X-Linked Epilepsies: A Narrative Review.

X-linked epilepsies are a heterogeneous group of epileptic conditions, which often overlap with X-linked intellectual disability. To date, various X-linked genes responsible for epilepsy syndromes and/or developmental and epileptic encephalopathies have been recognized. The electro-clinical phenotype is well described for some genes in which epilepsy represents the core symptom, while less phenotypic details have been reported for other recently identified genes. In this review, we comprehensively describe the main features of both X-linked epileptic syndromes thoroughly characterized to date (PCDH19-related DEE, CDKL5-related DEE, MECP2-related disorders), forms of epilepsy related to X-linked neuronal migration disorders (e.g., ARX, DCX, FLNA) and DEEs associated with recently recognized genes (e.g., SLC9A6, SLC35A2, SYN1, ARHGEF9, ATP6AP2, IQSEC2, NEXMIF, PIGA, ALG13, FGF13, GRIA3, SMC1A). It is often difficult to suspect an X-linked mode of transmission in an epilepsy syndrome. Indeed, different models of X-linked inheritance and modifying factors, including epigenetic regulation and X-chromosome inactivation in females, may further complicate genotype-phenotype correlations. The purpose of this work is to provide an extensive and updated narrative review of X-linked epilepsies. This review could support clinicians in the genetic diagnosis and treatment of patients with epilepsy featuring X-linked inheritance.

Gut microbiota profile in CDKL5 deficiency disorder patients.

CDKL5 deficiency disorder (CDD) is a neurodevelopmental condition characterized by global developmental delay, early-onset seizures, intellectual disability, visual and motor impairments. Unlike Rett Syndrome (RTT), CDD lacks a clear regression period. Patients with CDD frequently encounter gastrointestinal (GI) disturbances and exhibit signs of subclinical immune dysregulation. However, the underlying causes of these conditions remain elusive. Emerging studies indicate a potential connection between neurological disorders and gut microbiota, an area completely unexplored in CDD. We conducted a pioneering study, analyzing fecal microbiota composition in individuals with CDD (n = 17) and their healthy relatives (n = 17). Notably, differences in intestinal bacterial diversity and composition were identified in CDD patients. In particular, at genus level, CDD microbial communities were characterized by an increase in the relative abundance of Clostridium_AQ, Eggerthella, Streptococcus, and Erysipelatoclostridium, and by a decrease in Eubacterium, Dorea, Odoribacter, Intestinomonas, and Gemmiger, pointing toward a dysbiotic profile. We further investigated microbiota changes based on the severity of GI issues, seizure frequency, sleep disorders, food intake type, impairment in neuro-behavioral features and ambulation capacity. Enrichment in Lachnoclostridium and Enterobacteriaceae was observed in the microbiota of patients with more severe GI symptoms, while Clostridiaceae, Peptostreptococcaceae, Coriobacteriaceae, Erysipelotrichaceae, Christensenellaceae, and Ruminococcaceae were enriched in patients experiencing daily epileptic seizures. Our findings suggest a potential connection between CDD, microbiota and symptom severity. This study marks the first exploration of the gut-microbiota-brain axis in subjects with CDD. It adds to the growing body of research emphasizing the role of the gut microbiota in neurodevelopmental disorders and opens doors to potential interventions that target intestinal microbes with the aim of improving the lives of patients with CDD.

Genetic Advancements in Infantile Epileptic Spasms Syndrome and Opportunities for Precision Medicine.

Infantile epileptic spasms syndrome (IESS) is a devastating developmental epileptic encephalopathy (DEE) consisting of epileptic spasms, as well as one or both of developmental regression or stagnation and hypsarrhythmia on EEG. A myriad of aetiologies are associated with the development of IESS; broadly, 60% of cases are thought to be structural, metabolic or infectious in nature, with the remainder genetic or of unknown cause. Epilepsy genetics is a growing field, and over 28 copy number variants and 70 single gene pathogenic variants related to IESS have been discovered to date. While not exhaustive, some of the most commonly reported genetic aetiologies include trisomy 21 and pathogenic variants in genes such as TSC1, TSC2, CDKL5, ARX, KCNQ2, STXBP1 and SCN2A. Understanding the genetic mechanisms of IESS may provide the opportunity to better discern IESS pathophysiology and improve treatments for this condition. This narrative review presents an overview of our current understanding of IESS genetics, with an emphasis on animal models of IESS pathogenesis, the spectrum of genetic aetiologies of IESS (i.e., chromosomal disorders, single-gene disorders, trinucleotide repeat disorders and mitochondrial disorders), as well as available genetic testing methods and their respective diagnostic yields. Future opportunities as they relate to precision medicine and epilepsy genetics in the treatment of IESS are also explored.

Leukodystrophy with Macrocephaly, Refractory Epilepsy, and Severe Hyponatremia-The Neonatal Type of Alexander Disease.

INTRODUCTION: Alexander disease (AxD) is a rare neurodegenerative condition that represents the group of leukodystrophies. The disease is caused by GFAP mutation. Symptoms usually occur in the infantile age with macrocephaly, developmental deterioration, progressive quadriparesis, and seizures as the most characteristic features. In this case report, we provide a detailed clinical description of the neonatal type of AxD. METHOD: Next-Generation Sequencing (NGS), including a panel of 49 genes related to Early Infantile Epileptic Encephalopathy (EIEE), was carried out, and then Whole Exome Sequencing (WES) was performed on the proband's DNA extracted from blood. CASE DESCRIPTION: In the first weeks of life, the child presented with signs of increased intracranial pressure, which led to ventriculoperitoneal shunt implementation. Recurrent focal-onset motor seizures with secondary generalization occurred despite phenobarbital treatment. Therapy was modified with multiple anti-seizure medications. In MRI contrast-enhanced lesions in basal ganglia, midbrain and cortico-spinal tracts were observed. During the diagnostic process, GLUT-1 deficiency, lysosomal storage disorders, organic acidurias, and fatty acid oxidation defects were excluded. The NGS panel of EIEE revealed no abnormalities. In WES analysis, GFAP missense heterozygous variant NM_002055.5: c.1187C>T, p.(Thr396Ile) was detected, confirming the diagnosis of AxD. CONCLUSION: AxD should be considered in the differential diagnosis in all neonates with progressive, intractable seizures accompanied by macrocephaly.

A Potential Mechanism of Neurological Impairment in Children With Infantile Spasm: Based on Microanatomic Structure Analysis Employing Voxel-Based Morphometry and Surface-Based Morphometry.

BACKGROUND: Infantile epileptic spasms syndrome (IESS) would accompany with severe neurological impairment. Our study aimed to explore the potential mechanism by employing voxel-based and surface-based morphometry to detect brain microwould accompany with severe neurological impairment. Our study aimed to explore the potential mechanism by employing voxel-based and surface-based morphometry to detect brain microanatomic structure alteration. METHODS: The IESS group had 21 males and 13 females (mean age: 17.7 ± 15.6 months), whereas the healthy controls group had 22 males and 10 females (mean age: 29.4 ± 18.7 months). High-resolution 3D T1WI was performed. Computational Anatomy Toolbox implemented in Statistical Parametric Mapping 12 was used to measure the gray matter and white matter volume, and the cortical thickness separately. Independent sample t test was used to assess between-group differences. IESS group was assessed using the Bayley Scales of Infant Development. RESULTS: The IESS group showed a significantly decreased volume of gray matter in right middle temporal gyrus, inferior temporal gyrus, superior temporal gyrus, right fusiform, and bilateral precuneus (P < 0.001). There were no significant between-group differences with respect to white matter volume or cortical thickness (P > 0.001). The results of Bayley Scales of Infant Development showed that the Mental Development Index (MDI) and Psychomotor Development Index scores of children with IESS were almost concentrated in the range of <70. MDI score showed a positive correlation with gray matter reduction area in IESS group. CONCLUSION: Children with IESS had impaired cognitive and delayed motor development. And the decreased gray matter in the right temporal lobe, fusiform, and bilateral precuneus could be the potential anatomic basis for impaired function, such as hearing, visual, and language.

Timing the clinical onset of epileptic spasms in infantile epileptic spasms syndrome: A tertiary health center's experience.

OBJECTIVE: Lead time to treatment (clinical onset of epileptic spasms [ES] to initiation of appropriate treatment) is known to predict outcomes in infantile epileptic spasms syndrome (IESS). Timing the clinical onset of ES is crucial to establish lead time. We investigated how often ES onset could be established to the nearest week. We aimed to (1) ascertain the exact date or estimate the nearest week of ES onset and (2) compare clinical/demographic factors between patients where date of ES onset was determined or estimated to the nearest week and patients whose date of ES onset could not be estimated to the nearest week. Reasons for difficulties in estimating date of ES onset were explored. METHODS: Retrospective chart review of new onset IESS patients (January 2019-May 2022) extracted the date or week of the clinical onset of ES. Predictors of difficulty in date of ES onset estimation to the nearest week were examined by regression analysis. Sources contributing to difficulties determining date of ES onset were assessed after grouping into categories (provider-, caregiver-, disease-related). RESULTS: Among 100 patients, date of ES onset was estimated to the nearest week in 47%. On univariable analysis, age at diagnosis (p = .021), development delay (p = .007), developmental regression/stagnation (p = .021), ES intermixed with other seizures (p = .011), and nonclustered ES at onset (p = .005) were associated with difficulties estimating date of ES onset. On multivariable analysis, failure to establish date of ES onset was related to ES intermixed with other seizures (p = .004) and nonclustered ES at onset (p = .003). Sources contributing to difficulties determining date of ES onset included disease-related factors (ES characteristics, challenges interpreting electroencephalograms) and provider/caregiver-related factors (delayed diagnosis). SIGNIFICANCE: Difficulties with estimation of lead time (due to difficulties timing ES onset) can impact clinical care (prognostication), as even small increments in lead time duration can have adverse developmental consequences.

[Clinical features and genetic analysis of five children with epilepsies due to variants of SCN8A gene].

OBJECTIVE: To explore the clinical and genetic characteristics of five children with epilepsies due to variants of SCN8A gene. METHODS: Clinical data of five children (four males and one female) admitted to Linyi People's Hospital due to hereditary epilepsies between August 2015 and August 2022 were collected. Whole exome sequencing was carried out for these children, and candidate variants were verified by Sanger sequencing. RESULTS: All of the five children were found to harbor variants of the SCN8A gene. Case 1, who had benign familial infantile epilepsy, inherited a known pathogenic c.4840A>G variant from his father with similar symptoms. Cases 2 to 4 had presented with intermediate epilepsy. Among these, case 2 has harbored a de novo c.3967G>A variant which was rated as pathogenic (PS1+PS2+PM1+PM2_Supporting+PP3) based on the guidelines from the American College of Medical Genetics and Genomics. Cases 3 and 4 were found to respectively harbor a de novo c.415A>T and a c.4697C>T variant, which were both rated as likely pathogenic (PS2+PM1+PM2_Supporting+PP3). Case 5, who had early-onset infantile epileptic encephalopathy transformed into Lennox Gastaut-like syndrome, has harbored a de novo c.5615G>A variant, which was known to be pathogenic. The children had their age of onset ranging from 2 to 14 months, and all had focal seizures and generalized tonic clonic seizures. Four children (cases 1, 2, 3 and 5) had cluster seizures, four (cases 1 to 4) had become seizure-free after single or dual treatment and showed normal growth and development, whilst case 5 was drug-resistant and showed severe developmental retardation. CONCLUSION: The five children had new features such as cluster seizures, occasional benign seizures in adulthood, and intermediate epilepsy which are prone to relapse after discontinuation of medication, which may be attributed to the pathogenic variants of the SCN8A gene.

Type 1 early infantile epileptic encephalopathy: A case report and literature review.

BACKGROUND: Variants in the Aristaless-related homeobox (ARX) gene lead to a variety of phenotypes, with intellectual disability being a steady feature. Other features can include severe epilepsy, spasticity, movement disorders, hydranencephaly, and ambiguous genitalia in males. X-linked Ohtahara syndrome or Type 1 early infantile epileptic encephalopathy (EIEE1) is a severe early-onset epileptic encephalopathy with arrested psychomotor development caused by hemizygous mutations in the ARX gene, which encodes a transcription factor in fundamental brain developmental processes. METHODS: We presented a case report of a 2-year-old boy who exhibited symptoms such as microcephaly, seizures, and severe multifocal epileptic abnormalities, and genetic techniques such as autozygosity mapping, Sanger sequencing, and whole-exome sequencing. RESULTS: We confirmed that the patient had the NM_139058.3:c.84C>A; p.(Cys28Ter) mutation in the ARX gene. CONCLUSION: The patient with EIEE1 had physical symptoms and hypsarrhythmia on electroencephalogram. Genetic testing identified a causative mutation in the ARX gene, emphasizing the role of genetic testing in EIEE diagnosis.

Variable expression of MECP2, CDKL5, and FMR1 in the human brain: Implications for gene restorative therapies.

MECP2, CDKL5, and FMR1 are three X-linked neurodevelopmental genes associated with Rett, CDKL5-, and fragile-X syndrome, respectively. These syndromes are characterized by distinct constellations of severe cognitive and neurobehavioral anomalies, reflecting the broad but unique expression patterns of each of the genes in the brain. As these disorders are not thought to be neurodegenerative and may be reversible, a major goal has been to restore expression of the functional proteins in the patient's brain. Strategies have included gene therapy, gene editing, and selective Xi-reactivation methodologies. However, tissue penetration and overall delivery to various regions of the brain remain challenging for each strategy. Thus, gaining insights into how much restoration would be required and what regions/cell types in the brain must be targeted for meaningful physiological improvement would be valuable. As a step toward addressing these questions, here we perform a meta-analysis of single-cell transcriptomics data from the human brain across multiple developmental stages, in various brain regions, and in multiple donors. We observe a substantial degree of expression variability for MECP2, CDKL5, and FMR1 not only across cell types but also between donors. The wide range of expression may help define a therapeutic window, with the low end delineating a minimum level required to restore physiological function and the high end informing toxicology margin. Finally, the inter-cellular and inter-individual variability enable identification of co-varying genes and will facilitate future identification of biomarkers.

CDKL5 Deficiency Disorder: Some Lessons Learned 20 Years After the First Description.

Loss of function variants in the Cyclin-dependent kinase-like 5 gene (CDKL5) causes CDKL5 deficiency disorder (CDD). Most cases of CDD are due to a de novo missense or truncating variants. The CDKL5 gene was discovered in 1998 as part of the genomic mapping of the chromosome Xp22 region that led to the discovery of the serine-threonine kinases STK9. Since then, there have been significant advancements in the description of the disease in humans, the understanding of the pathophysiology, and the management of the disease. There have been many lessons learned since the initial description of the condition in humans in 2003. In this article, we will focus on pathophysiology, clinical manifestations, with particular focus on seizures because of its relevance to the medical practitioners and researchers and guidelines for management. We finalize the manuscript with the voice of the parents and caregivers, as discussed with the 2019 meeting with the Food and Drug Administration.

Alström syndrome mimicking spasmus nutans: report of a novel ALMS1 variant.

We report the case of an otherwise healthy 6-year-old girl presenting with poor visual acuity, photophobia, and abnormal eye and head movements who was initially diagnosed with spasmus nutans. A remote history of presumed viral cardiomyopathy and further electroretinography testing raised suspicion for Alström syndrome. She was diagnosed with a novel ALMS1 variant.

Early life seizures and epileptic spasms in STXBP1-related disorders.

OBJECTIVE: Individuals with disease-causing variants in STXBP1 frequently have epilepsy onset in the first year of life with a variety of seizure types, including epileptic spasms. However, the impact of early onset seizures and antiseizure medication (ASM) on the risk of developing epileptic spasms and impact on their trajectory are poorly understood, limiting informed and anticipatory treatment, as well as trial design. METHODS: We retrospectively reconstructed seizure and medication histories in weekly intervals for individuals with STXBP1 developmental and epileptic encephalopathy (DEE) with epilepsy onset in the first year of life and quantitatively analyzed longitudinal seizure histories and medication response. RESULTS: We included 61 individuals with early onset seizures, 29 of whom had epileptic spasms. Individuals with neonatal seizures were likely to have continued seizures after the neonatal period (25/26). The risk of developing epileptic spasms was not increased in individuals with neonatal seizures or early infantile seizures (21/41 vs. 8/16, odds ratio [OR] = 1, 95% confidence interval [CI] = .3-3.9, p = 1). We did not find any ASM associated with the development of epileptic spasms following prior seizures. Individuals with prior seizures (n = 16/21, 76%) had a higher risk of developing refractory epileptic spasms (n = 5/8, 63%, OR = 1.9, 95% CI = .2-14.6, p = .6). Individuals with refractory epileptic spasms had a later onset of epileptic spasms (n = 20, median = 20 weeks) compared to individuals with nonrefractory epileptic spasms (n = 8, median = 13 weeks, p = .08). SIGNIFICANCE: We provide a comprehensive assessment of early onset seizures in STXBP1-DEE and show that the risk of epileptic spasms is not increased following a prior history of early life seizures, nor by certain ASMs. Our study provides baseline information for targeted treatment and prognostication in early life seizures in STXBP1-DEE.

Adapting a measure of gross motor skills for individuals with CDKL5 deficiency disorder: A psychometric study.

PURPOSE: Validated measures capable of demonstrating meaningful interventional change in the CDKL5 deficiency disorder (CDD) are lacking. The study objective was to modify the Rett Syndrome Gross Motor Scale (RSGMS) and evaluate its psychometric properties for individuals with CDD. METHODS: Item and scoring categories of the RSGMS were modified. Caregivers registered with the International CDKL5 Clinical Research Network uploaded motor videos filmed at home to a protected server and completed a feedback questionnaire (n = 70). Rasch (n = 137), known groups (n = 109), and intra- and inter-rater reliability analyses (n = 50) were conducted. RESULTS: The age of individuals with CDD ranged from 1.5 to 34.1 years. The modified scale, Gross Motor-Complex Disability (GM-CD), comprised 17 items. There were no floor or ceiling effects and inter- and intra-rater reliability were good. Rasch analysis demonstrated that the items encompassed a large range of performance difficulty, although there was some item redundancy and some disordered categories. One item, Prone Head Position, was a poor fit. Caregiver-reported acceptability was positive. Scores differed by age and functional abilities. SUMMARY: GM-CD appears to be a suitable remotely administered measure and psychometrically sound for individuals with CDD. This study provides the foundation to propose the use of GM-CD in CDD clinical trials. Longitudinal evaluation is planned.

Metabolic causes of pediatric developmental & epileptic encephalopathies (DEE)- genetic variant analysis in a south Indian cohort.

PURPOSE: Drug-resistant epilepsy is seen in patients with inborn errors of metabolism and metabolic dysfunction in neurons is crucial to brain disorders associated with psychomotor impairment. Diagnostic rates of metabolic causes of developmental and epileptic encephalopathy (DEE) using next generation sequencing have been rarely studied in literature. METHODS: A prospective hospital study was carried out in 384 children with DEE, who underwent genetic testing. Metabolic disorders were evaluated with biochemical blood/urine assays and when required CSF estimations performed. RESULTS: A total of 154 pathogenic/likely pathogenic variants in 384 children were identified. Out of 384 children, 89 were clinically suspected to have probable or possible metabolic disorders. Pathogenic/likely pathogenic variants in metabolic genes were identified in 39 out of 89 (43.8 %) and promising VUS in 28 (31.4 %). These included variants for progressive myoclonus epilepsies (21; 53.8 %), DEE with focal/multifocal seizures (8; 20.5 %), generalized epilepsy (5;12.8 %), early myoclonic encephalopathy (2; 5.1 %), LGS (1; 2.6 %) and West syndrome (2; 5.1 %). CONCLUSION: Our cohort demonstrates for the first time from the Indian subcontinent that identification of metabolic variants can guide investigations and has therapeutic implications in patients with variable DEE phenotypes. A high utility is noted with regard to diagnosis and prognostication, given the low yield of available biochemical tests, indicating cost-effectiveness of this approach.

Purified cannabidiol as add-on therapy in children with treatment-resistant infantile epileptic spasms syndrome.

OBJECTIVE: The aim of this study was to assess efficacy, safety, and tolerability of highly purified cannabidiol oil (CBD) as add-on therapy for the treatment of a series of patients with infantile epileptic spasms syndrome (IESS) who were resistant to antiseizure medications and ketogenic dietary therapy. MATERIAL AND METHODS: We conducted a retrospective analysis of the medical records of 28 infants with treatment-resistant IESS aged 6 to 21 months who received highly purified CBD between July 2021 and June 2023. Data were collected on neurological examinations, EEG, Video-EEG and polygraphic recordings, imaging studies, laboratory testing, and seizure frequency, type, and duration, and adverse effects. As the primary outcome, a reduction of frequency of epileptic spasms (ES) was assessed. ES freedom was considered after a minimal time of 1 month without ES. RESULTS: Sixteen male and 12 female patients, aged 6-21 months, who received CBD for treatment-resistant IESS were included. The etiology was structural in 10, Down syndrome in seven, genetic in nine, and unknown in two. Initial CBD dose was 2 mg/kg/day, which was uptitrated to a median dose of 25 mg/kg/day (range, 2-50). Prior to CBD initiation, patients had a median of 69 ES in clusters per day (range, 41-75) and of 10 focal seizures per week (range, 7-13). After a mean and median follow-up of 15 and 12.5 months (range, 6-26 months), seven patients were ES free and 12 had a >50 % ES reduction. Five of seven patients (71 %) with Down syndrome and 3/5 (60 %) with cerebral palsy responded well. Adverse effects were mild. EEG improvements correlated with ES reductions. CONCLUSION: In this study evaluating the use of CBD in children with IESS, 19/28 (67.8 %) had a more than 50 % ES reduction with good tolerability.

Quantification of Hypsarrhythmia in Infantile Spasmatic EEG: A Large Cohort Study.

Infantile spasms (IS) is a neurological disorder causing mental and/or developmental retardation in many infants. Hypsarrhythmia is a typical symptom in the electroencephalography (EEG) signals with IS. Long-term EEG/video monitoring is most frequently employed in clinical practice for IS diagnosis, from which manual screening of hypsarrhythmia is time consuming and lack of sufficient reliability. This study aims to identify potential biomarkers for automatic IS diagnosis by quantitative analysis of the EEG signals. A large cohort of 101 IS patients and 155 healthy controls (HC) were involved. Typical hypsarrhythmia and non-hypsarrhythmia EEG signals were annotated, and normal EEG were randomly picked from the HC. Root mean square (RMS), teager energy (TE), mean frequency, sample entropy (SamEn), multi-channel SamEn, multi-scale SamEn, and nonlinear correlation coefficient were computed in each sub-band of the three EEG signals, and then compared using either a one-way ANOVA or a Kruskal-Wallis test (based on their distribution) and the receiver operating characteristic (ROC) curves. The effects of infant age on these features were also investigated. For most of the employed features, significant ( ) differences were observed between hypsarrhythmia EEG and non-hypsarrhythmia EEG or HC, which seem to increase with increased infant age. RMS and TE produce the best classification in the delta and theta bands, while entropy features yields the best performance in the gamma band. Our study suggests RMS and TE (delta and theta bands) and entropy features (gamma band) to be promising biomarkers for automatic detection of hypsarrhythmia in long-term EEG monitoring. The findings of our study indicate the feasibility of automated IS diagnosis using artificial intelligence.