Objective: The aims of this study were to assess embryonic development using a time-lapse monitoring system based on cleavage timing and the use of vitrification and to investigate the correlation between miRNA-429 expression and embryonic development in both fresh and vitrified-thawed embryos. Methods: Mouse embryos at the 1-cell stage were collected and randomly divided into fresh and vitrified-thawed groups. The embryos were monitored and further subdivided into early and delayed cleavage based on the timing of the third cleavage event at 55 hours after human chorionic gonadotropin injection. miRNA-429 extracted from spent media or embryos cultured in vitro was analyzed by quantitative reverse transcription-polymerase chain reaction. Results: Early cleavage was associated with a significantly higher blastulation rate, regardless of cryopreservation status. Notably, among vitrified-thawed embryos, outgrowth was greater in those exhibiting early cleavage compared to those with delayed cleavage. Furthermore, miRNA-429 expression was elevated in embryos exhibiting delayed cleavage, but only within the cryopreserved group. Conclusion Based on these findings, we suggest that the timing of the third cleavage event may be more critical than the vitrification process itself, and evaluating miRNA-429 expression could serve as an alternative non-invasive selection tool for vitrified surplus embryos.

Background/Aims: The absence of standardized clinical minimum inhibitory concentration (MIC) breakpoints for Helicobacter pylori infection has resulted in inconsistent resistance definitions, even within the same research group in Korea. Therefore, establishing epidemiological cutoff values (ECOFFs) is essential for standardization. Methods: The MIC distributions for antibiotics commonly used against H. pylori infection in South Korea were analyzed from 2015 to 2023. A total of 5,925 primary H. pylori isolates were collected from five data sources, and MIC values were determined using the serial 2-fold agar dilution method. The ECOFFinder program was used to establish ECOFFs for six antibiotics. Results: The tentative ECOFFs for amoxicillin and clarithromycin were 0.125 μg/mL. The ECOFFs for levofloxacin, metronidazole, and tetracycline were 0.5, 8.0, and 0.25 μg/mL, respec-tively. The ECOFF for rifabutin could not be determined due to insufficient data. On the basis of these ECOFFs, the resistance rate was 17.9% for amoxicillin, 31.9% for clarithromycin, 40.9% for levofloxacin, 24.7% for metronidazole, and 11.5% for tetracycline. Conclusions This comprehensive analysis defined regional antibiotic resistance patterns and established Korea-specific ECOFFs, providing a foundation for determining clinical breakpoints and optimizing H. pylori eradication strategies.

Background: and Purpose To compare the epidemiological and clinical features of the rare patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) with age- and sex-matched controls in a nationwide cohort from South Korea. Methods: This observational cohort study analyzed newly diagnosed CADASIL patients aged at least 20 years and matched controls using data from the National Health Information Database for 2004–2022. The cumulative incidence of CADASIL was assessed by age and sex, and compared between regions. Neurologic and systemic diseases were compared between the CADASIL and control groups. Results: The study analyzed 816 CADASIL patients and 816 age- and sex-matched controls aged 56.8±15.2 years (mean±standard deviation), among whom 48.3% were male. The cumulative incidence of CADASIL was 1.86 per 100,000 people (95% confidence interval [CI]=1.85– 1.87 per 100,000), and peaked at 60–69 years of age. In terms of regional distribution, the incidence was highest for Jeju, at 39.67 per 100,000 (95% CI 37.84–41.49 per 100,000). Neurologic diseases were more frequent in CADASIL patients, including Alzheimer’s disease (33.1% vs.20.0%), vascular dementia (84.9% vs. 5.0%), epilepsy (34.6% vs. 15.9%), stroke (70.7% vs. 27.6%), parkinsonism (18.9% vs. 11.0%), and depression (60.8% vs. 44.9%). Systemic diseases such as diabetes mellitus (78.9% vs. 68.9%) were also more common in CADASIL patients, while cancer (27.9% vs. 38.7%) and myocardial infarction (10.0% vs. 13.6%) were less common than in controls. The onset ages of all diseases were lower in CADASIL patients. Conclusions This study has provided a precise nationwide estimate of the CADASIL incidence and its regional distribution in South Korea. CADASIL patients showed higher incidence rates and earlier onsets of diverse clinical manifestations.

Background: and Purpose Whole-exome sequencing (WES) is a valuable tool for identifying causative mutations in adult moyamoya disease (MMD), thereby advancing our understanding of the genetic mechanisms underlying this condition. Here, we conducted the first WESbased association study aimed at identifying genetic modifiers implicated in MMD. Methods: This WES study involved 160 patients with MMD and 189 controls from a multicenter hospital-based biobank, and evaluated combined annotation-dependent depletion (CADD) scores. Mutant-allele frequencies were compared in 369,121 individuals derived from the UK Biobank (UKB) WES. Mutant-allele risk scores (MARSs) were created based on WESidentified mutations. Gene-based association analyses and pooled analyses in East-Asian populations were further performed. Results: Fourteen mutations reached the genome-wide significance criterion (p<5×10-8 ), among which the p.R4810K mutation in the ring finger protein 213 gene (RNF213) showed the strongest significance (odds ratio=117.4, p=8.54×10-24 ). Notably, two mutations—p.G576S (alpha-glucosidase [GAA]) and p.D54N (charged multivesicular body protein 6 [CHMP6])— exhibited high CADD scores of 32 and 25, respectively, whereas the RNF213 p.R4810K mutation demonstrated a moderate deleteriousness score of 10.63. Fourteen mutations exhibited significant differences in allele frequencies between patients and UKB controlled data (p<1×10-8 ).The MARS9 model (incorporating nine missense mutations) showed better predictability for MMD (90.89%). The analysis of gene-based associations revealed four candidate genes: GAA, RNF213, CHMP6, and CARD14 (p=5×10-19 to 4×10-7 ). The subsequent pooled analyses validated four mutations in East Asian populations: p.V1195M, p.D1331G, p.S2334N, and p.R4810K (p<3×10-8 ). Conclusions This pioneering study has corroborated the significance of p.R4810K and identified several causative mutations predisposing patients to MMD, which helps to improve the understanding of its polygenetic nature.

Background: To investigate Korean neurologists' perceptions of the non-standard term ‘jayulsingyeongsiljo’ and their actual evaluation and management of such patients. Methods: We performed an anonymous web-based cross-sectional survey of board-certified Korean neurologists by Korean Society of Pain and Autonomic Disorders between August 13 and September 10, 2025. A questionnaire sent by e-mail asked about demographics, experience with patients labeled with ‘jayulsingyeongsiljo,’ use and perceived usefulness of autonomic function tests, the impact of coronavirus disease 2019, and opinions on terminology and the role of neurologists. Results: In total, 109 neurologists responded. Most reported that patients presenting for ‘jayulsingyeongsiljo’ were young or middle-aged adults and that their numbers had increased over the preceding 2 years. Referrals frequently originated from Korean medicine clinics and other non-neurology departments, often after stand-alone heart rate variability testing. Fatigue, orthostatic intolerance, palpitations, sweating abnormalities, gastrointestinal symptoms, and anxiety or insomnia were common, and autonomic testing was generally regarded as helpful. Eighty percent felt that the risks associated with ‘jayulsingyeongsiljo’ are overstated, and 95% preferred replacing the term with standardized expressions such as autonomic dysfunction. Conclusions Korean neurologists view ‘jayulsingyeongsiljo’ as an unrecognized and potentially misleading label and support society-led standardization of terminology and guidance to improve autonomic dysfunction care and resource use.

Although splenomegaly is typically uncommon in myelodysplastic syndromes (MDS), it is associated with reduced engraftment rates and poor survival outcomes. Despite its clinical significance, the incidence and genetic associations of splenomegaly in MDS remain understudied. To address this, we conducted a retrospective study of 27 patients with MDS at the Veterans Health Service Medical Center in South Korea. Based on computed tomography scan evaluation, splenomegaly was identified in 26% of patients with MDS, and significant associations with variants in ASXL1 (P = 0.0089 for null and missense/inframe variants) and RUNX1 (P = 0.042 for null variants) were observed, suggesting that these variants are linked to an increased risk of splenomegaly. Notably, one patient with ASXL1 and TET2 variants developed severe splenomegaly (spleen size, 29 cm) following granulocyte colony-stimulating factor (G-CSF) treatment, requiring splenectomy. This case suggests a potential interaction between specific genetic variants and G-CSF sensitivity, potentially exacerbating splenomegaly. Our findings suggest that the incidence of splenomegaly in patients with MDS, including mild cases, is likely underestimated and that ASXL1 and RUNX1 variants increase the risk of splenomegaly. Furthermore, careful monitoring for the development of severe splenomegaly during G-CSF treatment may be warranted in genetically susceptible individuals with MDS.

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.

Purpose: Early differentiation between transient congenital hypothyroidism (TCH) and permanent congenital hypothyroidism (PCH) is crucial for optimizing the duration of treatment. This retrospective cohort study aimed to evaluate whether levothyroxine (LT4) dose requirements over time can predict TCH and guide earlier discontinuation of treatment. Methods: We retrospectively analyzed 105 infants with congenital hypothyroidism and normal thyroid glands confirmed by imaging at a single tertiary care center (Inha University Hospital) between January 2013 and December 2022. Patients were classified into TCH (n=70) or PCH (n=35) based on thyroid function after LT4 withdrawal at 3 years of age. LT4 dose/kg at 6, 12, and 24 months, along with clinical and biochemical parameters, were compared between the 2 groups. Receiver operating characteristic (ROC) curve analysis was used to assess the predictive performance of LT4 dose thresholds. Results: The LT4 dose was significantly lower in the TCH group at 6 (3.16±0.83 μg/kg vs. 3.75±0.99 μg/kg, P=0.005), 12 (2.51±0.82 μg/kg vs. 3.37±1.17 μg/kg, P<0.001), and 24 months (2.02±0.61 μg/kg vs. 3.09±1.19 μg/kg, P<0.001). ROC curve analysis showed an area under the curve (AUC) of 0.649, 0.746, and 0.794 at 6, 12, and 24 months, respectively. A logistic regression model incorporating LT4 dose, birth weight, and thyroid-stimulating hormone (TSH) levels improved prediction accuracy (AUC: 0.740, 0.782, 0.833 at 6, 12, and 24 months, respectively). Conclusion LT4 dose requirements at 6, 12, and 24 months serve as useful indicators for differentiating TCH from PCH. A combined predictive model incorporating LT4 dose, birth weight, and TSH levels may improve diagnostic accuracy, supporting earlier discontinuation of treatment.

Purpose: Endoscopic submucosal dissection (ESD) has become a standard minimally invasive treatment for selected patients with early gastric cancer (EGC). This study presents the first nationwide survey of patients with EGC treated with ESD in 2023, conducted by the Korean College of Helicobacter and Upper Gastrointestinal Research. Materials and Methods: Data were retrospectively collected from participating referral centers across Korea using a standardized case report form covering patient characteristics, tumor features, procedural details, histopathological findings, and clinical outcomes.Descriptive and comparative analyses were conducted to summarize nationwide ESD practice patterns and outcomes. Results: Data from 5,460 ESD cases from 5,250 patients across 27 institutions were analyzed. The mean age was 67.4 years, with 74.1% males. Multiple synchronous lesions were identified in 3.7%. Most lesions were located in the lower third of the stomach (64.0%), and differentiated-type adenocarcinomas accounted for 87.8%. The en bloc and complete resection rates were 99.2% and 91.4%, respectively. Curative resection was achieved in 80.5%, whereas local non-curative resection (L-NCR) and surgical non-curative resection (S-NCR) were identified in 2.8% and 16.7%, respectively. Additional surgery was performed more frequently in patients with S-NCR than in those with L-NCR (59.3% vs. 24.7%). The bleeding and perforation rates were 3.6% and 0.9%, respectively, and were mostly managed conservatively or endoscopically. The median length of hospitalization was 4.0 days. Conclusions This first nationwide survey provides a comprehensive overview of the current practice of EGC treatment using ESD in Korea, demonstrating high technical success and safety, and establishing a baseline dataset for future longitudinal research.

Purpose: This study evaluated long-term trends in gastric cancer epidemiology and survival with a focus on conditional relative survival (CRS). Materials and Methods: Using the Korea Central Cancer Registry, we analyzed 665,184 patients who were newly diagnosed with gastric cancer between 1999 and 2022.The study period was divided into four intervals: Period I (1999–2005), Period II (2006–2011), Period III (2012–2017), and Period IV (2018–2022). Temporal trends in the incidence and mortality were assessed using crude and age-standardized rates. Relative survival was estimated using the Ederer II method, and the 5-year CRS was calculated according to the survival duration after diagnosis. Results: The incidence of gastric cancer increased until 2011 and subsequently declined, with a marked decrease observed in 2020. Individuals aged ≥70 years consistently had the highest incidence rates. Mortality rates showed a sustained decline throughout the study period. The overall 5-year relative survival improved from 69.8% in Period II to 78.4% in Period IV. The 5-year CRS increased from 86.1% at 1 year after diagnosis to 96.3% at 5 years.Patients with localized stage maintained a 5-year CRS above 95% at 1 year after diagnosis, whereas those with regional and distant stages showed 5-year CRS that consistently remained below 95%. Conclusions The incidence and mortality rates of gastric cancer in Korea have declined over the past two decades, accompanied by improved survival outcomes. The CRS analysis suggests that long-term follow-up is warranted, with the optimal duration varying according to patient characteristics.