BACKGROUND:Infantile epileptic spasms syndrome (IESS) is a severe form of infantile epilepsy with a high lifetime morbidity burden. PURPOSE:We aimed to assess the long-term epilepsy and neurodevelopmental outcomes based on how children with IESS have been managed over the past few decades. METHODS:This retrospective multicenter study included children diagnosed with IESS between 1994 and 2021 with a minimum follow-up period of 2 years. Data on demographics, clinical features, medical history, diagnostic evaluations, and treatments used to control spasms were collected. Epilepsy and neurodevelopmental outcomes were assessed at final follow-up. RESULTS:A total of 378 infants with IESS were included. The mean age at onset of spasms was 7.3 (range, 1-24) months and mean follow-up duration was 7.9 (range, 2-28) years. Etiologies were identified in 65.1% of cases, with acquired structural etiologies being the most prevalent (29.9%). Among the genetic and genetic-structural etiologies, tuberous sclerosis complex (n=35), Down syndrome (n=8), Miller-Dieker syndrome (n=3), and 15q duplication syndrome (n=3) were the most common. Vigabatrin was prescribed to 93.9% of the patients, suggesting that it was the mainstay of treatment. At the last follow-up, 77.8% of the children remained on antiseizure medications and 29.1% had drug-resistant epilepsy. Approximately 90% had intellectual disabilities, and half of the eligible individuals had received special education. CONCLUSION:The IESS imposes a substantial burden on affected children and their families and often leads to chronic epilepsy and impaired cognitive function. Consensus diagnostic and treatment guidelines tailored to the Korean clinical practice are necessary to ensure early diagnosis and timely treatment.

Neurodevelopmental disorders (NDDs) often remain unexplained due to limited assessment of non-coding genomic elements. Motivated by recent reports implicating RNU4-2, which encodes a spliceosomal small nuclear RNA (snRNA), we analyzed whole-genome sequencing data from 15 450 Korean individuals, including 2797 unrelated NDD probands. Rare pathogenic RNU4-2 variants were identified in 20 probands (0.72%), including 17 (85%) with a recurrent n.64_65insT variant. RNA secondary structure modeling and molecular dynamics simulations demonstrated that n.64_65insT disrupts the U4/U6 snRNA duplex and impairs exposure of the U6 ACAGAGA motif required for 5' splice-site recognition. Whole-blood RNA-seq from carriers revealed increased alternative 5' splice-site usage and dysregulation of immune, chromosomal, and DNA metabolic gene programs. Clinically, affected individuals presented with global developmental delay, microcephaly, seizures, failure to thrive, and dysmorphic features. These findings establish RNU4-2, particularly n.64_65insT, as a cause of early-onset NDD. We advocate for routine assessment of spliceosomal RNA genes in genomic diagnostics and reanalysis of unsolved cases to improve yield and guide counseling in rare neurodevelopmental syndromes.

Purpose: Hexokinase 1 (HK1) encodes a ubiquitously expressed hexokinase, which is responsible for the first step of glycolysis, phosphorylation of glucose to glucose-6-phosphate. Both autosomal recessive and dominant variants in this gene have previously been shown to cause human disease, and presently, there are clinical data available for 27 individuals with the monoallelic neurodevelopmental disorder with visual defects and brain anomalies. Delineation of the entire phenotypic spectrum and genotype-phenotype relations will aid in management and counseling decisions. Methods: We present molecular and clinical data on 22 additional individuals with heterozygous, mostly de novo, variants in HK1. We also reviewed data from the published literature. Results: The clinical manifestations of neurodevelopmental disorder with visual defects and brain anomalies include varying degrees of intellectual disability/developmental delay, hypotonia, epileptic encephalopathy, visual deficits, a Leigh syndrome spectrum pattern on brain magnetic resonance imaging, and elevated lactate in blood and cerebrospinal fluid, suggesting mitochondrial dysfunction. Based on severity, individuals can be classified into mild, moderate, severe, or lethal forms. In terms of genotype-phenotype correlation, we find that all individuals carrying a missense variant at the threonine 457 residue have severe clinical features. Conclusion: HK1 should be included in mitochondrial disorder gene sequencing panels.

Background: This study aimed to explore the clinical utility of targeted MECP2 testing in a large cohort of females with neurodevelopmental delays. Our aim was to identify suitable candidates for testing based on prevailing diagnostic criteria. Methods: Eligible participants with global developmental delay/arrest or regression before age 36 months underwent MECP2 testing. MECP2-positive patients were further categorized based on Rett syndrome (RTT) diagnostic criteria, including typical, atypical, possible, and unclassified, to assess disease typicality and progression with respect to age. Results: Of the 683 patients, 162 (23.7%) were diagnosed with MECP2-related RTT. Global developmental delay was the predominant initial symptom in approximately 75% of the cohort with developmental arrest/regression at testing. Symptoms emerged before age six months in 14 patients (8.6%). The average age at the time of MECP2 testing was 3.7 years, with 31.5% of the patients tested under two years. Of those under two years, 15 were initially categorized into the unclassified group; however, 12 were later reclassified into the typical/atypical RTT groups based on follow-up evaluation. Among the 119 patients monitored beyond age five years, 80% displayed typical RTT symptoms, 10 remained unclassified, and 9.8% had exonic deletions, posing challenges for detection using next-generation sequencing. Conclusions: Targeted MECP2 testing has emerged as a clinically valuable tool with a high diagnostic yield, including the identification of small deletions. Given that younger patients may not always meet the classic RTT criteria, this study recommends targeted MECP2 testing in younger patients without typical RTT features. (c) 2024 Published by Elsevier Inc.

Pediatric multiple sclerosis (MS) and neuromyelitis optica (NMO) are rare acquired demyelinating syndrome with limited epidemiological data available, particularly in non-Western setting. This study aimed to demonstrate the epidemiology of pediatric MS and NMO in South Korea and to analyze of healthcare utilization and economic burden associated with these conditions. Using a nationwide population-based database from the Korean Health Insurance Review and Assessment Service database, we identified pediatric cases (age < 20 years) of MS and NMO from 2016 to 2020. We analyzed incidence, prevalence, healthcare utilization and medical costs. The study found low age-standardized incidence and prevalence rates for pediatric MS and NMO in South Korea. There was a marked disparity in healthcare utilization between urban and rural areas. Most healthcare interactions occurred in tertiary hospitals in urban settings, particularly in Seoul. The study also highlighted the substantial economic burden associated with the management of rare diseases, with annual variability in medical costs. Pediatric MS and NMO are extremely rare in South Korea, with significant regional disparity in healthcare utilization. The findings emphasize the need for targeted healthcare policies to improve access and reduce disparities, particularly for chronic and rare diseases requiring specialized care.

PURPOSE:Perampanel (PER) is expanding the therapeutic scope for pediatric epilepsy owing to its efficacy and favorable safety profile. However, concerns about psychiatric and behavioral adverse events (PBAEs) in combination therapy with levetiracetam (LEV) continue to contribute to hesitation in its prescription. We investigated the risk profiles for PBAEs when adding PER to pediatric epilepsy treatment and analyzed the differences according to the presence of concomitant LEV. METHODS:We retrospectively reviewed the medical records of children aged 4-18 years with epilepsy who were prescribed PER as adjunctive therapy from March 2016 to February 2023. We compared the occurrence and management of PBAEs between the PER without LEV and PER with LEV groups. The risk factors for PBAEs were also analyzed. RESULTS:Ninety-four patients (53 boys and 41 girls) were included in this study. The median age of total patients at the time of adding PER was 14.9 years (12.3-16.4 years), and 53 patients (56.4 %) had concomitant LEV. Forty-seven PBAEs occurred in 34 patients (36.2 %), with no significant differences depending on whether concomitant LEV is present or not. The most common PBAEs were aggression (14.9 %), irritability (9.6 %), affect lability (7.4 %), and acute psychosis (6.4 %). PBAEs occurred at a lower dosage (2-6 mg/day) in 70.6 % of the patients. In addition, 73.5 % of patients with PBAEs continued PER treatment by follow-up observation or by reducing the PER dosage. No risk factors, such as the presence of concomitant LEV or lamotrigine, any comorbid conditions, higher PER dosage (8-12 mg/day), two or more concomitant anti-seizure medications, and younger age (<13 years) at PER add-on, showed significant associations. CONCLUSION:When expanding the use of anti-seizure medications in pediatric patients, real-world evidence on safety issues is crucial for pediatric epileptologists. We confirmed that combination therapy with PER and LEV did not increase the risk profile of PBAEs.

Background Teenagers with epilepsy require special attention to ensure a successful treatment journey. Our objective was to delineate the clinical characteristics of adolescent-onset epilepsy (AOE) and investigate the predictive factors influencing first-year seizure freedom.Methods We retrospectively analyzed the medical records of patients whose first seizure occurred between the ages of 10 and 19 years and who received antiseizure medication (ASM) treatment for at least 12 months.Results A total of 67 patients were included, with an average age of 13.5 +/- 2.3 years at the onset of their first seizure. The average follow-up period was 45.2 +/- 16.9 months, and comorbid conditions were present in 23 patients (34.3%). The majority of the patient population (83.6%) was affected by generalized epilepsy. The most common epilepsy syndrome was epilepsy with generalized tonic-clonic seizures alone at 70.1% (juvenile myoclonic epilepsy 11.9%, juvenile absence epilepsy 1.5%). Regarding ASM treatment, 31 patients (46.3%) received monotherapy, and 28 (41.8%) received dual therapy. Five patients (7.5%) encountered issues related to medication adherence. First-year seizure freedom was observed in 42 patients (62.7%). In multivariate analysis, a negative family history of epilepsy (odds ratio 12.1, 95% confidence interval 1.27-115.44, p = 0.030) was identified as a strong predictive factor of first-year seizure freedom, along with ASM monotherapy (odds ratio 3.99, 95% confidence interval 1.05-15.21, p = 0.043).Conclusion These findings suggest that AOE typically exhibits effective control of seizures. A negative family history of epilepsy and ASM monotherapy emerges as robust predictor of achieving favorable outcomes within the early stage of treatment.

BackgroundRecurrent simple febrile seizure (SFS) refers to febrile seizures (FS) that recur within 24 hours. Patients with recurrent SFS often undergo unnecessary neurodiagnostic tests. To address this, we compared the clinical characteristics of recurrent SFS with those of SFS and investigated the risk factors associated with recurrent SFS.MethodsWe retrospectively reviewed electronic medical records of patients aged 6-60 months who had been hospitalized for FS at two training hospitals between January 2016 and December 2019. The primary outcome was a comparison of the clinical features of patients with SFS and recurrent SFS. Additionally, the risk factors associated with seizure recurrence within 24 hours were evaluated.ResultsThree-quarters (n=191, 75.2%) of the 254 enrolled patients experienced a single seizure episode during the febrile illness period. The remaining 63 patients (24.8%) were diagnosed as recurrent SFS. Significant differences between SFS and recurrent SFS were observed in the history of recurrent SFS, time from fever onset to seizure, and body temperature on hospital arrival. Multiple logistic regression analysis revealed that a history of previous recurrent SFS (odds ratio [OR] 10.161) and a body temperature below 39 °C on arrival (OR 2.377) were significantly associated with early seizure recurrence.ConclusionThis study highlights that early FS recurrence is common and has a self-limiting clinical course similar to that of SFS. We recommend close monitoring of the patient for 6–8 hours when a history of early recurrence is present or if the seizure occurs at a low body temperature.

Gabriele-de Vries syndrome (GADEVS) is an extremely rare genetic syndrome characterized by mild-to-profound intellectual disability/developmental delay and a wide spectrum of clinical features. Herein, we report a case involving a rare early childhood epilepsy phenotype in a patient diagnosed with GADEVS based on the typical clinical features and the identification of a pathologic variant of the Yin Yang 1 (YY1) gene. A 3-year-old girl with global developmental delay, failure to thrive, and facial dysmorphism was referred to our rare genetic clinic. She also presented with cognitive impairment, hypotonia, hyperlaxity, strabismus, and autistic features. Whole genome sequencing identified a de novo heterozygous missense variant in the YY1 (c.1130A>G; p.His377Arg) gene. Notably, she developed afebrile seizures with abnormal electroencephalogram in early childhood. Currently, she has been seizure-free for more than 2 years with valproic acid. This case expands the epilepsy phenotypic features of GADEVS and reviews the association between the loss-of-function of the YY1 gene and epileptogenesis and possible treatment options.

Purpose We aimed to evaluate the utility of facial analysis technology for genetic diagnoses in a typical pediatric genetic clinic. Methods A retrospective review identified children (aged <18 years) who had not previously received a definitive genetic diagnosis and underwent a comprehensive genetic evaluation. Their photographs and relevant clinical non-facial features were uploaded to the CLINIC application of the Face2Gene web interface, and the resulting analysis was accessed and correlated to the molecular diagnosis. Results Of the 23 children included, the overall diagnostic yield in this study was 60.9% (14/23). In total, 64.3% of patients had the correct condition suggested in the top 10 differential diagnoses. The gestalt similarity was only 55.6%, but the phenotypic features added by the clinician showed a similarity of more than the medium level in all patients. Conclusion Our data underscore the usefulness of facial analysis technology as an auxiliary point-of-care tool in pediatric genetic clinics, and we also present some considerations to increase accuracy.

Background: Our study aimed to characterize seizure incidence and seizure outcome of pediatric auto -immune encephalitis (AE) focusing on subgroup analysis based on antibody (Ab).Methods: Among 110 pediatric patients with AE, we compared seizure characteristics and outcomes in 68 patients with seizure, who satisfied the proposed criteria of pediatric AE. Accordingly, patients were classified into three groups, anti-myelin oligodendrocyte glycoprotein (anti-MOG) AE, anti-N-methyl-D-aspartic acid receptor (anti-NMDAR) AE, and Ab-negative AE. Univariate and multivariate analyses were performed to evaluate the risk factors for postencephalitic seizures, defined as persisting seizures six months after onset.Results: Seizure incidence in the anti-NMDAR (88.9%) and Ab-negative (71.1%) groups differed from anti-MOG group (37.8%). Median seizure frequency within six months was higher in the Ab-negative group (6.0, interquartile range [IQR] 3.0 to 13.0) than in the anti-NMDAR group (3.0, IQR 2.0 to 4.5) and anti-MOG group (2.0, IQR 1.0 to 5.0). Patients in the Ab-negative group tended to develop postencephalitic seizures more frequently and have a lower seizure freedom rate than those in the anti-NMDAR and anti-MOG groups. Ab-negative status, high seizure frequency within six months, and the presence of status epilepticus were associated with the development of postencephalitic seizures on univariate analysis. On multivariate analysis, Ab-negative status remained the only significant variable linked with post -encephalitic seizure (odds ratio, 4.17; 95% confidence interval, 1.02 to 18.05).Conclusions: We delineated the seizure incidence, evolution, and outcome of pediatric patients with Ab-positive and Ab-negative AE. Ab-negative status is predictive of higher seizure burden, more frequent development of postencephalitic seizures, and less favorable seizure outcome than anti-NMDAR and anti-MOG Ab-positive status.(c) 2022 Elsevier Inc. All rights reserved.

Emerging evidence indicates that probiotics can influence the gut-brain axis to ameliorate somatic and behavioral symptoms associated with brain disorders. However, whether probiotics have effects on the electrophysiological activities of individual neurons in the brain has not been evaluated at a single-neuron resolution, and whether the neuronal effects of probiotics depend on the gut microbiome status have yet to be tested. Thus, we conducted whole-cell patch-clamp recording-assisted electrophysiological characterizations of the neuronal effects of probiotics in male germ-free (GF) mice with and without gut microbiome colonization. Two weeks of treatment with probiotics (Lactobacillus rhamnosus and Bifidobacterium animalis) significantly and selectively increased the intrinsic excitability of hippocampal CA1 pyramidal neurons, whereas reconstituting gut microbiota in GF mice reversed the effects of the probiotics leading to a decreased intrinsic excitability in hippocampal neurons. This bidirectional modulation of neuronal excitability by probiotics was observed in hippocampal neurons with corresponding basal membrane property and action potential waveform changes. However, unlike the hippocampus, the amygdala excitatory neurons did not show any electrophysiological changes to the probiotic treatment in either GF or conventionalized GF mice. Our findings demonstrate for the first time how probiotic treatment can have a significant influence on the electrophysiological properties of neurons, bidirectionally modulating their intrinsic excitability in a gut microbiota and brain area-specific manner.

Introduction: Spinal muscular atrophy (SMA) is a degenerative neuromuscular disorder long recognized as the most common genetic cause of infantile mortality described so far. However, the emergence of some innovative therapies, such as nusinersen and onasemnogene abeparvovec (AVXS-101), have made it possible to change the disease course of SMA.Methods: In this study, five SMA type 1 and one SMA type 2 patients who received AVXS-101 were enrolled (7-24 months of age when administered). They were all previously treated with nusinersen, 4-5 times including loading doses, but stopped nusinersen maintenance after injection of AVXS-101. Patients were regularly followed up with laboratory tests and functional assessments after administration. Results: Liver enzymes (aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase) and monocyte count tended to be elevated but normalized after several weeks. Platelets and white blood cells were transiently decreased for a few weeks after injection. Prolonged elevation of liver enzymes was associated with steroid tapering earlier than 1 month post treatment. During the follow-up period (ranging from 5 to 17 months after injection), all patients showed improved motor function and there was no case of mortality or requirement for permanent ventilatory support. For one patient, use of bilevel positive airway pressure could be reduced from 16 h to 8 h a day during sleep at 6 months post treatment.Conclusion: Our experience of AVXS-101 treatment has shown that a single intravenous dose could be safe and effective for SMA patients without the need for any maintenance treatment. (c) 2022 The Japanese Society of Child Neurology. Published by Elsevier B.V.

Background Phase I of the Korean Undiagnosed Diseases Program (KUDP), performed for 3 years, has been completed. The Phase I program aimed to solve the problem of undiagnosed patients throughout the country and develop infrastructure, including a data management system and functional core laboratory, for long-term translational research. Herein, we share the clinical experiences of the Phase I program and introduce the activities of the functional core laboratory and data management system. Results During the program (2018–2020), 458 patients were enrolled and classified into 3 groups according to the following criteria: (I) those with a specific clinical assessment which can be verified by direct testing (32 patients); (II) those with a disease group with genetic and phenotypic heterogeneity (353 patients); and (III) those with atypical presentations or diseases unknown to date (73 patients). All patients underwent individualized diagnostic processes based on the decision of an expert consortium. Confirmative diagnoses were obtained for 242 patients (52.8%). The diagnostic yield was different for each group: 81.3% for Group I, 53.3% for Group II, and 38.4% for Group III. Diagnoses were made by next-generation sequencing for 204 patients (84.3%) and other genetic testing for 35 patients (14.5%). Three patients (1.2%) were diagnosed with nongenetic disorders. The KUDP functional core laboratory, with a group of experts, organized a streamlined research pipeline covering various resources, including animal models, stem cells, structural modeling and metabolic and biochemical approaches. Regular data review was performed to screen for candidate genes among undiagnosed patients, and six different genes were identified for functional research. We also developed a web-based database system that supports clinical cohort management and provides a matchmaker exchange protocol based on a matchbox, likely to reinforce the nationwide clinical network and further international collaboration. Conclusions The KUDP evaluated the unmet needs of undiagnosed patients and established infrastructure for a data-sharing system and future functional research. The advancement of the KUDP may lead to sustainable bench-to-bedside research in Korea and contribute to ongoing international collaboration.

Purpose: X-linked myotubular myopathy (XLMTM) is a rare condition of centronuclear myopathy caused by myotubularin 1 (MTM1) mutations. Patients with XLMTM show different neurodevelopmental outcomes after the neonatal period depending on age and acquired hypoxic damage. We aim to evaluate the clinical characteristics and neurodevelopmental outcomes of patients with XLMTM who were followed up at a single center. It is essential to understand the volume and conditions to prepare for being a candidate for new therapeutic strategies. Methods: Patients diagnosed with centronuclear myopathy by muscle pathology and MTM1 mutation analysis were included. We retrospectively investigated motor milestones, communication skills, and bulbar and respiratory function in the patients. The patients were categorized into two groups: with and without hypoxic insults (HI). Results: All 13 patients were severely affected by neonatal hypotonia and required respiratory support and a feeding tube during the neonatal period. The follow-up duration was 4.4 years (range, 0.3 to 8.9). In the non-HI group, developmental milestones were delayed but were slowly achieved. Some patients underwent training in oral feeding with thickened foods and weaning from ventilation. Patients with HI showed poor motor function catch-up and communication skills. Three deaths were associated with acute respiratory failure.Conclusion: Patients with XLMTM without HI can survive long-term with the slow achievement of motor milestones and bulbar and respiratory function. However, hypoxic brain damage following acute respiratory failure negatively influences their developmental potential or even lead to death. Therefore, parental education for proper respiratory management is necessary, especially for young children.

This corrects the article "Clinical Characteristics and Neurologic Outcomes of X-Linked Myotubular Myopathy" on page 127.

Purpose: The purpose of this study was to expand our understanding of phenotypic and genetic variation in Allan-Herndon-Dudley syndrome (AHDS), which is a rare X-linked mental retardation syndrome characterized by hypotonia, generalized spasticity, and moderate-to-severe psychomotor retardation. AHDS is caused by a mutation of solute carrier family 16 member 2 (SLC16A2), which encodes monocarboxylate transporter 8 (MCT8), the transporter of triiodothyronine (T3) into neurons. Methods: We enrolled nine patients with AHDS from unrelated families, except for two patients who were cousins, through a retrospective chart review. Clinical features, brain imaging, electroencephalograms, thyroid hormone profiles, and genetic data were reviewed retrospectively and compared with previously reported cases. Results: We found three novel and five previously reported pathogenic variants in nine patients from eight families. All patients presented with hypotonia, spasticity, severe developmental delay, and elevated serum T3 levels. Cataplexy, which is a previously unreported phenotype, was found in two patients with the same mutation. In our cohort, seizures were uncommon (n=1) but intractable. Conclusion: This study broadens the known phenotypic variations of AHDS, ranging from relatively mild global developmental delay to a severe form of encephalopathy with hypotonia, spasticity, and no acquisition of independent sitting. The syndromic classification or genetic etiology of global developmental delay is extremely heterogeneous; therefore, early clinical suspicion is challenging for clinicians. However, severe mental retardation with hypotonia, spasticity, and elevated serum T3 levels in male patients is a highly suspicious clinical clue for the early diagnosis of AHDS.

Emerging evidence suggests that the intestinal microbiota can influence brain functions and psychological behaviors. However, the underlying neurophysiological mechanisms associated with the gut microbiome-induced behavioral changes are largely unknown. To determine the gut-brain-behavior interaction mechanisms, we characterized both behaviors and electrophysiological effects of clinically efficacious probiotics in germ-free (GF) mice before or after conventionalization of their microbiome.