Timing the clinical onset of epileptic spasms in infantile epileptic spasms syndrome: A tertiary health center's experience.

OBJECTIVE: Lead time to treatment (clinical onset of epileptic spasms [ES] to initiation of appropriate treatment) is known to predict outcomes in infantile epileptic spasms syndrome (IESS). Timing the clinical onset of ES is crucial to establish lead time. We investigated how often ES onset could be established to the nearest week. We aimed to (1) ascertain the exact date or estimate the nearest week of ES onset and (2) compare clinical/demographic factors between patients where date of ES onset was determined or estimated to the nearest week and patients whose date of ES onset could not be estimated to the nearest week. Reasons for difficulties in estimating date of ES onset were explored. METHODS: Retrospective chart review of new onset IESS patients (January 2019-May 2022) extracted the date or week of the clinical onset of ES. Predictors of difficulty in date of ES onset estimation to the nearest week were examined by regression analysis. Sources contributing to difficulties determining date of ES onset were assessed after grouping into categories (provider-, caregiver-, disease-related). RESULTS: Among 100 patients, date of ES onset was estimated to the nearest week in 47%. On univariable analysis, age at diagnosis (p = .021), development delay (p = .007), developmental regression/stagnation (p = .021), ES intermixed with other seizures (p = .011), and nonclustered ES at onset (p = .005) were associated with difficulties estimating date of ES onset. On multivariable analysis, failure to establish date of ES onset was related to ES intermixed with other seizures (p = .004) and nonclustered ES at onset (p = .003). Sources contributing to difficulties determining date of ES onset included disease-related factors (ES characteristics, challenges interpreting electroencephalograms) and provider/caregiver-related factors (delayed diagnosis). SIGNIFICANCE: Difficulties with estimation of lead time (due to difficulties timing ES onset) can impact clinical care (prognostication), as even small increments in lead time duration can have adverse developmental consequences.

Delays to care in infantile epileptic spasms syndrome: Racial and ethnic inequities.

OBJECTIVE: Non-Hispanic (NH) Black children are less likely to receive a standard treatment course for infantile epileptic spasms syndrome (IESS) than White/NH children at pediatric tertiary care epilepsy centers in the United States. However, if inequities exist in time to diagnosis is unknown. Diagnostic delays as little as 1 week can be associated with worse developmental outcomes. METHODS: Diagnostic delays were evaluated in a retrospective cohort of 100 children with new onset IESS between January 2019 and May 2022. RESULTS: Children with Black, Indigenous, and People of Color (BIPOC) caregivers were more likely to experience clinically significant delays in referral from first provider to neurologist, when compared to White/NH children, even after controlling for other demographic and clinical variables (odds ratio = 4.98, confidence interval = 1.24-19.94, p = .023). SIGNIFICANCE: Disproportionate diagnostic delays place BIPOC children at risk of adverse developmental and epilepsy outcomes. Further interventional prospective and qualitative studies are needed to address inequities in care.

The ClinGen Brain Malformation Variant Curation Expert Panel: Rules for somatic variants in AKT3, MTOR, PIK3CA, and PIK3R2.

PURPOSE: Postzygotic (somatic) variants in the mTOR pathway genes cause a spectrum of distinct developmental abnormalities. Accurate classification of somatic variants in this group of disorders is crucial for affected individuals and their families. METHODS: The ClinGen Brain Malformation Variant Curation Expert Panel was formed to curate somatic variants associated with developmental brain malformations. We selected the genes AKT3, MTOR, PIK3CA, and PIK3R2 as the first set of genes to provide additional specifications to the 2015 American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) sequence variant interpretation guidelines, which currently focus solely on germline variants. RESULTS: A total of 24 of the original 28 ACMG/AMP criteria required modification. Several modifications used could be applied to other genes and disorders in which somatic variants play a role: 1) using variant allele fraction differences as evidence that somatic mutagenesis occurred as a proxy for de novo variation, 2) incorporating both somatic and germline evidence, and 3) delineating phenotype on the basis of variable tissue expression. CONCLUSION: We have established a framework for rigorous interpretation of somatic mosaic variants, addressing issues unique to somatic variants that will be applicable to many genes and conditions.

Infantile spasms: Assessing the diagnostic yield of an institutional guideline and the impact of etiology on long-term treatment response.

OBJECTIVE: Neuroimaging and genetic testing have been proposed for diagnostic evaluation of infantile spasms (IS), establishing etiology in ~60% of multicenter IS cohorts. A retrospective analysis of the yield of diagnostic etiology following an institutionally established guideline for investigation/treatment of IS was conducted, and the association between etiological subgroups and sustained response to standard treatment was evaluated. METHODS: Etiology of IS, neuroimaging, and genetic results were extracted from clinical records. Etiology was categorized as acquired or nonacquired, the latter including syndromic patients, nonsyndromic patients with confirmed etiology, and unknown cases. Regression analyses, using clinical variables including subtypes of etiology, were conducted to determine which factors correlated with favorable (spasm freedom at last follow-up after two or fewer standard treatments) versus unfavorable treatment outcome (refractory spasms despite two standard treatments or relapse). RESULTS: We included 127 IS patients (60% males) with a follow-up of 2.4 years (range = .6-5 years). All patients had neuroimaging, and 95% of patients in the nonacquired category (103 of 108 patients) had genetic testing. Etiology was identified in 103 of 127 (81%, 95% confidence interval = .73-.86). At last follow-up, 42 (33%) patients had favorable treatment outcome. No difference in treatment response was observed between acquired and nonacquired etiologies. Among patients with nonacquired etiologies, developmental delay prior to spasms onset increased the odds of unfavorable treatment outcome (p = .014), whereas a clearly recognizable dysmorphic/syndromic etiology was associated with a lower risk for treatment failure (p = .034). In nonacquired etiology without a recognizable dysmorphic/syndrome but with a genetic etiology, unfavorable treatment outcome was more likely (p = .043). SIGNIFICANCE: Rigorous evaluation with neuroimaging and genetic testing yields an etiological diagnosis in most patients with IS. Among patients with a nonacquired etiology, those with recognizable dysmorphic/syndromic diagnosis had a higher likelihood of a favorable treatment outcome, whereas the absence of such a finding, when associated with an identifiable genetic diagnosis, was associated with unfavorable treatment outcomes.

Chronic mTORC1 inhibition rescues behavioral and biochemical deficits resulting from neuronal Depdc5 loss in mice.

DEPDC5 is now recognized as one of the genes most often implicated in familial/inherited focal epilepsy and brain malformations. Individuals with pathogenic variants in DEPDC5 are at risk for epilepsy, associated neuropsychiatric comorbidities and sudden unexplained death in epilepsy. Depdc5flox/flox-Syn1Cre (Depdc5cc+) neuronal-specific Depdc5 knockout mice exhibit seizures and neuronal mTORC1 hyperactivation. It is not known if Depdc5cc+ mice have a hyperactivity/anxiety phenotype, die early from terminal seizures or whether mTOR inhibitors rescue DEPDC5-related seizures and associated comorbidities. Herein, we report that Depdc5cc+ mice were hyperactive in open-field testing but did not display anxiety-like behaviors on the elevated-plus maze. Unlike many other mTOR-related models, Depdc5cc+ mice had minimal epileptiform activity and rare seizures prior to seizure-induced death, as confirmed by video-EEG monitoring. Treatment with the mTORC1 inhibitor rapamycin starting after 3 weeks of age significantly prolonged the survival of Depdc5cc+ mice and partially rescued the behavioral hyperactivity. Rapamycin decreased the enlarged brain size of Depdc5cc+ mice with corresponding decrease in neuronal soma size. Loss of Depdc5 led to a decrease in the other GATOR1 protein levels (NPRL2 and NPRL3). Rapamycin failed to rescue GATOR1 protein levels but rather rescued downstream mTORC1 hyperactivity as measured by phosphorylation of S6. Collectively, our data provide the first evidence of behavioral alterations in mice with Depdc5 loss and support mTOR inhibition as a rational therapeutic strategy for DEPDC5-related epilepsy in humans.

Cost-effectiveness of adrenocorticotropic hormone versus oral steroids for infantile spasms.

OBJECTIVE: To compare the effectiveness and cost-effectiveness of adrenocorticotropic hormone (ACTH) and oral steroids as first-line treatment for infantile spasm resolution, we performed a systematic review, meta-analysis, and cost-effectiveness study. METHODS: A decision analysis model was populated with effectiveness data from a systematic review and meta-analysis of existing literature and cost data from publicly available prices. Effectiveness was defined as the probability of clinical spasm resolution 14 days after treatment initiation. RESULTS: We included 21 studies with a total of 968 patients. The effectiveness of ACTH was not statistically significantly different from that of oral steroids (.70, 95% confidence interval [CI] = .60-.79 vs. .63, 95% CI = .56-.70; p = .28). Considering only the three available randomized trials with a total of 185 patients, the odds ratio of spasm resolution at 14 days with ACTH compared to high-dose prednisolone (4-8 mg/kg/day) was .92 (95% CI = .34-2.52, p = .87). Adjusting for potential publication bias, estimates became even more favorable to high-dose prednisolone. Using US prices, the more cost-effective treatment was high-dose prednisolone, with an incremental cost-effectiveness ratio (ICER) of $333 per case of spasms resolved, followed by ACTH, with an ICER of $1 432 200 per case of spasms resolved. These results were robust to multiple sensitivity analyses and different assumptions. Prednisolone at 4-8 mg/kg/day was more cost-effective than ACTH under a wide range of assumptions. SIGNIFICANCE: For infantile spasm resolution 2 weeks after treatment initiation, current evidence does not support the preeminence of ACTH in terms of effectiveness and, especially, cost-effectiveness.

Defining the clinical, molecular and imaging spectrum of adaptor protein complex 4-associated hereditary spastic paraplegia.

Bi-allelic loss-of-function variants in genes that encode subunits of the adaptor protein complex 4 (AP-4) lead to prototypical yet poorly understood forms of childhood-onset and complex hereditary spastic paraplegia: SPG47 (AP4B1), SPG50 (AP4M1), SPG51 (AP4E1) and SPG52 (AP4S1). Here, we report a detailed cross-sectional analysis of clinical, imaging and molecular data of 156 patients from 101 families. Enrolled patients were of diverse ethnic backgrounds and covered a wide age range (1.0-49.3 years). While the mean age at symptom onset was 0.8 ± 0.6 years [standard deviation (SD), range 0.2-5.0], the mean age at diagnosis was 10.2 ± 8.5 years (SD, range 0.1-46.3). We define a set of core features: early-onset developmental delay with delayed motor milestones and significant speech delay (50% non-verbal); intellectual disability in the moderate to severe range; mild hypotonia in infancy followed by spastic diplegia (mean age: 8.4 ± 5.1 years, SD) and later tetraplegia (mean age: 16.1 ± 9.8 years, SD); postnatal microcephaly (83%); foot deformities (69%); and epilepsy (66%) that is intractable in a subset. At last follow-up, 36% ambulated with assistance (mean age: 8.9 ± 6.4 years, SD) and 54% were wheelchair-dependent (mean age: 13.4 ± 9.8 years, SD). Episodes of stereotypic laughing, possibly consistent with a pseudobulbar affect, were found in 56% of patients. Key features on neuroimaging include a thin corpus callosum (90%), ventriculomegaly (65%) often with colpocephaly, and periventricular white-matter signal abnormalities (68%). Iron deposition and polymicrogyria were found in a subset of patients. AP4B1-associated SPG47 and AP4M1-associated SPG50 accounted for the majority of cases. About two-thirds of patients were born to consanguineous parents, and 82% carried homozygous variants. Over 70 unique variants were present, the majority of which are frameshift or nonsense mutations. To track disease progression across the age spectrum, we defined the relationship between disease severity as measured by several rating scales and disease duration. We found that the presence of epilepsy, which manifested before the age of 3 years in the majority of patients, was associated with worse motor outcomes. Exploring genotype-phenotype correlations, we found that disease severity and major phenotypes were equally distributed among the four subtypes, establishing that SPG47, SPG50, SPG51 and SPG52 share a common phenotype, an 'AP-4 deficiency syndrome'. By delineating the core clinical, imaging, and molecular features of AP-4-associated hereditary spastic paraplegia across the age spectrum our results will facilitate early diagnosis, enable counselling and anticipatory guidance of affected families and help define endpoints for future interventional trials.

Brain MRI abnormalities in patients with infantile spasms and Down syndrome.

INTRODUCTION: Infantile spasms (IS) are the most frequent epilepsy syndrome in children with Down syndrome (DS). In DS, cellular (synaptic/dendritic changes) and molecular mechanisms are believed to contribute to epileptogenesis, rather than gross structural anomalies. Neuroimaging is a standard part of the evaluation of newly diagnosed infantile epilepsy including IS and, in this age group, often requires sedation. It is unclear if neuroimaging provides additional clinically useful etiologic information in IS associated with DS. METHODS: We conducted a retrospective chart review and detailed neuroimaging review in 36 patients (24 males) with IS and DS, cared for at Boston Children's Hospital. RESULTS: Incidental imaging abnormalities were common (42%), but potentially relevant etiologic abnormalities were rare (16%). Structural congenital or acquired abnormalities were associated with ongoing antiepileptic drug (AED) use (p = 0.02), as well as refractory epilepsy (p = 0.04). However, neuroimaging did not alter the treatment plan for any of these patients. CONCLUSIONS: Clinicians must carefully weigh the benefits and risks of neuroimaging in infants with DS and IS, as neuroimaging did not lead to any changes in clinical management in our patients but may offer information regarding prognosis.

De novo mutations in epileptic encephalopathies.

Epileptic encephalopathies are a devastating group of severe childhood epilepsy disorders for which the cause is often unknown. Here we report a screen for de novo mutations in patients with two classical epileptic encephalopathies: infantile spasms (n = 149) and Lennox-Gastaut syndrome (n = 115). We sequenced the exomes of 264 probands, and their parents, and confirmed 329 de novo mutations. A likelihood analysis showed a significant excess of de novo mutations in the ∼4,000 genes that are the most intolerant to functional genetic variation in the human population (P = 2.9 × 10(-3)). Among these are GABRB3, with de novo mutations in four patients, and ALG13, with the same de novo mutation in two patients; both genes show clear statistical evidence of association with epileptic encephalopathy. Given the relevant site-specific mutation rates, the probabilities of these outcomes occurring by chance are P = 4.1 × 10(-10) and P = 7.8 × 10(-12), respectively. Other genes with de novo mutations in this cohort include CACNA1A, CHD2, FLNA, GABRA1, GRIN1, GRIN2B, HNRNPU, IQSEC2, MTOR and NEDD4L. Finally, we show that the de novo mutations observed are enriched in specific gene sets including genes regulated by the fragile X protein (P < 10(-8)), as has been reported previously for autism spectrum disorders.

A mouse model of DEPDC5-related epilepsy: Neuronal loss of Depdc5 causes dysplastic and ectopic neurons, increased mTOR signaling, and seizure susceptibility.

DEPDC5 is a newly identified epilepsy-related gene implicated in focal epilepsy, brain malformations, and Sudden Unexplained Death in Epilepsy (SUDEP). In vitro, DEPDC5 negatively regulates amino acid sensing by the mTOR complex 1 (mTORC1) pathway, but the role of DEPDC5 in neurodevelopment and epilepsy has not been described. No animal model of DEPDC5-related epilepsy has recapitulated the neurological phenotypes seen in patients, and germline knockout rodent models are embryonic lethal. Here, we establish a neuron-specific Depdc5 conditional knockout mouse by cre-recombination under the Synapsin1 promotor. Depdc5flox/flox-Syn1Cre (Depdc5cc+) mice survive to adulthood with a progressive neurologic phenotype that includes motor abnormalities (i.e., hind limb clasping) and reduced survival compared to littermate control mice. Depdc5cc+ mice have larger brains with increased cortical neuron size and dysplastic neurons throughout the cortex, comparable to the abnormal neurons seen in human focal cortical dysplasia specimens. Depdc5 results in constitutive mTORC1 hyperactivation exclusively in neurons as measured by the increased phosphorylation of the downstream ribosomal protein S6. Despite a lack of increased mTORC1 signaling within astrocytes, Depdc5cc+ brains show reactive astrogliosis. We observed two Depdc5cc+ mice to have spontaneous seizures, including a terminal seizure. We demonstrate that as a group Depdc5cc+ mice have lowered seizure thresholds, as evidenced by decreased latency to seizures after chemoconvulsant injection and increased mortality from pentylenetetrazole-induced seizures. In summary, our neuron-specific Depdc5 knockout mouse model recapitulates clinical, pathological, and biochemical features of human DEPDC5-related epilepsy and brain malformations. We thereby present an important model in which to study targeted therapeutic strategies for DEPDC5-related conditions.

Megalencephaly and Macrocephaly.

Megalencephaly is a developmental disorder characterized by brain overgrowth secondary to increased size and/or numbers of neurons and glia. These disorders can be divided into metabolic and developmental categories based on their molecular etiologies. Metabolic megalencephalies are mostly caused by genetic defects in cellular metabolism, whereas developmental megalencephalies have recently been shown to be caused by alterations in signaling pathways that regulate neuronal replication, growth, and migration. These disorders often lead to epilepsy, developmental disabilities, and behavioral problems; specific disorders have associations with overgrowth or abnormalities in other tissues. The molecular underpinnings of many of these disorders are now understood, providing insight into how dysregulation of critical pathways leads to disease. The advances in molecular understanding are leading to improved diagnosis of these conditions, as well as providing new avenues for therapeutic interventions.

Neural Mechanisms Underlying Musical Pitch Perception and Clinical Applications Including Developmental Dyslexia.

Music production and perception invoke a complex set of cognitive functions that rely on the integration of sensorimotor, cognitive, and emotional pathways. Pitch is a fundamental perceptual attribute of sound and a building block for both music and speech. Although the cerebral processing of pitch is not completely understood, recent advances in imaging and electrophysiology have provided insight into the functional and anatomical pathways of pitch processing. This review examines the current understanding of pitch processing and behavioral and neural variations that give rise to difficulties in pitch processing, and potential applications of music education for language processing disorders such as dyslexia.

SLC25A22 is a novel gene for migrating partial seizures in infancy.

OBJECTIVE: To identify a genetic cause for migrating partial seizures in infancy (MPSI). METHODS: We characterized a consanguineous pedigree with MPSI and obtained DNA from affected and unaffected family members. We analyzed single nucleotide polymorphism 500K data to identify regions with evidence of linkage. We performed whole exome sequencing and analyzed homozygous variants in regions of linkage to identify a candidate gene and performed functional studies of the candidate gene SLC25A22. RESULTS: In a consanguineous pedigree with 2 individuals with MPSI, we identified 2 regions of linkage, chromosome 4p16.1-p16.3 and chromosome 11p15.4-pter. Using whole exome sequencing, we identified 8 novel homozygous variants in genes in these regions. Only 1 variant, SLC25A22 c.G328C, results in a change of a highly conserved amino acid (p.G110R) and was not present in control samples. SLC25A22 encodes a glutamate transporter with strong expression in the developing brain. We show that the specific G110R mutation, located in a transmembrane domain of the protein, disrupts mitochondrial glutamate transport. INTERPRETATION: We have shown that MPSI can be inherited and have identified a novel homozygous mutation in SLC25A22 in the affected individuals. Our data strongly suggest that SLC25A22 is responsible for MPSI, a severe condition with few known etiologies. We have demonstrated that a combination of linkage analysis and whole exome sequencing can be used for disease gene discovery. Finally, as SLC25A22 had been implicated in the distinct syndrome of neonatal epilepsy with suppression bursts on electroencephalogram, we have expanded the phenotypic spectrum associated with SLC25A22.

Hospital readmissions in children with new-onset infantile epileptic spasms syndrome.

OBJECTIVE: To describe inpatient resource use in the 2 years following infantile epileptic spasms syndrome (IESS) diagnosis, examine the association between clinical/demographic variables and incidence of readmission, and identify risk factors/reasons for frequent readmissions. METHODS: Retrospective cohort analysis of readmissions (scheduled/unscheduled) within the first 2 years following IESS diagnosis, details of readmissions (number/time between rehospitalizations, and length of stay), demographic/clinical variables, and reasons for readmissions were collected. Negative binomial regression analysis evaluated associations between incidence of readmissions (both scheduled/unscheduled and unscheduled alone) and demographic/clinical factors. Logistic regression assessed the risk of having recurrent readmissions (≥5 readmissions). RESULTS: Among 93 (60% males) new-onset IESS patients, there were 394 readmissions (56% scheduled and 44% unscheduled) within 2-years following IESS diagnosis. Mean length of stay was 3.5 days (SD: 5.9). Readmissions occurred in 82 patients (88%) and 37 (40%) experienced ≥5 readmissions. On multivariate regression analysis, readmissions were increased with use of multiple first-line treatments for IESS (P = 0.006), technology assistance (P ≤ 0.001), and multispecialty care (P = 0.01); seizure freedom (P = 0.015) and known etiology (P = 0.011) lowered the incidence of readmissions. Examining unscheduled readmissions separately, increased readmissions occurred with public insurance (P = 0.013), technology use (P ≤ 0.0.001), and multispecialty care (P = 0.013); seizure freedom decreased unscheduled readmissions (P = 0.006). Technology assistance (G-tube, NG tube, VP shunt, and tracheostomy use) increased the odds (P = 0.007) for recurrent readmissions. Reasons for readmissions included EEG monitoring (protocol driven for verification of IESS remission/characterization of events/EEG surveillance/presurgical monitoring) (51%), acute medical issues (21%), and seizure exacerbation (15%). Protocol-driven readmissions declined an estimated 52% following protocol modification during the study. SIGNIFICANCE: In the 2 years following IESS diagnosis, there is substantial inpatient resource use with nearly 40% experiencing ≥5 readmissions (mostly epilepsy related). Since readmissions are increased by intrinsic patient characteristics such as medical complexity (technology use and multispecialty care) or epilepsy-related issues, the preventability of readmissions is uncertain, except for protocol-driven ones.

Clinical characteristics of children with infantile epileptic spasms syndrome from a tertiary-care hospital in Dhaka, Bangladesh.

Background: We describe patient characteristics and response to initial treatment in a large case series of children presenting with infantile epileptic spasms syndrome to a tertiary-care hospital with a pediatric neurology service in Bangladesh. The purpose of the study was to add to the growing body of literature on infantile epileptic spasms syndrome in low- and middle-income countries. Methods: We enrolled 212 infants with new-onset infantile epileptic spasms syndrome (IESS) at the time of initial presentation to the National Institute of Neurosciences and Hospital (NINS) in Dhaka, Bangladesh, between January 2019 and August 2021. We collected data about seizure type and frequency, etiology, medication dosage, and available neuroimaging. Results: Median age at initial presentation to NINS was 9 months. Developmental delay and regression prior to presentation were found in 83% and 36%, respectively. Prior to their presentation at NINS, 197 (93%) patients had received anti-seizure medication to treat spasms, of whom only 8 (4%) had received standard therapy with ACTH, prednisolone, or vigabatrin. At NINS, 207 (98%) of patients received standard therapy, most frequently ACTH in 154 (73%). Median time between seizure onset to receipt of first-line therapy was 5 months. Of the 169 patients who were seen in follow-up at average of 5 weeks, 92 (54%) reported absence of clinical epileptic spasms. No serious adverse events requiring hospitalization were reported. Conclusions: This study highlights the long lead times to treatment for IESS in a low- and middle-income country, and the need for early referral of children with suspected epileptic spasms to epilepsy care centers.

Utility of Exome Sequencing for Diagnosis in Unexplained Pediatric-Onset Epilepsy.

Importance: Genomic advances inform our understanding of epilepsy and can be translated to patients as precision diagnoses that influence clinical treatment, prognosis, and counseling. Objective: To delineate the genetic landscape of pediatric epilepsy and clinical utility of genetic diagnoses for patients with epilepsy. Design, Setting, and Participants: This cohort study used phenotypic data from medical records and treating clinicians at a pediatric hospital to identify patients with unexplained pediatric-onset epilepsy. Exome sequencing was performed for 522 patients and available biological parents, and sequencing data were analyzed for single nucleotide variants (SNVs) and copy number variants (CNVs). Variant pathogenicity was assessed, patients were provided with their diagnostic results, and clinical utility was evaluated. Patients were enrolled from August 2018 to October 2021, and data were analyzed through December 2022. Exposures: Phenotypic features associated with diagnostic genetic results. Main Outcomes and Measures: Main outcomes included diagnostic yield and clinical utility. Diagnostic findings included variants curated as pathogenic, likely pathogenic (PLP), or diagnostic variants of uncertain significance (VUS) with clinical features consistent with the involved gene's associated phenotype. The proportion of the cohort with diagnostic findings, the genes involved, and their clinical utility, defined as impact on clinical treatment, prognosis, or surveillance, are reported. Results: A total of 522 children (269 [51.5%] male; mean [SD] age at seizure onset, 1.2 [1.4] years) were enrolled, including 142 children (27%) with developmental epileptic encephalopathy and 263 children (50.4%) with intellectual disability. Of these, 100 participants (19.2%) had identifiable genetic explanations for their seizures: 89 participants had SNVs (87 germline, 2 somatic mosaic) involving 69 genes, and 11 participants had CNVs. The likelihood of identifying a genetic diagnosis was highest in patients with intellectual disability (adjusted odds ratio [aOR], 2.44; 95% CI, 1.40-4.26), early onset seizures (aOR, 0.93; 95% CI, 0.88-0.98), and motor impairment (aOR, 2.19; 95% CI 1.34-3.58). Among 43 patients with apparently de novo variants, 2 were subsequently determined to have asymptomatic parents harboring mosaic variants. Of 71 patients who received diagnostic results and were followed clinically, 29 (41%) had documented clinical utility resulting from their genetic diagnoses. Conclusions and Relevance: These findings suggest that pediatric-onset epilepsy is genetically heterogeneous and that some patients with previously unexplained pediatric-onset epilepsy had genetic diagnoses with direct clinical implications.

National assessment of anti-epileptic drug exposures among pre-teens and adolescents, 2000-2020.

BACKGROUND AND OBJECTIVES: Anti-epileptic drugs (AEDs) are increasingly used to treat psychiatric conditions, exposing many children to potentially harmful medications. This includes adolescents, who are at higher risk for self-harm. The purpose of this study was to describe the epidemiology of pediatric AED poisonings and assess which AEDs are associated with more severe clinical outcomes. METHODS: This retrospective cross-sectional analysis examined single-substance AED exposure cases in pre-teens (10-14 years) and adolescents (15-19 years) reported to the National Poison Database System (NPDS) between 2000 and 2020 (cases through 2019 were included for trend analysis due to incomplete population data). We described characteristics of ingestions by age group, including AEDs implicated. RESULTS: There were 74,818 AED exposure cases reported to the NPDS, including 25,928 (34.7%) in pre-teens and 48,890 (65.3%) in adolescents. Among adolescents, 35,570 (72.8%) exposure cases were intentional, with 27,655 (56.6%) specifically related to a suspected suicide attempt. The most common AEDs implicated in poisonings were clonazepam (19.8%), valproic acid (15.3%), and lamotrigine (13.8%). The odds of hospitalization (adjusted odds ratio [aOR] 2.0 [95% confidence interval [CI], 2.0-2.1]), intubation (aOR 2.1 [95% CI, 1.8-2.4]), seizure (aOR 1.6 [95% CI, 1.4-1.9]), and serious outcome (aOR 1.8 [95% CI, 1.7-1.9]) were higher in the adolescent group compared to the pre-teen group. Intentional ingestions increased by a yearly rate of 2.8% (95% CI, 2.3-3.2). Intentional tiagabine exposure was associated with the greatest increased odds of serious outcome (aOR 4.7 [95% CI, 3.6-6.3]). DISCUSSION: In this cross-sectional analysis of pediatric AED exposure cases reported to the NPDS, AED poisonings among pre-teens and adolescents increased significantly between 2000 and 2019. Of particular concern is the large increase in intentional exposure cases related to AEDs. With the population-adjusted rate of epilepsy diagnoses remaining relatively unchanged, these results may indicate that the rise in AED exposure cases may be related to increased prescribing of AEDs for psychiatric indications as opposed to epilepsy. CONCLUSIONS: Pediatric AED poisonings reported to the NPDS are increasing, especially among adolescents engaging in intentional ingestions. These findings provide additional information for consideration in risk-benefit assessments when selecting medications for the treatment of psychiatric conditions in children.

The non-essential TSC complex component TBC1D7 restricts tissue mTORC1 signaling and brain and neuron growth.

The tuberous sclerosis complex (TSC) 1 and 2 proteins associate with TBC1D7 to form the TSC complex, which is an essential suppressor of mTOR complex 1 (mTORC1), a ubiquitous driver of cell and tissue growth. Loss-of-function mutations in TSC1 or TSC2, but not TBC1D7, give rise to TSC, a pleiotropic disorder with aberrant activation of mTORC1 in various tissues. Here, we characterize mice with genetic deletion of Tbc1d7, which are viable with normal growth and development. Consistent with partial loss of function of the TSC complex, Tbc1d7 knockout (KO) mice display variable increases in tissue mTORC1 signaling with increased muscle fiber size but with strength and motor defects. Their most pronounced phenotype is brain overgrowth due to thickening of the cerebral cortex, with enhanced neuron-intrinsic mTORC1 signaling and growth. Thus, TBC1D7 is required for full TSC complex function in tissues, and the brain is particularly sensitive to its growth-suppressing activities.

DEPDC5-dependent mTORC1 signaling mechanisms are critical for the anti-seizure effects of acute fasting.

Caloric restriction and acute fasting are known to reduce seizures but through unclear mechanisms. mTOR signaling has been suggested as a potential mechanism for seizure protection from fasting. We demonstrate that brain mTORC1 signaling is reduced after acute fasting of mice and that neuronal mTORC1 integrates GATOR1 complex-mediated amino acid and tuberous sclerosis complex (TSC)-mediated growth factor signaling. Neuronal mTORC1 is most sensitive to withdrawal of leucine, arginine, and glutamine, which are dependent on DEPDC5, a component of the GATOR1 complex. Metabolomic analysis reveals that Depdc5 neuronal-specific knockout mice are resistant to sensing significant fluctuations in brain amino acid levels after fasting. Depdc5 neuronal-specific knockout mice are resistant to the protective effects of fasting on seizures or seizure-induced death. These results establish that acute fasting reduces seizure susceptibility in a DEPDC5-dependent manner. Modulation of nutrients upstream of GATOR1 and mTORC1 could offer a rational therapeutic strategy for epilepsy treatment.