Higher Risk of Psychiatric Disorders in Children With Febrile Seizures: A Nationwide Cohort Study in Taiwan.

BACKGROUND: Febrile seizures occur commonly in children aged between six months and six years. A previous Danish study found a positive correlation between febrile seizures and the overall incidence of psychiatric disorders. This population-based nationwide observational study was conducted to investigate the association between febrile seizures and different psychiatric disorders in Taiwan and the associated risk factors. METHODS: This cohort study used data from the National Health Insurance Research Database in Taiwan-a nationwide claims database covering >99% of the Taiwanese population. The study period was from January 2000 to December 2015; the overall median follow-up time was 11.04 ± 10.95 years. Overall, 2464 children with febrile seizures diagnosed between 2000 and 2015 met the inclusion criteria, and 7392 children without febrile seizures matched by index year, age, and sex were included in the control cohorts. Febrile seizures and psychiatric disorders were measured as the exposure and main outcomes, respectively. RESULTS: Children with febrile seizures (n = 2463) were at a high risk of psychiatric disorders (adjusted hazard ratio, 4.70; 95% confidence interval [CI], 2.44 to 7.30; P < 0.001). The risk for anxiety was the highest (adjusted hazard ratio, 21.92; 95% CI, 11.40 to 34.05; P < 0.001). CONCLUSIONS: When treating children with febrile seizures, particular attention should be paid to the symptoms of psychiatric disorders, as early referral may be beneficial for these children.

Cerebral hemiatrophy and hemiparesis following hemiclonic status epilepticus in Dravet syndrome.

Dravet syndrome is currently considered as an developmental and epileptic encephalopathy and, recently, mandatory, alert, and exclusionary criteria have been proposed. Here, we describe three patients with Dravet syndrome with the typical early presentation including febrile and afebrile alternating hemiclonic seizures due to loss-of-function SCN1A variants. Subsequently, they developed episodes of febrile focal status epilepticus (SE) associated with hemiparesis and cerebral hemiatrophy with posterior focal seizures, as a consequence of Dravet syndrome. This sequence of events has been previously published in patients with Dravet syndrome and does not contradict the recent classification by the International League Against Epilepsy (ILAE). The ILAE guidance identifies "Focal neurological findings" as alert criteria and "MRI showing a causal focal lesion" as exclusionary criteria for making an initial diagnosis of Dravet syndrome at presentation. Our three patients would correspond to a severe phenotype, similar to the well-known presentation of generalized atrophy following prolonged status epilepticus. Common genetic findings in cases of diffuse and unilateral brain involvement may help explain these clinical presentations. Further genotype-phenotype studies may provide additional insights into this electroclinical behavior.

Febrile Seizure Causes Deficit in Social Novelty, Gliosis, and Proinflammatory Cytokine Response in the Hippocampal CA2 Region in Rats.

Febrile seizure (FS), which occurs as a response to fever, is the most common seizure that occurs in infants and young children. FS is usually accompanied by diverse neuropsychiatric symptoms, including impaired social behaviors; however, research on neuropsychiatric disorders and hippocampal inflammatory changes following febrile seizure occurrences is very limited. Here, we provide evidence linking FS occurrence with ASD pathogenesis in rats. We developed an FS juvenile rats model and found ASD-like abnormal behaviors including deficits in social novelty, repetitive behaviors, and hyperlocomotion. In addition, FS model juvenile rats showed enhanced levels of gliosis and inflammation in the hippocampal CA2 region and cerebellum. Furthermore, abnormal levels of social and repetitive behaviors persisted in adults FS model rats. These findings suggest that the inflammatory response triggered by febrile seizures in young children could potentially serve as a mediator of social cognitive impairments.

Risk factors of Omicron variant associated acute encephalitis/encephalopathy in children.

BACKGROUND: Outbreak of Omicron BA.2 in Taiwan led to an increased number of acute encephalitis/encephalopathy cases in children and several fatal cases drew public attention. In pre-Omicron period, pediatric cases of COVID-19-associated acute encephalitis have been reported and during Omicron epidemic, febrile convulsions, encephalitis were mentioned more frequently. The outcome of patients with neurological complications was worse. However, few studies investigated the risk factors, pathophysiology and prognosis of COVID-19-associated encephalitis/encephalopathy. Here, we describe the presentation of pediatric cases of COVID-19-associated acute encephalitis/encephalopathy and explore the associated risk factors. METHODS: Pediatric patients with confirmed SARS-CoV-2 infections were prospectively enrolled at admission at Chang Gung Memorial Hospital between April and August 2022. Patients were categorized into groups of acute encephalitis/encephalopathy, febrile convulsions or mild disease. Demographic descriptions, clinical manifestations and laboratory data were collected. RESULTS: Of 288 acute COVID-19 patients, there were 38 (13.2%) acute encephalitis/encephalopathy, 40 (13.9%) febrile convulsions, and 210 (72.9%) mild disease. Among acute encephalitis/encephalopathy group, the mean age was 68.3 ± 45.0 months. The common neurological symptoms were lethargy (65.8%), seizures (52.6%), and impaired consciousness (34.2%). Over 3 years old (adjusted odds ratio [aOR]: 7.57, p < 0.001), absolute neutrophil count ≥3150/µL (aOR: 5.46, p = 0.008), and procalcitonin ≥0.5 ng/mL (aOR: 4.32, p = 0.021) were independent factors for acute encephalitis/encephalopathy. CONCLUSIONS: Most cases of COVID-19-associated acute encephalitis/encephalopathy showed no evidence of direct viral invasion but associations with older age, increased peripheral neutrophil, and serum procalcitonin. These findings may imply the neutrophil-mediated systemic inflammatory response plays an important role on central nerve system, leading to cerebral dysfunction.

Are brief febrile seizures benign? A systematic review and narrative synthesis.

Febrile seizures affect 2%-5% of U.S. children and are considered benign although associated with an increased risk of epilepsy and, rarely, with sudden unexplained death. We compared rates of mortality, neurodevelopmental disorders, and neuropathology in young children with simple and complex febrile seizures to healthy controls. We systematically reviewed studies of 3- to 72-month-old children with simple or complex febrile seizures ≤30 min. We searched studies with outcome measures on mortality, neurodevelopment, or neuropathology through July 18, 2022. Bias risk was assessed per study design. Each outcome measure was stratified by study design. PROSPERO registration is CRD42022361645. Twenty-six studies met criteria reporting mortality (11), neurodevelopment (11), and neuropathology (13), including 2665 children with febrile seizures and 1206 seizure-free controls. Study designs varied: 15 cohort, 2 cross-sectional, 3 case-control, 5 series, and 1 case report. Mortality outcomes showed stark contrasts. Six cohort studies following children after febrile seizure (n = 1348) reported no deaths, whereas four child death series and 1 case report identified 24.1% (108/449) deaths associated with simple (n = 104) and complex (n = 3) febrile seizures ≤30 min. Minor hippocampal histopathological anomalies were common in sudden deaths with or without febrile seizure history. Most electroencephalography (EEG) studies were normal. Neuroimaging studies suggested increased right hippocampal volumes. When present, neurodevelopmental problems usually preexisted febrile-seizure onset. Risk bias was medium or high in 95% (18/19) of cohort and case-control studies vs medium to low across remaining study designs. Research on outcomes after simple or brief complex febrile seizures is limited. Cohort studies suffered from inadequate sample size, bias risk, and limited follow-up durations to make valid conclusions on mortality, neurodevelopment, and neuropathology. Sudden death registries, focused on a very small percentage of all cases, strongly suggest that simple febrile seizures are associated with increased mortality. Although most children with febrile seizures have favorable outcomes, longer-term prospective studies are needed.

Influenza-associated neurologic complications in children from an H3N2 outbreak in Shenzhen, China during COVID-19 lockdown.

OBJECTIVES: To identify the characteristics of influenza-associated neurologic complications (INCs) in children from a recent H3N2 outbreak in Shenzhen, China during COVID-19 lockdown. METHODS: A retrospective cohort study of INCs in children hospitalized with H3N2 infection was conducted. RESULTS: From June 01, 2022 to July 01, 2022, 513 children with H3N2 infection were hospitalized and 97 developed INCs. Of the 18 patients with encephalopathy/encephalitis, 13 were previously healthy. Three developed acute necrotizing encephalopathy and two died. Of the 63 patients with febrile seizures, 55 (87%) had simple febrile seizures. Of the 14 patients with an exacerbation of seizure with underlying epilepsy, the seizure symptoms occurred mostly within 24 hours of disease onset (13/14). The comparison of the three groups (encephalopathy/encephalitis, febrile seizure and exacerbation of seizure with underlying epilepsy) reported no significant differences in sex, pre-existing neurologic diseases, vaccination rate, white blood cell count, C-reactive protein, procalcitonin, blood glucose, lactic acid, or duration of fever. The influenza vaccination rates were generally low (22% vs 32% vs 21%). Patients with encephalopathy/encephalitis had a higher rate of elevated alanine aminotransferase (28% vs 3% vs 0, P = 0.005). CONCLUSION: H3N2-related neurologic complications in children mainly occur early in the disease course. Most patients were previously healthy and unvaccinated against influenza. Elevated alanine aminotransferase is more common in encephalopathy/encephalitis.

Anemia and Poor Iron Indices Are Associated With Susceptibility to Febrile Seizures in Children: A Systematic Review and Meta-analysis.

Introduction: Febrile seizures are the most common type of seizure in children under the age of 5, and a number of risk factors for this condition have been identified. Several studies have examined the connection between iron deficiency anemia and febrile seizures in children, with inconsistent results. As a result, the authors sought to determine the precise link between iron deficiency anemia and its indices (mean corpuscular volume, serum iron, total iron-binding capacity, and ferritin) in conjunction to febrile seizures. Methods: A systematic literature search from several databases (PubMed, Europe PMC, ScienceDirect) was conducted from database inception until November 30, 2022. Studies were eligible if they investigated the relationship of the iron deficiency anemia and the aforementioned indices with the likelihood of febrile seizures. Results: This meta-analysis comprised 20 case-control studies with a total of 3856 participants. Our study revealed that iron deficiency anemia, low mean corpuscular volume, low serum iron, high total iron-binding capacity, and low ferritin were associated with the incremental risk of developing febrile seizures, with the odds ratios ranging from 1.24 to 1.59. Moreover, diagnostic test accuracy meta-analysis indicated that low serum ferritin level had the highest overall area under the curve value amid other iron deficiency anemia indices regarding our outcomes of interest. Conclusion: This study suggest that iron deficiency anemia and poor iron indices are associated with increased risk of febrile seizures in children.

Exploring the Age-Old Question: What Is the Predictive Value of EEG for Future Epilepsy in Children With Complex Febrile Seizures?

Children with complex febrile seizures (CFS) have increased risk for the development of epilepsy, but varying prognostic value has been ascribed to abnormal post-CFS electroencephalograms (EEGs). We conducted a retrospective cohort study of 621 children with post-CFS EEGs and identified an association between CFS and midline-vertex discharges, which were present in 52% of the 56 EEGs with interictal epileptiform discharges. Among patients who completed at least 1 year of follow-up, 24.7% subsequently developed epilepsy. Most patients had normal EEGs but 20% had interictal epileptiform discharges. Midline-vertex discharges were seen at a similar rate in children who did not develop epilepsy (55%) and those who developed epilepsy (45%). The development of epilepsy was not associated with any interictal epileptiform discharge localization. Logistic regression modeling identified 4 predictors of future epilepsy: >3 febrile seizures in 24 hours, interictal epileptiform discharges during post-CFS EEG, family history of afebrile seizures, and age of CFS onset ≥ 3 years.

Spatial learning impairments and discoordination of entorhinal-hippocampal circuit coding following prolonged febrile seizures.

How the development and function of neural circuits governing learning and memory are affected by insults in early life remains poorly understood. The goal of this study was to identify putative changes in cortico-hippocampal signaling mechanisms that could lead to learning and memory deficits in a clinically relevant developmental pathophysiological rodent model, Febrile status epilepticus (FSE). FSE in both pediatric cases and the experimental animal model, is associated with enduring physiological alterations of the hippocampal circuit and cognitive impairment. Here, we deconstruct hippocampal circuit throughput by inducing slow theta oscillations in rats under urethane anesthesia and isolating the dendritic compartments of CA1 and dentate gyrus subfields, their reception of medial and lateral entorhinal cortex inputs, and the efficacy of signal propagation to each somatic cell layer. We identify FSE-induced theta-gamma decoupling at cortical synaptic input pathways and altered signal phase coherence along the CA1 and dentate gyrus somatodendritic axes. Moreover, increased DG synaptic activity levels are predictive of poor cognitive outcomes. We propose that these alterations in cortico-hippocampal coordination interfere with the ability of hippocampal dendrites to receive, decode and propagate neocortical inputs. If this frequency-specific syntax is necessary for cortico-hippocampal coordination and spatial learning and memory, its loss could be a mechanism for FSE cognitive comorbidities.

Epilepsy with anterior temporal encephaloceles: Baseline characteristics, post-surgical outcomes, and comparison to mesial temporal sclerosis.

OBJECTIVE: To review clinical and neuropsychological characteristics and natural history of a series of patients with temporal lobe epilepsy (TLE) and anterior temporal encephaloceles (ATE) and compare them to a similar series of TLE patients with mesial temporal sclerosis (MTS) to identify characteristics suggestive of ATE-related epilepsy. METHODS: Patients with epilepsy and ATE were identified via clinic encounters and consensus epilepsy surgery conference at a Level 4 epilepsy center. The drug-resistant subset of these patients who underwent epilepsy surgery (twenty-two of thirty-five) were compared to age- and laterality-matched patients with MTS. Clinical, neuropsychological, electrophysiologic, and surgical data were abstracted through chart review. RESULTS: In comparison with MTS, ATE patients were more often female, had significantly later onset of epilepsy, and did not have prior febrile seizures. In addition, ATE patients were more likely to have chronic headaches and other historical features consistent with idiopathic intracranial hypertension (IIH). Failure to identify ATE on initial imaging was common. Most patients had limited temporal cortical resections sparing mesial structures. Of the twenty ATE patients who had a long-term postsurgical follow-up, seventeen (85%) had International League Against Epilepsy (ILAE) Class 1 or 2 outcomes. SIGNIFICANCE: A shorter duration of epilepsy, female gender, and lack of history of febrile seizures may suggest ATE as an etiology of refractory TLE in adults. Targeted encephalocele resections can result in seizure freedom, underscoring the importance of encephalocele identification.

A Case of Acute Encephalopathy Associated with Acute Focal Bacterial Nephritis.

Acute encephalopathy is a syndrome characterized by an acute onset of disturbance of consciousness. Many acute encephalopathies are caused by viral infections; however, they can also be a result of bacterial infections. Acute focal bacterial nephritis (AFBN) can cause neurological symptoms, such as irritation, unconsciousness, and seizures. In some cases, AFBN-associated acute encephalopathy has also been reported. This report describes the first case of acute encephalopathy with AFBN without significant findings on brain MRI. The patient was a 3-year-old male, who had two episodes of febrile seizures at the ages of 1 and 2 years. He developed disturbance of consciousness, irritability, excitability, and neck stiffness on the day after admission. There were no abnormal findings on brain MRI; however, a generalized high-voltage slow wave was noted on electroencephalography (EEG). His urinary sediment count was elevated, and Morganella morganii and Enterococcus faecalis were detected in the urinary culture. A diagnosis of acute encephalopathy with urinary tract infection (UTI) was made. Intravenous (IV) antibiotics were administered to treat the UTI, while methylprednisolone pulse therapy and IV immunoglobulin were administered to treat acute encephalopathy. Additionally, AFBN was detected in both kidneys on contrast-enhanced CT. The patient received a second course of methylprednisolone pulse therapy due to the persistent high voltage slow wave noted on the EEG on day 8. Furthermore, contrast-enhanced CT revealed AFBN in both kidneys. The final diagnosis was acute encephalopathy with AFBN; however, we had initially diagnosed febrile seizures associated with UTI. It should be noted that acute encephalopathy is associated with AFBN.

Prediction and assessment of acute encephalopathy syndromes immediately after febrile status epilepticus.

OBJECTIVE: This study aimed to predict occurrence of acute encephalopathy syndromes (AES) immediately after febrile status epilepticus in children and to explore the usefulness of electroencephalogram (EEG) in the early diagnosis of AES. METHODS: We reviewed data from 120 children who had febrile status epilepticus lasting >30 min and were admitted to our hospital between 2012 and 2019. AES with reduced diffusion on brain magnetic resonance imaging was diagnosed in 11 of these patients. EEG and serum cytokines were analyzed in AES patients. Clinical symptoms and laboratory data were compared between AES and non-AES patients. Logistic regression analysis was used to identify early predictors of AES. RESULTS: Multivariate logistic regression identified serum creatinine as a risk factor for developing AES. A scoring model to predict AES in the post-ictal phase that included serum creatinine, sodium, aspartate aminotransferase, and glucose was developed, and a score of 2 or more predicted AES with sensitivity of 90.9% and specificity of 71.6%. Post-ictus EEG revealed non-convulsive status epilepticus in four of the seven AES patients. CONCLUSION: Children with febrile status epilepticus may be at risk of developing severe AES with reduced diffusion. Post-ictus EEG and laboratory data can predict the occurrence of severe AES.

Evaluation of the risk factors for recurrence and the development of epilepsy in patients with febrile seizure.

BACKGROUND: Although febrile seizure (FS) is generally considered benign and self-limiting, there are differences regarding the risk factors, the prognosis, and the development of epilepsy. OBJECTIVE: To examine the clinical and sociodemographic characteristics of patients diagnosed with FS, and to determine the risks of recurrence and the development of epilepsy. METHODS: Between 2015 and 2019, we performed a retrospective evaluation of 300 patients with FS followed for at least 24 months. RESULTS: The first episode of FS was simple in 72.7% of the patients and complex in 27.3%, and it recurred in 40%. Age under 12 months in the first FS, complex FS, and neurodevelopmental delay were found to statistically increase the risk of recurrence (p < 0.05). A total of 7% of the patients developed epilepsy, and this rate was found to be higher in patients with neurodevelopmental delay and long-term use of antiepileptic drugs (p < 0.001). The development of epilepsy was also observed in 77.8% of the patients with abnormal electroencephalogram (EEG). Epilepsy developed more frequently in those with abnormal EEG (p<0.001). CONCLUSIONS: Neurodevelopmental delay was an important risk factor for FS recurrence and the development of epilepsy. Abnormality in the EEG is an important risk factor for the development of epilepsy. We found that the long-term prophylactic treatment did not cause decreases in the recurrence of FS nor in the development of epilepsy.

ANTECEDENTES: Embora a convulsão febril (CF) seja geralmente considerada benigna e autolimitada, existem diferenças nos fatores de risco, prognóstico e desenvolvimento de epilepsia. OBJETIVO: O objetivo foi examinar as características clínicas e sociodemográficas de pacientes diagnosticados com CF e determinar os riscos de recorrência e desenvolvimento de epilepsia. MéTODOS: Trezentos pacientes com CF, acompanhados por pelo menos 24 meses, foram avaliados retrospectivamente entre 2015 e 2020. RESULTADOS: A primeira CF foi simples em 72,7% dos pacientes e complexa em 27,3%. CS foi recorrente em 40% dos pacientes. Encontrou-se que a idade da primeira CF inferior a 12 meses, CF complexa e atraso no neurodesenvolvimento aumentaram estatisticamente o risco de recorrência (p < 0,05). Epilepsia se desenvolveu em 7% dos pacientes. A epilepsia foi maior em pacientes com atraso no desenvolvimento neurológico e uso prolongado de drogas antiepilépticas (p < 0,001). A epilepsia se desenvolveu em 77,8% dos pacientes com eletroencefalograma (EEG) anormal. Uma diferença estatisticamente significativa foi determinada em pacientes com EEG anormal em risco de epilepsia (p < 0,001). CONCLUSõES: O atraso no neurodesenvolvimento foi um importante fator de risco para recorrência de CF e epilepsia. A anormalidade do EEG é um importante fator de risco para o desenvolvimento de epilepsia. O tratamento de profilaxia a longo prazo não diminuiu a recorrência de CS e o desenvolvimento de epilepsia.

A Comparative Study of Febrile Seizures and Febrile Convulsions Associated With Mild Gastroenteritis.

BACKGROUND: Children presenting with complex febrile seizures (FS) have an increased risk of developing epilepsy. This study aimed to investigate the occurrence of complex seizures in children presenting with FS and those with both convulsions associated with mild gastroenteritis (CwG) and fever. METHODS: Children admitted to our Pediatric Emergency Department between January 2017 and April 2019 with seizures were enrolled in this cross-sectional study. Patients were grouped according to the etiology as FS and febrile CwG. FS classification criteria of simple FS and complex FS was applied to both groups to allow a comparison between them. Prevalence ratios (PRs) of complex seizures, estimated through a log binomial model, were used to compare the occurrence of complex seizures between the two groups, using the FS group as reference category. RESULTS: A total of 294 patients were enrolled: 231 with FS and 63 with febrile CwG. Complex seizures occurred in 31 patients with FS (13.4%) and 21 patients (33.3%) with febrile CwG. The PR of complex seizures was 2.48 (95% confidence interval, 1.54 to 4.01). CONCLUSIONS: Children with febrile CwG showed a higher rate of complex seizures when compared with those with FS.

SCN1A overexpression, associated with a genomic region marked by a risk variant for a common epilepsy, raises seizure susceptibility.

Mesial temporal lobe epilepsy with hippocampal sclerosis and a history of febrile seizures is associated with common variation at rs7587026, located in the promoter region of SCN1A. We sought to explore possible underlying mechanisms. SCN1A expression was analysed in hippocampal biopsy specimens of individuals with mesial temporal lobe epilepsy with hippocampal sclerosis who underwent surgical treatment, and hippocampal neuronal cell loss was quantitatively assessed using immunohistochemistry. In healthy individuals, hippocampal volume was measured using MRI. Analyses were performed stratified by rs7587026 type. To study the functional consequences of increased SCN1A expression, we generated, using transposon-mediated bacterial artificial chromosome transgenesis, a zebrafish line expressing exogenous scn1a, and performed EEG analysis on larval optic tecta at 4 day post-fertilization. Finally, we used an in vitro promoter analysis to study whether the genetic motif containing rs7587026 influences promoter activity. Hippocampal SCN1A expression differed by rs7587026 genotype (Kruskal-Wallis test P = 0.004). Individuals homozygous for the minor allele showed significantly increased expression compared to those homozygous for the major allele (Dunn's test P = 0.003), and to heterozygotes (Dunn's test P = 0.035). No statistically significant differences in hippocampal neuronal cell loss were observed between the three genotypes. Among 597 healthy participants, individuals homozygous for the minor allele at rs7587026 displayed significantly reduced mean hippocampal volume compared to major allele homozygotes (Cohen's D = - 0.28, P = 0.02), and to heterozygotes (Cohen's D = - 0.36, P = 0.009). Compared to wild type, scn1lab-overexpressing zebrafish larvae exhibited more frequent spontaneous seizures [one-way ANOVA F(4,54) = 6.95 (P < 0.001)]. The number of EEG discharges correlated with the level of scn1lab overexpression [one-way ANOVA F(4,15) = 10.75 (P < 0.001]. Finally, we showed that a 50 bp promoter motif containing rs7587026 exerts a strong regulatory role on SCN1A expression, though we could not directly link this to rs7587026 itself. Our results develop the mechanistic link between rs7587026 and mesial temporal lobe epilepsy with hippocampal sclerosis and a history of febrile seizures. Furthermore, we propose that quantitative precision may be important when increasing SCN1A expression in current strategies aiming to treat seizures in conditions involving SCN1A haploinsufficiency, such as Dravet syndrome.

SCN1A Variants as the Underlying Cause of Genetic Epilepsy with Febrile Seizures Plus in Two Multi-Generational Colombian Families.

Genetic epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant disorder with febrile or afebrile seizures that exhibits phenotypic variability. Only a few variants in SCN1A have been previously characterized for GEFS+, in Latin American populations where studies on the genetic and phenotypic spectrum of GEFS+ are scarce. We evaluated members in two multi-generational Colombian Paisa families whose affected members present with classic GEFS+. Exome and Sanger sequencing were used to detect the causal variants in these families. In each of these families, we identified variants in SCN1A causing GEFS+ with incomplete penetrance. In Family 047, we identified a heterozygous variant (c.3530C > G; p.(Pro1177Arg)) that segregates with GEFS+ in 15 affected individuals. In Family 167, we identified a previously unreported variant (c.725A > G; p.(Gln242Arg)) that segregates with the disease in a family with four affected members. Both variants are located in a cytoplasmic loop region in SCN1A and based on our findings the variants are classified as pathogenic and likely pathogenic, respectively. Our results expand the genotypic and phenotypic spectrum associated with SCN1A variants and will aid in improving molecular diagnostics and counseling in Latin American and other populations.

Whole exome sequencing and co-expression analysis identify an SCN1A variant that modifies pathogenicity in a family with genetic epilepsy and febrile seizures plus.

OBJECTIVE: Family members carrying the same SCN1A variant often exhibit differences in the clinical severity of epilepsy. This variable expressivity suggests that other factors aside from the primary sodium channel variant influence the clinical manifestation. However, identifying such factors has proven challenging in humans. METHODS: We perform whole exome sequencing (WES) in a large family in which an SCN1A variant (p.K1372E) is segregating that is associated with a broad spectrum of phenotypes ranging from lack of epilepsy, to febrile seizures and absence seizures, to Dravet syndrome. We assessed the hypothesis that the severity of the SCN1A-related phenotype was affected by alternate alleles at a modifier locus (or loci). RESULTS: One of our top candidates identified by WES was a second variant in the SCN1A gene (p.L375S) that was shared exclusively by unaffected carriers of the K1372E allele. To test the hypothesized that L375S variant nullifies the loss-of-function effect of K1372E, we transiently expressed Nav1.1 carrying the two variants in HEK293T cells and compared their biophysical properties with the wild-type (WT) variant, and then co-expressed WT with K1372E or L375S with K1372E in equal quantity and tested the functional consequence. The data demonstrated that co-expression of the L375S and K1372E alleles reversed the loss-of-function property brought by the K1372E variant, whereas WT-K1372E co-expression remained partial loss-of-function. SIGNIFICANCE: These results support the hypothesis that L375S counteracts the loss-of-function effect of K1372E such that individuals carrying both alleles in trans do not present epilepsy-related symptoms. We demonstrate that monogenic epilepsies with wide expressivity can be modified by additional variants in the disease gene, providing a novel framework for the gene-phenotype relationship in genetic epilepsies.

Life-span characterization of epilepsy and comorbidities in Dravet syndrome mice carrying a targeted deletion of exon 1 of the Scn1a gene.

OBJECTIVE: Dravet Syndrome (DS) is a catastrophic form of paediatric epilepsy associated with multiple comorbidities mainly caused by mutations in the SCN1A gene. DS progresses in three different phases termed febrile, worsening and stabilization stage. Mice that are haploinsufficient for Scn1a faithfully model each stage of DS, although various aspects have not been fully described, including the temporal appearance and sex differences of the epilepsy and comorbidities. The aim of the present study was to investigate the epilepsy landscape according to the progression of DS and the long-term co-morbidities in the Scn1a(+/-)tm1Kea DS mouse line that are not fully understood yet. METHODS: Male and female F1.Scn1a(+/+) and F1.Scn1a(+/-)tm1Kea mice were assessed in the hyperthermia model or monitored by video electroencephalogram (vEEG) and wireless video-EEG according to the respective stage of DS. Long-term comorbidities were investigated through a battery of behaviour assessments in ~6 month-old mice. RESULTS: At P18, F1.Scn1a(+/-)tm1Kea mice showed the expected sensitivity to hyperthermia-induced seizures. Between P21 and P28, EEG recordings in F1.Scn1a(+/-)tm1Kea mice combined with video monitoring revealed a high frequency of SRS and SUDEP (sudden unexpected death in epilepsy). Power spectral analyses of background EEG activity also revealed that low EEG power in multiple frequency bands was associated with SUDEP risk in F1.Scn1a(+/-)tm1Kea mice during the worsening stage of DS. Later, SRS and SUDEP rates stabilized and then declined in F1.Scn1a(+/-)tm1kea mice. Incidence of SRS ending with death in F1.Scn1a(+/-)tm1kea mice displayed variations with the time of day and sex, with female mice displaying higher numbers of severe seizures resulting in greater SUDEP risk. F1.Scn1a(+/-)tm1kea mice ~6 month-old displayed fewer behavioural impairments than expected including hyperactivity, impaired exploratory behaviour and poor nest building performance. SIGNIFICANCE: These results reveal new features of this model that will optimize use and selection of phenotype assays for future studies on the mechanisms, diagnosis, and treatment of DS.

Proteomic differences in hippocampus and cortex of sudden unexplained death in childhood.

Sudden unexplained death in childhood (SUDC) is death of a child over 1 year of age that is unexplained after review of clinical history, circumstances of death, and complete autopsy with ancillary testing. Multiple etiologies may cause SUDC. SUDC and sudden unexpected death in epilepsy (SUDEP) share clinical and pathological features, suggesting some similarities in mechanism of death and possible abnormalities in hippocampus and cortex. To identify molecular signaling pathways, we performed label-free quantitative mass spectrometry on microdissected frontal cortex, hippocampal dentate gyrus (DG), and cornu ammonis (CA1-3) in SUDC (n = 19) and pediatric control cases (n = 19) with an explained cause of death. At a 5% false discovery rate (FDR), we found differential expression of 660 proteins in frontal cortex, 170 in DG, and 57 in CA1-3. Pathway analysis of altered proteins identified top signaling pathways associated with activated oxidative phosphorylation (p = 6.3 × 10-15, z = 4.08) and inhibited EIF2 signaling (p = 2.0 × 10-21, z = - 2.56) in frontal cortex, and activated acute phase response in DG (p = 8.5 × 10-6, z = 2.65) and CA1-3 (p = 4.7 × 10-6, z = 2.00). Weighted gene correlation network analysis (WGCNA) of clinical history indicated that SUDC-positive post-mortem virology (n = 4/17) had the most significant module in each brain region, with the top most significant associated with decreased mRNA metabolic processes (p = 2.8 × 10-5) in frontal cortex. Additional modules were associated with clinical history, including fever within 24 h of death (top: increased mitochondrial fission in DG, p = 1.8 × 10-3) and febrile seizure history (top: decreased small molecule metabolic processes in frontal cortex, p = 8.8 × 10-5) in all brain regions, neuropathological hippocampal findings in the DG (top: decreased focal adhesion, p = 1.9 × 10-3). Overall, cortical and hippocampal protein changes were present in SUDC cases and some correlated with clinical features. Our studies support that proteomic studies of SUDC cohorts can advance our understanding of the pathogenesis of these tragedies and may inform the development of preventive strategies.