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Voltage-gated ion channels are key players in neuronal excitability, synaptic transmission, and neuronal synchrony and represent one of the major sources of abnormal function of neuronal circuits occurring during epilepsy. Epilepsy does not result solely from the imbalance between excitatory and inhibitory ion channels; loss of function in excitatory channels or gain of function in inhibitory channels is also reported in epileptic encephalopathies. Synaptic inhibition triggers focal epilepsies, possibly through the facilitation of excitatory synaptic transmission due to the deinactivation of axonal sodium channels. Neural synchrony and its transmission within neural microcircuits is controlled by voltage-gated ion channels located in the axon, the dendrites, and the cell body. New molecules targeting excitatory and inhibitory ion channels need to be identified and tested in in vitro and in vivo models of epileptic encephalopathies. Epileptic encephalopathies are generally considered to be functional disruptions in the balance between neural excitation and inhibition. Excitatory and inhibitory voltage-gated ion channels are key targets of antiepileptic drugs, playing a critical role in regulating neuronal excitation and synaptic transmission. Recent research has highlighted the significance of ion channels in various aspects of epilepsy, including presynaptic neurotransmitter release, intrinsic neuronal excitability, and neural synchrony. Genetic alterations in excitatory and inhibitory ion channels within principal neurons and in inhibitory interneurons have also been identified as key contributors to the development of epilepsies. We review these recent studies and shed light on the bidirectional relationship between epilepsy and neuronal excitability and the latest advancements in pharmacological therapeutics targeting ion channels for epilepsy treatment. [ABSTRACT FROM AUTHOR]

Introduction: Epilepsy is one of the most common neurological disorders present in sub-Saharan Africa and most of these cases are underdiagnosed due to a lack of resources. Epileptic encephalopathies are a broad spectrum of seizure disorders characterized by epileptic activity itself impairing cognitive and behavioral function more than what is expected from the underlying pathology alone. Epileptic encephalopathy resulting from the CACNA1A variant is extremely challenging to treat and prognosis is poor if prompt diagnosis is not made. Case Presentation: This is a 7-year-old male patient of African descent with a history of recurrent seizures since infancy. He has been kept on several anticonvulsants without success to control seizure attacks. The patient had more than three attacks in a single month despite being on anticonvulsants. EEG (electro-encephalography) was done and genetic studies showed a diagnosis consistent with CACNA1A variant-associated epileptic encephalopathy. Anticonvulsants were revised and a combination of new medications as suggested by current guidelines was initiated, and the patient is followed up closely on a monthly basis. Conclusion: Despite being challenging to treat epileptic encephalopathies associated with CACNA1A variants all patients initiated with antiepileptic therapy should be followed closely and monitored for control of seizure attacks. If EEG alone does not point out the diagnosis, appropriate investigations such as genetic studies should be considered. Early diagnosis is crucial for the prognosis of such kind of cases, especially in resource-limited settings where diagnostic equipments are scarce. All clinicians in these areas should have a high suspicion index in pediatric patients with recurrent seizure attacks to rule out epileptic encephalopathies.

Potassium channels have recently emerged as suitable target for the treatment of epileptic diseases. Among potassium channels, KCNT1 channels are the most widely characterized as responsible for several epileptic and developmental encephalopathies. Nevertheless, the medicinal chemistry of KCNT1 blockers is underdeveloped so far. In the present review, we describe and analyse the papers addressing the issue of KCNT1 blockers' development and identification, also evidencing the pros and the cons of the scientific approaches therein described. After a short introduction describing the epileptic diseases and the structure–function of potassium channels, we provide an extensive overview of the chemotypes described so far as KCNT1 blockers, and the scientific approaches used for their identification. [ABSTRACT FROM AUTHOR]

Glutamine synthetase (GS), encoded by GLUL , catalyzes the conversion of glutamate to glutamine. GS is pivotal for the generation of the neurotransmitters glutamate and gamma-aminobutyric acid and is the primary mechanism of ammonia detoxification in the brain. GS levels are regulated post-translationally by an N-terminal degron that enables the ubiquitin-mediated degradation of GS in a glutamine-induced manner. GS deficiency in humans is known to lead to neurological defects and death in infancy, yet how dysregulation of the degron-mediated control of GS levels might affect neurodevelopment is unknown. We ascertained nine individuals with severe developmental delay, seizures, and white matter abnormalities but normal plasma and cerebrospinal fluid biochemistry with de novo variants in GLUL. Seven out of nine were start-loss variants and two out of nine disrupted 5′ UTR splicing resulting in splice exclusion of the initiation codon. Using transfection-based expression systems and mass spectrometry, these variants were shown to lead to translation initiation of GS from methionine 18, downstream of the N-terminal degron motif, resulting in a protein that is stable and enzymatically competent but insensitive to negative feedback by glutamine. Analysis of human single-cell transcriptomes demonstrated that GLUL is widely expressed in neuro- and glial-progenitor cells and mature astrocytes but not in post-mitotic neurons. One individual with a start-loss GLUL variant demonstrated periventricular nodular heterotopia, a neuronal migration disorder, yet overexpression of stabilized GS in mice using in utero electroporation demonstrated no migratory deficits. These findings underline the importance of tight regulation of glutamine metabolism during neurodevelopment in humans. [Display omitted] Start-loss variants in GLUL result in a severe developmental and epileptic phenotype through the stabilization of glutamine synthetase, an enzyme crucial for brain function. This disorder is unusual in its gain-of-stabilization mechanism contrasting with the allelic deficiency disorder. [ABSTRACT FROM AUTHOR]

In the context of childhood epilepsy, the concept of continuous spike–waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau–Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies. [ABSTRACT FROM AUTHOR]

Variants in the GABRB gene, which encodes the β subunit of the GABAA receptor, have been implicated in various epileptic encephalopathies and related neurodevelopmental disorders such as Dravet syndrome and Angelman syndrome. These conditions are often associated with early-onset seizures, developmental regression, and cognitive impairments. The severity and specific features of these encephalopathies can differ based on the nature of the genetic variant and its impact on GABAA receptor function. These variants can lead to dysfunction in GABAA receptor-mediated inhibition, resulting in an imbalance between neuronal excitation and inhibition that contributes to the development of seizures. Here, 13 de novo EE-associated GABRB variants, occurring as missense mutations, were analyzed to determine their impact on protein stability and flexibility, channel function, and receptor biogenesis. Our results showed that all mutations studied significantly impact the protein structure, altering protein stability, flexibility, and function to varying degrees. Variants mapped to the GABA-binding domain, coupling zone, and pore domain significantly impact the protein structure, modifying the β+/α− interface of the receptor and altering channel activation and receptor trafficking. Our study proposes that the extent of loss or gain of GABAA receptor function can be elucidated by identifying the specific structural domain impacted by mutation and assessing the variability in receptor structural dynamics. This paves the way for future studies to explore and uncover links between the incidence of a variant in the receptor topology and the severity of the related disease. [ABSTRACT FROM AUTHOR]

Background. Treatment of epileptic seizures in young children, especially with epileptic encephalopathies (EE), is a difficult task, which is impossible in modern conditions without the use of a personified (precision) therapy. The diagnostic algorithm for EE must include genetic examination by the next-generation sequencing, which makes it possible to prescribe targeted therapy depending on the genetic etiology of the disorder. The article presents the results of own research on the effectiveness and approaches to targeted therapy of genetic epileptic encephalopathies in young children. Materials and methods. Fifty-eight children aged 0–3 years with clinical manifestations of epileptic encephalopathies, onset of seizures in the first year of life and diagnosed genetic etiology were included in the study. Pathogenic variants in genes associated with the development of epileptic seizures were identified in all children using the next-generation sequencing. The study included assessment of neurological status, history collection, evaluation of semiology and seizure type, development and screening for autism spectrum disorders at the age of 18 and 24 months, video-electroencephalography during night sleep, magnetic resonance imaging of the brain, assessment of antiepileptic treatment received by the child. Results. Of 58 children with EE who were prescribed antie­pileptic drugs, 10 (17.2 %) received monotherapy, 40 patients (69 %) received combined therapy with two anticonvulsants, and 8 children (13.8 %) — combined therapy with three or more anticonvulsants. Levetiracetam (31 patients), valproic acid salt preparations (20 cases), topiramate (11 children) and vigabatrin (10 cases) were most used antiepileptic drugs. In all examined patients with EE, we used schemes of targeted (persona­lized) antiepileptic therapy focused on the genetic etiology of the disorder. In children with tuberous sclerosis caused by mutations in the TSC1 and TSC2 genes, vigabatrin (50–150 mg/kg per day) was included in the antiepileptic therapy and showed efficacy in 75.0 % (9/12) of children with infantile spasms. Corticosteroids (adrenocorticotropic hormone or prednisone) were additionally included in the treatment regimen and showed effectiveness in 66.7 % of cases (4/6). In children with mutations in SCN1A gene, combined therapy including valproic acid, topiramate and clobazam, or valproic acid with levetiracetam and corticosteroids was used, which showed effectiveness in reducing the frequency of seizures in 100 % of cases. Conclusions. Epileptic encephalopathies are a heterogeneous group of genetic disorders in young children that are difficult to treat and often have a malignant course. Since standard antiepileptic drugs are often insufficiently effective in epileptic encephalopathies, the use of targeted therapy drugs and alternative treatments such as hormone therapy are extremely important. The goal of treatment for epileptic encephalopathies is not only to control seizures, but also to prevent the development of neurological and cognitive deficits and restore lost functions.

We identified the PACS2 gene responsible for the multifunctional sorting protein that play a role in nuclear gene expression as well as pathway traffic regulation. Diseases associated with PACS2 include early infantile epileptic encephalopathy (EIEE66), alacrima, achalasia, and mental retardation syndrome. Whole exome sequencing (WES) technique was used for the identification of variants that may lead to the disease. We identified a consanguineous Saudi family segregating developmental delay, mental retardation and epilepsy. Our results showed a heterozygous missense variant PACS2 gene leading to intellectual disability, epilepsy and cause epileptic encephalopathies (EIEE66) disorder. WES data was analyzed and identified variants were further confirmed by Sanger sequencing validation technique. We identified a heterozygous missense c.625G>A p.Glu209Lys in exon-6 of PACS2. The detected heterozygous mutation in the exon-6 region of PACS2 gene change the protein features and may cause disease. Further, explain the possibility that PACS2 gene play important role to cause intellectual disability, epilepsy and epileptic encephalopathies in this Saudi family. [ABSTRACT FROM AUTHOR]

Potassium channels have recently emerged as suitable target for the treatment of epileptic diseases. Among potassium channels, KCNT1 channels are the most widely characterized as responsible for several epileptic and developmental encephalopathies. Nevertheless, the medicinal chemistry of KCNT1 blockers is underdeveloped so far. In the present review, we describe and analyse the papers addressing the issue of KCNT1 blockers’ development and identification, also evidencing the pros and the cons of the scientific approaches therein described. After a short introduction describing the epileptic diseases and the structure–function of potassium channels, we provide an extensive overview of the chemotypes described so far as KCNT1 blockers, and the scientific approaches used for their identification.

In the context of childhood epilepsy, the concept of continuous spike–waves during slow sleep (CSWS) includes several childhood-onset heterogeneous conditions that share electroencephalograms (EEGs) characterized by a high frequency of paroxysmal abnormalities during sleep, which have negative effects on the cognitive development and behavior of the child. These negative effects may have the characteristics of a clear regression or of a slowdown in development. Seizures are very often present, but not constantly. The above makes it clear why CSWS have been included in epileptic encephalopathies, in which, by definition, frequent EEG paroxysmal abnormalities have an unfavorable impact on cognitive functions, including socio-communicative skills, causing autistic features, even regardless of the presence of clinically overt seizures. Although several decades have passed since the original descriptions of the electroclinical condition of CSWS, there are still many areas that are little-known and deserve to be further studied, including the EEG diagnostic criteria, the most effective electrophysiological parameter for monitoring the role of the thalamus in CSWS pathogenesis, its long-term evolution, the nosographic location of Landau–Kleffner syndrome, standardized neuropsychological and behavioral assessments, and pharmacological and non-pharmacological therapies.

Epileptic encephalopathies (EEs) are severe brain disorders with excessive ictal (seizure) and interictal (electrographic epileptiform discharges) activity in developing brain which may result in progressive cognitive and neuropsychological deterioration. In contrast to regular epilepsy where the treatment goal is to prevent the seizure (ictal) recurrence, in patients with EE the goal is to treat both ictal as well as interictal activity to prevent further progression. With the introduction of genetic sequencing technologies over the past 20 years, there is growing recognition of the genetic basis of EE, with the majority due to monogenic causes. Monogenic etiologies of EE include pathogenic variants in the γ‐aminobutyric acid type A receptor (GABA‐A) encoding gene family. We present a 2‐year‐old patient with EE, hypotonia, and global developmental delays. Clinical trio exome sequencing showed a novel, de novo variant in GABRG1. GABRG1 encodes the γ1 subunit of the GABA‐A receptor. To date, there has not been an association of EE with pathogenic variants in GABRG1. This variant is predicted to be damaging to protein structure and function, and the patient's phenotype is similar to those with pathogenic variants in other members of the GABA‐A receptor encoding gene family. [ABSTRACT FROM AUTHOR]

In recent years, precision medicine has emerged as a new paradigm for improved and more individualized patient care. Its key objective is to provide the right treatment, to the right patient at the right time, by basing medical decisions on individual characteristics, including specific genetic biomarkers. In order to realize this objective researchers and physicians must first identify the underlying genetic cause; over the last 10 years, advances in genetics have made this possible for several monogenic epilepsies. Through next generation techniques, a precise genetic aetiology is attainable in 30–50% of genetic epilepsies beginning in the paediatric age. While committed in such search for novel genes carrying disease‐causing variants, progress in the study of experimental models of epilepsy has also provided a better understanding of the mechanisms underlying the condition. Such advances are already being translated into improving care, management and treatment of some patients. Identification of a precise genetic aetiology can already direct physicians to prescribe treatments correcting specific metabolic defects, avoid antiseizure medicines that might aggravate functional consequences of the disease‐causing variant or select the drugs that counteract the underlying, genetically determined, functional disturbance. Personalized, tailored treatments should not just focus on how to stop seizures but possibly prevent their onset and cure the disorder, often consisting of seizures and its comorbidities including cognitive, motor and behaviour deficiencies. This review discusses the therapeutic implications following a specific genetic diagnosis and the correlation between genetic findings, pathophysiological mechanisms and tailored seizure treatment, emphasizing the impact on current clinical practice. [ABSTRACT FROM AUTHOR]

With the increasing use of genetic testing in pediatric epilepsy, it is important to describe the diagnostic outcomes as they relate to clinical care. The goal of this study was to assess the diagnostic yield and impact on patient care of genetic epilepsy panel testing. We conducted a retrospective chart review of patients at the Children's Hospital of Eastern Ontario (CHEO) who had genetic testing between the years of 2013–2020. We identified 227 patients that met criteria for inclusion. The majority of patients had their testing performed as "out-of-province" tests since province-based testing during this period was limited. The diagnostic yield for multi-gene epilepsy panel testing was 17% (39/227) and consistent with the literature. Variants of unknown significance (VUS) were reported in a significant number of undiagnosed individuals (77%; 128/163). A higher diagnostic rate was observed in patients with a younger age of onset of seizures (before one year of age; 32%; 29/90). A genetic diagnosis informed prognosis, recurrence risk counselling and expedited access to resources in all those with a diagnosis. A direct change in clinical management as a result of the molecular diagnosis was evident for 9% (20/227) of patients. The information gathered in this study provides evidence of the clinical benefits of genetic testing in epilepsy and serves as a benchmark for comparison with the current provincial Ontario Epilepsy Genetic Testing Program (OEGTP) that began in 2020. [ABSTRACT FROM AUTHOR]

We report on the rare case of a male toddler presenting with myoclonic epilepsy characterized by daily episodes of upward movements of the eyebrows, and myoclonic jerks of both head and upper limbs. In addition, the child showed speech delay, tremors, and lack of motor coordination. Next Generation Sequencing analysis (NGS) performed in trio revealed in the proband the c.889C>T de novo missense variant in the KCNA2 gene in heterozygous state. This is the first case of myoclonic epilepsy in a toddler due to a c.889C>T KCNA2 missense variant. The patient was treated with valproic acid and ethosuximide with a good clinical response. At 6 years old, follow-up revealed that the proband was seizure-free with tremors and clumsiness in movements. According to the literature, this case supports the correlation between myoclonic epilepsy and KCNA2 alterations. This evidence suggests that performing genomic testing including the KCNA2 gene in preschool patients affected by myoclonic epilepsy, especially when associated with delayed neurodevelopment. Our goal is to expand the phenotypical spectrum of this rare condition and adding clinical features following a genotype-first approach. [ABSTRACT FROM AUTHOR]

SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptor) are an heterogeneous family of proteins that, together with their key regulators, are implicated in synaptic vesicle exocytosis and synaptic transmission. SNAREs represent the core component of this protein complex. Although the specific mechanisms of the SNARE machinery is still not completely uncovered, studies in recent years have provided a clearer understanding of the interactions regulating the essential fusion machinery for neurotransmitter release. Mutations in genes encoding SNARE proteins or SNARE complex associated proteins have been associated with a variable spectrum of neurological conditions that have been recently defined as "SNAREopathies." These include neurodevelopmental disorder, autism spectrum disorder (ASD), movement disorders, seizures and epileptiform abnormalities. The SNARE phenotypic spectrum associated with seizures ranges from simple febrile seizures and infantile spasms, to severe early-onset epileptic encephalopathies. Our study aims to review and delineate the epileptic phenotypes associated with dysregulation of synaptic vesicle exocytosis and transmission, focusing on the main proteins of the SNARE core complex (STX1B, VAMP2, SNAP25), tethering complex (STXBP1), and related downstream regulators. [ABSTRACT FROM AUTHOR]

Variants in KCNT1, encoding a sodium-gated potassium channel (subfamily T member 1), have been associated with a spectrum of epilepsies and neurodevelopmental disorders. These range from familial autosomal dominant or sporadic sleep-related hypermotor epilepsy to epilepsy of infancy with migrating focal seizures (EIMFS) and include developmental and epileptic encephalopathies. This study aims to provide a comprehensive overview of the phenotypic and genotypic spectrum of KCNT1 mutation-related epileptic disorders in 248 individuals, including 66 previously unpublished and 182 published cases, the largest cohort reported so far. Four phenotypic groups emerged from our analysis: (i) EIMFS (152 individuals, 33 previously unpublished); (ii) developmental and epileptic encephalopathies other than EIMFS (non-EIMFS developmental and epileptic encephalopathies) (37 individuals, 17 unpublished); (iii) autosomal dominant or sporadic sleep-related hypermotor epilepsy (53 patients, 14 unpublished); and (iv) other phenotypes (six individuals, two unpublished). In our cohort of 66 new cases, the most common phenotypic features were: (i) in EIMFS, heterogeneity of seizure types, including epileptic spasms, epilepsy improvement over time, no epilepsy-related deaths; (ii) in non-EIMFS developmental and epileptic encephalopathies, possible onset with West syndrome, occurrence of atypical absences, possible evolution to developmental and epileptic encephalopathies with sleep-related hypermotor epilepsy features; one case of sudden unexplained death in epilepsy; (iii) in autosomal dominant or sporadic sleep-related hypermotor epilepsy, we observed a high prevalence of drug-resistance, although seizure frequency improved with age in some individuals, appearance of cognitive regression after seizure onset in all patients, no reported severe psychiatric disorders, although behavioural/psychiatric comorbidities were reported in ∼50% of the patients, sudden unexplained death in epilepsy in one individual; and (iv) other phenotypes in individuals with mutation of KCNT1 included temporal lobe epilepsy, and epilepsy with tonic-clonic seizures and cognitive regression. Genotypic analysis of the whole cohort of 248 individuals showed only missense mutations and one inframe deletion in KCNT1. Although the KCNT1 mutations in affected individuals were seen to be distributed among the different domains of the KCNT1 protein, genotype-phenotype considerations showed many of the autosomal dominant or sporadic sleep-related hypermotor epilepsy-associated mutations to be clustered around the RCK2 domain in the C terminus, distal to the NADP domain. Mutations associated with EIMFS/non-EIMFS developmental and epileptic encephalopathies did not show a particular pattern of distribution in the KCNT1 protein. Recurrent KCNT1 mutations were seen to be associated with both severe and less severe phenotypes. Our study further defines and broadens the phenotypic and genotypic spectrums of KCNT1-related epileptic conditions and emphasizes the increasingly important role of this gene in the pathogenesis of early onset developmental and epileptic encephalopathies as well as of focal epilepsies, namely autosomal dominant or sporadic sleep-related hypermotor epilepsy. [ABSTRACT FROM AUTHOR]

Alessandra Morano,1 Martina Fanella,1 Mariarita Albini,1 Pierangelo Cifelli,2,3 Eleonora Palma,2 Anna Teresa Giallonardo,1 Carlo Di Bonaventura1 1Epilepsy Unit, Department of Human Neurosciences, “Sapienza” University of Rome, Rome, Italy; 2Department of Physiology and Pharmacology, Pasteur Institute-Cenci Bolognetti Foundation, University of Rome Sapienza, Rome, Italy; 3IRCCS “Neuromed”, Pozzilli, IS, ItalyCorrespondence: Carlo Di BonaventuraEpilepsy Unit, Department of Human Neurosciences, “Sapienza” University of Rome, P.le A. Moro, 5, Rome 00185, ItalyEmail c_dibonaventura@yahoo.itAbstract: Cannabidiol (CBD) is one of the prominent phytocannabinoids found in Cannabis sativa, differentiating from Δ9-tetrahydrocannabinol (THC) for its non-intoxicating profile and its antianxiety/antipsychotic effects. CBD is a multi-target drug whose anti-convulsant properties are supposed to be independent of endocannabinoid receptor CB1 and might be related to several underlying mechanisms, such as antagonism on the orphan GPR55 receptor, regulation of adenosine tone, activation of 5HT1A receptors and modulation of calcium intracellular levels. CBD is a lipophilic compound with low oral bioavailability (6%) due to poor intestinal absorption and high first-pass metabolism. Its exposure parameters are greatly influenced by feeding status (ie, high fat-containing meals). It is mainly metabolized by cytochrome P 450 (CYP) 3A4 and 2C19, which it strongly inhibits. A proprietary formulation of highly purified, plant-derived CBD has been recently licensed as an adjunctive treatment for Dravet syndrome (DS) and Lennox-Gastaut syndrome (LGS), while it is being currently investigated in tuberous sclerosis complex. The regulatory agencies’ approval was granted based on four pivotal double-blind, placebo-controlled, randomized clinical trials (RCTs) on overall 154 DS patients and 396 LGS ones, receiving CBD 10 or 20 mg/kg/day BID as active treatment. The primary endpoint (reduction in monthly seizure frequency) was met by both CBD doses. Most patients reported adverse events (AEs), generally from mild to moderate and transient, which mainly consisted of somnolence, sedation, decreased appetite, diarrhea and elevation in aminotransferase levels, the last being documented only in subjects on concomitant valproate therapy. The interaction between CBD and clobazam, likely due to CYP2C19 inhibition, might contribute to some AEs, especially somnolence, but also to CBD clinical effectiveness. Cannabidivarin (CBDV), the propyl analogue of CBD, showed anti-convulsant properties in pre-clinical studies, but a plant-derived, purified proprietary formulation of CBDV recently failed the Phase II RCT in patients with uncontrolled focal seizures.Keywords: cannabidiol, cannabidivarin, phytocannabinoids, epileptic encephalopathies, tuberous sclerosis complex, drug-resistance

We report on the rare case of a male toddler presenting with myoclonic epilepsy characterized by daily episodes of upward movements of the eyebrows, and myoclonic jerks of both head and upper limbs. In addition, the child showed speech delay, tremors, and lack of motor coordination. Next Generation Sequencing analysis (NGS) performed in trio revealed in the proband the c.889C>T de novo missense variant in the KCNA2 gene in heterozygous state. This is the first case of myoclonic epilepsy in a toddler due to a c.889C>T KCNA2 missense variant. The patient was treated with valproic acid and ethosuximide with a good clinical response. At 6 years old, follow-up revealed that the proband was seizure-free with tremors and clumsiness in movements. According to the literature, this case supports the correlation between myoclonic epilepsy and KCNA2 alterations. This evidence suggests that performing genomic testing including the KCNA2 gene in preschool patients affected by myoclonic epilepsy, especially when associated with delayed neurodevelopment. Our goal is to expand the phenotypical spectrum of this rare condition and adding clinical features following a genotype-first approach.

SNAREs (soluble N-ethylmaleimide sensitive factor attachment protein receptor) are an heterogeneous family of proteins that, together with their key regulators, are implicated in synaptic vesicle exocytosis and synaptic transmission. SNAREs represent the core component of this protein complex. Although the specific mechanisms of the SNARE machinery is still not completely uncovered, studies in recent years have provided a clearer understanding of the interactions regulating the essential fusion machinery for neurotransmitter release. Mutations in genes encoding SNARE proteins or SNARE complex associated proteins have been associated with a variable spectrum of neurological conditions that have been recently defined as “SNAREopathies.” These include neurodevelopmental disorder, autism spectrum disorder (ASD), movement disorders, seizures and epileptiform abnormalities. The SNARE phenotypic spectrum associated with seizures ranges from simple febrile seizures and infantile spasms, to severe early-onset epileptic encephalopathies. Our study aims to review and delineate the epileptic phenotypes associated with dysregulation of synaptic vesicle exocytosis and transmission, focusing on the main proteins of the SNARE core complex (STX1B, VAMP2, SNAP25), tethering complex (STXBP1), and related downstream regulators.

Introduction: Epilepsy is one of the most common neurological disorders present in sub-Saharan Africa and most of these cases are underdiagnosed due to a lack of resources. Epileptic encephalopathies are a broad spectrum of seizure disorders characterized by epileptic activity itself impairing cognitive and behavioral function more than what is expected from the underlying pathology alone. Epileptic encephalopathy resulting from the CACNA1A variant is extremely challenging to treat and prognosis is poor if prompt diagnosis is not made., Case Presentation: This is a 7-year-old male patient of African descent with a history of recurrent seizures since infancy. He has been kept on several anticonvulsants without success to control seizure attacks. The patient had more than three attacks in a single month despite being on anticonvulsants. EEG (electro-encephalography) was done and genetic studies showed a diagnosis consistent with CACNA1A variant-associated epileptic encephalopathy. Anticonvulsants were revised and a combination of new medications as suggested by current guidelines was initiated, and the patient is followed up closely on a monthly basis., Conclusion: Despite being challenging to treat epileptic encephalopathies associated with CACNA1A variants all patients initiated with antiepileptic therapy should be followed closely and monitored for control of seizure attacks. If EEG alone does not point out the diagnosis, appropriate investigations such as genetic studies should be considered. Early diagnosis is crucial for the prognosis of such kind of cases, especially in resource-limited settings where diagnostic equipments are scarce. All clinicians in these areas should have a high suspicion index in pediatric patients with recurrent seizure attacks to rule out epileptic encephalopathies., Competing Interests: The authors declare no conflicts of interests., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

RHOBTB2 was first described as epileptogenic when it presents a missense variant in 2016 and studied more specifically in 2018. It is a gene that causes rare, but potentially severe childhood epileptic encephalopathy. In 2021, research confirmed that heterozygous mutations of RHOBTB2 included other clinical signs besides these encephalopathies. Thus, these infantile epilepsies are mainly associated with highly variable phenotypes, with developmental delay, post-traumatic encephalitis, paroxysmal movement disorders and iconographic brain damage. In this work, after presenting a clinical case, we will recall the role of RhoGTPases on neuronal development. We will then discuss a study which highlighted the neurodevelopmental impact of mutations on the RHOBTB2 gene by carrying out work on Drosophila melanogaster flies. Finally, we will compare the presented clinical case with a literature review.

Purpose of Review: Lennox-Gastaut syndrome (LGS) is an epileptic encephalopathy that is challenging to treat, with >80% of patients remaining refractory to therapy. Patient-oriented clinical outcome measures are essential for treatment guidance and the development of new therapies. Here, we provide a comprehensive review of outcome measures used in clinical trials targeting patients with LGS, in order to inform future studies, develop, and implement targeted patient and caregiver-relevant outcome measures. Recent Findings: Published clinical trials that include, or specifically target, individuals with LGS are reviewed, and primary and secondary outcome measurements are examined. Outcome measures are grouped and discussed as (1) seizure-related, (2) cognitive, (3) functional, (4) quality of life, and (5) psychosocial for both the LGS patient and caregiver. In patients with LGS, seizure frequency is the most common outcome measured by clinicians, while quality of life and psychosocial effect of treatments are often most important to families. Summary: Therefore, a disconnect exists between outcome measurements used in clinical trials and those rated important by families. Furthermore, cognitive, functional, and psychosocial outcome measures are often insufficiently sensitive for many LGS patients, and thus, using better targeted measures may result in an increased availability of treatment options. [ABSTRACT FROM AUTHOR]

Epileptic encephalopathies represent a group of devastating epileptic disorders that occur early in life and are often characterized by pharmaco-resistant epilepsy, persistent severe electroencephalographic abnormalities, and cognitive dysfunction or decline. Next generation sequencing technologies have increased the speed of gene discovery tremendously. Whereas ion channel genes were long considered to be the only significant group of genes implicated in the genetic epilepsies, a growing number of non-ion-channel genes are now being identified. As a subgroup of the genetically mediated epilepsies, epileptic encephalopathies are complex and heterogeneous disorders, making diagnosis and treatment decisions difficult. Recent exome sequencing data suggest that mutations causing epileptic encephalopathies are often sporadic, typically resulting from de novo dominant mutations in a single autosomal gene, although inherited autosomal recessive and X-linked forms also exist. In this review we provide a summary of the key features of several early- and mid-childhood onset epileptic encephalopathies including Ohtahara syndrome, Dravet syndrome, Infantile spasms and Lennox Gastaut syndrome. We review the recent next generation sequencing findings that may impact treatment choices. We also describe the use of conventional and newer anti-epileptic and hormonal medications in the various syndromes based on their genetic profile. At a biological level, developments in cellular reprogramming and genome editing represent a new direction in modeling these pediatric epilepsies and could be used in the development of novel and repurposed therapies.

Background: Epileptic encephalopathies (EEs) are a pediatric entity with highly phenotypic and genetic heterogeneity. Both single nucleotide variants (SNVs)/Indels and copy number variations (CNVs) could be the causes. Whole exome sequencing (WES) is widely applied to detect SNVs/Indels, but the bioinformatics approach for detecting CNVs is still limited and weak. In the current study, the possibility of profiling both disease-causing SNVs/Indels and CNVs in a single test based on WES in EEs was evaluated.Methods: The infants diagnosed with EEs were enrolled from a single pediatric epilepsy center between January 2018 and February 2020. Demographic and clinical data were collected. In WES data, the pathogenic SNVs were identified through an in-house pipeline, and pathogenic CNVs were identified by CNVkit. The diagnostic rate was evaluated, and the molecular findings were characterized.Results: A total of 73 infants were included; 36 (49.32%) of them were males. The median age was 7 months. Thirty-two (43.84%) infants had been diagnosed with epilepsy syndrome. The most common type of syndrome was West syndrome (22/73, 30.1%), followed by Dravet syndrome (20/77, 27.4%). Fifty-four (73.97%) had intellectual development delay. The genetic cause of EEs, pathogenic or likely pathogenic variants, were successfully discovered in 46.6% (34/73) of the infants, and 29 (39.7%) infants carried SNVs/Indels, while 5 (6.8%) carried CNVs. The majority of the disease-causing variants were inherited in de novo pattern (25, 71.4%). In addition to showing that the variants in the ion channel encoding genes accounted for the main etiology, we discovered and confirmed two new disease-causing genes, CACNA1E and WDR26. Five discovered CNVs were deletions of 2q24.3, 1p36, 15q11-q13, 16p11.2, and 17p13.3, and all were confirmed by array comparative genomic hybridization.Conclusion: The application of both SNVs/Indels and CNVs detection in a single test based on WES yielded a high diagnosis rate in EEs. WES may serve as a first-tier test with cost-effective benefit in EEs.

Cannabidiol has been approved for the treatment of drug-resistant childhood epilepsies including Dravet syndrome (DS). Although the mechanism of anticonvulsant action of cannabidiol is unknown, emerging data suggests involvement of the transient receptor potential cation channel subfamily V member 1 (Trpv1). Pharmacological and genetic studies in conventional seizure models suggest Trpv1 is a novel anticonvulsant target. However, whether targeting Trpv1 is anticonvulsant in animal models of drug-resistant epilepsies is not known. Thus, we examined whether Trpv1 affects the epilepsy phenotype of the F1.Scn1a+/− mouse model of DS. We found that cortical Trpv1 mRNA expression was increased in seizure susceptible F1.Scn1a+/− mice with a hybrid genetic background compared to seizure resistant 129.Scn1a+/− mice isogenic on 129S6/SvEvTac background, suggesting Trpv1 could be a genetic modifier. Previous studies show functional loss of Trpv1 is anticonvulsant. However, Trpv1 selective antagonist SB-705498 did not affect hyperthermia-induced seizure threshold, frequency of spontaneous seizures or survival of F1.Scn1a+/− mice. Surprisingly, Trpv1 deletion had both pro- and anti-seizure effects. Trpv1 deletion did not affect hyperthermia-induced seizure temperature thresholds of F1.Scn1a+/−; Trpv1+/− at P14-16 but was proconvulsant at P18 as it reduced seizure temperature thresholds. Conversely, Trpv1 deletion did not alter the frequency of spontaneous seizures but reduced their severity. These results suggest that Trpv1 is a modest genetic modifier of spontaneous seizure severity in the F1.Scn1a+/− model of DS. However, the opposing pro- and anti-seizure effects of Trpv1 deletion and the lack of effects of Trpv1 inhibition suggest that Trpv1 is unlikely a viable anticonvulsant drug target in DS.

The precise coordination of neuronal activity is critical for optimal brain function. When such coordination fails, this can lead to dire consequences. In this review, I will present evidence that in epilepsy, failed coordination leads not only to seizures but also to alterations of the rhythmical patterns observed in the electroencephalogram and cognitive deficits. Restoring the dynamic coordination of epileptic networks could therefore both improve seizures and cognitive outcomes. [ABSTRACT FROM AUTHOR]

Purpose of reviewWe aim to review the most recent advances in the field of epilepsy genetics with particular focus on the progress in gene discovery in monogenic epilepsies, identification of risk genes in complex genetic epilepsies and recent findings in the field of epilepsy pharmacogenomics.Recent findingsDuring the last 12 months, the use of massive parallel sequencing technologies has allowed for the discovery of several genes for monogenic epilepsies. Most importantly, PRRT2 was identified as the long-sought gene for benign familial infantile seizures. Mutations in KCNT1 were found in two seemingly unrelated monogenic epilepsies including malignant migrating partial seizures of infancy and severe autosomal dominant nocturnal frontal lobe epilepsy. A genome-wide association study in idiopathic generalized epilepsy revealed the first common risk variants for human seizure disorders including variants in VRK2, PNPO and SCN1A. Furthermore, a landmark study provided evidence that screening for the HLA-B1502 variant may prevent carbamazepine CBZ-induced side effects in the Taiwanese population. Also, HLA-A3101 variants were identified as a risk factor for carbamazepine side effects in Europeans.SummaryNovel technologies and an unprecedented level of international collaboration have resulted in identification of novel genes for monogenic and complex genetic epilepsies as well as risk factors for side effects of antiepileptic drugs. This review provides an overview of the most relevant studies in the last year and highlights the future direction of the field.

Introduction: The landscape of epilepsy treatment has undergone a significant transformation with the emergence of cannabidiol as a potential therapeutic agent. Epidiolex, a pharmaceutical formulation of highly purified CBD, garnered significant attention not just for its therapeutic potential but also for being the first cannabis-derived medication to obtain approval from regulatory bodies., Area Covered: In this narrative review the authors explore the intricate landscape of CBD as an antiseizure medication, deepening into its pharmacological mechanisms and clinical trials involving various epileptic encephalopathies. This exploration serves as a comprehensive guide, shedding light on a compound that holds promise for individuals contending with the significant challenges of drug-resistant epilepsy., Expert Opinion: Rigorous studies highlight cannabidiol's efficacy, safety profile, and potential cognitive benefits, warranting further exploration for its approval in various drug-resistant epilepsy forms. As a promising therapeutic option, cannabidiol not only demonstrates efficacy in seizure control but also holds the potential for broader enhancements in the quality of life, especially for patients with epileptic encephalopathies.

Aim: To determine main etiologies and clinical features of neonatal seizures (NS) in groups of newborns of different gestational age (GA).Materials and Methods. Main etiologies of NS were evaluated in 165 newborns divided into four groups: I – 84 early preterm newborns with GA of 28 weeks or less, II – 52 newborns with 29-32 weeks GA, III – 12 newborns with 33-36 weeks GA, and IV – 17 term infants with GA between 37 and 41 wks.Results. In the above 165 infants, the following causes of NS were found: perinatal hypoxia-ischemia – 72.1% of cases, grade III-IV intracranial hemorrhage – 6.1%, congenital infections in 9.7%, CNS infections (bacterial meningitis and viral meningoencephalitis) – 9.7%, сerebral dysgenesis – 1.2%, and inborn errors of metabolism and neurodegenerative diseases accounted for 1.2%. Intracranial hemorrhage (grade III-IV) was detected in newborns with GA less than 32 wks only. The etiological role of CNS infections was higher in term newborns (23.5%) than in the other groups.Conclusion. In examining newborns with NS, genetic mechanisms should be taken into consideration, especially when no indications of early brain damage are apparent. This approach is important today as targeted therapies of gene-associated epileptic syndromes are becoming feasible. In the present article, the use of levetiracetam in infants with NS and early onset epilepsy is discussed.

Abstract Background At the onset, differentiation between abnormal non-epileptic movements, and epileptic seizures presenting in early life is difficult as is clinical diagnosis and prognostic evaluation of the various seizure disorders presenting at this age. Seizures starting in the first year of life including the neonatal period might have a favorable course, such as in infants presenting with benign familial neonatal epilepsy, febrile seizures simplex or acute symptomatic seizures. However, in some cases, the onset of seizures at birth or in the first months of life have a dramatic evolution with severe cerebral impairment. Seizure disorders starting in early life include the “epileptic encephalopathies”, a group of conditions characterized by drug resistant seizures, delayed developmental skills, and intellective disability. This group of disorders includes early infantile epileptic encephalopathy also known as Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, infantile spasms syndrome (also known as West syndrome), severe myoclonic epilepsy in infancy (also known as Dravet syndrome) and, myoclonic encephalopathies in non-progressive disorder. Here we report on seizures manifesting in the first year of life including the neonatal period. Conditions with a benign course, and those with severe evolution are presented. At this early age, clinical identification of seizures, distinction of each of these disorders, type of treatment and prognosis is particularly challenging. The aim of this report is to present the clinical manifestations of each of these disorders and provide an updated review of the conditions associated with seizures in the first year of life.

Electrical status epilepticus of slow sleep (ESES) is a sleep EEG pattern with a continuous (85-100%) diffuse epileptiform activity. The morphology of these epileptiform complexes is identical to benign epileptiform discharges of childhood (BEDC). Epilepsy with ESES (or Penelope Syndrome) is a form of age-dependent epileptic encephalopathies with continuous spike-wave activity during slow wave sleep. This group of epilepsies also includes Pseudo-Lennox syndrome, Landau-Kleffner syndrome, autistic epileptiform regression and some others. Usually, the ESES pattern correlates with the severity of cognitive deficit in epileptic children. The list of anti-epileptic drugs (AEDs) used in pharmacotherapy of epileptic encephalopathies includes valproates, levetiracetam, ethosuximide, sulthiame, topiramate, zonisamide and benzodiazepines; those are given in monotherapy or rationalized combined therapy. Levetiracetam was highly effective in 67.6% of patients with ESES (n=23); among them, two cases of clinical and EEG remission during the pre-puberty period, nine cases of clinical remission and 12 cases with a significant decrease in seizures and epileptiform discharges. In 20.6% of patients (n=7), the pharmacotherapy showed low efficacy. In 11.8% of patients (n=4), aggravation of the disease was noted. Combinations of levetiracetam with valproates and levetiracetam with ethosuximide were found the most effective AEDs. In the cases of epileptogenic structural defect that underlines drug-resistant epilepsy with ESES, neurosurgical intervention is recommended.

The majority of epilepsy cases have their onset in childhood. Compared to their peers, many more children with epilepsy suffer from severe neurodevelopmental disorders, including intellectual disability and autism spectrum disorders. In the present report, the incidence of intellectual disability and autism spectrum disorders among children with epilepsy is reviewed. Four types of connection between epilepsy and autism are discussed: these two conditions are independent as they have different etiologies and may co-occur just by chance; epilepsy and autism are associated because both originate from the same genetic defect or from an early CNS damage; autism is caused by the epileptic process, which interferes with the developing brain networks involved in communication and social behavior. Studies demonstrating positive effects of levetiracetam on the behavioral and cognitive functions (memory, attention) in epileptic children are cited.

• Common epilepsy forms observed in specific rare, monogenetic, neurodevelopmental disorder patients are highlighted. • Characteristics of epilepsy types and hyper-excitable networks seen in mouse models of these conditions are discussed. • Areas of strong and weak correlations between patient presentations mouse model phenotypes are discussed. Genetic neurodevelopmental disorders - that often include epilepsy as part of their phenotype - are a heterogeneous and clinically challenging spectrum of disorders in children. Although seizures often contribute significantly to morbidity in these affected populations, the mechanisms of epileptogenesis in these conditions remain poorly understood. Different model systems have been developed to aid in unraveling these mechanisms, which include a number of specific mutant mouse lines which genocopy specific general types of mutations present in patients. These mouse models have not only allowed for assessments of behavioral and electrographic seizure phenotypes to be ascertained, but also have allowed effects on the neurodevelopmental alterations and cognitive impairments associated with these disorders to be examined. In addition, these models play a role in advancing our understanding of these epileptic processes and developing preclinical therapeutics. The concordance of seizure phenotypes – in a select group of rare, genetic, neurodevelopmental disorders and epileptic encephalopathies – found between human patients and their model counterparts will be summarized. This review aims to assess whether models of Rett syndrome, CDKL5 deficiency disorder, Fragile-X syndrome, Dravet syndrome, and Ohtahara syndrome phenocopy the seizures seen in human patients. [ABSTRACT FROM AUTHOR]

Epileptic encephalopathies are conditions in which the abundant epileptiform activity itself interferes with development, resulting in cognitive slowing and often regression, psychiatric and behavioral disturbances. Nonconvulsive status epilepticus has been defined as ongoing or nonrecovering nonconvulsive seizures. It has been challenging to differentiate clinical and electroencephalographic patterns in epileptic encephalopathies from those attributed to nonconvulsive status epilepticus, since several different epileptic encephalopathies may show continuous or subcontinuous epileptiform activity. Especially for patients with known epileptic encephalopathy, the new proposal for diagnosis of nonconvulsive status epilepticus suggests an increase in prominence or frequency of specific electroencephalographic features as compared to baseline correlated to clinical and EEG responsiveness to intravenous anti-seizure drugs. This clinical change may be unclear, particularly in patients with pre-existent cognitive or behavioral impairments. This review intends to organize previously published data, with available information in the literature on some of those specific epileptic syndromes and diseases, focusing on two main questions: i. When should specialists suspect of nonconvulsive status epilepticus in epileptic encephalopathies? ii. Could epileptic encephalopathies themselves be nonconvulsive status epilepticus presentations? Lastly, the rationale for definition and treatment in many of the epileptic encephalopathies is the effect of ongoing frequent epileptiform activity on development and cognition, and this will require monitoring with serial clinical, neurophysiological, functional neuroimaging, and neuropsychological assessments. Whether there would be an association or causality between epileptic encephalopathies and nonconvulsive status epilepticus is a key question demanding further research. [ABSTRACT FROM AUTHOR]

Copyright of Mezdunarodnyj Nevrologiceskij Zurnal is the property of Zaslavsky O.Yu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mezdunarodnyj Nevrologiceskij Zurnal is the property of Zaslavsky O.Yu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Brivaracetam was found to be effective and well tolerated in cases with epileptic encephalopathies. • Twenty-six patients of 42 (62.1%) had a greater than 50% decrease in seizures. • Three patients of 42 (9.5%) became seizure free. • Brivaracetam is a good option when levetiracetam is not well tolerated and not efficacious. Here we present a multicenter series of patients with developmental epileptic encephalopathies (DEE) who were treated with brivaracetam (BRV) as add-on therapy. Medical records of 42 patients with DEE treated with add-on BRV seen at four pediatric neurology centers in Argentina between January 2021 and July 2023 were retrospectively analyzed. We included 42 patients (26 males, 16 females) with a mean age of 7 years (SD, ± 3.8; median, 9; range, 2–16). The children had different types of childhood-onset treatment-resistant DEEs and received BRV as add-on therapy for a mean period of 2 years (SD, ± 1.3 years; median, 1.5 years; range, 0.5–3 years). Thirty-three patients received levetiracetam (LEV) before the introduction of BRV. In nine patients, BRV was started without prior LEV because of behavioral disturbances. Three patients (9.5 %) became seizure free and 26/42 patients (62.1 %) had a greater than 50 % decrease in seizures after a mean follow-up of 21 months. Ten patients (23.8 %) had a 25–50 % seizure reduction, while seizure frequency remained unchanged in two (4.7 %) and increased in one patient (2.4 %). The interictal EEG abnormalities improved in all the responders. Adverse effects, consisting of drowsiness, irritability, and decreased appetite, were observed in seven patients (16.6 %), but did not lead to treatment discontinuation. Brivaracetam was found to be effective, safe, and well tolerated in children with DEE. In patients on LEV with behavioral disturbances, BRV may be tried. BRV may also be given without a previous trial with LEV in patients with behavioral problems. [ABSTRACT FROM AUTHOR]

Drug-refractory epilepsy is a commonly prevalent pediatric neurological illness of global significance. Ketogenic diet (KD) is a time-tested therapeutic modality for refractory epilepsy, which has reemerged as a robust alternative to anti-epileptic pharmacotherapy. There is a growing body of evidence which supports the anti-seizure efficacy, safety profile and feasibility of KD use in childhood epilepsy. In addition, this modality has been recognized to reduce anti-epileptic exposure, improve cognition and behavioral profile of patients as well as improve the quality-of-life of care-givers. Current indications of KD include refractory epilepsy syndromes, selected metabolic disorders (such as pyruvate dehydrogenase deficiency) and a host of varied neurological entities. KD research has broadened the knowledge-base about its mechanisms of action. Four types of KD are in vogue currently with varying nutritional constitution, palatability, administration protocols and comparable efficacy. KD initiation and maintenance are the result of concerted effort of a team of pediatric neurologist/epileptologist, nutritionist and patient's primary care-giver. Consensus is being formulated about various practical aspects of KD such as patient-selection, parental counseling, baseline work-up, dietary prescription, nutritional supplementation, concurrent anti-epileptic drug administration, follow-up and treatment-duration. Novel applications of KD include its use in neonatal epilepsy and super-refractory status epilepticus and tailor-made formulations such as cooking oil-based KD in predominantly rice-fed populations. Increasing body of clinical experience, improved nutritional designs and translational research are promoting KD as a major therapeutic modality. Currently, KD forms a core essence in the armamentarium against refractory epilepsy. In this review, we summarize the recent advances and current perspectives in the use of KD in refractory epilepsy. [ABSTRACT FROM AUTHOR]

Introduction: Vitamin B6 dependent epilepsies are a group of treatable diseases (ALDH7A1 deficiency, PNPO deficiency, PLP binding protein deficiency, hyperprolinaemia type II and hypophosphatasia and glycosylphosphatidylinositol anchor synthesis defects) responding to pyridoxine or pyridoxal-5I-phosphate. Areas covered: A critical review was conducted on the therapeutic management of all the reported patients with genetically confirmed diagnoses of diseases affecting vitamin B6 metabolism and presenting with pyridoxine or pyridoxal-5I-phosphate dependent-seizures. Data about safety and efficacy were analyzed as well as the management of supplementation with pyridoxine or pyridoxal-5I-phosphate both in the acute phases and in the maintenance therapies. The authors also analyzed alternative therapeutic strategies for ALDH7A1 deficiency (lysine-restricted diet, arginine supplementation, oligonucleotide antisense therapy, upstream inhibition of aminoadipic semialdehyde synthase). Expert opinion: The administration of pyridoxine or pyridoxal-5I-phosphate should be considered in all intractable seizures also beyond the first year of life. Lysine restricted diet and arginine supplementation should be introduced in all the confirmed ALDH7A1 deficient patients. Pre or post-natal supplementation with pyridoxine should be given in familial cases until an eventual molecular genetic disconfirmation. Minor data about alternative therapies are available for other disorders of vitamin B6 metabolism. [ABSTRACT FROM AUTHOR]

Objective: Developmental epileptic encephalopathies (DEEs) are genetically heterogeneous severe childhood‐onset epilepsies with developmental delay or cognitive deficits. In this study, we explored the pathogenic mechanisms of DEE‐associated de novo mutations in the CACNA1A gene. Methods: We studied the functional impact of four de novoDEE‐associated CACNA1A mutations, including the previously described p.A713T variant and three novel variants (p.V1396M, p.G230V, and p.I1357S). Mutant cDNAs were expressed in HEK293 cells, and whole‐cell voltage‐clamp recordings were conducted to test the impacts on CaV2.1 channel function. Channel localization and structure were assessed with immunofluorescence microscopy and three‐dimensional (3D) modeling. Results: We find that the G230V and I1357S mutations result in loss‐of‐function effects with reduced whole‐cell current densities and decreased channel expression at the cell membrane. By contrast, the A713T and V1396M variants resulted in gain‐of‐function effects with increased whole‐cell currents and facilitated current activation (hyperpolarized shift). The A713T variant also resulted in slower current decay. 3D modeling predicts conformational changes favoring channel opening for A713T and V1396M. Significance: Our findings suggest that both gain‐of‐function and loss‐of‐function CACNA1A mutations are associated with similarly severe DEEs and that functional validation is required to clarify the underlying molecular mechanisms and to guide therapies. [ABSTRACT FROM AUTHOR]

Highlights • Epilepsy syndromes affect ∼1–3% of the world's population. • Epilepsy-linked mutations are common in α, β, γ and δ GABA A receptor subunits. • GABA A receptors are pentameric Cys-loop ligand-gated ion channels. • Epileptogenic structural cassettes are present within GABA A receptors. • Mutations with deleterious effects are privileged in structural cassettes. Abstract Understanding the genetic variation in GABA A receptor subunit genes (GABRs), GABRA1-6 , GABRB1-3 , GABRG1-3 and GABRD, in individuals affected by epilepsy may improve the diagnosis and treatment of epilepsy syndromes through identification of disease-associated variants. However, the lack of functional analysis and validation of many novel and previously reported familial and de novo mutations have made it challenging to address meaningful gene associations with epilepsy syndromes. GABA A receptors belong to the Cys-loop receptor family. Even though GABA A receptor mutant residues are widespread among different GABR s, their frequent occurrence in important structural domains that share common functional features suggests associations between structure and function. [ABSTRACT FROM AUTHOR]

Summary: Severe early onset epilepsies are often caused by de novo pathogenic variants. Few studies have reported the frequency of somatic mosaicism in parents of children with severe epileptic encephalopathies. Here we aim to investigate the frequency of mosaicism in the parents of children with epilepsy caused by alleged de novo variants. We tested parental genomic DNA derived from different tissues for 75 cases using targeted next‐generation sequencing. Five parents (6.6%) showed mosaicism at minor allele frequencies of 0.8%‐29% for the pathogenic variant detected in their offspring. Parental mosaicism was observed in the following genes: SCN1A, SCN2A, SCN8A, and STXBP1. One of the identified parents had epilepsy himself. Our results show that de novo events can occur already in parental tissue and in some cases can be detected in peripheral blood. Consequently, parents affected by low‐grade mosaicism are faced with an increased recurrence risk for transmitting the pathogenic variant, compared to the overall recurrence risk for a second affected child estimated at approximately 1%. However, testing for parental somatic mosaicism will help identifying those parents who truly are at higher risk and will significantly improve genetic counseling in the respective families. [ABSTRACT FROM AUTHOR]

We report on a peculiar way of chronic cognitive impairment associated with interictal epileptic activity during NREM sleep. We review three major groups of epilepsy: mesiotemporal epilepsy (MTLE) involving the epileptic derailment of the hippocampal declarative memory system; childhood developmental epileptic encephalopathies; and the spectrum disorders of the perisylvian communication network with the centrotemporal spike phenomenon, overarching child- and adulthood epilepsies, totaling up the majority of epilepsies in childhood. We outline high impact research-lines on the cognitive harm of epilepsy; causing specific or global cognitive decline through its interference with sleep plastic functions. We highlight the key role of interictal activity in the development of cognitive impairment and the fact that we are unarmed against this harm, antiepileptic pharmaco-therapy being ineffective against the interictal process marked by spikes and high frequency oscillations. [ABSTRACT FROM AUTHOR]