Cerebrospinal Fluid Homovanillic and 5-Hydroxyindoleacetic Acids in a Large Pediatric Population; Establishment of Reference Intervals and Impact of Disease and Medication.

BACKGROUND: Cerebrospinal fluid (CSF) homovanillic (HVA), and 5-hydroxyindoleacetic acids (5-HIAA) are biomarkers of neurological diseases affecting the dopaminergic and serotoninergic pathways. Establishing reference intervals for these metabolites faces the challenges of a lack of healthy controls and a negative correlation with age, making stratified intervals unrealistic. We propose a pipeline to determine continuous reference intervals for HVA and 5-HIAA using an indirect method. We also studied the confounding effects of different variables and explored the impact of antiepileptic and neuroleptic treatments on HVA and 5-HIAA values. METHODS: The study used least squares regression to fit age-concentration curves from a cohort of pediatric patients (n = 1533), where the residuals represent metabolite values excluding age effect. Presuming that HVA and 5-HIAA primary deficiencies characterize a distinct subpopulation, we fitted a two-component finite mixture model in age-normalized data and set reference intervals at the central 95% of the nondeficient population. RESULTS: Patients with primary genetic deficiencies of HVA and/or 5-HIAA consistently fall outside the proposed continuous reference intervals. Using the new continuous reference intervals reduces the number of secondary deficiencies detected compared with using stratified values. No correlations were observed between CSF HVA and 5-HIAA values across the studied drug categories (antiseizure and neuroleptic medications). In addition, biopterin values positively influenced both metabolite concentrations. CONCLUSION: The proposed continuous reference intervals caused a substantial reduction in the number of secondary deficiencies detected, most of which demonstrated no conclusive correlations between the diseases and altered HVA and 5-HIAA values.

Management of seizures in patients with primary mitochondrial diseases: consensus statement from the InterERNs Mitochondrial Working Group.

BACKGROUND AND PURPOSE: Primary mitochondrial diseases (PMDs) are common inborn errors of energy metabolism, with an estimated prevalence of one in 4300. These disorders typically affect tissues with high energy requirements, including heart, muscle and brain. Epilepsy may be the presenting feature of PMD, can be difficult to treat and often represents a poor prognostic feature. The aim of this study was to develop guidelines and consensus recommendations on safe medication use and seizure management in mitochondrial epilepsy. METHODS: A panel of 24 experts in mitochondrial medicine, pharmacology and epilepsy management of adults and/or children and two patient representatives from seven countries was established. Experts were members of five different European Reference Networks, known as the Mito InterERN Working Group. A Delphi technique was used to allow the panellists to consider draft recommendations on safe medication use and seizure management in mitochondrial epilepsy, using two rounds with predetermined levels of agreement. RESULTS: A high level of consensus was reached regarding the safety of 14 out of all 25 drugs reviewed, resulting in endorsement of National Institute for Health and Care Excellence guidelines for seizure management, with some modifications. Exceptions including valproic acid in POLG disease, vigabatrin in patients with γ-aminobutyric acid transaminase deficiency and topiramate in patients at risk for renal tubular acidosis were highlighted. CONCLUSIONS: These consensus recommendations describe our intent to improve seizure control and reduce the risk of drug-related adverse events in individuals living with PMD-related epilepsy.

MLe-KCNQ2: An Artificial Intelligence Model for the Prognosis of Missense KCNQ2 Gene Variants.

Despite the increasing availability of genomic data and enhanced data analysis procedures, predicting the severity of associated diseases remains elusive in the absence of clinical descriptors. To address this challenge, we have focused on the KV7.2 voltage-gated potassium channel gene (KCNQ2), known for its link to developmental delays and various epilepsies, including self-limited benign familial neonatal epilepsy and epileptic encephalopathy. Genome-wide tools often exhibit a tendency to overestimate deleterious mutations, frequently overlooking tolerated variants, and lack the capacity to discriminate variant severity. This study introduces a novel approach by evaluating multiple machine learning (ML) protocols and descriptors. The combination of genomic information with a novel Variant Frequency Index (VFI) builds a robust foundation for constructing reliable gene-specific ML models. The ensemble model, MLe-KCNQ2, formed through logistic regression, support vector machine, random forest and gradient boosting algorithms, achieves specificity and sensitivity values surpassing 0.95 (AUC-ROC > 0.98). The ensemble MLe-KCNQ2 model also categorizes pathogenic mutations as benign or severe, with an area under the receiver operating characteristic curve (AUC-ROC) above 0.67. This study not only presents a transferable methodology for accurately classifying KCNQ2 missense variants, but also provides valuable insights for clinical counseling and aids in the determination of variant severity. The research context emphasizes the necessity of precise variant classification, especially for genes like KCNQ2, contributing to the broader understanding of gene-specific challenges in the field of genomic research. The MLe-KCNQ2 model stands as a promising tool for enhancing clinical decision making and prognosis in the realm of KCNQ2-related pathologies.

De Novo Variants in LMNB1 Cause Pronounced Syndromic Microcephaly and Disruption of Nuclear Envelope Integrity.

Lamin B1 plays an important role in the nuclear envelope stability, the regulation of gene expression, and neural development. Duplication of LMNB1, or missense mutations increasing LMNB1 expression, are associated with autosomal-dominant leukodystrophy. On the basis of its role in neurogenesis, it has been postulated that LMNB1 variants could cause microcephaly. Here, we confirm this hypothesis with the identification of de novo mutations in LMNB1 in seven individuals with pronounced primary microcephaly (ranging from -3.6 to -12 SD) associated with relative short stature and variable degree of intellectual disability and neurological features as the core symptoms. Simplified gyral pattern of the cortex and abnormal corpus callosum were noted on MRI of three individuals, and these individuals also presented with a more severe phenotype. Functional analysis of the three missense mutations showed impaired formation of the LMNB1 nuclear lamina. The two variants located within the head group of LMNB1 result in a decrease in the nuclear localization of the protein and an increase in misshapen nuclei. We further demonstrate that another mutation, located in the coil region, leads to increased frequency of condensed nuclei and lower steady-state levels of lamin B1 in proband lymphoblasts. Our findings collectively indicate that de novo mutations in LMNB1 result in a dominant and damaging effect on nuclear envelope formation that correlates with microcephaly in humans. This adds LMNB1 to the growing list of genes implicated in severe autosomal-dominant microcephaly and broadens the phenotypic spectrum of the laminopathies.

The gain of function SCN1A disorder spectrum: novel epilepsy phenotypes and therapeutic implications.

Brain voltage-gated sodium channel NaV1.1 (SCN1A) loss-of-function variants cause the severe epilepsy Dravet syndrome, as well as milder phenotypes associated with genetic epilepsy with febrile seizures plus. Gain of function SCN1A variants are associated with familial hemiplegic migraine type 3. Novel SCN1A-related phenotypes have been described including early infantile developmental and epileptic encephalopathy with movement disorder, and more recently neonatal presentations with arthrogryposis. Here we describe the clinical, genetic and functional evaluation of affected individuals. Thirty-five patients were ascertained via an international collaborative network using a structured clinical questionnaire and from the literature. We performed whole-cell voltage-clamp electrophysiological recordings comparing sodium channels containing wild-type versus variant NaV1.1 subunits. Findings were related to Dravet syndrome and familial hemiplegic migraine type 3 variants. We identified three distinct clinical presentations differing by age at onset and presence of arthrogryposis and/or movement disorder. The most severely affected infants (n = 13) presented with congenital arthrogryposis, neonatal onset epilepsy in the first 3 days of life, tonic seizures and apnoeas, accompanied by a significant movement disorder and profound intellectual disability. Twenty-one patients presented later, between 2 weeks and 3 months of age, with a severe early infantile developmental and epileptic encephalopathy and a movement disorder. One patient presented after 3 months with developmental and epileptic encephalopathy only. Associated SCN1A variants cluster in regions of channel inactivation associated with gain of function, different to Dravet syndrome variants (odds ratio = 17.8; confidence interval = 5.4-69.3; P = 1.3 × 10-7). Functional studies of both epilepsy and familial hemiplegic migraine type 3 variants reveal alterations of gating properties in keeping with neuronal hyperexcitability. While epilepsy variants result in a moderate increase in action current amplitude consistent with mild gain of function, familial hemiplegic migraine type 3 variants induce a larger effect on gating properties, in particular the increase of persistent current, resulting in a large increase of action current amplitude, consistent with stronger gain of function. Clinically, 13 out of 16 (81%) gain of function variants were associated with a reduction in seizures in response to sodium channel blocker treatment (carbamazepine, oxcarbazepine, phenytoin, lamotrigine or lacosamide) without evidence of symptom exacerbation. Our study expands the spectrum of gain of function SCN1A-related epilepsy phenotypes, defines key clinical features, provides novel insights into the underlying disease mechanisms between SCN1A-related epilepsy and familial hemiplegic migraine type 3, and identifies sodium channel blockers as potentially efficacious therapies. Gain of function disease should be considered in early onset epilepsies with a pathogenic SCN1A variant and non-Dravet syndrome phenotype.

Pathogenic convergence of CNVs in genes functionally associated to a severe neuromotor developmental delay syndrome.

BACKGROUND: Complex developmental encephalopathy syndromes might be the consequence of unknown genetic alterations that are likely to contribute to the full neurological phenotype as a consequence of pathogenic gene combinations. METHODS: To identify the additional genetic contribution to the neurological phenotype, we studied as a test case a boy, with a KCNQ2 exon-7 partial duplication, by single-nucleotide polymorphism (SNP) microarray to detect copy-number variations (CNVs). RESULTS: The proband presented a cerebral palsy like syndrome with a severe motor and developmental encephalopathy. The SNP array analysis detected in the proband several de novo CNVs, nine partial gene losses (LRRC55, PCDH9, NALCN, RYR3, ELAVL2, CDH13, ATP1A2, SLC17A5, ANO3), and two partial gene duplications (PCDH19, EFNA5). The biological functions of these genes are associated with ion channels such as calcium, chloride, sodium, and potassium with several membrane proteins implicated in neural cell-cell interactions, synaptic transmission, and axon guidance. Pathogenically, these functions can be associated to cerebral palsy, seizures, dystonia, epileptic crisis, and motor neuron dysfunction, all present in the patient. CONCLUSIONS: Severe motor and developmental encephalopathy syndromes of unknown origin can be the result of a phenotypic convergence by combination of several genetic alterations in genes whose physiological function contributes to the neurological pathogenic mechanism.

Monoamine neurotransmitters in early epileptic encephalopathies: New insights into pathophysiology and therapy.

AIM: To study neurotransmitter status in children with early epileptic and developmental and epileptic encephalopathy (DEE) and to explore the clinical response to dopaminergic and serotoninergic therapies in a group of patients. METHOD: Two hundred and five patients (111 males [54.1.%] and 94 females [45.9%], mean age 10 months at the onset of epilepsy [SD 1 year 1 month], range 0-3 year) with epileptic encephalopathy/DEE were recruited, including those with West syndrome, Ohtahara syndrome, early myoclonic encephalopathy, epilepsy of infancy with migrating focal seizures, myoclonic encephalopathy in non-progressive disorders, infantile spasms, Doose syndrome, Lennox-Gastaut syndrome, Landau-Kleffner syndrome, and those unclassified. Cerebrospinal fluid (CSF) neurotransmitter studies and patients' medical records were reviewed. Additionally, we present clinical data of 10 patients with low CSF neurotransmitter levels who received dopaminergic/serotoninergic treatments. RESULTS: Abnormal neurotransmitter values were identified in 68 (33%) patients. 5-Hydroxyindoleacetic acid (5-HIAA) deficit was the most prevalent alteration (91%). Low CSF 5-HIAA levels were significantly higher in 1- to 3-year-old children. A negative significant correlation was found between 5-HIAA levels and epilepsy duration before CSF study (Spearman's ρ=-0.191, p=0.007). Abnormalities in deep grey matter were associated with low levels of CSF homovanillic acid and 5-HIAA. Ten patients with low CSF neurotransmitter levels received dopamine and/or serotonin therapies. Six of them showed initial decrease of seizure frequency and severity and maintained improvement in some neurodevelopmental skills. INTERPRETATION: A considerable number of patients showed neurotransmitter abnormalities. Age at seizure onset and duration of epilepsy before CSF study were the principal factors related to neurotransmitter depletion. Early monoamine supplementation would seem advisable as a neuroprotective strategy. WHAT THIS PAPER ADDS: 5-Hydroxyindoleacetic acid homeostasis is especially vulnerable in patients with epileptic encephalopathy/developmental and epileptic encephalopathy. Age of seizure onset and duration of epilepsy are determinants of neurotransmitter depletion.

Novel Dominant KCNQ2 Exon 7 Partial In-Frame Duplication in a Complex Epileptic and Neurodevelopmental Delay Syndrome.

Complex neurodevelopmental syndromes frequently have an unknown etiology, in which genetic factors play a pathogenic role. This study utilizes whole-exome sequencing (WES) to examine four members of a family with a son presenting, since birth, with epileptic-like crises, combined with cerebral palsy, severe neuromotor and developmental delay, dystonic tetraparexia, axonal motor affectation, and hyper-excitability of unknown origin. The WES study detected within the patient a de novo heterozygous in-frame duplication of thirty-six nucleotides within exon 7 of the human KCNQ2 gene. This insertion duplicates the first twelve amino acids of the calmodulin binding site I. Molecular dynamics simulations of this KCNQ2 peptide duplication, modelled on the 3D structure of the KCNQ2 protein, suggest that the duplication may lead to the dysregulation of calcium inhibition of this protein function.

Clinical and genetic features of 13 Spanish patients with KCNQ2 mutations.

The KCNQ2 gene codifies a subunit of the voltage-gated potassium M channel underlying the neuronal M-current. Classically, mutations in this gene have been associated with benign familial neonatal seizures, however, in recent years KCNQ2 mutations have been reported associated to early-onset epileptic encephalopathy. In this work, detailed familiar, clinical and genetic data were collected for 13 KCNQ2-positive patients revealed among a cohort of 80 epileptic pediatric probands from Spain who were analyzed through a targeted next-generation sequencing assay for 155 epilepsy-associated genes. This work shows for the first time the association between KCNQ2 mutations and startle attacks in 38% of patients, which opens the possibility to define electroclinical phenotypes associated to KCNQ2 mutations. It also demonstrates that KCNQ2 mutations contribute to an important percentage of Spanish patients with epilepsy. The study confirm the high genetic heterogeneity of this gene with 13 different mutations found, 10 of them novel and the better outcome of patients treated with sodium channel blockers.

Faulty cardiac repolarization reserve in alternating hemiplegia of childhood broadens the phenotype.

Alternating hemiplegia of childhood is a rare disorder caused by de novo mutations in the ATP1A3 gene, expressed in neurons and cardiomyocytes. As affected individuals may survive into adulthood, we use the term 'alternating hemiplegia'. The disorder is characterized by early-onset, recurrent, often alternating, hemiplegic episodes; seizures and non-paroxysmal neurological features also occur. Dysautonomia may occur during hemiplegia or in isolation. Premature mortality can occur in this patient group and is not fully explained. Preventable cardiorespiratory arrest from underlying cardiac dysrhythmia may be a cause. We analysed ECG recordings of 52 patients with alternating hemiplegia from nine countries: all had whole-exome, whole-genome, or direct Sanger sequencing of ATP1A3. Data on autonomic dysfunction, cardiac symptoms, medication, and family history of cardiac disease or sudden death were collected. All had 12-lead electrocardiogram recordings available for cardiac axis, cardiac interval, repolarization pattern, and J-point analysis. Where available, historical and prolonged single-lead electrocardiogram recordings during electrocardiogram-videotelemetry were analysed. Half the cohort (26/52) had resting 12-lead electrocardiogram abnormalities: 25/26 had repolarization (T wave) abnormalities. These abnormalities were significantly more common in people with alternating hemiplegia than in an age-matched disease control group of 52 people with epilepsy. The average corrected QT interval was significantly shorter in people with alternating hemiplegia than in the disease control group. J wave or J-point changes were seen in six people with alternating hemiplegia. Over half the affected cohort (28/52) had intraventricular conduction delay, or incomplete right bundle branch block, a much higher proportion than in the normal population or disease control cohort (P = 0.0164). Abnormalities in alternating hemiplegia were more common in those ≥16 years old, compared with those <16 (P = 0.0095), even with a specific mutation (p.D801N; P = 0.045). Dynamic, beat-to-beat or electrocardiogram-to-electrocardiogram, changes were noted, suggesting the prevalence of abnormalities was underestimated. Electrocardiogram changes occurred independently of seizures or plegic episodes. Electrocardiogram abnormalities are common in alternating hemiplegia, have characteristics reflecting those of inherited cardiac channelopathies and most likely amount to impaired repolarization reserve. The dynamic electrocardiogram and neurological features point to periodic systemic decompensation in ATP1A3-expressing organs. Cardiac dysfunction may account for some of the unexplained premature mortality of alternating hemiplegia. Systematic cardiac investigation is warranted in alternating hemiplegia of childhood, as cardiac arrhythmic morbidity and mortality are potentially preventable.

Accessibility, availability and common practices regarding genetic testing for epilepsy across Europe: A survey of the European Reference Network EpiCARE.

OBJECTIVE: The increasingly rapid pace of advancement in genetic testing may lead to inequalities in technical and human resources with a negative impact on optimal epilepsy clinical practice. In this view, the European Reference Network (ERN) for Rare and Complex Epilepsies EpiCARE conducted a survey addressing several aspects of accessibility, availability, costs, and standard practices on genetic testing across ERN EpiCARE centers. METHODS: An online Google form was sent to 70 representatives of ERN EpiCARE centers. Descriptive statistics and qualitative analysis were used for data presentation. RESULTS: We received 45 responses (1/center) representing 23 European countries with a better representation of Western Europe. Forty-five percent of the centers did not have access to all available types of genetic testing, mainly reflecting the limited availability of whole-genome sequencing (WGS). Thirty-five percent of centers report cost coverage only for some of the available tests, while costs per test varied significantly (interquartile range IQR ranging from 150 to 1173 euros per test across centers). Urgent genetic testing is available in 71.7% of countries (time-to-urgent result: 2 day to 2 months). The average time-to-result of specific tests in case of non-urgent prescription has a significant variance across centers, with the biggest range observed for whole-exome sequencing (6-128 weeks, IQR: 27 weeks). The percentage of agreement among the experts regarding the choice of genetic test at first intention in specific clinical situations was in all cases less than 50 percent (34.9% to 47% according to the proposed scenarios). SIGNIFICANCE: Costs, time to deliver the results to the clinician, and type of first-line genetic testing vary widely across Europe, even in countries where ERN EpiCARE centers are present. Increased availability of genetic tests and guidance for optimal test choices in epilepsy remains essential to avoid diagnostic delays and excess health costs. PLAIN LANGUAGE SUMMARY: The survey of the ERN EpiCARE highlights disparities in genetic testing for epilepsy across 45 ERN EpiCARE centers in 23 European countries. The findings reveal variable access to certain genetic tests, with lowest access to WGS. Costs and time-to-results vary widely. Urgent genetic testing is available in 71.7% of countries. Agreement among experts on first-line genetic tests for specific patient scenarios is below 50%. The study emphasizes the need for improved test availability and guidance to avoid diagnostic delays and unnecessary costs. EpiCARE has the mission to contribute in homogenizing best practices across Europe.

Antibodies Against ZSCAN1 in Pediatric and Adult Patients With Non-Paraneoplastic ROHHAD Syndrome.

OBJECTIVES: To report the association of zinc finger and SCAN domain containing 1 antibodies (ZSCAN1-abs) with rapid-onset obesity, hypothalamic dysfunction, hypoventilation, and autonomic dysregulation (ROHHAD) syndrome in patients without tumor. METHODS: Patients with symptoms compatible with ROHHAD syndrome but without an associated tumor were selected from our database. Serum and CSF samples were examined for the presence of ZSCAN1-abs by an in-house cell-based assay. In addition, samples from 149 patients with several inflammatory and noninflammatory disorders and 50 healthy participants served as controls. RESULTS: Thirteen patients with ROHHAD syndrome were identified. Of these, we had paired serum/CSF samples from 6 patients and only serum from the other 7. Five of 6 patients (83.3%) with paired serum/CSF (4 children, 1 adult) had ZSCAN-abs only in CSF and 1 had antibodies in serum and CSF. ZSCAN1-abs were not detected in the remaining 7 patients with ROHHAD with only serum available or in any of the 199 control samples. DISCUSSION: Patients with ROHHAD syndrome should be investigated for the presence of ZSCAN1-abs in CSF. The antibodies do not necessarily predict the presence of a tumor. The detection of ZSCAN1-abs in an adult patient suggests that this condition also occurs beyond the pediatric age.

Children and Adolescent Patients with Variants in the ATP1A3 -encoded Sodium-Potassium ATPase Alpha-3 Subunit Demonstrate an Impaired QT Response to Bradycardia and Predisposition to Sinus Node Dysfunction.

Background: Alternating hemiplegia of childhood (AHC) is a rare disorder with both neurologic and cardiac manifestations. The ATP1A3-D801N variant is associated with a pathologically short QT interval and risk of ventricular arrhythmia following bradycardia; however, the mechanism of this remains unknown. We investigated the relationship between heart rate (HR), QT, and QTc, hypothesizing that individuals with ATP1A3-D801N have abnormal, impaired shortening of QT and QTc at lower HR leading to arrhythmia predisposition. Methods: We performed a retrospective observational study of individuals who underwent clinical evaluation, Holter monitoring, and genetic testing for AHC at Duke University Hospitals. We also compiled a group of healthy individuals as a control cohort. A larger, worldwide cohort of individuals with ATP1A3 - related phenotypes was compiled to investigate sinus node dysfunction. Linear regression analysis was then performed. Results: The cohort consisted of 44 individuals with ATP1A3 -related phenotypes with 81 Holter recordings (52.27% female; mean age at first Holter 8.04 years, range 0.58 - 33 years), compared to 36 healthy individuals with 57 Holter recordings (52.78% female; mean age at first Holter 9.84 years, range 0.08 - 38 years). Individuals with ATP1A3-D801N had reduced prolongation of QT at lower HR, manifest as a significantly lower slope for HR vs QT compared to healthy (P<0.0001). This resulted in a significantly higher slope of the relationship for HR vs QTc compared to healthy (P<0.0001). Individuals with ATP1A3 - related phenotypes and baseline QTc <350 milliseconds (ms) had increased shortening of QT and QTc at lower HR compared to those with normal QTc (P=0.003; P=0.001). Among worldwide cases, 3 out of 131 individuals with ATP1A3 -related phenotypes required device implantation and/or had sinus pauses >4 seconds. Conclusions: Individuals with the ATP1A3-D801N variant exhibit paradoxical shortening of QT and QTc at lower HR, which contribute to an increased risk of arrhythmias during bradycardia. This is exacerbated by an underlying risk of sinus node dysfunction. Clinical Perspective: What is Known: Individuals with ATP1A3-D801N have a short baseline QTc.Two individuals with AHC experienced ventricular fibrillation following bradycardia. What the Study Adds: The QT and QTc shorten to a greater extent at lower heart rate in individuals with ATP1A3-D801N than in healthy individuals. Individuals with ATP1A3 -related phenotypes and QTc <350ms show greater impairment of QT and QTc dynamics than those with normal QTc. There is low prevalence of device implantation and significant sinus pauses in individuals with ATP1A3 -related phenotypes, with a relatively greater prevalence in those with ATP1A3-D801N.

Relationship Between Epileptic Activity and Developmental Outcome in KCNQ2-Related Epilepsy.

BACKGROUND: We aim to describe a cohort of patients with KCNQ2-related epilepsy and evaluate the relationship between epileptic activity and developmental outcome. This topic is relevant for the selection of clinical end points in future clinical trials, since cessation of seizures may or may not be the most important outcome. METHODS: This retrospective cohort study of children with self-limited (familial) neonatal epilepsy and developmental and epileptic encephalopathy due to pathogenic variants in KCNQ2 was conducted between 2019 and 2021. We collected clinical, therapeutic, and genetic information. Available electroencephalographic recordings were reviewed by a neurophysiologist. Gross motor function was determined using the Gross Motor Function Classification System (GMFCS). The Vineland Adaptive Behavior Composite standard score (ABC SS) was used to measure adaptive functioning. RESULTS: Among 44 children (mean age 8.1 ± 4.0 years, 45.5% were male), 15 of 44 had S(F)NE, and 29 of 44 had DEE. Delayed seizure freedom was more frequent in DEE than in S(F)NE (P = 0.025), but no correlation was observed between age at seizure freedom and developmental outcome in patients with DEE. Multifocal interictal epileptiform abnormalities at epilepsy onset were more frequent in DEE than in S(F)NE (P = 0.014), and were associated with higher GMFCS (P = 0.027) and lower ABC SS (P = 0.048) in patients with DEE. Disorganized background activity at follow-up was more frequent in DEE than in S(F)NE (P = 0.001), and was associated with higher GMFCS levels (P = 0.009) and lower ABC SS (P = 0.005) in patients with DEE. CONCLUSIONS: This study shows a partial correlation between epileptic activity and developmental outcome in KCNQ2-related epilepsy.

Methodology of a Natural History Study of a Rare Neurodevelopmental Disorder: Alternating Hemiplegia of Childhood as a Prototype Disease.

Here, we describe the process of development of the methodology for an international multicenter natural history study of alternating hemiplegia of childhood as a prototype disease for rare neurodevelopmental disorders. We describe a systematic multistep approach in which we first identified the relevant questions about alternating hemiplegia of childhood natural history and expected challenges. Then, based on our experience with alternating hemiplegia of childhood and on pragmatic literature searches, we identified solutions to determine appropriate methods to address these questions. Specifically, these solutions included development and standardization of alternating hemiplegia of childhood-specific spell video-library, spell calendars, adoption of tailored methodologies for prospective measurement of nonparoxysmal and paroxysmal manifestations, unified data collection protocols, centralized data platform, adoption of specialized analysis methods including, among others, Cohen kappa, interclass correlation coefficient, linear mixed effects models, principal component, propensity score, and ambidirectional analyses. Similar approaches can, potentially, benefit in the study of other rare pediatric neurodevelopmental disorders.

Exploring the Spectrum of RHOBTB2 Variants Associated with Developmental Encephalopathy 64: A Case Series and Literature Review.

Background: Rho-related BTB domain-containing protein 2 (RHOBTB2) is a protein that interacts with cullin-3, a crucial E3 ubiquitin ligase for mitotic cell division. RHOBTB2 has been linked to early infantile epileptic encephalopathy, autosomal dominant type 64 (OMIM618004), in 34 reported patients. Methods: We present a case series of seven patients with RHOBTB2-related disorders (RHOBTB2-RD), including a description of a novel heterozygous variant. We also reviewed previously published cases of RHOBTB2-RD. Results: The seven patients had ages ranging from 2 years and 8 months to 26 years, and all had experienced seizures before the age of one (onset, 4-12 months, median, 4 months), including various types of seizures. All patients in this cohort also had a movement disorder (onset, 0.3-14 years, median, 1.5 years). Six of seven had a baseline movement disorder, and one of seven only had paroxysmal dystonia. Stereotypies were noted in four of six, choreodystonia in three of six, and ataxia in one case with multiple movement phenotypes at baseline. Paroxysmal movement disorders were observed in six of seven patients for whom carbamazepine or oxcarbazepine treatment was effective in controlling acute or paroxysmal movement disorders. Four patients had acute encephalopathic episodes at ages 4 (one patient) and 6 (three patients), which improved following treatment with methylprednisolone. Magnetic resonance imaging scans revealed transient fluid-attenuated inversion recovery abnormalities during these episodes, as well as myelination delay, thin corpus callosum, and brain atrophy. One patient had a novel RHOBTB2 variant (c.359G>A/p.Gly120Glu). Conclusion: RHOBTB2-RD is characterized by developmental delay or intellectual disability, early-onset seizures, baseline movement disorders, acute or paroxysmal motor phenomena, acquired microcephaly, and episodes of acute encephalopathy. Early onsets of focal dystonia, acute encephalopathic episodes, episodes of tongue protrusion, or peripheral vasomotor disturbances are important diagnostic clues. Treatment with carbamazepine or oxcarbazepine was found to be effective in controlling acute or paroxysmal movement disorders. Our study highlights the clinical features and treatment response of RHOBTB2-RD.

Development and testing of methods to record and follow up spells in patients with alternating hemiplegia of childhood.

BACKGROUND: Developing methods to record Alternating Hemiplegia of Childhood (AHC) spells is essential for clinical trials and patient care. OBJECTIVES: Test the following hypotheses: 1) Video-library training improves participants' ability to correctly identify AHC spells. 2) A custom-designed event-calendar with weekly reviews results in consistent documentation of such events over time. 3) Use of an electronic diary (e-Diary) to register events is a useful tool. METHODS: 1) A video-library of AHC type spells was developed along with specific training; the effect of the training was tested in 36 caregivers. 2) An event-calendar was similarly developed and provided to 5 caregivers with weekly videoconference meetings for 8 weeks. 3) An e-Diary was developed and offered to 33 patients; time of usage and caregivers' feedback (telephone interview) were analyzed. RESULTS: 1) Video-library training: Wilcoxon test showed improvement in caregiver identification of spells (p = 0.047), Cohen's Kappa demonstrated high degree of agreement between caregivers'-experts' classifications (>0.9). 2) Event-calendar: 96.42% of entries had complete information; this did not change during follow up (p = 0.804). 3) e-Diary: whereas 52% of respondents used the e-Diary when offered (duration: 10.5 ± 8.1 months), 96.3% indicated they would use it in future studies. Those who used it for 13 months, were very likely to use it during the rest of that year. CONCLUSIONS: Video-library training improved spell identification. Calendar with weekly reviews resulted in a sustained and consistent record keeping. Caregivers' e-Diary feedback was encouraging with long-term usage in many. These approaches could be helpful for AHC and, potentially, in similar disorders.

Pre-surgical evaluation challenges and long-term outcome in children operated on for Low Grade Epilepsy Associated brain Tumors.

OBJETIVE: Analyze pre-surgical evaluation modalities, surgical failures, long-term results of surgery and neurocognitive outcome in children with Low-grade Epilepsy Associated brain Tumors (LEAT). METHODS: Retrospective observational study of 37 children who underwent epilepsy surgery, with a minimum follow-up of 12 months. At time of surgery, pharmaco-sensitivity (Group 1; n = 8) and drug-resistance (Group 2; n = 29), were considered. RESULTS: Age range of seizure onset was 5 months-14 years (mean 5.73years) and age at surgery was 2.2-18.7years (mean 10.7years). Gangliogliomas (35.1%) or DNTs (29.7%), combined or not to a focal cortical dysplasia (FCD), were the most frequent. Extended lesionectomy 16 children (43.2%) were the most frequently used surgical approach in both groups. At one year of follow-up, 36 children (97.2%) were classified as Engel I. Within the age-range studied, duration of epilepsy and time to surgery appeared to have no impact on clinical and neurocognitive outcome in both groups. It is noteworthy, however, that antiseizure medications (ASMs) were withdrawn in 100% of the pharmacosensitive group vs 34.5% of the drug-resistant group (p = 0.002). In children with a pharmaco-sensitive epilepsy, neurocognitive evaluation showed significant improvement in the verbal comprehension index (p = 0.029). CONCLUSIONS: Epilepsy-surgery is a safe therapeutic option for LEATs including for children with seizures controlled by ASMs. Presence of associated lesions is not rare. Comprehensive pre-surgical evaluation increases the chances for control of the seizures, the early discontinuation of medications and favours neurocognitive development.

Cerebrospinal Fluid Ion Analysis in Neonatal Seizures.

BACKGROUND: There is a gap of knowledge regarding cerebrospinal fluid (CSF) ion concentrations in normal and pathological states, particularly during the neonatal period. We aim to compare CSF ion concentrations in newborns with different causes of neonatal-onset epilepsy (NOE) and acute symptomatic seizures (ASS) and controls, to examine their usefulness for diagnostic purposes. METHODS: A descriptive retrospective study was conducted from January 2019 to June 2020 in a tertiary hospital. We analyzed CSF K+, Na+, Cl-, and Ca2+ concentrations in frozen samples from patients with neonatal seizures (NS) secondary to NOE and ASS (neonatal arterial ischemic stroke [NAIS] and hypoxic-ischemic encephalopathy). As the control group, we selected CSF samples from newborns who had undergone CSF analysis as part of the diagnostic workup and in whom central nervous system infections had been ruled out, without signs of dehydration, gastroenteritis, or history of seizures. RESULTS: Sixty-eight newborns were included, 16 with NOE, 13 with ASS, and 39 without NS (control group). In comparison with the control group, [K+]CSF was lower in patients with KCNQ2-related epilepsy (P = 0.007), other causes of NOE (P = 0.010), and NAIS (P = 0.002). Changes in [Na+]CSF, [Cl-]CSF, and [Ca2+]CSF were less consistent among subgroups. CONCLUSIONS: Here we report for the first time ionic imbalances in the CSF of neonates with NOE and NAIS. No differences were observed between newborns with different causes of NS. Further studies should be undertaken to investigate the physiopathology behind these changes and their impact on biological function.