Genetic pathogenesis of the epileptogenic lesions in Tuberous Sclerosis Complex: Therapeutic targeting of the mTOR pathway.

Tuberous sclerosis complex (TSC) is a genetic multisystem disease due to the mutation in one of the two genes TSC1 and TSC2, affecting several organs and systems and carrying a significant risk of early onset and refractory seizures. The pathogenesis of this complex disorder is now well known, with most of TSC-related manifestations being a consequence of the overactivation of the mammalian Target of Rapamycin (mTOR) complex. The discovery of this underlying mechanism paved the way for the use of a class of drugs called mTOR inhibitors including rapamycin and everolimus and specifically targeting this pathway. Rapamycin has been widely used in different animal models of TSC-related epilepsy and proved to be able not only to suppress seizures but also to prevent the development of epilepsy, thus demonstrating an antiepileptogenic potential. In some models, it also showed some benefit on neuropsychiatric manifestations associated with TSC. Everolimus has recently been approved by the US Food and Drug Administration and the European Medical Agency for the treatment of refractory seizures associated with TSC starting from the age of 2 years. It demonstrated a clear benefit when compared to placebo on reducing the frequency of different seizure types and exerting a higher effect in younger children. In conclusion, mTOR cascade can be a potentially major cause of TSC-associated epilepsy and neurodevelopmental disability, and additional research should investigate if early suppression of abnormal mTOR signal with mTOR inhibitors before seizure onset can be a more efficient approach and an effective antiepileptogenic and disease-modifying strategy in infants with TSC.

Neonatal developmental and epileptic encephalopathy due to autosomal recessive variants in SLC13A5 gene.

OBJECTIVE: Autosomal recessive pathogenic variants of the SLC13A5 gene are associated with severe neonatal epilepsy, developmental delay, and tooth hypoplasia/hypodontia. We report on 14 additional patients and compare their phenotypic features to previously published patients to identify the clinical hallmarks of this disorder. METHODS: We collected clinical features of 14 patients carrying biallelic variants in SLC13A5 and performed a PubMed search to identify previously published patients. RESULTS: All patients presented clonic or tonic seizures in the first days of life, evolving into status epilepticus in 57%. Analysis of seizure frequency and developmental milestones divided into five epochs showed an evolutionary trajectory of both items. In the first 3 years of life, 72% of patients had weekly/monthly seizures, often triggered by fever; 14% were seizure-free. Between the ages of 3 and 12 years, 60% become seizure-free; in the following years, up to age 18 years, 57% were seizure-free. After the age of 18 years, all three patients reaching this age were seizure-free. Similarly, 86% of patients at onset presented mild to moderate developmental impairment and diffuse hypotonia. In late childhood, all had developmental delay that was severe in most. Benzodiazepines, phenobarbital, phenytoin, and carbamazepine were the most effective drugs. Eight probands carried heterozygous compound variants, and homozygous pathogenic variants occurred in six. Literature review identified 45 patients carrying SLC13A5 gene pathogenic variants whose clinical features overlapped with our cohort. A peculiar and distinguishing sign is the presence of tooth hypoplasia and/or hypodontia in most patients. SIGNIFICANCE: Autosomal recessive pathogenic variants in SLC13A5 are associated with a distinct neonatal epileptic encephalopathy evolving into severe cognitive and motor impairment, yet with seizures that settle down in late childhood. Tooth hypoplasia or hypodontia remains the peculiar feature. The SLC13A5 gene should be screened in neonatal epileptic encephalopathies; its recessive inheritance has relevance for genetic counseling.

Biological concepts in human sodium channel epilepsies and their relevance in clinical practice.

OBJECTIVE: Voltage-gated sodium channels (SCNs) share similar amino acid sequence, structure, and function. Genetic variants in the four human brain-expressed SCN genes SCN1A/2A/3A/8A have been associated with heterogeneous epilepsy phenotypes and neurodevelopmental disorders. To better understand the biology of seizure susceptibility in SCN-related epilepsies, our aim was to determine similarities and differences between sodium channel disorders, allowing us to develop a broader perspective on precision treatment than on an individual gene level alone. METHODS: We analyzed genotype-phenotype correlations in large SCN-patient cohorts and applied variant constraint analysis to identify severe sodium channel disease. We examined temporal patterns of human SCN expression and correlated functional data from in vitro studies with clinical phenotypes across different sodium channel disorders. RESULTS: Comparing 865 epilepsy patients (504 SCN1A, 140 SCN2A, 171 SCN8A, four SCN3A, 46 copy number variation [CNV] cases) and analysis of 114 functional studies allowed us to identify common patterns of presentation. All four epilepsy-associated SCN genes demonstrated significant constraint in both protein truncating and missense variation when compared to other SCN genes. We observed that age at seizure onset is related to SCN gene expression over time. Individuals with gain-of-function SCN2A/3A/8A missense variants or CNV duplications share similar characteristics, most frequently present with early onset epilepsy (<3 months), and demonstrate good response to sodium channel blockers (SCBs). Direct comparison of corresponding SCN variants across different SCN subtypes illustrates that the functional effects of variants in corresponding channel locations are similar; however, their clinical manifestation differs, depending on their role in different types of neurons in which they are expressed. SIGNIFICANCE: Variant function and location within one channel can serve as a surrogate for variant effects across related sodium channels. Taking a broader view on precision treatment suggests that in those patients with a suspected underlying genetic epilepsy presenting with neonatal or early onset seizures (<3 months), SCBs should be considered.

NBEA: Developmental disease gene with early generalized epilepsy phenotypes.

NBEA is a candidate gene for autism, and de novo variants have been reported in neurodevelopmental disease (NDD) cohorts. However, NBEA has not been rigorously evaluated as a disease gene, and associated phenotypes have not been delineated. We identified 24 de novo NBEA variants in patients with NDD, establishing NBEA as an NDD gene. Most patients had epilepsy with onset in the first few years of life, often characterized by generalized seizure types, including myoclonic and atonic seizures. Our data show a broader phenotypic spectrum than previously described, including a myoclonic-astatic epilepsy-like phenotype in a subset of patients. Ann Neurol 2018;84:796-803.

Recessive loss-of-function mutations in AP4S1 cause mild fever-sensitive seizures, developmental delay and spastic paraplegia through loss of AP-4 complex assembly.

We report two siblings with infantile onset seizures, severe developmental delay and spastic paraplegia, in whom whole-genome sequencing revealed compound heterozygous mutations in the AP4S1 gene, encoding the σ subunit of the adaptor protein complex 4 (AP-4). The effect of the predicted loss-of-function variants (p.Gln46Profs*9 and p.Arg97*) was further investigated in a patient's fibroblast cell line. We show that the premature stop mutations in AP4S1 result in a reduction of all AP-4 subunits and loss of AP-4 complex assembly. Recruitment of the AP-4 accessory protein tepsin, to the membrane was also abolished. In retrospect, the clinical phenotype in the family is consistent with previous reports of the AP-4 deficiency syndrome. Our study reports the second family with mutations in AP4S1 and describes the first two patients with loss of AP4S1 and seizures. We further discuss seizure phenotypes in reported patients, highlighting that seizures are part of the clinical manifestation of the AP-4 deficiency syndrome. We also hypothesize that endosomal trafficking is a common theme between heritable spastic paraplegia and some inherited epilepsies.

De novo loss-of-function mutations in CHD2 cause a fever-sensitive myoclonic epileptic encephalopathy sharing features with Dravet syndrome.

Dravet syndrome is a severe epilepsy syndrome characterized by infantile onset of therapy-resistant, fever-sensitive seizures followed by cognitive decline. Mutations in SCN1A explain about 75% of cases with Dravet syndrome; 90% of these mutations arise de novo. We studied a cohort of nine Dravet-syndrome-affected individuals without an SCN1A mutation (these included some atypical cases with onset at up to 2 years of age) by using whole-exome sequencing in proband-parent trios. In two individuals, we identified a de novo loss-of-function mutation in CHD2 (encoding chromodomain helicase DNA binding protein 2). A third CHD2 mutation was identified in an epileptic proband of a second (stage 2) cohort. All three individuals with a CHD2 mutation had intellectual disability and fever-sensitive generalized seizures, as well as prominent myoclonic seizures starting in the second year of life or later. To explore the functional relevance of CHD2 haploinsufficiency in an in vivo model system, we knocked down chd2 in zebrafish by using targeted morpholino antisense oligomers. chd2-knockdown larvae exhibited altered locomotor activity, and the epileptic nature of this seizure-like behavior was confirmed by field-potential recordings that revealed epileptiform discharges similar to seizures in affected persons. Both altered locomotor activity and epileptiform discharges were absent in appropriate control larvae. Our study provides evidence that de novo loss-of-function mutations in CHD2 are a cause of epileptic encephalopathy with generalized seizures.

Testing patients during seizures: A European consensus procedure developed by a joint taskforce of the ILAE - Commission on European Affairs and the European Epilepsy Monitoring Unit Association.

There is currently no international consensus procedure for performing comprehensive periictal testing of patients in the epilepsy monitoring units (EMUs). Our primary goal was to develop a standardized procedure for managing and testing patients during and after seizures in EMUs. The secondary goal was to assess whether it could be implemented in clinical practice (feasibility). A taskforce was appointed by the International League Against Epilepsy (ILAE)-Commission on European Affairs and the European Epilepsy Monitoring Unit Association, to develop a standardized ictal testing battery (ITB) based on expert opinion and experience with various local testing protocols. ITB contains a comprehensive set of 10 items that evidence the clinically relevant semiologic features, and it is adaptive to the dynamics of the individual seizures. The feasibility of the ITB was prospectively evaluated on 250 seizures from 152 consecutive patients in 10 centers. ITB was successfully implemented in clinical practice in all 10 participating centers and was considered feasible in 93% of the tested seizures. ITB was not feasible for testing seizures of very short duration.

Current use of imaging and electromagnetic source localization procedures in epilepsy surgery centers across Europe.

OBJECTIVE: In 2014 the European Union-funded E-PILEPSY project was launched to improve awareness of, and accessibility to, epilepsy surgery across Europe. We aimed to investigate the current use of neuroimaging, electromagnetic source localization, and imaging postprocessing procedures in participating centers. METHODS: A survey on the clinical use of imaging, electromagnetic source localization, and postprocessing methods in epilepsy surgery candidates was distributed among the 25 centers of the consortium. A descriptive analysis was performed, and results were compared to existing guidelines and recommendations. RESULTS: Response rate was 96%. Standard epilepsy magnetic resonance imaging (MRI) protocols are acquired at 3 Tesla by 15 centers and at 1.5 Tesla by 9 centers. Three centers perform 3T MRI only if indicated. Twenty-six different MRI sequences were reported. Six centers follow all guideline-recommended MRI sequences with the proposed slice orientation and slice thickness or voxel size. Additional sequences are used by 22 centers. MRI postprocessing methods are used in 16 centers. Interictal positron emission tomography (PET) is available in 22 centers; all using 18F-fluorodeoxyglucose (FDG). Seventeen centers perform PET postprocessing. Single-photon emission computed tomography (SPECT) is used by 19 centers, of which 15 perform postprocessing. Four centers perform neither PET nor SPECT in children. Seven centers apply magnetoencephalography (MEG) source localization, and nine apply electroencephalography (EEG) source localization. Fourteen combinations of inverse methods and volume conduction models are used. SIGNIFICANCE: We report a large variation in the presurgical diagnostic workup among epilepsy surgery centers across Europe. This diversity underscores the need for high-quality systematic reviews, evidence-based recommendations, and harmonization of available diagnostic presurgical methods.

Recessive mutations in SLC13A5 result in a loss of citrate transport and cause neonatal epilepsy, developmental delay and teeth hypoplasia.

The epileptic encephalopathies are a clinically and aetiologically heterogeneous subgroup of epilepsy syndromes. Most epileptic encephalopathies have a genetic cause and patients are often found to carry a heterozygous de novo mutation in one of the genes associated with the disease entity. Occasionally recessive mutations are identified: a recent publication described a distinct neonatal epileptic encephalopathy (MIM 615905) caused by autosomal recessive mutations in the SLC13A5 gene. Here, we report eight additional patients belonging to four different families with autosomal recessive mutations in SLC13A5. SLC13A5 encodes a high affinity sodium-dependent citrate transporter, which is expressed in the brain. Neurons are considered incapable of de novo synthesis of tricarboxylic acid cycle intermediates; therefore they rely on the uptake of intermediates, such as citrate, to maintain their energy status and neurotransmitter production. The effect of all seven identified mutations (two premature stops and five amino acid substitutions) was studied in vitro, using immunocytochemistry, selective western blot and mass spectrometry. We hereby demonstrate that cells expressing mutant sodium-dependent citrate transporter have a complete loss of citrate uptake due to various cellular loss-of-function mechanisms. In addition, we provide independent proof of the involvement of autosomal recessive SLC13A5 mutations in the development of neonatal epileptic encephalopathies, and highlight teeth hypoplasia as a possible indicator for SLC13A5 screening. All three patients who tried the ketogenic diet responded well to this treatment, and future studies will allow us to ascertain whether this is a recurrent feature in this severe disorder.

Summary of recommendations for the management of infantile seizures: Task Force Report for the ILAE Commission of Pediatrics.

Evidence-based guidelines, or recommendations, for the management of infants with seizures are lacking. A Task Force of the Commission of Pediatrics developed a consensus document addressing diagnostic markers, management interventions, and outcome measures for infants with seizures. Levels of evidence to support recommendations and statements were assessed using the American Academy of Neurology Guidelines and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. The report contains recommendations for different levels of care, noting which would be regarded as standard care, compared to optimal care, or "state of the art" interventions. The incidence of epilepsy in the infantile period is the highest of all age groups (strong evidence), with epileptic spasms the largest single subgroup and, in the first 2 years of life, febrile seizures are the most commonly occurring seizures. Acute intervention at the time of a febrile seizure does not alter the risk for subsequent epilepsy (class 1 evidence). The use of antipyretic agents does not alter the recurrence rate (class 1 evidence), and there is no evidence to support initiation of regular antiepileptic drugs for simple febrile seizures (class 1 evidence). Infants with abnormal movements whose routine electroencephalography (EEG) study is not diagnostic, would benefit from video-EEG analysis, or home video to capture events (expert opinion, level U recommendation). Neuroimaging is recommended at all levels of care for infants presenting with epilepsy, with magnetic resonance imaging (MRI) recommended as the standard investigation at tertiary level (level A recommendation). Genetic screening should not be undertaken at primary or secondary level care (expert opinion). Standard care should permit genetic counseling by trained personal at all levels of care (expert opinion). Genetic evaluation for Dravet syndrome, and other infantile-onset epileptic encephalopathies, should be available in tertiary care (weak evidence, level C recommendation). Patients should be referred from primary or secondary to tertiary level care after failure of one antiepileptic drug (standard care) and optimal care equates to referral of all infants after presentation with a seizure (expert opinion, level U evidence). Infants with recurrent seizures warrant urgent assessment for initiation of antiepileptic drugs (expert opinion, level U recommendation). Infantile encephalopathies should have rapid introduction and increment of antiepileptic drug dosage (expert opinion, level U recommendation). There is no high level evidence to support any particular current agents for use in infants with seizures. For focal seizures, levetiracetam is effective (strong evidence); for generalized seizures, weak evidence supports levetiracetam, valproate, lamotrigine, topiramate, and clobazam; for Dravet syndrome, strong evidence supports that stiripentol is effective (in combination with valproate and clobazam), whereas weak evidence supports that topiramate, zonisamide, valproate, bromide, and the ketogenic diet are possibly effective; and for Ohtahara syndrome, there is weak evidence that most antiepileptic drugs are poorly effective. For epileptic spasms, clinical suspicion remains central to the diagnosis and is supported by EEG, which ideally is prolonged (level C recommendation). Adrenocorticotropic hormone (ACTH) is preferred for short-term control of epileptic spasms (level B recommendation), oral steroids are probably effective in short-term control of spasms (level C recommendation), and a shorter interval from the onset of spasms to treatment initiation may improve long-term neurodevelopmental outcome (level C recommendation). The ketogenic diet is the treatment of choice for epilepsy related to glucose transporter 1 deficiency syndrome and pyruvate dehydrogenase deficiency (expert opinion, level U recommendation). The identification of patients as potential candidates for epilepsy surgery should be part of standard practice at primary and secondary level care. Tertiary care facilities with experience in epilepsy surgery should undertake the screening for epilepsy surgical candidates (level U recommendation). There is insufficient evidence to conclude if there is benefit from vagus nerve stimulation (level U recommendation). The key recommendations are summarized into an executive summary. The full report is available as Supporting Information. This report provides a comprehensive foundation of an approach to infants with seizures, while identifying where there are inadequate data to support recommended practice, and where further data collection is needed to address these deficits.

Epilepsy in Rett syndrome--lessons from the Rett networked database.

OBJECTIVE: Rett syndrome is an X-linked dominant neurodevelopmental disorder caused by mutations in the MECP2 gene, and characterized by cognitive and communicative regression, loss of hand use, and midline hand stereotypies. Epilepsy is a core symptom, but literature is controversial regarding genotype-phenotype correlation. Analysis of data from a large cohort should overcome this shortcoming. METHODS: Data from the Rett Syndrome Networked Database on 1,248 female patients were included. Data on phenotypic and genotypic parameters, age of onset, severity of epilepsy, and type of seizures were collected. Statistical analysis was done using the IBM SPSS Version 21 software, logistic regression, and Kaplan-Meier survival curves. RESULTS: Epilepsy was present in 68.1% of the patients, with uncontrolled seizures in 32.6% of the patients with epilepsy. Mean age of onset of epilepsy was 4.68 ± (standard deviation) 3.5 years. Younger age of onset was correlated to severity of epilepsy (Spearman correlation r = 0.668, p < 0.01). Patients with late truncating deletions had lower prevalence of epilepsy. Compared to them, the p.R133C mutation, associated with a milder Rett phenotype, increased the risk for epilepsy (odds ratio [OR] 2.46, confidence interval [CI] 95% 1.3-4.66), but not for severe epilepsy. The p.R255X mutation conferred an increased risk for epilepsy (OR 2.07, CI 95% 1.2-3.59) as well as for severe epilepsy (OR 3.4, CI 95% 1.6-7.3). The p.T158M and p.C306C mutations relatively increased the risk for severe epilepsy (OR 3.09 and 2.69, CI 95% 1.48-6.4 and 1.19-6.05, respectively), but not for epilepsy occurrence. SIGNIFICANCE: Various mutations in the MECP2 gene have a different influence on epilepsy, unrelated to the severity of the general Rett phenotype. This might suggest a site-specific effect of MeCp2 on epileptic pathways. Further investigation of these mechanisms should promote better understanding of epileptogenesis in Rett syndrome.

A Multinational Survey on Actual Diagnostics and Treatment of Subacute Sclerosing Panencephalitis.

Subacute sclerosing panencephalitis (SSPE) is a chronic infection of the central nervous system caused by the measles virus (MV). Its prevalence remains high in resource poor countries and is likely to increase in the Northern Europe as vaccination rates decrease. Clinical knowledge of this devastating condition, however, is limited. We therefore conducted this multinational survey summarizing experience obtained from more than 500 patients treated by 24 physicians in seven countries. SSPE should be considered in all patients presenting with otherwise unexplained acquired neurological symptoms. In most patients, the diagnosis will be established by the combination of typical clinical symptoms (characteristic repetitive myoclonic jerks), a strong intrathecal synthesis of antibodies to MV and typical electroencephalogram findings (Radermecker complexes). Whereas the therapeutic use of different antiviral (amantadine, ribavirin) and immunomodulatory drugs (isoprinosine, interferons) and of immunoglobulins has been reported repeatedly, optimum application regimen of these drugs has not been established. This is partly due to the absence of common diagnostic and clinical standards focusing on neurological and psychosocial aspects. Carbamazepine, levetiracetam, and clobazam are the drugs most frequently used to control myoclonic jerks. We have established a consensus on essential laboratory and clinical parameters that should facilitate collaborative studies. Those are urgently needed to improve outcome.

Co-occurring malformations of cortical development and SCN1A gene mutations.

OBJECTIVE: To report on six patients with SCN1A mutations and malformations of cortical development (MCDs) and describe their clinical course, genetic findings, and electrographic, imaging, and neuropathologic features. METHODS: Through our database of epileptic encephalopathies, we identified 120 patients with SCN1A mutations, of which 4 had magnetic resonance imaging (MRI) evidence of MCDs. We collected two further similar observations through the European Task-force for Epilepsy Surgery in Children. RESULTS: The study group consisted of five males and one female (mean age 7.4 ± 5.3 years). All patients exhibited electroclinical features consistent with the Dravet syndrome spectrum, cognitive impairment, and autistic features. Sequencing analysis of the SCN1A gene detected two missense, two truncating, and two splice-site mutations. Brain MRI revealed bilateral periventricular nodular heterotopia (PNH) in two patients and focal cortical dysplasia (FCD) in three, and disclosed no macroscopic abnormality in one. In the MRI-negative patient, neuropathologic study of the whole brain performed after sudden unexpected death in epilepsy (SUDEP), revealed multifocal micronodular dysplasia in the left temporal lobe. Two patients with FCD underwent epilepsy surgery. Neuropathology revealed FCD type IA and type IIA. Their seizure outcome was unfavorable. All four patients with FCD exhibited multiple seizure types, which always included complex partial seizures, the area of onset of which co-localized with the region of structural abnormality. SIGNIFICANCE: MCDs and SCN1A gene mutations can co-occur. Although epidemiology does not support a causative role for SCN1A mutations, loss or impaired protein function combined with the effect of susceptibility factors and genetic modifiers of the phenotypic expression of SCN1A mutations might play a role. MCDs, particularly FCD, can influence the electroclinical phenotype in patients with SCN1A-related epilepsy. In patients with MCDs and a history of polymorphic seizures precipitated by fever, SCN1A gene testing should be performed before discussing any epilepsy surgery option, due to the possible implications for outcome.

Molecular and Phenotypic Characterization of the RORB-Related Disorder.

BACKGROUND AND OBJECTIVES: Heterozygous variants in RAR-related orphan receptor B (RORB) have recently been associated with susceptibility to idiopathic generalized epilepsy. However, few reports have been published so far describing pathogenic variants of this gene in patients with epilepsy and intellectual disability (ID). In this study, we aimed to delineate the epilepsy phenotype associated with RORB pathogenic variants and to provide arguments in favor of the pathogenicity of variants. METHODS: Through an international collaboration, we analyzed seizure characteristics, EEG data, and genotypes of a cohort of patients with heterozygous variants in RORB. To gain insight into disease mechanisms, we performed ex vivo cortical electroporation in mouse embryos of 5 selected variants, 2 truncating and 3 missense, and evaluated on expression and quantified changes in axonal morphology. RESULTS: We identified 35 patients (17 male, median age 10 years, range 2.5-23 years) carrying 32 different heterozygous variants in RORB, including 28 single-nucleotide variants or small insertions/deletions (12 missense, 12 frameshift or nonsense, 2 splice-site variants, and 2 in-frame deletions), and 4 microdeletions; de novo in 18 patients and inherited in 10. Seizures were reported in 31/35 (89%) patients, with a median age at onset of 3 years (range 4 months-12 years). Absence seizures occurred in 25 patients with epilepsy (81%). Nineteen patients experienced a single seizure type: absences, myoclonic absences, or absences with eyelid myoclonia and focal seizures. Nine patients had absence seizures combined with other generalized seizure types. One patient had presented with absences associated with photosensitive occipital seizures. Three other patients had generalized tonic-clonic seizures without absences. ID of variable degree was observed in 85% of the patients. Expression studies in cultured neurons showed shorter axons for the 5 tested variants, both truncating and missense variants, supporting an impaired protein function. DISCUSSION: In most patients, the phenotype of the RORB-related disorder associates absence seizures with mild-to-moderate ID. In silico and in vitro evaluation of the variants in our cohort, including axonal morphogenetic experiments in cultured neurons, supports their pathogenicity, showing a hypomorphic effect.

What is special about the adolescent (JME) brain?

Juvenile myoclonic epilepsy (JME) involves cortico-thalamo-cortical networks. Thalamic, frontal gray matter, connectivity, and neurotransmitter disturbances have been demonstrated by structural/functional imaging studies. Few patients with JME show mutations in genes coding ion channels or GABAA (gamma-aminobutyric acid) receptor subunits. Recent research points to EFHC1 gene mutations leading to microdysgenesis and possible aberrant circuitry. Imaging studies have shown massive structural/functional changes of normally developing adolescent brain structures maturing at strikingly different rates and times. Gray matter (GM) volume diminishes in cortical areas (frontal and parietal) and deep structures (anterior thalamus, putamen, and caudate). Diffusion tensor imaging (DTI) findings support continued microstructural change in WM (white matter) during late adolescence with robust developmental changes in thalamocortical connectivity. The GABAA receptor distribution and specific receptor subunits' expression patterns change with age from neonate to adolescent/adult, contributing to age-related changes in brain excitability. Hormonal influence on brain structure development during adolescence is presented. Possible implications of brain changes during adolescence on the course of JME are discussed.

Rett networked database: an integrated clinical and genetic network of Rett syndrome databases.

Rett syndrome (RTT) is a neurodevelopmental disorder with one principal phenotype and several distinct, atypical variants (Zappella, early seizure onset and congenital variants). Mutations in MECP2 are found in most cases of classic RTT but at least two additional genes, CDKL5 and FOXG1, can underlie some (usually variant) cases. There is only limited correlation between genotype and phenotype. The Rett Networked Database (http://www.rettdatabasenetwork.org/) has been established to share clinical and genetic information. Through an "adaptor" process of data harmonization, a set of 293 clinical items and 16 genetic items was generated; 62 clinical and 7 genetic items constitute the core dataset; 23 clinical items contain longitudinal information. The database contains information on 1838 patients from 11 countries (December 2011), with or without mutations in known genes. These numbers can expand indefinitely. Data are entered by a clinician in each center who supervises accuracy. This network was constructed to make available pooled international data for the study of RTT natural history and genotype-phenotype correlation and to indicate the proportion of patients with specific clinical features and mutations. We expect that the network will serve for the recruitment of patients into clinical trials and for developing quality measures to drive up standards of medical management.

Spontaneous recurrent mutations and a complex rearrangement in the MECP2 gene in the light of current models of mutagenesis.

Mutations in the methyl-CpG-binding protein 2 (MECP2) gene are associated with Rett syndrome (RTT). The MECP2 gene has some unique characteristics: (1) it is mainly affected by de novo mutations, due to recurrent independent mutational events in a defined "hot spot" regions or positions; (2) complex mutational events along a single allele are frequently found in this gene; (3) most mutations arise on paternal X chromosome. The recurrent point mutations involve mainly CpG dinucleotides, where C>T transitions are explained by methylation-mediated deamination. The complex mutational events might be explained by the genomic architecture of the region involving the MECP2 gene. The finding that most spontaneous mutations arise on paternal X-chromosome supports the higher contribution of replication-mediated mechanism of mutagenesis. We present 9 types of mutations in the MECP2 gene, detected in a group of 22 Bulgarian and 6 Romanian classical RTT patients. Thirteen patients were clarified on molecular level (46.4%). The point mutations in our sample account for 61.5%. One intraexonic deletion was detected in the present study (7.7%). One novel insertion c.321_322insGAAG, p.(Lys107_Leu108insGluAlafs2*) was found (7.7%). Large deletions and complex mutations account for 23%. A novel complex mutational event c.[584_624del41insTT; 638delTinsCA] was detected in a Romanian patient. We discuss different types of the MECP2 mutations detected in our sample in the light of the possible mechanisms of mutagenesis. Complex gene rearrangements involving a combination of deletions and insertions have always been most difficult to detect, to specify precisely and hence to explain in terms of their underlying mutational mechanisms.

Crisis of confidence in vaccination and the role of social media.

INTRODUCTION: The aim of this paper is to review the current situation of vaccine hesitancy, with emphasis on children with neurological disorders, and to present the role social media plays in this situation. METHODS: A literature review using the following search words was performed: vaccine∗ OR immune∗ AND hesitancy OR confidence AND social media. RESULTS: The search retrieved 277 results; 17 duplicates and 234 irrelevant articles were excluded. 43 articles were fully analyzed. CONCLUSIONS: An increasing number of parents are becoming vaccine hesitant. Their motives are complex and nuanced and involve factors related to vaccine safety and efficiency, perceived personal risks and benefits, socio-demographic and psychological characteristics. Attitudes toward vaccination differ in adolescents from their parents. In children with neurological disorders, factors involved in vaccination decision included physicians' knowledge of neurological diseases and parents' concerns that vaccination would exacerbate the chronic disorder. Unfortunately, the current pandemic is associated with an increase in vaccine hesitancy and brought forward unique determinants. The social media platforms can be a tool for the anti-vaccine movement to spread misinformation, but it can also be valued as a way for promoting health and pro-vaccine information.

Vaccination and childhood epilepsies.

INTRODUCTION: The evidence relating vaccination to febrile seizures and epilepsy is evaluated with an emphasis on febrile seizures (FS), Dravet syndrome (DS), West syndrome, and other developmental and epileptic encephalopathies. METHODS: A systematic literature review using search words vaccination/immunization AND febrile seizures/epilepsy/Dravet/epileptic encephalopathy/developmental encephalopathy was performed. The role of vaccination as the cause/trigger/aggravation factor for FS or epilepsies and preventive measures were analyzed. RESULTS: From 1428 results, 846 duplicates and 447 irrelevant articles were eliminated; 120 were analyzed. CONCLUSIONS: There is no evidence that vaccinations cause epilepsy in healthy populations. Vaccinations do not cause epileptic encephalopathies but may be non-specific triggers to seizures in underlying structural or genetic etiologies. The first seizure in DS may be earlier in vaccinated versus non-vaccinated patients, but developmental outcome is similar in both groups. Children with a personal or family history of FS or epilepsy should receive all routine vaccinations. This recommendation includes DS. The known risks of the infectious diseases prevented by immunization are well established. Vaccination should be deferred in case of acute illness. Acellular pertussis DTaP (diphtheria-tetanus-pertussis) is recommended. The combination of certain vaccine types may increase the risk of febrile seizures however the public health benefit of separating immunizations has not been proven. Measles-containing vaccine should be administered at age 12-15 months. Routine prophylactic antipyretics are not indicated, as there is no evidence of decreased FS risk and they can attenuate the antibody response following vaccination. Prophylactic measures (preventive antipyretic medication) are recommended in DS due to the increased risk of prolonged seizures with fever.

Clinical and genomic findings in brain heterotopia: Report of a pediatric patient cohort from Romania.

Brain heterotopia is a group of rare malformations with a heterogeneous phenotype, ranging from asymptomatic to a severe clinical picture (drug-resistant epilepsy, severe developmental delay). The etiology is multifactorial, including both genetic and environmental factors. In the present study, a cohort of 15 pediatric patients with brain heterotopia were investigated by clinical examination, electroencephalographic studies, brain imaging, and genomic tests. Most of the patients had epileptic seizures, often difficult to control with one antiepileptic drug; another frequent characteristic in the cohort was developmental delay or intellectual disability, in some cases associated with behavioral problems. The genomic studies revealed an interstitial 22q11.2 microduplication, an anomaly not reported previously in heterotopia patients. Comparing the cohort of the present study with that of a previous series of heterotopia patients, both adult and pediatric, similar aspects, such as the high frequency of drug-resistant epilepsy were observed as well as some differences, such as no systemic malformations and no cases with fatal evolution. The current findings add new data to existing knowledge on a rare heterogeneous disorder. The detailed clinical description, including the epilepsy phenotypes, and genomic profiles bring new insights into a group of disorders, yet to be fully understood.