Encephalocraniocutaneous lipomatosis phenotype associated with mosaic biallelic pathogenic variants in the NF1 gene.

Encephalocraniocutaneous lipomatosis (ECCL) is a sporadic congenital condition characterised by ocular, cutaneous and central nervous system involvement. Mosaic activating variants in FGFR1 and KRAS have been reported in several individuals with this syndrome. We report on a patient with neurofibromatosis type 1 (NF1) with a germline pathogenic variant in the NF1 gene and an ECCL phenotype, suggesting ECCL to be part of a spectrum of malformations associated with NF1 pathogenic variants. An anatomical hemispherectomy was performed for intractable epilepsy. Through genetic analysis of blood, cerebral tissue and giant cell lesions in both jaws, we identified the germline NF1 pathogenic variant in all samples and a second-hit pathogenic NF1 variant in cerebral tissue and both giant cell lesions. Both NF1 variants were located on different alleles resulting in somatic mosaicism for a biallelic NF1 inactivation originating in early embryogenesis (second-hit mosaicism or Happle type 2 mosaicism). The biallelic deficit in NF1 in the left hemicranium explains the severe localised, congenital abnormality in this patient. Identical first and second-hit variants in a giant cell lesion of both upper and lower jaws provide confirmatory evidence for an early embryonic second hit involving at least the neural crest. We suggest that the ECCL phenotype may be part of a spectrum of congenital problems associated with mosaic NF1 nullisomy originating during early embryogenesis. The biallelic NF1 inactivation during early embryogenesis mimics the severe activation of the RAS-MAPK pathway seen in ECCL caused by embryonic mosaic activating FGFR1 and KRAS variants in the cranial region. We propose that distinct mechanisms of mosaicism can cause the ECCL phenotype through convergence on the RAS-MAPK pathway.

Factors associated with poor sleep in children with drug-resistant epilepsy.

OBJECTIVE: We aimed to investigate sleep in children with drug-resistant epilepsy (DRE), including developmental and epileptic encephalopathies (DEEs). Next, we examined differences in sleep macrostructure and microstructure and questionnaire outcomes between children with well-controlled epilepsy (WCE) and children with DRE. Furthermore, we wanted to identify factors associated with poor sleep outcome in these children, as some factors might be targets to improve epilepsy and neurodevelopmental outcomes. METHODS: A cross-sectional study was conducted in children 4 to 18-years-old. Children without epilepsy, with WCE, and with DRE were included. Overnight electroencephalography (EEG), including chin electromyography and electrooculography, to allow sleep staging, was performed. Parents were asked to fill out a sleep questionnaire. Classical five-stage sleep scoring was performed manually, spindles were automatically counted, and slow wave activity (SWA) in the first and last hour of slow wave sleep was calculated. RESULTS: One hundred eighty-two patients were included: 48 without epilepsy, 75 with WCE, and 59 with DRE. We found that children with DRE have significantly lower sleep efficiency (SE%), less time spent in rapid eye movement (REM) sleep, fewer sleep spindles, and a lower SWA decline over the night compared to children with WCE. Subjectively more severe sleep problems were reported by the caregivers and more daytime sleepiness was present in children with DRE. Least absolute shrinkage and selection operator (LASSO) regression showed that multifocal interictal epileptiform discharges (IEDs), benzodiazepine treatment, and longer duration of epilepsy were associated with lower SE% and lower REM sleep time. The presence of multifocal discharges and cerebral palsy was associated with fewer spindles. Benzodiazepine treatment, drug resistance, seizures during sleep, intellectual disability, and older age were associated with lower SWA decline. SIGNIFICANCE: Both sleep macrostructure and microstructure are severely impacted in children with DRE, including those with DEEs. Epilepsy parameters play a distinct role in the disruption REM sleep, spindle count, and SWA decline.

Call for the use of the ILAE terminology for seizures and epilepsies by health care professionals and regulatory agencies to benefit patients and caregivers.

The International League Against Epilepsy (ILAE) introduced a classification for seizure types in 2017 and updated the classification for epilepsy syndromes in 2022. These classifications aim to improve communication among healthcare professionals and help patients better describe their condition. So far, regulatory agencies have used different terminology. This paper stresses the crucial need for consistently adopting ILAE terminology in both regulatory processes and clinical practice. It highlights how language plays a significant role in healthcare communication and how standardized terminology can enhance patient comprehension. The ongoing review of guidelines by regulatory bodies offers a timely opportunity. Aligning regulatory terminologies holds the potential to facilitate discussions on future drug development and harmonize practices across diverse regions, ultimately fostering improved care and research outcomes in epilepsy treatment.

Comprehensive scoping review of fenfluramine's role in managing generalized tonic-clonic seizures in developmental and epileptic encephalopathies.

Developmental and epileptic encephalopathies (DEEs) are characterized by pharmacoresistant seizures and developmental delay. Patients with DEEs experience multiple seizure types, including tonic-clonic seizures (TCS) that can be generalized tonic-clonic (GTCS) or focal evolving to bilateral tonic-clonic (FBTCS). Fenfluramine (FFA) has demonstrated efficacy in reduction of TCS in patients with Dravet syndrome (DS), Lennox-Gastaut syndrome (LGS), and other DEEs. Using the PRISMA-ScR (Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Review) guidelines, we performed a scoping review to describe changes in TCS in patients treated with FFA. A comprehensive search of five literature databases was conducted up to February 14, 2023. Studies were included if they reported change in GTCS or TCS (but not FBTCS) after treatment with FFA in patients with DEEs. Duplicate patients and studies with unclear efficacy data were excluded. Fourteen of 422 studies met the eligibility criteria. Data extracted and evaluated by expert clinicians identified 421 unique patients with DS (in nine studies), CDKL5 deficiency disorder, SCN8A-related disorder, LGS, SCN1B-related disorder, and other DEEs. The median percent reduction in GTCS or TCS from baseline was available in 10 studies (n = 328) and ranged from 47.2% to 100%. Following FFA treatment, 10 studies (n = 144) reported ≥50% reduction in GTCS or TCS from baseline in 72% of patients; in nine of those (n = 112), 54% and 29% of patients achieved ≥75% and 100% reduction in GTCS or TCS from baseline, respectively. Overall, this analysis highlighted improvements in GTCS or TCS frequency when patients were treated with FFA regardless of the DEE evaluated. Future studies may confirm the impact of FFA on TCS reduction and on decreased premature mortality risk (including sudden unexpected death in epilepsy), improvement in comorbidities and everyday executive function, decreased health care costs, and improvement in quality of life.

Developmental epileptic encephalopathy in DLG4-related synaptopathy.

OBJECTIVE: The postsynaptic density protein of excitatory neurons PSD-95 is encoded by discs large MAGUK scaffold protein 4 (DLG4), de novo pathogenic variants of which lead to DLG4-related synaptopathy. The major clinical features are developmental delay, intellectual disability (ID), hypotonia, sleep disturbances, movement disorders, and epilepsy. Even though epilepsy is present in 50% of the individuals, it has not been investigated in detail. We describe here the phenotypic spectrum of epilepsy and associated comorbidities in patients with DLG4-related synaptopathy. METHODS: We included 35 individuals with a DLG4 variant and epilepsy as part of a multicenter study. The DLG4 variants were detected by the referring laboratories. The degree of ID, hypotonia, developmental delay, and motor disturbances were evaluated by the referring clinician. Data on awake and sleep electroencephalography (EEG) and/or video-polygraphy and brain magnetic resonance imaging were collected. Antiseizure medication response was retrospectively assessed by the referring clinician. RESULTS: A large variety of seizure types was reported, although focal seizures were the most common. Encephalopathy related to status epilepticus during slow-wave sleep (ESES)/developmental epileptic encephalopathy with spike-wave activation during sleep (DEE-SWAS) was diagnosed in >25% of the individuals. All but one individual presented with neurodevelopmental delay. Regression in verbal and/or motor domains was observed in all individuals who suffered from ESES/DEE-SWAS, as well as some who did not. We could not identify a clear genotype-phenotype relationship even between individuals with the same DLG4 variants. SIGNIFICANCE: Our study shows that a subgroup of individuals with DLG4-related synaptopathy have DEE, and approximately one fourth of them have ESES/DEE-SWAS. Our study confirms DEE as part of the DLG4-related phenotypic spectrum. Occurrence of ESES/DEE-SWAS in DLG4-related synaptopathy requires proper investigation with sleep EEG.

A tool for Dravet syndrome-associated neuropsychiatric comorbidities evaluation (DANCE).

BACKGROUND: Dravet syndrome (DS) is a rare and severe form of epilepsy that begins in infancy, which is primarily caused by pathogenic variants in the SCN1A gene. DS is characterized by prolonged and frequent drug-resistant seizures, as well as developmental delays and behavioral problems. The identification of these comorbidities is based on clinical interview and relies on healthcare professionals (HCPs) experience. METHODS: We assembled a group of expert HCPs and caregivers to create a screening checklist for assessing DS-Associated Neuropsychiatric Comorbidities (DANC). The checklist includes questions related to cognitive and psychiatric domains, motor skills, and the impact of DS on families' daily lives. We administered the checklist to 24 caregivers of DS patients from Belgium, France, and Spain. After piloting, we obtained feedback from expert HCPs and caregivers to refine the checklist. RESULTS: DS patients showed a wide array of neuropsychiatric symptoms related to DS. The most common cognitive domains reported were attention difficulties and multitasking problems (18/24 caregivers), and impulsivity (17/24), while the most common psychiatric symptoms were temper tantrums (14/24), mood swings (13/24) and autism spectrum disorder (12/24). Balance and coordination problem have been reported in almost all patients with a statement of only 4/23 with complete mobility. Most patients were dependent on others for self-care and eating, and presented sleeping disturbances. Caregivers reported high levels of stress in the family unit, both between siblings and parents. Results show that the main concerns of parents were the behavior and the cognition of the person with DS. The quantitative feedback results showed good-to-very good scores on usefulness, ease of completion, clarity and comprehensiveness of the checklist. CONCLUSIONS: This pilot study suggests that the DANCE checklist could be a useful screening tool in daily practice for neuropsychiatric comorbidities facilitating their diagnosis and treatment, and empowering both caregivers and patients.

Wearable detection of tonic seizures in childhood epilepsy: An exploratory cohort study.

OBJECTIVE: To investigate the performance of a multimodal wearable device for the offline detection of tonic seizures (TS) in a pediatric childhood epilepsy cohort, with a focus on patients with Lennox-Gastaut syndrome. METHODS: Parallel with prolonged video-electroencephalography (EEG), the Plug 'n Patch system, a multimodal wearable device using the Sensor Dot and replaceable electrode adhesives, was used to detect TS. Multiple biosignals were recorded: behind-the-ear EEG, surface electromyography, electrocardiography, and accelerometer/gyroscope. Biosignals were annotated blindly by a neurologist. Seizure characteristics were described, and performance was assessed by sensitivity, positive predictive value (PPV), F1 score, and false alarm rate (FAR) per hour. Performance was compared to seizure diaries kept by the caretaker. RESULTS: Ninety-nine TS were detected in 13 patients. Seven patients (54%) had Lennox-Gastaut syndrome and six patients (46%) had other forms of (developmental) epileptic encephalopathies or drug-resistant epilepsy. All but one patient had intellectual disability. Overall sensitivity was 41%, with a PPV of 9%, an F1 score of 14%, and a median FAR per hour of 0.75. Performance increased to an F1 score of 66% for nightly seizures lasting at least 10 s (sensitivity 66%, PPV 66%) and 71% for nightly seizures lasting at least 20 s (sensitivity 62%, PPV 82%). For these seizures there were no false alarms in 10 of 13 patients. Sensitivity of seizure diaries reached a maximum of 52% for prolonged (≥20 s) nightly seizures, even though caretakers slept in the same room. SIGNIFICANCE: We showed that it is feasible to use a multimodal wearable device with multiple adhesive sites in children with epilepsy and intellectual disability. For prolonged nightly seizures, offline manual detection of TS outperformed seizure diaries. The recognition of seizure-specific signatures using multiple modalities can help in the development of automated TS detection algorithms.

Long-term safety and efficacy of adjunctive brivaracetam in pediatric patients with epilepsy: An open-label, follow-up trial.

OBJECTIVE: This study was undertaken to evaluate the long-term safety, tolerability, and efficacy of adjunctive brivaracetam (BRV) treatment in pediatric patients with epilepsy. METHODS: A phase 3, open-label, multicenter, long-term follow-up trial (N01266; NCT01364597) was conducted on patients (aged 1 month to <17 years at core trial entry; direct enrollers aged 4 to <17 years) treated with BRV. Outcomes included treatment-emergent adverse events (TEAEs), behavior assessments (Achenbach Child Behavior Checklist [CBCL], Behavior Rating Inventory of Executive Function [BRIEF]/BRIEF-Preschool version [BRIEF-P]), and efficacy outcomes (percent change in focal seizure frequency, 50% responder rate for all seizure types for patient subgroups <2 years and ≥2 years of age using daily record card data). RESULTS: Of 257 patients with ≥1 dose of BRV (141 [54.9%] male; mean age = 8.0 years [SD = 4.5]), 36 patients were <2 years of age, and 72.0% of patients had a history of focal seizures. Mean BRV exposure was 3.2 patient-years. At least one TEAE occurred in 93.4% patients, and 32.3% had serious TEAEs. Seven patients died during the trial; no deaths were considered treatment-related. Patients ≥2 years of age had a median decrease in 28-day adjusted focal seizure frequency of 62.9%, and 50.9% had a ≥50% response in all seizures. Patients <2 years of age had a median decrease in 28-day adjusted focal seizure frequency of 96.9%, and 68.2% had a ≥50% response in all seizures. Kaplan-Meier estimated treatment retention was 72.7%, 64.5%, 57.8%, 53.3%, 50.1%, and 44.8% at 1, 2, 3, 4, 5, and 6 years, respectively. Mean changes (baseline to last evaluation) for all Achenbach CBCL and BRIEF-P/BRIEF subscale scores were negative, reflecting stability/slight improvement. SIGNIFICANCE: Long-term adjunctive BRV treatment was generally well tolerated and efficacious in reducing seizure frequency, and had high retention rates, with generally stable cognitive/behavioral scores in pediatric patients with epilepsy.

Fenfluramine in the treatment of Dravet syndrome: Results of a third randomized, placebo-controlled clinical trial.

OBJECTIVE: This study was undertaken to assess the safety and efficacy of fenfluramine in the treatment of convulsive seizures in patients with Dravet syndrome. METHODS: This multicenter, randomized, double-blind, placebo-controlled, parallel-group, phase 3 clinical trial enrolled patients with Dravet syndrome, aged 2-18 years with poorly controlled convulsive seizures, provided they were not also receiving stiripentol. Eligible patients who had ≥6 convulsive seizures during the 6-week baseline period were randomized to placebo, fenfluramine .2 mg/kg/day, or fenfluramine .7 mg/kg/day (1:1:1 ratio) administered orally (maximum dose = 26 mg/day). Doses were titrated over 2 weeks and maintained for an additional 12 weeks. The primary endpoint was a comparison of the monthly convulsive seizure frequency (MCSF) during baseline and during the combined titration-maintenance period in patients given fenfluramine .7 mg/kg/day versus patients given placebo. RESULTS: A total of 169 patients were screened, and 143 were randomized to treatment. Mean age was 9.3 ± 4.7 years (±SD), 51% were male, and median baseline MCSF in the three groups ranged 12.7-18.0 per 28 days. Patients treated with fenfluramine .7 mg/kg/day demonstrated a 64.8% (95% confidence interval = 51.8%-74.2%) greater reduction in MCSF compared with placebo (p < .0001). Following fenfluramine .7 mg/kg/day, 72.9% of patients had a ≥50% reduction in MCSF compared with 6.3% in the placebo group (p < .0001). The median longest seizure-free interval was 30 days in the fenfluramine .7 mg/kg/day group compared with 10 days in the placebo group (p < .0001). The most common adverse events (>15% in any group) were decreased appetite, somnolence, pyrexia, and decreased blood glucose. All occurred in higher frequency in fenfluramine groups than placebo. No evidence of valvular heart disease or pulmonary artery hypertension was detected. SIGNIFICANCE: The results of this third phase 3 clinical trial provide further evidence of the magnitude and durability of the antiseizure response of fenfluramine in children with Dravet syndrome.

Fenfluramine provides clinically meaningful reduction in frequency of drop seizures in patients with Lennox-Gastaut syndrome: Interim analysis of an open-label extension study.

OBJECTIVE: This study was undertaken to evaluate the long-term safety and effectiveness of fenfluramine in patients with Lennox-Gastaut syndrome (LGS). METHODS: Eligible patients with LGS who completed a 14-week phase 3 randomized clinical trial enrolled in an open-label extension (OLE; NCT03355209). All patients were initially started on .2 mg/kg/day fenfluramine and after 1 month were titrated by effectiveness and tolerability, which were assessed at 3-month intervals. The protocol-specified treatment duration was 12 months, but COVID-19-related delays resulted in 142 patients completing their final visit after 12 months. RESULTS: As of October 19, 2020, 247 patients were enrolled in the OLE. Mean age was 14.3 ± 7.6 years (79 [32%] adults) and median fenfluramine treatment duration was 364 days; 88.3% of patients received 2-4 concomitant antiseizure medications. Median percentage change in monthly drop seizure frequency was -28.6% over the entire OLE (n = 241) and -50.5% at Month 15 (n = 142, p < .0001); 75 of 241 patients (31.1%) experienced ≥50% reduction in drop seizure frequency. Median percentage change in nondrop seizure frequency was -45.9% (n = 192, p = .0038). Generalized tonic-clonic seizures (GTCS) and tonic seizures were most responsive to treatment, with median reductions over the entire OLE of 48.8% (p < .0001, n = 106) and 35.8% (p < .0001, n = 186), respectively. A total of 37.6% (95% confidence interval [CI] = 31.4%-44.1%, n = 237) of investigators and 35.2% of caregivers (95% CI = 29.1%-41.8%, n = 230) rated patients as Much Improved/Very Much Improved on the Clinical Global Impression of Improvement scale. The most frequent treatment-emergent adverse events were decreased appetite (16.2%) and fatigue (13.4%). No cases of valvular heart disease (VHD) or pulmonary arterial hypertension (PAH) were observed. SIGNIFICANCE: Patients with LGS experienced sustained reductions in drop seizure frequency on fenfluramine treatment, with a particularly robust reduction in frequency of GTCS, the key risk factor for sudden unexpected death in epilepsy. Fenfluramine was generally well tolerated; VHD or PAH was not observed long-term. Fenfluramine may provide an important long-term treatment option for LGS.

Neurodevelopmental profile and stages of regression in Phelan-McDermid syndrome.

AIM: To characterize the neurodevelopmental profile of patients with Phelan-McDermid syndrome (PMS) and describe the nature and trajectory of regression. METHOD: This was a retrospective, monocentric study examining the clinical and developmental data of 24 patients (average age = 25 years 6 months, range = 6-56 years, n = 13 males) with a confirmed 22q13.3 terminal deletion carried out at the Centre for Human Genetics, University Hospital Leuven. The neurodevelopmental profile of individuals with PMS was examined, combining both cross-sectional and longitudinal data obtained by systematic review of digital medical records. RESULTS: Remarkable loss of skills was present in 19 individuals affecting both language and motor skills. The first manifestations of neurodevelopmental regression occurred, on average, at the age of 7 years 6 months (range = 5-11 years). Language skills (active vocabulary) were primarily affected followed by, in order of loss, psychosocial adaptability, fine motor skills, and walking ability. The course of regression was characterized by a distinctive four-stage pattern. The first stage often occurred around mid-childhood and was defined by a pronounced and abrupt decline of language skills. This stage was generally followed by the second stage where a (prolonged) period of stagnation of regression was seen. The third stage was defined by acute neuropsychiatric decline (e.g. catatonia, hallucinations, psychosis). Acute events such as severe sickness, hormonal shifts, and psychosocial stress frequently preceded the fourth and final stage, which was characterized by severe neuromotor degeneration. INTERPRETATION: Neurodevelopmental regression should be considered as a key feature of PMS. We present a four-stage model of neurodevelopmental regression, entailing language skills, fine and gross motor function, and psychosocial adaptation, which can be applied in future practice and research.

Prevention of Epilepsy in Infants with Tuberous Sclerosis Complex in the EPISTOP Trial.

OBJECTIVE: Epilepsy develops in 70 to 90% of children with tuberous sclerosis complex (TSC) and is often resistant to medication. Recently, the concept of preventive antiepileptic treatment to modify the natural history of epilepsy has been proposed. EPISTOP was a clinical trial designed to compare preventive versus conventional antiepileptic treatment in TSC infants. METHODS: In this multicenter study, 94 infants with TSC without seizure history were followed with monthly video electroencephalography (EEG), and received vigabatrin either as conventional antiepileptic treatment, started after the first electrographic or clinical seizure, or preventively when epileptiform EEG activity before seizures was detected. At 6 sites, subjects were randomly allocated to treatment in a 1:1 ratio in a randomized controlled trial (RCT). At 4 sites, treatment allocation was fixed; this was denoted an open-label trial (OLT). Subjects were followed until 2 years of age. The primary endpoint was the time to first clinical seizure. RESULTS: In 54 subjects, epileptiform EEG abnormalities were identified before seizures. Twenty-seven were included in the RCT and 27 in the OLT. The time to the first clinical seizure was significantly longer with preventive than conventional treatment [RCT: 364 days (95% confidence interval [CI] = 223-535) vs 124 days (95% CI = 33-149); OLT: 426 days (95% CI = 258-628) vs 106 days (95% CI = 11-149)]. At 24 months, our pooled analysis showed preventive treatment reduced the risk of clinical seizures (odds ratio [OR] = 0.21, p = 0.032), drug-resistant epilepsy (OR = 0.23, p = 0.022), and infantile spasms (OR = 0, p < 0.001). No adverse events related to preventive treatment were noted. INTERPRETATION: Preventive treatment with vigabatrin was safe and modified the natural history of seizures in TSC, reducing the risk and severity of epilepsy. ANN NEUROL 2021;89:304-314.

Automated detection of absence seizures using a wearable electroencephalographic device: a phase 3 validation study and feasibility of automated behavioral testing.

OBJECTIVE: Our primary goal was to measure the accuracy of fully automated absence seizure detection, using a wearable electroencephalographic (EEG) device. As a secondary goal, we also tested the feasibility of automated behavioral testing triggered by the automated detection. METHODS: We conducted a phase 3 clinical trial (NCT04615442), with a prospective, multicenter, blinded study design. The input was the one-channel EEG recorded with dry electrodes embedded into a wearable headband device connected to a smartphone. The seizure detection algorithm was developed using artificial intelligence (convolutional neural networks). During the study, the predefined algorithm, with predefined cutoff value, analyzed the EEG in real time. The gold standard was derived from expert evaluation of simultaneously recorded full-array video-EEGs. In addition, we evaluated the patients' responsiveness to the automated alarms on the smartphone, and we compared it with the behavioral changes observed in the clinical video-EEGs. RESULTS: We recorded 102 consecutive patients (57 female, median age = 10 years) on suspicion of absence seizures. We recorded 364 absence seizures in 39 patients. Device deficiency was 4.67%, with a total recording time of 309 h. Average sensitivity per patient was 78.83% (95% confidence interval [CI] = 69.56%-88.11%), and median sensitivity was 92.90% (interquartile range [IQR] = 66.7%-100%). The average false detection rate was .53/h (95% CI = .32-.74). Most patients (n = 66, 64.71%) did not have any false alarms. The median F1 score per patient was .823 (IQR = .57-1). For the total recording duration, F1 score was .74. We assessed the feasibility of automated behavioral testing in 36 seizures; it correctly documented nonresponsiveness in 30 absence seizures, and responsiveness in six electrographic seizures. SIGNIFICANCE: Automated detection of absence seizures with a wearable device will improve seizure quantification and will promote assessment of patients in their home environment. Linking automated seizure detection to automated behavioral testing will provide valuable information from wearable devices.

SLC7A3: In Silico Prediction of a Potential New Cause of Childhood Epilepsy.

We report an in-depth genetic analysis in an 11-year-old boy with drug-resistant, generalized seizures and developmental disability. Three distinct variants of unknown clinical significance (VUS) were detected by whole exome sequencing (WES) but not by initial genetic analyses (microarray and epilepsy gene panel). These variants involve the SLC7A3, CACNA1H, and IGLON5 genes, which were subsequently evaluated by computational analyses using the InterVar tool and MutationTaster. While future functional studies are necessary to prove the pathogenicity of a certain VUS, segregation analyses over three generations and in silico predictions suggest the X-linked gene SLC7A3 (transmembrane solute carrier transporter) as the likely culprit gene in this patient. In addition, a search via GeneMatcher unveiled two additional patients with a VUS in SLC7A3. We propose SLC7A3 as a likely candidate gene for epilepsy and/or developmental/cognitive delay and provide an overview of the 27 SLC genes related to epilepsy by other preclinical and/or clinical studies.

Evolution of electroencephalogram in infants with tuberous sclerosis complex and neurodevelopmental outcome: a prospective cohort study.

AIM: To describe the evolution of electroencephalogram (EEG) characteristics in infants with tuberous sclerosis complex (TSC) and the relationship with neurodevelopmental outcome at 24 months. METHOD: Eighty-three infants were enrolled in the EPISTOP trial and underwent serial EEG follow-up until the age of 24 months (males n=45, females n=37, median age at enrolment 28d, interquartile range 14-54d). Maturation of the EEG background and epileptiform discharges were compared between the TSC1 and TSC2 variants and between preventive and conventional groups respectively. RESULTS: Children with TSC2 more frequently had a slower posterior dominant rhythm (PDR) at 24 months (51% vs 11%, p=0.002), a higher number of epileptiform foci (median=8 vs 4, p=0.003), and a lower fraction of EEGs without epileptiform discharges (18% vs 61%, p=0.001) at follow-up. A slower PDR at 24 months was significantly associated with lower cognitive (median=70 vs 80, p=0.028) and motor developmental quotients (median=70 vs 79, p=0.008). A higher fraction of EEGs without epileptiform discharges was associated with a lower probability of autism spectrum disorder symptoms (odds ratio=0.092, 95% confidence interval=0.009-0.912, p=0.042) and higher cognitive (p=0.004), language (p=0.002), and motor (p=0.001) developmental quotients at 24 months. INTERPRETATION: TSC2 is associated with more abnormal EEG characteristics compared to TSC1, which are predictive for neurodevelopmental outcome.

Aberrant Inclusion of a Poison Exon Causes Dravet Syndrome and Related SCN1A-Associated Genetic Epilepsies.

Developmental and epileptic encephalopathies (DEEs) are a group of severe epilepsies characterized by refractory seizures and developmental impairment. Sequencing approaches have identified causal genetic variants in only about 50% of individuals with DEEs.1-3 This suggests that unknown genetic etiologies exist, potentially in the ∼98% of human genomes not covered by exome sequencing (ES). Here we describe seven likely pathogenic variants in regions outside of the annotated coding exons of the most frequently implicated epilepsy gene, SCN1A, encoding the alpha-1 sodium channel subunit. We provide evidence that five of these variants promote inclusion of a "poison" exon that leads to reduced amounts of full-length SCN1A protein. This mechanism is likely to be broadly relevant to human disease; transcriptome studies have revealed hundreds of poison exons,4,5 including some present within genes encoding other sodium channels and in genes involved in neurodevelopment more broadly.6 Future research on the mechanisms that govern neuronal-specific splicing behavior might allow researchers to co-opt this system for RNA therapeutics.

Dravet syndrome.

PURPOSE OF REVIEW: This review will illustrate the electroclinical description of Dravet syndrome, highlighting the difficulty to understand the correlation between the SCN1A mutation and clinical characteristics, including the frequent comorbidities. Therefore, the efficacy of the new treatment options, which now become available, should not only focus on seizure frequency reduction but also on the long-term effects on these comorbidities, such as intellectual disability, motor and sleep problems. RECENT FINDINGS: Comprehensive guidelines for a more standardized treatment in children with Dravet syndrome have been published. First-line and second-line treatments actually include only a few antiseizure medications, such as valproate, clobazam, stiripentol, topiramate and bromide. Cannabidiol and fenfluramine were shown to be very effective drugs and will become standard second-line drugs in Dravet syndrome. There are preliminary data showing that both drugs also have a positive effect on quality of life and on cognitive functioning. Genetic treatments in Dravet syndrome most likely will dramatically change the natural course of this refractory epilepsy syndrome. SUMMARY: A better understanding of the full clinical picture is necessary to understand the potential value of new treatment options in Dravet syndrome. Treatment nowadays with the newer drugs becomes much more standardized and effective, and this will have a positive effect on long-term overall outcome.

MicroRNA-34a activation in tuberous sclerosis complex during early brain development may lead to impaired corticogenesis.

AIMS: Tuberous sclerosis complex (TSC) is a genetic disorder associated with dysregulation of the mechanistic target of rapamycin complex 1 (mTORC1) signalling pathway. Neurodevelopmental disorders, frequently present in TSC, are linked to cortical tubers in the brain. We previously reported microRNA-34a (miR-34a) among the most upregulated miRs in tubers. Here, we characterised miR-34a expression in tubers with the focus on the early brain development and assessed the regulation of mTORC1 pathway and corticogenesis by miR-34a. METHODS: We analysed the expression of miR-34a in resected cortical tubers (n = 37) compared with autopsy-derived control tissue (n = 27). The effect of miR-34a overexpression on corticogenesis was assessed in mice at E18. The regulation of the mTORC1 pathway and the expression of the bioinformatically predicted target genes were assessed in primary astrocyte cultures from three patients with TSC and in SH-SY5Y cells following miR-34a transfection. RESULTS: The peak of miR-34a overexpression in tubers was observed during infancy, concomitant with the presence of pathological markers, particularly in giant cells and dysmorphic neurons. miR-34a was also strongly expressed in foetal TSC cortex. Overexpression of miR-34a in mouse embryos decreased the percentage of cells migrated to the cortical plate. The transfection of miR-34a mimic in TSC astrocytes negatively regulated mTORC1 and decreased the expression of the target genes RAS related (RRAS) and NOTCH1. CONCLUSIONS: MicroRNA-34a is most highly overexpressed in tubers during foetal and early postnatal brain development. miR-34a can negatively regulate mTORC1; however, it may also contribute to abnormal corticogenesis in TSC.

Antiepileptic Drug Teratogenicity and De Novo Genetic Variation Load.

OBJECTIVE: The mechanisms by which antiepileptic drugs (AEDs) cause birth defects (BDs) are unknown. Data suggest that AED-induced BDs may result from a genome-wide increase of de novo variants in the embryo, a mechanism that we investigated. METHODS: Whole exome sequencing data from child-parent trios were interrogated for de novo single-nucleotide variants/indels (dnSNVs/indels) and de novo copy number variants (dnCNVs). Generalized linear models were applied to assess de novo variant burdens in children exposed prenatally to AEDs (AED-exposed children) versus children without BDs not exposed prenatally to AEDs (AED-unexposed unaffected children), and AED-exposed children with BDs versus those without BDs, adjusting for confounders. Fisher exact test was used to compare categorical data. RESULTS: Sixty-seven child-parent trios were included: 10 with AED-exposed children with BDs, 46 with AED-exposed unaffected children, and 11 with AED-unexposed unaffected children. The dnSNV/indel burden did not differ between AED-exposed children and AED-unexposed unaffected children (median dnSNV/indel number/child [range] = 3 [0-7] vs 3 [1-5], p = 0.50). Among AED-exposed children, there were no significant differences between those with BDs and those unaffected. Likely deleterious dnSNVs/indels were detected in 9 of 67 (13%) children, none of whom had BDs. The proportion of cases harboring likely deleterious dnSNVs/indels did not differ significantly between AED-unexposed and AED-exposed children. The dnCNV burden was not associated with AED exposure or birth outcome. INTERPRETATION: Our study indicates that prenatal AED exposure does not increase the burden of de novo variants, and that this mechanism is not a major contributor to AED-induced BDs. These results can be incorporated in routine patient counseling. ANN NEUROL 2020;87:897-906.

Accurate detection of typical absence seizures in adults and children using a two-channel electroencephalographic wearable behind the ears.

OBJECTIVE: Patients with absence epilepsy sensitivity <10% of their absences. The clinical gold standard to assess absence epilepsy is a 24-h electroencephalographic (EEG) recording, which is expensive, obtrusive, and time-consuming to review. We aimed to (1) investigate the performance of an unobtrusive, two-channel behind-the-ear EEG-based wearable, the Sensor Dot (SD), to detect typical absences in adults and children; and (2) develop a sensitive patient-specific absence seizure detection algorithm to reduce the review time of the recordings. METHODS: We recruited 12 patients (median age = 21 years, range = 8-50; seven female) who were admitted to the epilepsy monitoring units of University Hospitals Leuven for a 24-h 25-channel video-EEG recording to assess their refractory typical absences. Four additional behind-the-ear electrodes were attached for concomitant recording with the SD. Typical absences were defined as 3-Hz spike-and-wave discharges on EEG, lasting 3 s or longer. Seizures on SD were blindly annotated on the full recording and on the algorithm-labeled file and consequently compared to 25-channel EEG annotations. Patients or caregivers were asked to keep a seizure diary. Performance of the SD and seizure diary were measured using the F1 score. RESULTS: We concomitantly recorded 284 absences on video-EEG and SD. Our absence detection algorithm had a sensitivity of .983 and false positives per hour rate of .9138. Blind reading of full SD data resulted in sensitivity of .81, precision of .89, and F1 score of .73, whereas review of the algorithm-labeled files resulted in scores of .83, .89, and .87, respectively. Patient self-reporting gave sensitivity of .08, precision of 1.00, and F1 score of .15. SIGNIFICANCE: Using the wearable SD, epileptologists were able to reliably detect typical absence seizures. Our automated absence detection algorithm reduced the review time of a 24-h recording from 1-2 h to around 5-10 min.