pool for the validation study. In the validation study, a total of 2,448, 3,228, and 6,420 upper respiratory samples were used for geneLEAD-PS, Panther-PS, and Biomek-PS, respectively, and the diagnostic performances were compared with the reference RT‒PCR assay. A pool size of 6 for geneLEAD-PS and a pool size of 4 for Panther-PS and Biomek-PS were selected for the validation studies. All three systems showed high positive percent agreement values of ≥90.5% and negative percent agreement values of ≥99.8% for any specimen type. Pooled testing resulted in a 65%-71% reduction in cost per sample. The testing capacities of geneLEAD-PS, Panther-PS, and Biomek-PS were 144 samples in 3 hours, 384 samples in 5.5 hours, and 376 samples in 4 hours, respectively. The developed pooling systems showed robust diagnostic performances and will increase the testing capacities of molecular diagnostic tests while saving costs and may contribute to infection control of COVID-19.IMPORTANCEDuring the COVID-19 pandemic, there have been surges in demand for accurate molecular diagnostic testing and laboratory supply shortages. Pooled testing combined with highly sensitive molecular testing, which entails mixing multiple samples as a single sample, is a promising approach to increase testing capacities while reducing the use of consumables. However, pooled testing is associated with risks that compromise diagnostic performance, such as false negatives due to dilution of positive samples or false positives due to cross-contamination. To perform reliable pooled testing, three different pooling systems (an automated pooling device, an automated molecular detection platform, and a laboratory information management system) were developed to accurately interpret pooled testing results. These three systems were validated using multiple clinical samples and showed high concordance with individual testing. The developed pooling systems will contribute to increasing reliable molecular testing capacities while using fewer consumables and saving costs.

Occurrence and characteristics of elderly With Covid-19 in southern Brazil

This study aimed to describe the occurrence of COVID-19 in elderly patients treated at public health services in southern Brazil cities and their clinical and sociodemographic characteristics. This is a cross-sectional, observational, and retrospective study. From July 2020 to May 2021, medical records of elderly patients who underwent a test for COVID-19 at the molecular diagnostics laboratory of the University of Cruz Alta were selected. 310 elderly patients, with an average age of 60 to 99 years, were included in the study. Information was collected regarding the result of the RT-qPCR test, gender, symptoms, and comorbidities. We identified that 24.2% of the elderly evaluated in the study had a positive molecular diagnosis for COVID-19. The average age of the sample studied was 69 years (±8.89). Females had a higher proportion of positive cases (69.3%) compared to males (30.7%) (p=0.017). A higher proportion of individuals infected with SARS-Cov2 among those who reported cough, fever &gt;37°C and pre-existing cardiovascular diseases (p = 0.028; 0.015; 0.017 respectively) was also identified. Learning the clinical and sociodemographic profile of the elderly with COVID-19 can contribute to strategies for care and prevention of the disease in this group. The study findings indicate that greater attention should be given to the elderly with heart diseases and those who have fevers and coughs.

Rift Valley Fever virus M and L genome segment detection: a comparison of field-deployable reverse transcription insulated isothermal PCR (RT-iiPCR) and laboratory-based multiplex reverse transcription real-time PCR.

The content of this manuscript is of interest to the diverse readership of the Journal of Clinical Microbiology, including research scientists, diagnosticians, healthcare professionals, and policymakers. Rift Valley Fever virus (RVFV) is a zoonotic mosquito-borne pathogen that causes major agricultural and public health problems. Current and most sensitive diagnostic approaches that are molecular-based are performed in highly specialized molecular diagnostic laboratories. To address diagnostic needs, we developed a novel, rapid, and sensitive molecular method using a portable PCR machine, POCKIT, capable of immediate deployment at sites of suspected outbreaks. Here, we demonstrate that field-deployable RVFV detection can provide reliable, sensitive, and specific point-of-need viral RNA detection that could be used for diagnostic investigations and epidemiological studies, and can be performed in the field.

A Retrospective Observational Study to Assess the Quality Management System in a Molecular Diagnostic Laboratory of a COVID-19 Dedicated Hospital in Delhi, India

Introduction: A molecular diagnostic laboratory is the cornerstone of Coronavirus Disease-2019 (COVID-19) disease diagnosis, as the patient’s treatment and management protocol depend on molecular results. Therefore, the laboratory conducting these tests must adhere to quality management process to increase the accuracy and validity of the generated reports. Rajiv Gandhi Super Speciality Hospital established its molecular diagnostic set-up at the beginning of the pandemic. Hence, this study aims to generate quality management data to help improve weak points. Aim: To assess the quality management system for COVID-19 diagnosis. Materials and Methods: This retrospective observational study was conducted at Rajiv Gandhi Super Speciality Hospital in Delhi, India. A total of 14,561 samples were collected over six months, from February 2021 to July 2021. Data from all samples received during this period for COVID-19 ReverseTranscriptase Polymerase Chain Reaction (RT-PCR) testing were included. Data were retrospectively collected from the electronic Laboratory Information Management System (LIMS). Quality variables were analysed over six months from July to December 2021 and classified into preanalytical, analytical, and postanalytical variables. Quality Indicators (QIs) were selected from a common model of QIs set by the International Federation of Clinical Chemistry and Laboratory Medicine. The results were presented in percentages, and descriptive statistics were analysed using Statistical Package for Social Sciences (SPSS) software. Results: During the six-month study period, the molecular laboratory received 14,561 samples. Among the preanalytical variables, sample leakage was the most common cause of sample rejection (134 samples, 0.92%), followed by the non generation of Specimen Referral Form (SRF) identification (76 samples, 0.52%), and non compliance with triple packaging (44 samples, 0.3%). Other preanalytical aspects assessed included incomplete patient identification (17 samples, 0.11%), insufficient sample quantity (12 samples, 0.08%), missing forms/samples (7 samples, 0.04%), samples in the wrong vials/ empty Viral Transport Media (VTM) tubes (5 samples, 0.03%), and incomplete LIMS entry (2 samples, 0.01%). Internal Quality Control (QC) was not obtained in 55 samples (0.37%), and two incidents of cross-contamination resulted in false-positive results. Among the postanalytical factors, 11 samples (0.07%) could not be dispatched within the stipulated time frame. Conclusion: The assessment of the quality management system revealed some areas for improvement, emphasising the importance of adhering to QC processes for the smooth operation of diagnostic laboratories, especially those involved in critical reporting. The assessment of QIs helped monitor laboratory parameters effectively.

Performa Rapid Diagnostik Tes Hepatitis B dengan ELISA sebagai Gold Standar

The ELISA (Enzyme Linked Immunoassay) method has high sensitivity and specificity, qualitatively and quantitatively detecting Hepatitis B Surface Antigen (HBsAg) levels, but the process is long, expensive and requires special expertise, compared to the Rapid Diagnostic Test (RDT) as a rapid test which is more practical and cheaper. The aim of this study was to compare the sensitivity and specificity of the Entebe Rapid Test Diagnostic (ERTD) produced by PT. Hepatika Mataram, with ELISA as the gold standard in detecting HBsAg. The requirement for interpreting sensitivity and specificity results according to World Health Organization (WHO) standards is a minimum of 95%. Testing with a negative panel of 00 samples and a positive panel of 1 samples from Papua in 012 at -80℃ storage. Testing in April 023 at the Molecular Diagnostics and Research Laboratory, Mataram University Hospital. Statistical analysis using MedCal software. ERD HBsAg produced by PT. Hepatika Mataram has a sensitivity of 95.45%, specificity of 99.50%, positive predictive value of 93.59%, negative predictive value of 99.65%, and accuracy of 99.21%.

Genomic Landscape of NSCLC in the Republic of Ireland

IntroductionThe identification of genomic “targets” through next-generation sequencing (NGS) of patient’s NSCLC tumors has resulted in a rapid expansion of targeted treatment options for selected patients. This retrospective study aims to identify the proportion of patients with advanced NSCLC in the Republic of Ireland whose tumors harbor actionable genomic alterations through broad NGS panel testing. MethodsInstitutional review board approval was obtained before study initiation. Patients with NSCLC whose tumors underwent genomic testing through the largest available NGS panel at a nationally funded Cancer Molecular Diagnostics laboratory (St. James’s Hospital) between June 2017 and June 2022 were identified. Patient demographics and tumor-related data were collected by retrospective review from all cancer centers in Ireland, referring to the Cancer Molecular Diagnostics laboratory. A total of 203 (9%) tumor samples were excluded due to insufficient neoplastic cell content. Genomic data were collected through retrospective search of Ion Reporter software. The spectrum and proportion of patients with oncogenic driver mutations were evaluated using descriptive statistics (SPSS version 29.0). ResultsIn total, 2052 patients were identified. Patients were referred from 23 different hospital sites and all four geographic regions (Leinster = 1091, 53%; Munster = 763, 37.2%; Connacht = 191, 9.3%; Ulster = 7, 0.3%). Median age was 69 (range: 26–94) years; 53% were male. The most common tumor histologic subtype was adenocarcinoma (77%, n = 1577). An actionable genomic alteration was identified in 1099 cases (53%), the most common of which was KRAS (n = 657, 32%). Less frequently, NSCLC tumors harbored the following: MET exon 14 skipping (n = 53, 2.6%), MET amplification (n = 26, 1.3%), EGFR (n = 181, 8.8%), HER2 (n = 35, 1.7%), and BRAF (n = 72, 3.5%) mutations. Fusions were detected in 76 patients (3.7%) including ALK (n = 44, 58%), RET (n = 11, 14.5%), ROS1 (n = 16, 21%), and FGFR3 (n = 5, 6.6%), whereas no NTRK fusion was identified. Co-alterations were detected in 114 patients (5.6%), the most common of which was KRAS/PIK3CA (n = 19, 17%), EGFR/PIK3CA (n = 10, 8.5%), and KRAS/IDH1 (n = 9, 8%). Other co-alterations of interest identified included KRAS G12A/ROS1 fusion (n = 1) and KRAS G12C/BRAF G469A (n = 2). ConclusionsThis is the first retrospective study to comprehensively characterize the genomic landscape of NSCLC in Ireland, using the broadest available NGS panel. Actionable alterations were identified in 53.4% of the patients, and KRAS was the most common oncogenic driver alteration. Our study revealed a lower prevalence of patients whose tumor harbors ALK, ROS1, and RET fusions, compared with similar data sets.

984. Detection of Mycobacterial Species from Specimens Submitted for Metagenomic Analysis

Abstract Background A national U.S. epidemic of non-tuberculous mycobacterial (NTM) infections is occurring at rates unseen over earlier decades, resulting in substantial numbers of pathogenic sequelae. Culture of mycobacteria is laborious, often requiring weeks for cultivation and speciation. Next generation sequencing (NGS) to detect NTM from clinical specimens has advantages over culture methods. From January 2018 to June 2022 we queried a large national NGS database to detect NTM rates and species. Methods DNA was isolated from 431,716 patient specimens collected from a variety of body sites: sputum, urine, sinus, wound or an unspecified swabs. Employing an Illumina’s 16S and ITS targeted-gene, deep sequencing approach, bacterial and/or fungal species resident in the specimen were determined. The identity and relative abundance of mycobacterial DNA recovered for each specimen were reported by species as the primary outcomes. Results Of the 431,716 specimens analyzed in this 4.5 year retrospective study, 0.001% (468) contained mycobacterial DNA. Forty different species of mycobacteria were detected with the most common frequency including: M abscessus, 40%; M mucogenicum, 13%; M. tuberculosis, 8.5% and M immunogenum 4.6%. M. avian and M. intracellulare were each detected in only 4% of the positive NTM specimens. 15% were other NTM species and 15% were not speciated NTM. Between 2018-2022 of the 468 NTM, the annual number of M. abscessus was 38, 53, 41 and 41, respectively. The concentration or relative abundance of mycobacterial DNA within each specimen varied from 4 to 100% of the total bacterial DNA recovered. Conclusion Over 4.5 years , NGS performed at a national molecular diagnostic laboratory detected 40 NTM species with a predominant fraction as M. abscessus (40%), supporting the clinical concern for an epidemic increase in M. abscessus infections during the last half decade. These data support the view that NGS metagenomics can uncover NTM epidemiological trends and implicate NTM infections. Disclosures Joseph F. John, Jr., MD, FACP, FIDSA, MicroGenDx: Advisor/Consultant Michael G. Schmidt, PhD, MicroGenDx: Advisor/Consultant Courtney L. Jarvis, PhD, MicroGenDX: Employee Niccole Diaz, BS, MicroGenDX: Advisor/Consultant Rick Martin, BS, MicroGenDX: Ownership Interest

Monitoring the quality of SARS-CoV-2 virus detection in molecular diagnostic laboratories in the Eastern Mediterranean Region during the COVID-19 pandemic.

The COVID-19 pandemic placed unprecedented stress on laboratories in the Eastern Mediterranean Region. Building on existing capacity for influenza diagnostics, countries introduced COVID-19 diagnostic support to ~100% regional coverage. A key challenge during the expansion was maintaining quality testing in laboratories, ensuring that correct results were shared with medical facilities. WHO organized two rounds of independently monitored severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) external quality assurance programs (EQAP). The Public Health Laboratory (PHL) division of WHO supplied external quality assurance (EQA) panels, from the Royal College of Pathologists of Australasia Quality Assurance Programme (RCPAQAP) Australia to laboratories not enrolled in recurring Global Influenza Surveillance and Response System (GISRS) quality assurance programs, in which national influenza centers routinely participate. Fifteen and 14 countries participated in PHL/EQAP for SARS-CoV-2 between 2020 and 2022. Concordance was consistent between rounds, reaching 96.4% and 89.9%. A separate assessment of GISRS/EQAP to national-level laboratories identified high levels of response and concordance for SARS-CoV-2 (100% response, 93% concordance), which was reduced for influenza (50% response rate, 80% concordance), reflecting the challenge of prioritizing pathogens during outbreaks. The proliferation of laboratories in response to COVID-19 was a success story from the pandemic. However, monitoring the quality of laboratories was challenging via existing EQAP. The addition of PHL/EQAP provided a mechanism to monitor performance of laboratories that were not designated as national influenza centers. While a high proportion of laboratories attained good results, continual emphasis on quality and enrollment in EQAP is key to ensuring sustainability of laboratory testing in future.

Validation of a Molecular Diagnostic Test for Circulating Tumor DNA by Next-Gen Sequencing.

A modified version of the PGDx elioTM Plasma Resolve assay was validated as a laboratory-developed test (LDT) for clinical use in the Molecular Diagnostics Laboratory at Fox Chase Cancer Center. The test detects single nucleotide variants (SNVs) and small insertions and deletions (indels) in 33 target genes using fragmented genomic DNA extracted from plasma. The analytical performance of this assay was assessed with reference standard DNA and 29 samples from cancer patients and detected 66 SNVs and 23 indels. Using 50 ng of input DNA, the sensitivity was 95.5% to detect SNVs at 0.5% allele frequency, and the specificity was 92.3%. The sensitivity to detect indels at 1% allele frequency was 70.4%. A cutoff of 0.25% variant allele frequency (VAF) was set up for diagnostic reporting. An inter-laboratory study of concordance with an orthologous test resulted in a positive percent agreement (PPA) of 91.7%.

Clinical SMN1 and SMN2 Gene-Specific Sequencing to Enhance the Clinical Sensitivity of Spinal Muscular Atrophy Diagnostic Testing

Purpose. Therapeutic advances in the treatment of spinal muscular atrophy (SMA) prompt the need for robust and efficient molecular diagnosis of this disease. Approximately five percent of SMA cases are attributable to one copy of SMN1 with a hypomorphic or inactivating variant in trans with a deleted or converted allele. These intragenic variants are challenging to definitively localize to SMN1 due to its sequence homology with the SMN2 gene. To enhance the clinical sensitivity of SMA diagnostic testing, we present an optimized gene-specific sequencing assay to localize variants to either SMN1 or SMN2. Methods. SMN1 and SMN2 genes are independently amplified by long-range allele-specific PCR. Long-range products are used in subsequent nested PCR reactions to amplify the coding exons of SMN1 and SMN2. The resulting products are sequenced using standard Sanger-based methodologies and analyzed for disease-associated alterations. Results. 83 probands suspicious for a clinical diagnosis of SMA with a nondiagnostic SMN dosage result were sequenced for intragenic variants in the SMN1 gene. Gene-specific sequencing revealed likely disease-associated variants in SMN1 in 42 cases (50.6%). Of the 42 variants, 27 are unique including 16 loss-of-function variants, 9 missense variants, 1 in-frame deletion variant, and 1 splice site variant. Conclusions. Herein, we describe an optimized assay for clinical sequencing of the full coding region of SMN1 and SMN2. This assay uses standard techniques and equipment readily available to most molecular diagnostic laboratories.

Identification and Analysis of the Ankle Microbiome Using Next-Generation DNA Sequencing: An Observational Analysis

Category: Ankle; Basic Sciences/Biologics Introduction/Purpose: Next-generation DNA sequencing (NGS) technologies have increased the sensitivity of bacterial cultures and has been used in other areas of orthopaedics to better understand the native microbiome of various joints. This study uses NGS to determine whether (1) a unique microbiome exists in human ankle tissues, (2) if components of the ankle microbiome impact patient outcomes, and (3) whether microbes found on the skin are a normal part of the ankle microbiome. Methods: A prospective study recruited 32 patients undergoing total ankle arthroplasty (TAA, n=23) or ankle arthrodesis via an anterior approach (n=9) during 2020-2021 with one of two fellowship-trained foot and ankle surgeons at an academic medical center. During the operation, the surgeon would swab five layers of the ankle for analysis at a CLIA-licensed molecular diagnostic laboratory: skin (n=32), retinaculum (n=31), tibialis anterior tendon (n=31), joint capsule (n=31), and distal tibia (n=32). Demographics, medical comorbidities, surgical indication, postoperative complications, and readmission and reoperation rates were collected from patient records. Results: Of the 157 swabs sent for NGS, 19 (12.1%) indicated 27 bacteria were present (positive), while the remaining 138 (87.9%) had no bacteria present (negative). The most common organisms were Cutibacterium acnes, present in 11 ankles (34.4%), and Staphylococcus epidermidis, present in 3 ankles (9.4%). The most bacteria were found in the retinaculum (29.6%). No PROM nor follow-up duration was associated with the presence of bacteria, or the number of bacteria or affected layers. Similarly, complication (positive=18.2%, negative=23.8%; p=1.000), nonunion (positive=0.0%, negative=28.6%; p=1.000), infection (positive=0.0%, negative=4.8%; p=1.000), 90-day readmission (positive=0.0%, negative=4.8%; p=1.000), and reoperation (positive=0.0%, negative=4.8%; p=1.000) rates did not differ if a subject’s NGS profile was positive or negative. Conclusion: This study found that C. acnes and S. epidermidis were most commonly found in the ankle microbiome, with C. acnes being present in 34% of ankles. There was no difference in complication rates between patient with and without positive bacterial cultures following TAA or ankle arthrodesis.

Identification and Analysis of The Microbiome in Patients Undergoing Removal of Hardware

Category: Basic Sciences/Biologics; Ankle Introduction/Purpose: Next-generation DNA sequencing (NGS) technologies have increased the sensitivity of bacterial cultures and helped to better understand the normal flora of different joints. Researchers have utilized NGS to identify organisms associated with reoperations in shoulder surgery, but there is very little data on the field of foot and ankle. This study uses NGS to determine whether there is a unique microbiome that exists on orthopaedic hardware in the foot and ankle. Methods: A prospective study recruited 34 patients undergoing hardware removal surgery from the foot or ankle during 2020- 2023 with one of two fellowship-trained foot and ankle surgeons at an academic medical center. Patients were excluded based on the diagnosis or suspicion of infection prior to surgery. Explanted hardware was sent for analysis at a CLIA-licensed molecular diagnostic laboratory. Demographics, medical comorbidities, surgical indication, postoperative complications, readmission, and reoperation rates were collected from patient records. The majority of patients underwent surgery for diagnosis with painful orthopaedic hardware (70.6%). The cohort was majority female (67.6%) and average age was 53.15 (range 18-78) years. Results: Of the 34 samples sent for NGS, 5 (14.7%) indicated 9 bacteria were present (positive), while the remaining 29 (85.3%) had no bacteria present (negative). The most common organisms were of the genus Staphylococcus, representing 4 bacteria (44.4%), and Corynebacterium, representing 2 bacteria (22.2%). C. acnes was only present in one sample. There was no relationship between bacterial presence and patients undergoing hardware removal for diagnosis of painful orthopaedic hardware. No demographics nor postoperative outcomes were statistically associated with the presence of bacteria on removed hardware samples. The overall rate of complication, reoperation, and readmission were 8.8%, 2.9%, and 2.9%, respectively. Conclusion: This study found that there is no common microbial community present in patients undergoing hardware removal surgery. The most commonly present bacteria were of the genus Staphylococcus, bacteria overall were isolated in 14.7% of specimens. C acnes appeared to be uncommon. Further research should be done with a larger sample to support these findings.

Accurate molecular identification of different meat adulterations without carryover contaminations on a microarray chip PCR-directed microfluidic lateral flow strip device

Meat adulteration-based food fraud has recently become one of the global major economical, illegal, religious, and public health concerns. In this work, we developed a microarray chip polymerase chain reaction (PCR)-directed microfluidic lateral flow strip (LFS) device that facilitates the accurate and simultaneous identification of beef adulterated with chicken, duck, and pork, especially in processed beef products. To realize this goal, four pairs of amplification primers were designed and applied for specifically amplifying genomic DNA extracted from mixed meat powders in microarray chip. With the prominent advantage of this device lies in the flexible combination and integration of sample loading, detection, and reporting in microstructures, all the DNA amplicons can be individually visualized on the LFS unit, leading to the appearance of test lines (TC line, TD line, TP line, or TB line) as well as the control line (C line) for the species identification and quantification in beef products. Based on this new method, the adulterants were successfully distinguished and identified in mixtures down to 0.01% (wt.%) while the carryover aerogel contamination in routine molecular diagnostic laboratories was effectively avoided. The practicability, accuracy, and reliability of the device were further confirmed by using real-time PCR as a gold standard control on the successful identification of 50 processed ground meat samples sourced from local markets. The method and device proposed herein could be a useful tool for on-site identification of food authentication.