Differentiating non-epileptic seizures from epileptic seizures in Glut1 deficiency syndrome.

AIM: To investigate the clinical characteristics of non-epileptic seizures due to transient brain dysfunction caused by energy deficiency after prolonged fasting or exercise in individuals with glucose transporter type 1 deficiency syndrome (Glut1DS), and then elucidate further the seizure features to distinguish non-epileptic seizures from epileptic seizures. METHOD: This retrospective case-control study included 57 non-epileptic seizures and 23 epileptic seizures (control group) in 14 individuals (11 males, three females; aged 5-44 years, median = 20 years) with Glut1DS, all with a heterozygous pathogenic SLC2A1 mutation. RESULTS: Non-epileptic seizures were classified as paroxysmal altered consciousness (n = 8), movement disorders (n = 35) (eye-head movements, ataxia, spasticity, weakness, involuntary movement), dysaesthesia (n = 8), and vomiting (n = 6) at the peak ages at onset of 5 to 10 years. Ketogenic diet therapy was effective in 33 of 43 (77%) non-epileptic seizures. Providing supplementary food before high-impact exercise or during attacks prevented or mitigated non-epileptic seizures in some individuals. Glut1DS-associated non-epileptic seizures are fundamentally situation-related seizures with specific provoking and ameliorating factors. Non-epileptic seizures can be distinguished from epileptic seizures by the absence of complete consciousness loss and rapid postictal recovery despite prolonged seizures. INTERPRETATION: Non-epileptic seizures are not well recognized but require different therapeutic approaches compared to epileptic seizures. Awareness of the differentiation of non-epileptic seizures from epileptic seizures is essential when performing preventive or therapeutic decision-making for acute exacerbation seizures.

A reappraisal of interictal EEG characteristics in self-limited epilepsy with autonomic seizures, formerly known as Panayiotopoulos syndrome or early-onset benign occipital epilepsy.

PURPOSE: In the 2022 New International Classification of Epilepsy Syndromes, self-limited epilepsy with autonomic seizures (SeLEAS), formerly known as Panayiotopoulos syndrome is recognized as an electroclinical syndrome that is clinically characterized by autonomic seizures and electroencephalographically by multifocal EEG foci. EEG studies were reviewed herein and the suitability of the EEG definition to characterize SeLEAS was assessed. METHODS AND RESULTS: The EEG findings of SeLEAS studies published to date were reviewed and typical sites of EEG foci and their evolutionary changes with age were analyzed. Although previous studies investigated the details of interictal EEG characteristics in a sufficient number of SeLEAS cases, there were few systematically analyzing cross sectional and longitudinal EEG changes except one study. Despite these limited evidence, I propose the following practical and useful EEG definition. The interictal EEG characteristics of SeLEAS are multifocal EEG foci with age-dependent predominant locations; occipital (O) at 2-5 years old, and occipital and frontopolar (synchronous and independent O and Fp spikes) at 4-7 years old and centro-parieto-temporal (CPT) at 6-10 years old. O EEG foci evolve to multifocal EEG foci with a O-Fp or CPT predominance with age and disappear by 12∼16 years old. O-Fp EEG foci may further evolve to generalized spike-wave complexes and rarely to spike-wave activated in sleep. In rare cases, the EEGs do not have epileptic EEG foci. CONCLUSION: Interictal EEG foci in SeLAES may have different EEG patterns in terms of location and the mode of appearance depending on the age at which EEG is recorded. O-Fp EEG foci may be a specific EEG pattern indicating a diagnosis of SeLEAS.

[Epilepsy in Children].

Childhood epilepsy is characterized by specific epilepsy syndromes that occur during each developmental age. These "age-dependent" epilepsy syndromes are clinically categorized into a self-limited epilepsy group with good prognosis and high prevalence rate and a pharmacoresistant epilepsy group with poor prognosis despite low prevalence rates. Many children develop pharmacoresistant epilepsy beginning in early infancy and progress to developmental epileptic encephalopathy, which is associated with intellectual, behavioral, and/or motor disabilities. These children do not show remission in epilepsy and are transitioned to the adult service and require comprehensive medical care.

Non-lesional late-onset epilepsy in the elderly Japanese patients: Presenting characteristics and seizure outcomes with regard to comorbid dementia.

The objective of the present retrospective study was analysis of clinical, radiological, and electrophysiological characteristics of the non-lesional late-onset epilepsy (NLLOE) in the elderly Japanese patients, and comparison of the seizure outcomes in this population with regard to presence of comorbid dementia. The study cohort comprised 89 consecutive patients with NLLOE aged ≥ 65 years. In 49 cases (55%), NLLOE manifested with a single type of seizure. Focal impaired awareness seizures (FIAS) were encountered most often (in 69 patients; 78%). Ten patients (11%) had a history of the status epilepticus. Comorbid dementia was diagnosed in 31 patients (35%). Localized or diffuse white matter hyperintensity was the most common imaging finding (66 cases). Epileptiform discharges in the temporal area represented the most frequent abnormality on interictal EEG (24 cases). Seizure-free status for ≥ 12 months was attained in 46 out of 64 patients (72%), who were followed for ≥ 12 months (range, 12 - 110 months), and 42 of them received monotherapy, mainly with levetiracetam (21 patients), carbamazepine (10 patients), or lacosamide (8 patients). In comparison to their counterparts, the rate of seizure-free status for ≥ 12 months was significantly lower in patients with comorbid dementia (81% vs. 52%; P = 0.0205). In conclusion, the NLLOE among Japanese patients aged ≥ 65 years has variable presenting characteristics, and comorbid dementia is diagnosed in one-third of cases. Seizure-free status for ≥ 12 months may be attained in more than two-thirds of treated patients, but comorbid dementia is associated with significantly worse response to antiseizure therapy.

CUX2 deficiency causes facilitation of excitatory synaptic transmission onto hippocampus and increased seizure susceptibility to kainate.

CUX2 gene encodes a transcription factor that controls neuronal proliferation, dendrite branching and synapse formation, locating at the epilepsy-associated chromosomal region 12q24 that we previously identified by a genome-wide association study (GWAS) in Japanese population. A CUX2 recurrent de novo variant p.E590K has been described in patients with rare epileptic encephalopathies and the gene is a candidate for the locus, however the mutation may not be enough to generate the genome-wide significance in the GWAS and whether CUX2 variants appear in other types of epilepsies and physiopathological mechanisms are remained to be investigated. Here in this study, we conducted targeted sequencings of CUX2, a paralog CUX1 and its short isoform CASP harboring a unique C-terminus on 271 Japanese patients with a variety of epilepsies, and found that multiple CUX2 missense variants, other than the p.E590K, and some CASP variants including a deletion, predominantly appeared in patients with temporal lobe epilepsy (TLE). The CUX2 variants showed abnormal localization in human cell culture analysis. While wild-type CUX2 enhances dendritic arborization in fly neurons, the effect was compromised by some of the variants. Cux2- and Casp-specific knockout mice both showed high susceptibility to kainate, increased excitatory cell number in the entorhinal cortex, and significant enhancement in glutamatergic synaptic transmission to the hippocampus. CASP and CUX2 proteins physiologically bound to each other and co-expressed in excitatory neurons in brain regions including the entorhinal cortex. These results suggest that CUX2 and CASP variants contribute to the TLE pathology through a facilitation of excitatory synaptic transmission from entorhinal cortex to hippocampus.

Epilepsy with myoclonic-atonic seizures, also known as Doose syndrome: Modification of the diagnostic criteria.

PURPOSE: The aim of this review is to propose the updated diagnostic criteria of epilepsy with myoclonic-atonic seizures (EMAS), which is a recent subject of genetic studies. Although EMAS has been well known as Doose syndrome, it is often difficult to diagnose due to a lack of consensus regarding some of the inclusion criteria. Along with progress in molecular genetic study on the syndrome, it becomes important to recruit electroclinical homogeneous EMAS patients, hence the validity of the clinical criteria should be verified based on recent clinical researches. At present, the most updated ILAE diagnostic manual of EMAS includes: (1) normal development and cognition before the onset of epilepsy; (2) onset of epilepsy between 6 months and 6 years of age (peak: 2-4 years); (3) myoclonic-atonic seizures (MAS) are mandatory (4) presence of generalized spike-wave discharges at 2-3 Hz without persistent focal spike discharges; and (5) exclusion of other myoclonic epilepsy syndromes. In the criteria, we should emphasize that the age at onset of MAS is between 2-5 years in (2), presence of myoclonic-atonic, atonic or myoclonic-flexor seizures (MASs) causing drop attacks associated with generalized spike-wave discharges is mandatory in (3), and epileptic spasms causing drop attacks must be excluded in (5). In the modified criteria, I propose that EMAS is redesignated as genetic generalized epilepsy with MASs, consistent with the familial genetic study conducted by Doose and the recent identification of candidate genes. It should also be noted that EMASs evolves to transient or long-lasting epileptic encephalopathy.

Ictal vocalizations are relatively common in myoclonic-atonic seizures associated with Doose syndrome: an audio-video-polygraphic analysis.

The aim of this study was to investigate ictal vocalizations associated with myoclonic (MS) and myoclonic-atonic seizures (MAS) in patients with myoclonic epilepsy in infants (MEI) and epilepsy with myoclonic-atonic seizures (EMAS, Doose syndrome), respectively. Subjects were retrospectively recruited among patients with MEI and EMAS for whom ictal video-polygraphs were recorded between 1990 and 2019. We reviewed all MS and MAS in order to estimate how often they were associated with vocalizations, and analyze the temporal relationship between vocalizations and spike-wave complexes (SWCs) and myoclonic EMG potentials based on simultaneous examination of the polygraphs and sound signals. Ictal video-polygraphs from 15 patients with MEI (2-34 MS per patient) and 26 with EMAS (2-26 MAS per patient) were examined. Ictal vocalizations were audible in two patients with MEI (11%; 3-18 MS per patient) and nine with EMAS (35%; 2-11 MAS per patient). Sounds were always non-speech and were immediately followed by head or body dropping in the case of MAS. Detailed analysis based on simultaneous and synchronous examination of video-polygraphs and sound signals in one patient with MEI and five patients with EMAS demonstrated that the onset of the ictal vocalizations corresponded to that of the myoclonic EMG potentials and negative spike components of SWC. Comparison of the length of myoclonic EMG potentials as well as the strength of drop seizures between MAS with and without vocalizations revealed that MAS with vocalizations were associated with longer myoclonic EMG potentials and stronger drop seizures than MAS without vocalizations (p<0.05), suggesting that the vocalizations result from strong contraction of axial muscles. Ictal vocalizations due to massive motor seizure activity are a relatively common finding in MAS in Doose syndrome, which may help in the differential diagnosis of epileptic drop attacks.

Focal atonic seizures originated in the posterior temporoparietal area: A case report.

Atonic seizures are typically observed in younger children with Lennox-Gastaut syndrome and have been rarely described in adults. Herein we present a case of the adolescent-onset drug-resistant focal epilepsy in a 31-year-old woman with focal atonic seizures originating in the left posterior temporoparietal area and manifesting without aura with abrupt impairment of consciousness and slow falling down. According to the video-EEG monitoring, the seizure began with the medium amplitude spikes principally at T5 area evolving onto the left centroparietal area, which was immediately followed by the diffuse suppression of the background EEG activity. The underlying mechanism might be related to high-frequency electrical stimulation of the negative motor areas within the inferior frontal gyrus or anterior to the supplementary sensorimotor area.

Morphometric analysis of spike-wave complexes (SWCs) causing myoclonic seizures in children with idiopathic myoclonic epilepsies - A positive SWC component correlates with myoclonic intensity.

AIM: To elucidate the morphological characteristics of spike-wave complexes (SWCs) causing myoclonic seizures (MS) in childhood-onset idiopathic myoclonic epilepsies. SUBJECTS AND METHODS: The subjects were 8 patients, including 4 with epilepsy with myoclonic-atonic seizures (EMAS), 3 with myoclonic epilepsy in infancy (MEI) and 1 with idiopathic unclassifiable myoclonic epilepsy. Morphometric parameters of the SWCs were compared between those with MS [SWC-MS (+)] and those without MS [SWC-MS (-)], and a correlation coefficient analysis was performed between the SWC parameters and the duration of myoclonic electromyogram (EMG) potentials. RESULTS: A total of 155 SWC-MS (+) (range: 7 ∼ 34) and 80 SWC-MS (-) (10 each as a control) were analyzed. Comparison of the parameters of the SWCs between SWC-MS (+) and SWC-MS (-) demonstrated that the depth and the width of the positive-sharp-components (PSC) in the SWC-MS (+) were significantly deeper in amplitude and longer in duration than those in the SWC-MS (-), respectively, in all 8 patients (P < 0.05), whereas the number of the polyphasic-multiple-spike-components (PMSC) and the height of negative-spike-components (NSC) were not significantly different in most of the patients, respectively. The depth and the width of PSC were also significantly correlated with the duration of myoclonic EMG potentials in all patients except one [depth of PSC (n = 7): r = 0.623 ∼ 0.888; width of PSC (n = 8): r = 0.676 ∼ 0.948, P < 0.05]. CONCLUSIONS: This study revealed that the depth and width of PSC of the SWC are positively correlated with the MS intensity in childhood-onset idiopathic myoclonic epilepsies and are an important neurophysiological marker to generate MS.

Transition from pediatric to adult care in a Japanese cohort of childhood-onset epilepsy: prevalence of epileptic syndromes and complexity in the transition.

AIM: We retrospectively examined patients with childhood-onset epilepsy who transitioned from pediatric to adult care to reveal the clinical characteristics and evaluate the complexity of transitioning. METHODS: The subjects were 220 patients (89 males, 131 females) who had been treated at our pediatric epilepsy clinic and had transferred to adult care between 2014 and 2018 without attending a transition clinic or program. The demographic data of the patients were retrospectively analyzed. RESULTS: The ages at transition ranged from 15 to 54 years (median: 27 years old). There were 91 patients with focal epilepsies (FEs) and 129 patients with generalized epilepsies [genetic generalized epilepsy (GGE) n = 30, generalized epilepsy of various etiologies (GEv) n = 99]. A most frequent epileptic syndrome was temporal lobe epilepsy followed by frontal lobe epilepsy in FEs, GTCS only followed by juvenile myoclonic epilepsy in GGE and Lennox-Gastaut syndrome followed by Dravet syndrome in GEv. At the age of transition, a total of 77 of the 96 patients with developmental and epileptic encephalopathies (DEE) had pharmacoresistant seizures, which was positively correlated with a late transition age (P≤0.05). More than monthly seizures and greater than moderate disabilities were noted in 45% and 55% of the patients, respectively. CONCLUSION: The patients with childhood-onset epilepsy transitioned to adult care from the hospital-based pediatric epilepsy clinic were characterized by generalized>focal epilepsy, a frequent complication of DEE, more than monthly seizures, and worse than moderate intellectual disabilities. The complication of DEE made a smooth transition difficult and delayed the transition age.

Unexpected elevation in valproic acid concentration and agranulocytosis in a patient with short-chain acyl-CoA dehydrogenase deficiency.

BACKGROUND: Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is an autosomal recessive metabolic disorder or condition of fatty acid ß-oxidation, caused by mutations in the gene encoding SCAD (ACADS). We report an infant with SCAD deficiency who unexpectedly exhibited an extremely high blood concentration of valproic acid (VPA) and agranulocytosis. CASE REPORT: An 8-month-old girl was diagnosed with West syndrome (infantile spasms), and VPA was administered at the standard level of 25 mg/kg/day. However, the blood concentration of VPA rose unexpectedly to 230 µg/mL (two- to three-fold higher than the expected value), and continued to remain relatively high even after the dosage was reduced (7 mg/kg/day, blood concentration of 88 µg/mL). Furthermore, she presented with a high-grade fever with agranulocytosis (neutrophil 231/µL). The abnormal pharmacokinetics and toxicity of VPA raised the suspicion of possible inborn errors of metabolism in the fatty acid ß-oxidation pathway. Blood tandem mass spectrometry revealed a transient elevation of C4, and urine gas chromatography-mass spectrometry revealed a continuous elevation of ethylmalonate. Finally, gene analysis revealed compound heterozygous mutations, c.625G > A (p.G209S) and c.1031A > G (p.E344G), in ACADS. CONCLUSION: VPA should be avoided if a patient is suspected to have inborn errors of ß-oxidation including SCAD deficiency.

Low-dose phenobarbital for epilepsy with myoclonic absences: A case report.

BACKGROUND: Epilepsy with myoclonic absences (EMA) is a rare childhood-onset syndrome characterized by absences of responsiveness accompanied by bilateral rhythmic clonic-like myoclonic jerks. Herein, we describe the case of a child with EMA, resistant to multiple commonly used antiepileptic drugs, in whom low-dose phenobarbital unexpectedly achieved complete remission of epilepsy. CASE REPORT: A 10-year-old boy was referred to our hospital because of pharmaco-resistant frequent myoclonic absence seizures (MASs) and occasional generalized tonic-clonic seizures (GTCSs) that had commenced at the age of 7 years. Antiepileptic drugs including valproate sodium (VPA), levetiracetam, ethosuximide (ESM), clobazam, zonisamide, topiramate, clonazepam and lamotrigine were tested without significant effects. At the age of 8 years, phenobarbital was added to the VPA and ESM and increased to 1.2 mg/kg/day (blood concentration 8.6 µg/mL), which suppressed MASs completely within 1 month, and epileptic discharges on electroencephalography (EEG) within 5 months. To date, the boy has been seizure-free with normal EEG for 2 years. CONCLUSION: Phenobarbital is a potential therapeutic option for pharmaco-resistant EMA.

Wearable EEG Device for Continuous Spike-Wave in Sleep.

Investigators from the Hospital Dona Estefânia, Escola Superior de Tecnologias e Saúde de Lisboa and Centro Hospitalar Psiquiátrico de Lisboa investigated 38 patients with continuous spike-wave of sleep (CSWS) syndrome.

Glut1 Deficiency Syndrome (Glut1DS): State of the art in 2020 and recommendations of the international Glut1DS study group.

Glut1 deficiency syndrome (Glut1DS) is a brain energy failure syndrome caused by impaired glucose transport across brain tissue barriers. Glucose diffusion across tissue barriers is facilitated by a family of proteins including glucose transporter type 1 (Glut1). Patients are treated effectively with ketogenic diet therapies (KDT) that provide a supplemental fuel, namely ketone bodies, for brain energy metabolism. The increasing complexity of Glut1DS, since its original description in 1991, now demands an international consensus statement regarding diagnosis and treatment. International experts (n = 23) developed a consensus statement utilizing their collective professional experience, responses to a standardized questionnaire, and serial discussions of wide-ranging issues related to Glut1DS. Key clinical features signaling the onset of Glut1DS are eye-head movement abnormalities, seizures, neurodevelopmental impairment, deceleration of head growth, and movement disorders. Diagnosis is confirmed by the presence of these clinical signs, hypoglycorrhachia documented by lumbar puncture, and genetic analysis showing pathogenic SLC2A1 variants. KDT represent standard choices with Glut1DS-specific recommendations regarding duration, composition, and management. Ongoing research has identified future interventions to restore Glut1 protein content and function. Clinical manifestations are influenced by patient age, genetic complexity, and novel therapeutic interventions. All clinical phenotypes will benefit from a better understanding of Glut1DS natural history throughout the life cycle and from improved guidelines facilitating early diagnosis and prompt treatment. Often, the presenting seizures are treated initially with antiseizure drugs before the cause of the epilepsy is ascertained and appropriate KDT are initiated. Initial drug treatment fails to treat the underlying metabolic disturbance during early brain development, contributing to the long-term disease burden. Impaired development of the brain microvasculature is one such complication of delayed Glut1DS treatment in the postnatal period. This international consensus statement should facilitate prompt diagnosis and guide best standard of care for Glut1DS throughout the life cycle.

A de novo GABRB2 variant associated with myoclonic status epilepticus and rhythmic high-amplitude delta with superimposed (poly) spikes (RHADS).

We report a child who developed myoclonic status epilepticus (MSE) at four months of age, associated with rhythmic high-amplitude delta and superimposed (poly) spikes (RHADS), harbouring a GABRB2 (ß2 subunit of the GABA A receptor) variant. The patient was treated under a presumptive diagnosis of neonatal-onset Alpers syndrome (AS) and underwent targeted sequence analysis for POLG1 (polymerase gamma 1) and subsequent whole-exome sequence analysis (WES). The patient is currently a 10-year, eight-month-old boy, suffering from daily MSE associated with RHADS and severe global developmental delay from early infancy. Although POLG1 mutation was negative, WES revealed a de novo missense variant of GABRB2 (NM_021911.2: c.784G>T, p.[Val262Phe]). Based on a review of case series with GABRB2 variants, we found that five of the 18 cases shared the clinical and EEG characteristics associated with our patient. In summary, this de novo GABRB2 variant was associated with an AS phenotype, characterized by treatment-resistant MSE and RHADS, and may represent an alternative aetiology for neonatal-onset AS without POLG1 mutation [Published with video sequence].

Encephalopathy related to status epilepticus during slow sleep (ESES) as atypical evolution of Panayiotopoulos syndrome: an EEG and neuropsychological study.

We report two patients with Panayiotopoulos syndrome (PS) who developed encephalopathy related to status epilepticus during slow sleep (ESES) at the peak of their clinical course. Clinical charts and EEG data were reviewed. The patients exhibited nocturnal autonomic seizures and occipital EEG foci, the latter of which later evolved into multifocal EEG foci with synchronous frontopolar and occipital spikes (Fp-O EEG foci), and finally into continuous spikes-waves during sleep (CSWS; spike-wave index >85% based on whole-night sleep recording) at eight years and seven years of age, respectively. The occipital spikes always preceded frontopolar spikes by 30∼50 mseconds based on the analysis of CSWS. Neuropsychological ability, including IQ, deteriorated during the CSWS period in both patients. The autonomic seizures and focal to bilateral tonic-clonic seizures were initially resistant to antiepileptic drugs (AEDs), and occurred more than 10 times in both patients. However, the seizures and EEG findings gradually resolved, and AEDs were successfully terminated in both patients. PS can progress to ESES if the clinical course exhibits atypical evolution. The initial autonomic symptom of the seizures and interictal Fp-O EEG foci should be carefully monitored in patients with CSWS or ESES.

Recurrent NUS1 canonical splice donor site mutation in two unrelated individuals with epilepsy, myoclonus, ataxia and scoliosis - a case report.

BACKGROUND: We encountered two unrelated individuals suffering from neurological disorders, including epilepsy and scoliosis. CASE PRESENTATION: Whole-exome sequencing identified the same recurrent, de novo, pathogenic variant in NUS1 [NM_138459.4:c.691 + 1C > A] in both individuals. This variant is located in the conserved cis-prenyltransferase domain of the nuclear undecaprenyl pyrophosphate synthase 1 gene (NUS1), which encodes the Nogo-B receptor, an essential catalyst for protein glycosylation. This variant was confirmed to create a new splice donor site, resulting in aberrant RNA splicing resulting in a 91-bp deletion in exon 3 in both individuals. The mutant mRNA was partially degraded by nonsense mediated mRNA decay. To date, only four de novo variants and one homozygous variant have been reported in NUS1, which cause developmental and epileptic encephalopathy, early onset Parkinson's disease, and a congenital disorder of glycosylation. Seven patients, including our two patients, have presented with epileptic seizures and intellectual disabilities. CONCLUSIONS: Our study strongly supports the finding that this recurrent, de novo, variant in NUS1 causes developmental and epileptic encephalopathy with involuntary movement, ataxia and scoliosis.

A missense variant of SMC1A causes periodic pharmaco-resistant cluster seizures similar to PCDH19-related epilepsy.

SMC1A variants causing Cornelia de Lange syndrome (CdLS) produce another phenotype characterized by moderate to severe neurological impairment and severe early-onset epilepsy without morphological characteristics of CdLS. The patients are all female and have truncation mutations in SMC1A. The epilepsy also follows a characteristic clinical course with pharmaco-resistant cluster seizures since infancy, mimicking that of PCDH19-related epilepsy. We report here that a missense variant of the SMC1A gene affecting a daughter (proband) and her mother caused similar phenotypes of early-onset (2 years and 1 month of age) and late-onset (12 years of age) epilepsy, respectively. Both patients lacked the morphological characteristics of CdLS, and had severe and moderate intellectual disability, respectively. The cluster seizures were characteristic, occurring approximately every 2-4 weeks (interval; mean ±â€¯SD: 20.2 ±â€¯8.3 days) at the peak of the clinical course, especially in the proband. Thus, SMC1A-related encephalopathy is caused not only by truncation mutations but also by missense variants of the SMC1A gene. The periodicity of cluster seizures mimicking that of PCDH19-related epilepsy may characterize SMC1A-related encephalopathy.

Genomic backgrounds of Japanese patients with undiagnosed neurodevelopmental disorders.

BACKGROUND: Recently, many genes related to neurodevelopmental disorders have been identified by high-throughput genomic analysis; however, a comprehensive understanding of the mechanism underlying neurodevelopmental disorders remains to be established. To further understand these underlying mechanisms, we performed a comprehensive genomic analysis of patients with undiagnosed neurodevelopmental disorders. METHODS: Genomic analysis using next-generation sequencing with a targeted panel was performed for a total of 133 Japanese patients (male/female, 81/52) with previously undiagnosed neurodevelopmental disorders, including developmental delay (DD), intellectual disability (ID), autism spectrum disorder (ASD), and epilepsy. Genomic copy numbers were also analyzed using the eXome Hidden Markov Model (XHMM). RESULTS: Thirty-nine patients (29.3%) exhibited pathogenic or likely pathogenic findings with single-gene variants or chromosomal aberrations. Among them, 20 patients were presented here. Pathogenic or likely pathogenic variants were identified in 18 genes, including ACTG1, CACNA1A, CHD2, CDKL5, DNMT3A, EHMT1, GABRB3, GABRG2, GRIN2B, KCNQ3, KDM5C, MED13L, SCN2A, SHANK3, SMARCA2, STXBP1, SYNGAP1, and TBL1XR1. CONCLUSION: A diagnostic yield of 29.3% in this study was nearly the same as that previously reported from other countries. Thus, we suggest that there is no difference in genomic backgrounds in Japanese patients with undiagnosed neurodevelopmental disabilities. Although most of the patients possessed de novo variants, one of the patients showed an X-linked inheritance pattern. As X-linked recessive disorders exhibit the possibility of recurrent occurrence in the family, comprehensive molecular diagnosis is important for genetic counseling.