Annals of Laboratory Medicine最新文献

Flow cytometric lymphocyte subset analysis (FCLSA) is essential for assessing immune status across various diseases and clinical settings. We surveyed current clinical laboratory practices related to FCLSA to establish a baseline reference for future standardization in Korea. Nine university hospitals actively performing FCLSA responded to the 22-question survey, which covered seven categories of laboratory practice. These hospitals used commercial reagent antibody kits from either Beckton Dickinson Biosciences (N=4) or Beckman Coulter Diagnostics (N=5). Most hospitals performed daily instrument setup and scheduled maintenance every 2-6 months. Two levels of commercial quality control materials were routinely used each day. Sample and reagent antibody volumes varied across hospitals, even when the same reagent kit was used. Acquired cell counts ranged from 5×10³ to 5×10⁴ cells, with two hospitals adjusting counts based on the cell type analyzed. Most laboratories reported percentages and general opinions; some additionally reported white blood cell and lymphocyte counts, along with lymphocyte percentages. This is the first comprehensive survey on the clinical laboratory practice of FCLSA in Korea. Standardization of FCLSA should be accelerated to ensure reliable and reproducible results.

Background: Mycoplasma pneumoniae is a major cause of community-acquired pneumonia (CAP) in children, with a rising incidence of macrolide resistance. Early diagnosis is crucial for reducing the disease burden; however, current diagnostic tools have limitations. We evaluated the diagnostic accuracy of serological assays and their performance based on symptom onset in children with CAP.

Methods: From September 2023 to September 2024, we prospectively enrolled children with CAP, classified as M. pneumoniae pneumonia (MPP) or non-MPP, from 16 hospitals in Korea. Serological testing included chemiluminescence immunoassay (CLIA) and ELISA for detecting IgM and IgG, along with particle agglutination (PA) for total antibody measurements. Serological responses were analyzed at different times after symptom onset (0-4, 5-9, and 10-21 days).

Results: Among 472 children with CAP (362 MPP, 110 non-MPP), 138 (29.2%) underwent PA testing, and 334 (70.8%) underwent IgM testing. PA at a 1:640 cutoff showed 48.0% sensitivity and 100% specificity. CLIA and ELISA showed comparable sensitivities (69.1% vs. 69.2%) and specificities (76.9% vs. 66.7%) for IgM testing. Seropositivity increased significantly with time since symptom onset (P for trend<0.001), reaching 97.9% for IgM, 62.5% for IgG, and 94.7% for PA at 10-21 days.

Conclusions: The time post-symptom onset significantly influenced the diagnostic utility of serological tests for pediatric MPP, which showed limited value during the early stage of illness. These findings emphasize the importance of symptom onset-based interpretation of serological test results and their utility in complementing PCR when optimizing MPP diagnosis in children.

Background: Retinitis pigmentosa (RP) comprises a heterogeneous group of inherited retinal dystrophies. The genetic landscape of RP has been characterized; however, knowledge gaps regarding age-specific genetic variation trends in Korean patients remain. We comprehensively characterized the age-stratified genetic landscape of RP in Korean patients, with a focus on identifying novel mutational trends and clinically actionable insights.

Methods: We performed targeted next-generation sequencing of 199 genes associated with RP and related disorders in a cohort of 403 unrelated patients clinically diagnosed as having RP. We analyzed the inheritance patterns, variation spectrum, and prevalence of pathogenic variants, stratifying the results by age, and conducted copy number variation (CNV) analysis.

Results: A genetic diagnosis was achieved for 193 of the 403 patients (48%). The diagnostic yield was highest in patients diagnosed before 20 yrs of age (60%), with lower yields in older age groups. Although USH2A and EYS, the most common causative genes in autosomal recessive inheritance, were frequently identified, RPGR pathogenic variants accounted for a significantly larger proportion of genetically solved cases diagnosed before the age of 20 yrs (27%-28%) than in those with later-onset disease (9%-15%). CNVs were identified in 4% of genetically solved cases.

Conclusions: The results underscore distinct, age-related genetic contributions to RP in Korean patients, with RPGR variants demonstrating relevance in early-onset disease, and provide diagnostic insights to improve current practices. These findings can aid in prioritizing gene therapy targets and refining screening strategies.

Background: Precision oncology is advancing, increasing the demand for comprehensive, non-invasive genomic profiling tools. Liquid biopsy using circulating tumor DNA (ctDNA) enables real-time molecular profiling, treatment monitoring, and early detection of resistance variants. We developed the PAN100 panel (Dxome), a hybridization capture panel targeting 101 genes, as a pan-cancer genotyping assay to detect clinically actionable variants across various cancer types. This study presents the first comprehensive validation of the PAN100 panel including both analytical and clinical performance across eight cancer types using reference materials and matched tissue samples.

Methods: For analytical validation, we assessed accuracy, limit of detection (LoD), and precision using Seraseq ctDNA v2 Reference Materials (SeraCare, Milford, MA, USA). Clinical validation was performed using plasma samples from 27 patients with eight types of cancer and 17 matched tumor samples. Positive percent agreement (PPA) between ctDNA and tissue next-generation sequencing (NGS) results was assessed using TruSight Oncology 500 and TruSight Tumor 170 assays. The limit of blank (LoB) was evaluated in 34 healthy individuals.

Results: The PAN100 panel demonstrated high precision and linearity (LoD, 0.3%; 95.0% confidence interval, 0.29-0.35) variant allele frequency. The PPA between ctDNA and tissue NGS was 73.1% for single-nucleotide variants, 80.0% for insertions/deletions, and 74.2% overall. The LoB was 0.00001%.

Conclusions: The PAN100 panel is a robust tool for detecting clinically significant variants with high concordance with tissue NGS. Its sensitivity for low-frequency variants enables real-time treatment adaptation, supporting precision oncology. Its comprehensive design is particularly valuable for challenging diagnoses and clonal evolution monitoring.

Background: Cytomegalovirus (CMV) infection is prevalent worldwide. Although Korea has historically shown high CMV IgG seropositivity (>95%), declines have been reported recently. We assessed current CMV IgG seropositivity and analyzed prevailing trends in the Korean population.

Methods: Residual samples from individuals undergoing regular health checkups were analyzed. We assessed 1,978 samples (from 937 men and 1,041 women) where the age group distribution was relatively balanced. CMV IgG levels were measured at two institutions using a commercial immunoassay (Alinity i CMV IgG Reagent Kit, Abbott) following the manufacturer's instructions. Results were interpreted as "reactive" when the CMV IgG concentration was ≥ 6.0 arbitrary units (AU)/mL or "nonreactive" when the CMV IgG concentration was <6.0 AU/mL. Seropositivity was compared by sex and across age groups (20-29, 30-39, 40-49, and 50-59 yrs).

Results: The overall CMV IgG seropositivity was 89.9% (1,778/1,978) and was significantly higher in men (91.7%, 859/937) than in women (88.3%, 919/1,041) (difference: 3.4%; 95% confidence interval: 0.8%-6.0%; P =0.012, chi-square test). No significant differences with regard to sex were found within each age group. Seropositivity increased with age, from 76.3% (347/455, 20-29 yrs) to 99.8% (448/449, 50-59 yrs) (P for trend <0.001), consistently in both sexes.

Conclusions: Our findings provide the most up-to-date estimate of CMV IgG seropositivity in the Korean adult population. Because of lower seropositivity in younger adults, continued monitoring and further education are essential for CMV control and prevention.

Background: Multidrug-resistant yeast Candida (Candidozyma) auris, responsible for healthcare-associated outbreaks and high mortality, is a major global health threat. Rapid and scalable molecular diagnostics is essential; however, few automated platforms can accommodate both commercial assays and laboratory-developed tests (LDTs). We evaluated the analytical and clinical performance of two real-time PCR assays for C. auris detection using the AltoStar Automation System AM16.

Methods: One assay was an in-house LDT (targeting the internal transcribed spacer region), while the other was AltoStar C. auris PCR Kit 1.5 (Altona Diagnostics) assay. An integrated workflow, which included automated nucleic acid extraction and PCR setup, was employed. Analytical performance was evaluated in terms of precision, specificity, and limit of detection (LoD) using C. auris Clades I, II, and VI. Clinical accuracy was assessed using a 36-sample panel (surveillance swabs and contrived positives) tested in parallel with the DiaSorin Simplexa C. auris Direct assay (DiaSorin Molecular LLC), with culture as the reference standard.

Results: Both assays demonstrated excellent reproducibility, with CVs below 5%, and 100% analytical specificity. The in-house LDT showed greater sensitivity, with LoDs of 25-191 colony-forming units (CFU)/mL (1.56-12 CFU/reaction) versus 52-235 CFU/mL (3.25-15 CFU/reaction) for the Altona assay. Regarding clinical accuracy, the LDT, Altona assay, and DiaSorin assay showed 100% positive and negative agreement with the culture results (Cohen's kappa=1.00).

Conclusions: This is the first documented comparison of a commercial assay and an LDT on the AltoStar AM16, demonstrating the platform's flexibility, which can enhance laboratory adaptability and capacity to combat the spread of C. auris, a critical fungal pathogen.