Developmental Regression Research Articles

Rett syndrome.

Rett syndrome (RTT) is a severe, progressive, neurodevelopmental disorder, which affects predominantly females. In most cases, RTT is associated with pathogenic variants in MECP2. MeCP2, the protein product of MECP2, is known to regulate gene expression and is highly expressed in the brain. RTT is characterized by developmental regression of spoken language and hand use that, with hand stereotypies and impaired ambulation, constitute the four core diagnostic features. Affected individuals may present multiple other neurological impairments and comorbidities, such as seizures, breathing irregularities, anxiety and constipation. Studies employing neuroimaging, neuropathology, neurochemistry and animal models show reductions in brain size and global decreases in neuronal size, as well as alterations in multiple neurotransmitter systems. Management of RTT is mainly focused on preventing the progression of symptoms, currently improved by guidelines based on natural history studies. Animal and cellular models of MeCP2 deficiency have helped in understanding the pathophysiology of RTT and guided the development of trofinetide, an IGF1-related compound, which is an approved drug for RTT, as well as of other drugs and gene therapies currently under investigation.

A case of a 6-year-old girl with a rare compound heterozygous mutation of KCTD7 presenting with progressive myoclonic epilepsy

BackgroundProgressive myoclonic epilepsy is a clinically and genetically heterogeneous group of diseases characterized by myoclonic seizures, drug-resistant epilepsy and neurodevelopmental regression. The disease is attributed to mutations in KCTD7 (a member of the potassium channel tetramerization domain).Case presentationWe report the case of a 6-year-old girl with compound heterozygous mutation in KCTD7. Whole-exome sequencing was carried out to detect the mutations followed by Sanger sequencing of the patient in addition to the unaffected parents which confirmed the diagnosis. The first mutation [c. 202A > G (p.Thr68Ala)] was inherited from mother and the second one [c. 458G > A (p.Arg153His)] was inherited from father.ConclusionsTo our knowledge, this is the first report of compound heterozygousKCTD7-related progressive myoclonic epilepsy in Iran with c.202A > G in particular as a novel mutation. Our findings widen the scope of our knowledge of the underlying genetic etiology of the aforementioned disease which can further help us in the genetic diagnosis of these patients.

Solving the Etiology of Developmental and Epileptic Encephalopathy with Spike-Wave Activation in Sleep (D/EE-SWAS).

To understand the etiological landscape and phenotypic differences between 2 developmental and epileptic encephalopathy (DEE) syndromes: DEE with spike-wave activation in sleep (DEE-SWAS) and epileptic encephalopathy with spike-wave activation in sleep (EE-SWAS). All patients fulfilled International League Against Epilepsy (ILAE) DEE-SWAS or EE-SWAS criteria with a Core cohort (n = 91) drawn from our Epilepsy Genetics research program, together with 10 etiologically solved patients referred by collaborators in the Expanded cohort (n = 101). Detailed phenotyping and analysis of molecular genetic results were performed. We compared the phenotypic features of individuals with DEE-SWAS and EE-SWAS. Brain-specific gene co-expression analysis was performed for D/EE-SWAS genes. We identified the etiology in 42/91 (46%) patients in our Core cohort, including 29/44 (66%) with DEE-SWAS and 13/47 (28%) with EE-SWAS. A genetic etiology was identified in 31/91 (34%). D/EE-SWAS genes were highly co-expressed in brain, highlighting the importance of channelopathies and transcriptional regulators. Structural etiologies were found in 12/91 (13%) individuals. We identified 10 novel D/EE-SWAS genes with a range of functions: ATP1A2, CACNA1A, FOXP1, GRIN1, KCNMA1, KCNQ3, PPFIA3, PUF60, SETD1B, and ZBTB18, and 2 novel copy number variants, 17p11.2 duplication and 5q22 deletion. Although developmental regression patterns were similar in both syndromes, DEE-SWAS was associated with a longer duration of epilepsy and poorer intellectual outcome than EE-SWAS. DEE-SWAS and EE-SWAS have highly heterogeneous genetic and structural etiologies. Phenotypic analysis highlights valuable clinical differences between DEE-SWAS and EE-SWAS which inform clinical care and prognostic counseling. Our etiological findings pave the way for the development of precision therapies. ANN NEUROL 2024;96:932-943.

Voltage-Gated Ion Channel Compensatory Effect in DEE: Implications for Future Therapies.

Developmental and Epileptic Encephalopathies (DEEs) represent a clinically and genetically heterogeneous group of rare and severe epilepsies. DEEs commonly begin early in infancy with frequent seizures of various types associated with intellectual disability and leading to a neurodevelopmental delay or regression. Disease-causing genomic variants have been identified in numerous genes and are implicated in over 100 types of DEEs. In this context, genes encoding voltage-gated ion channels (VGCs) play a significant role, and part of the large phenotypic variability observed in DEE patients carrying VGC mutations could be explained by the presence of genetic modifier alleles that can compensate for these mutations. This review will focus on the current knowledge of the compensatory effect of DEE-associated voltage-gated ion channels and their therapeutic implications in DEE. We will enter into detailed considerations regarding the sodium channels SCN1A, SCN2A, and SCN8A; the potassium channels KCNA1, KCNQ2, and KCNT1; and the calcium channels CACNA1A and CACNA1G.

Nephrocalcinosis, distal renal tubular acidosis and skeletal abnormality in two siblings with ROGDI-related Kohlschütter-Tönz syndrome.

Kohlschütter-Tönz (KTS) is a rare autosomal recessive, genetically heterogeneous disorder characterized by a triad of early-onset seizures, global developmental delay or regression, and amelogenesis imperfecta of both temporary and permanent teeth. To date, 66 cases have been reported in the literature, of which 44 with genetic confirmation. Here we report the observation of sibling pairs in a family from a small village in India who presented with nephrocalcinosis, distal renal tubular acidosis, and skeletal abnormality. Nephrocalcinosis has only been reported once before in an individual affected with KTS. Trio exome sequencing revealed a novel, homozygous, likely pathogenic variant, c.646-2_649del, in exon 9 of the ROGDI gene (NM_024589.3) in the first child. Sanger sequencing confirmed homozygosity in both children. Both parents are heterozygous carriers of the same variant. Further research needs to be done to identify the exact mechanism by which ROGDI-encoded protein deficiency leads to nephrocalcinosis and distal renal tubular acidosis.

Clinical characteristics of children with MT-TK gene m.8344A>G variation

Objective: To summarize the clinical characteristics of children carrying the m.8344A>G variant of MT-TK gene. Methods: A case series study was conducted to retrospectively collect data of 22 children with mitochondrial disease caused by MT-TK gene m.8344A>G variation who were treated at the Department of Neurology of Beijing Children's Hospital of Capital Medical University from January 2012 to January 2024. Their clinical data, laboratory tests, muscle pathology, genetic testing, and the follow-up results were analyzed. Pearson correlation analysis was used for correlation analysis. Results: Among the 22 children, there were 13 boys and 9 girls. The age of onset was 5.00 (2.75, 9.00) years. Fifteen children had myoclonic epilepsy with ragged-red fibers (MERRF), 3 had Leigh syndrome (LS), and 4 had LS-MERRF overlap syndrome (LS-MERRF). Myoclonus presented and worsened progressively in all 15 MERRF children, with 10 as the initial symptom and 5 developing progressively during the disease course. Myoclonus was predominantly focal, worsening with fine motor tasks or stress. Electroencephalogram monitoring in the 15 MERRF children revealed myoclonic seizures in 10 children, with 6 classified as myoclonic epilepsy, and 4 as subcortical myoclonus. Two children had generalized myoclonic seizures, and 1 each had absence seizures and generalized seizures. Twelve children had cerebellar ataxia, 10 children exhibited exercise intolerance, and 8 children had muscle weakness. Magnetic resonance imaging (MRI) revealed periventricular white matter involvement in 1 child and bilateral hippocampal involvement in 1 child, likely due to frequent seizures. All 3 children with LS exhibited developmental regressions, accompanied with 2 symptoms include cerebellar ataxia, muscle weakness, and dysphagia. The clinical manifestations of 4 LS-MERRF overlap children presented with combined features of MERRF and LS. Cranial MRI in the 7 LS and LS-MERRF children showed brainstem involvement (all affecting the midbrain) in 6 children and basal ganglia involvement in 4 children. Among the 22 children, 12 had m.8344A>G variant levels >90%, 3 had >80%-90%, 4 had >70%-80%, and 3 had >60%-70%. Higher variant level correlated with the LS phenotype and earlier onset age (r=0.47, -0.50; P=0.018 and 0.029, respectively). Sanger sequencing in 19 mothers revealed m.8344A>G variations in 18, with 4 showing exercise intolerance. Follow-up of 13 children on antimyoclonic treatment showed>75% reduction in seizures with levetiracetam monotherapy in 2 children, with combination therapy required in others. Most achieved >50% seizures reduction within 2 years, but the effectiveness declined with disease progression. Conclusions: The m.8344A>G variant is rare, with MERRF being the most common phenotype, while LS and LS-MERRF are less common. Children with higher ratio of the m.8344A>G variant are more likely to present LS phenotype. Myoclonus, primarily focal, is a key feature, with levetiracetam as the first-line treatment and benzodiazepines recommended for refractory cases.

Providing Insight for Pediatric Ear Surgery: Analysis of Middle Ear Development via HRCT.

Providing insight for pediatric ear surgery via investigations on the development patterns of ossicles, mastoid, and external auditory canal (EAC). This retrospective study analyzed high-resolution computed tomography (HRCT) scans of 191 healthy temporal bones ranging from infants to adults. Subjects were grouped by 1-year intervals for developmental regression models and 3-year intervals for stage comparisons using t-tests or Mann-Whitney U tests. The size of auditory ossicles and tympanic cavity (TC) remained stable during development, while the minimum diameter of the tympanic sinus (TS) entrance was reduced. Regarding mastoid pneumatization, the air cells can be observed at birth, became pronounced at 2 years old, and were fully developed around the age of 5, with subsequent growth primarily involving radial expansion. Furthermore, the EAC demonstrated significant growth with age: the width of EAC increased linearly ( = 0.12x + 4.01, R2 = 0.85), while the length of EAC followed a polynomial growth pattern ( = -0.03x2 + 1.15x + 6.25, R2 = 0.96). Ossicles and TC remain stable during development. Furthermore, mastoid air cells may have developed in the early stages of life, while their diameter increases synchronously with EAC. All in all, ossicular chain reconstruction surgery and endoscopic ear surgery can be performed in babies. NA Laryngoscope, 2024.

Copy Number Variants in 30 Saudi Pediatric Patients with Neurodevelopmental Disorders: From Unknown Significance to Diagnosis.

Structural variants (SVs), such as copy number variants (CNVs), insertions, deletions, inversions, and translocations, contribute significantly to genetic diversity and disease etiology. CNVs, which involve the duplication or deletion of DNA segments, are particularly impactful on genes crucial for biological functions and disease processes. To reassess unclassified SVs that may be underlying unresolved neurodevelopmental disorders among Saudi patients. In this retrospective study conducted at King Saud Medical City, Riyadh, Saudi Arabia, 30 probands with neurodevelopmental disorders and congenital malformations were examined using next-generation sequencing methods-exome sequencing, gene panels, or SNP arrays (the Illumina platform). Reclassification was aided by online tools such as VarSome and ClinVar, with pathogenicity assessments using the ClinGen CNV Pathogenicity Calculator based on American College of Medical Genetics and Genomics criteria for CNV loss and gain, and dosage sensitivity. A total of 31 CNVs were analyzed, of which 2 were reclassified: one as benign and the other as pathogenic. The pathogenic CNV, [3p13p12.3 (70411134_75249376) x1], included a deletion of the FOXP1 gene and was associated with an intellectual developmental disorder, language impairment, possible autistic features, psychomotor impairment, developmental regression, and epilepsy. This study underscores the importance of continuously documenting and revisiting unclassified CNVs in accessible databases to enhance the diagnosis and understanding of complex genotype-phenotype relationships. Reclassifying these CNVs not only accelerates diagnostic processes but also enriches our insight into their significant roles in health and disease.

Griscelli syndrome: a diagnostic challenge of a rare disease: a case report

Introduction: Griscelli syndrome (GS) is a rare autosomal recessive genetic disorder that primarily manifests as hair and skin hypopigmentation, with three types differentiated by their specific genetic defects as well as by their clinical features. Clinically, GS type 1 is characterized by early neurological alterations, while GS type 2 is characterized by immunodeficiency and could present with neurological symptoms, and type 3 is characterized by a chromosomal anomaly without a specific clinical profile besides hypopigmentation. This article details the challenges faced in the diagnosis of a patient with GS who presents with neurological symptoms followed by immunological deficits. Case presentation: A 7-month-old female presented with complaints of developmental delay following an otitis media infection. Upon examination, she exhibited signs of psychomotor developmental regression and had pale bronze skin and silvery-gray hair, as well as hepatosplenomegaly. The examination of her hair shaft revealed a pattern consistent with GS. During her hospitalization, the patient developed an intermittent fever and signs of hemophagocytic lymphohistiocytosis (HLH). She subsequently developed recurrent seizures treated with phenytoin and Aciclovir. Shortly she succumbed to respiratory distress syndrome and multisystem failure. Discussion: The presence of HLH confirms the type of GS. However, in some cases, the HLH criteria could not be fulfilled, presenting a diagnostic challenge. Conclusion: The genetic examination is the only way to differentiate GS type 1 from type 2. However, when it is not available, the presence of specific symptoms and features may assist in the classification. Furthermore, treatments should be administered when GS type 2 is suspected since they have the potential to improve life quality through treating HLH, delaying and altering the neurological symptoms.

POLR3B is associated with a developmental and epileptic encephalopathy with myoclonic-atonic seizures and ataxia.

POLR3B encodes the second largest subunit of RNA polymerase III, which is essential for transcription of small non-coding RNAs. Biallelic pathogenic variants in POLR3B are associated with an inherited hypomyelinating leukodystrophy. Recently, de novo heterozygous variants in POLR3B were reported in six individuals with ataxia, spasticity, and demyelinating peripheral neuropathy. Three of these individuals had epileptic seizures. The aim of this article is to precisely define the epilepsy phenotype associated with de novo heterozygous POLR3B variants. We used online gene-matching tools to identify 13 patients with de novo POLR3B variants. We systematically collected genotype and phenotype data from clinicians using two standardized proformas. All 13 patients had novel POLR3B variants. Twelve of 13 variants were classified as pathogenic or likely pathogenic as per American College of Medical Genetics (ACMG) criteria. Patients presented with generalized myoclonic, myoclonic-atonic, atypical absence, or tonic-clonic seizures between the ages of six months and 4 years. Epilepsy was classified as epilepsy with myoclonic-atonic seizures (EMAtS) in seven patients and "probable EMAtS" in two more. Seizures were treatment resistant in all cases. Three patients became seizure-free. All patients had some degree of developmental delay or intellectual disability. In most cases developmental delay was apparent before the onset of seizures. Three of 13 cases were reported to have developmental stagnation or regression in association with seizure onset. Treatments for epilepsy that were reported by clinicians to be effective were: sodium valproate, which was effective in five of nine patients (5/9) who tried it; rufinamide (2/3); and ketogenic diet (2/3). Additional features were ataxia/incoordination (8/13); microcephaly (7/13); peripheral neuropathy (4/13), and spasticity/hypertonia (6/13). POLR3B is a novel genetic developmental and epileptic encephalopathy (DEE) in which EMAtS is the predominant epilepsy phenotype. Ataxia, neuropathy, and hypertonia may be variously observed in these patients.

Defining Developmental Regression in Rare Neurodevelopmental Disorders of Genetic Etiology: A Scoping Review

Background: Some genetic neurodevelopmental disorders (NDDs) are linked to a loss of acquired abilities. No universal term or severity measure exists for this phenomenon. This scoping review aims further to define developmental regression in NDDs of genetic etiology. Method: We used the PRISMA checklist and searched PubMed, medRxiv, and Google Scholar for developmental regression literature. After data extraction, qualitative (e.g., assessment methods) and quantitative (e.g., mentioned NDDs) data were analyzed. Results: A total of 59 relevant articles from 2074 unique records were identified, associating 18 NDDs of genetic etiology with developmental regression. Multiple terms (e.g., loss of skills, deterioration) and definitions were used across syndromes. Conclusions: A uniform definition of developmental regression was formulated based on literature diversity and NDD heterogeneity. The study also offers guidance on identifying and monitoring developmental regression and its underlying causes.

Deciphering Developmental Epileptic Encephalopathies (DEE): Unravelling the Key Signs

<p><strong>Background:</strong> Epilepsy, a chronic neurological disorder affecting over 50 million people worldwide, is marked by recurrent seizures and loss of consciousness. It is categorized based on EEG features, etiologies, and comorbidities. Developmental Encephalopathy (DE) involves developmental delays and early-onset seizures without causing developmental regression. In contrast, Epileptic Encephalopathy (EE) features severe epilepsy syndromes where frequent seizures result in developmental delays or regression.</p><p><strong>Methods:</strong> This review explores the clinical definitions, epidemiology, and diagnostic criteria for DE, EE, and DEEs. It covers their etiologies, clinical features, diagnostic methods, and treatment strategies, including genetic, structural, metabolic, and immune-related factors.</p><p><strong>Results:</strong> DE features developmental impairment with epilepsy, while EE involves severe epilepsy causing cognitive and behavioral dysfunction. DEEs are marked by early-onset severe epilepsy and EEG abnormalities that worsen developmental impairments. Essential diagnostic tools include EEG, neuroimaging, and genetic testing. Effective management requires personalized interventions to control seizures and address cognitive deficits.</p><p><strong>Conclusion:</strong> DEEs are a complex epilepsy subset with major developmental and cognitive challenges. Early diagnosis and targeted treatments are crucial for improving outcomes. Ongoing research into DEEs' genetic and pathophysiological mechanisms is key to enhancing understanding and management.</p>

Ready-to-use iPSC-derived microglia progenitors for the treatment of CNS disease in mouse models of neuropathic mucopolysaccharidoses

Mucopolysaccharidoses are inherited metabolic disorders caused by the deficiency in lysosomal enzymes required to break down glycosaminoglycans. Accumulation of glycosaminoglycans leads to progressive, systemic degenerative disease. The central nervous system is particularly affected, resulting in developmental delays, neurological regression, and early mortality. Current treatments fail to adequately address neurological defects. Here we explore the potential of human induced pluripotent stem cell (hiPSC)-derived microglia progenitors as a one-time, allogeneic off-the-shelf cell therapy for several mucopolysaccharidoses (MPS). We show that hiPSC-derived microglia progenitors, possessing normal levels of lysosomal enzymes, can deliver functional enzymes into four subtypes of MPS knockout cell lines through mannose-6-phosphate receptor-mediated endocytosis in vitro. Additionally, our findings indicate that a single administration of hiPSC-derived microglia progenitors can reduce toxic glycosaminoglycan accumulation and prevent behavioral deficits in two different animal models of MPS. Durable efficacy is observed for eight months after transplantation. These results suggest a potential avenue for treating MPS with hiPSC-derived microglia progenitors.

Phenotypic spectrum of iron-sulfur cluster assembly gene IBA57 mutations: c.286 T > C identified as a hotspot mutation in Chinese patients with a stable natural history.

Mutations in IBA57 disrupt iron-sulfur clusters maturation, causing a rare mitochondrial disease. Clinical manifestations vary from neonatal lethality to childhood-onset spastic paraparesis, yet the ethnic heterogeneity and natural history remain unclear, necessitating further exploration. This study aimed to delineate the genotype-phenotype correlation of IBA57 mutations by analyzing diverse clinical presentations. We report 11 Chinese patients and include literature-reported cases, totaling 61 patients enrolled for analysis. Clinical, neuroimaging, genetic, and disease progression information were collected. Among these, 46 presented as multiple mitochondrial dysfunctions syndrome 3 (MMDS3), with 58.7% originating from Chinese population. Based on disease course, we propose three clinical subtypes: neonatal, infant and childhood subtypes. Neonatal cases universally displayed hypotonia and respiratory distress at presentation, deceased within three months. Most infancy and childhood cases exhibited developmental regression and impaired motor function. Cavitating leukoencephalopathy was a typical neuroimaging finding in MMDS3 patients. The c.286 T > C mutation was reported in 85.2% of Chinese patients. A significantly lower mortality rate was observed compared to the non-Chinese group (P = 0.002), with a survival rate exceeding 90% at 5 years, indicating a relatively stable disease progression. Fifteen cases from three families manifested the spastic paraplegia 74 phenotype, demonstrating normal development before onset, with common clinical manifestations including spastic paraplegia (14/15), visual impairment (10/13), and peripheral neuropathy (9/13). In conclusion, this study indicates a hotspot mutation in Chinese and analyses the disease progression with different clinical subtypes.

Phenotyping mitochondrial glutamyl-tRNA synthetase deficiency (EARS2): A case series and systematic literature review

Mitochondrial glutamyl-aminoacyl tRNA synthetase deficiency, stemming from biallelic mutations in the EARS2 gene, was first described in 2012. With <50 cases reported globally, this condition exhibits a distinct phenotype of neonatal or childhood-onset, often referred to as leukoencephalopathy with thalamus and brainstem involvement and high lactate (LTBL). It has also been one of the few reversible mitochondrial disorders described. The natural history of these patients is poorly documented, ranging from clinical and radiological improvement to early death.Herein, we detail three cases from our centre, including follow-up on the Portuguese patient reported by Steenweg et al., These cases illustrate the phenotypic spectrum: i) rapidly progressive neonatal presentation with lactic acidemia and corpus callosum agenesis, leading to early death; ii) early onset with a severe, slowly progressive course; iii) early onset with a milder phenotype, showing some improvement and mild neurological symptoms. Additionally, we conducted a systematic literature review on cases of EARS2-deficient patients, focusing on clinical manifestations, laboratory findings, radiological aspects, and disease progression over time, along with respective data analysis. “Patients with EARS2 deficiency typically present within the first year of life with a well-defined neurometabolic disorder picture, often including hypotonia and/or spasticity, along with neurodevelopmental delay or regression. There are no pathognomonic features specific to EARS2 deficiency, and no genotype-phenotype correlation has been identified.” Comparing to initial characterization by Steenweg et al., this analysis reveals an expanded disease spectrum. We propose a novel strategy for clustering phenotypes into severe, moderate, or mild disease based on initial presentation, seemingly correlating with disease progression. The paucity of data on the disease's natural history highlights the need for a multicentric approach to enhance understanding and management. Take-home messageAnalysis of all cases published with EARS2 deficiency allows for establish disease spectrum and a novel strategy for clustering phenotypes which correlate to disease progression.

Clinical and genetic analysis of 23 Chinese children with epilepsy associated with KCNQ2 gene mutations.

To summarize the clinical features and genetic mutation characteristics of Chinese children with KCNQ2-related epilepsy. A cohort of children with genetically caused epilepsy was evaluated at Linyi People's Hospital from January 2017 to December 2023. After next-generation sequencing and pathogenicity analysis, we summarized the medical records and genetic testing data of the children who had KCNQ2 gene mutations. We identified 23 KCNQ2 gene mutations. 73.9% (n = 17) of the mutation sites were located in S5-S6 segments and the C-terminal region. In addition to the common phenotypes, 2 new phenotypes were identified: infantile convulsion with paroxysmal choreoathetosis (ICCA) and febrile seizure plus (FS+). Of all the cases with abnormal video-electro-encephalography, three cases with self-limited familial infantile epilepsy (SeLNE) exhibited a small number of multifocal discharges. Of the patients who have taken a particular antiepileptic drug, the statistics on the number of patients who have responded to the drug are as follows: oxcarbazepine (8/9, 88.9%), levetiracetam (5/7, 71.4%), phenobarbital (9/16, 56.3%), and topiramate (2/5, 40.0%). However, the efficacy of phenobarbital varied widely in treating SeLNE and KCNQ2-DEE. At the final follow-up, 1 case with SeLNE had a transient developmental regression and 7 cases with KCNQ2-DEE had mild to severe developmental backwardness. Although clinically rare, we report 10 new KCNQ2 mutations and two new phenotypes: ICCA and FS+. This further expands genetic and phenotypic spectrum of KCNQ2-related epilepsy. The gene mutation sites are mostly located in S5-S6 segments and the C-terminal region, and the former is usually associated with KCNQ2-DEE. Sodium channel blockers (including oxcarbazepine and topiramate) and levetiracetam should be prioritized over phenobarbital for KCNQ2-DEE. Some cases with KCNQ2-related epilepsy may have transient developmental regression during periods of frequent seizures. Early treatment and early seizure control may be beneficial for willing outcomes in children with KCNQ2-DEE. This article reports 23 cases of children with KCNQ2-related epilepsy, including 10 new mutation sites and 2 new phenotypes. It further expands the genetic and phenotypic spectrum of KCNQ2-related epilepsy. In addition, the article summarizes the gene mutation characteristics and clinical manifestations of children with KCNQ2-related epilepsy, with the expectation of providing a certain theoretical basis for the diagnosis and treatment of such patients.

Severe Acute Motor Exacerbations (SAME) across Metabolic, Developmental and Genetic Disorders.

Acute presentation of severe motor disorders is a diagnostic and management challenge. We define severe acute motor exacerbations (SAME) as acute/subacute motor symptoms that persist for hours-to-days with a severity that compromise vital signs (temperature, breath, and heart rate) and bulbar function (swallowing/dysphagia). Phenomenology includes dystonia, choreoathetosis, combined movement disorders, weakness, and hemiplegic attacks. SAME can develop in diverse diseases and can be preceded by triggers or catabolic states. Recent descriptions of SAME in complex neurodevelopmental and epileptic encephalopathies have broadened appreciation of this presentation beyond inborn errors of metabolism. A high degree of clinical suspicion is required to identify appropriately targeted investigations and management. We conducted a comprehensive literature analysis of etiologies. Reported triggers are described and classified as per pathophysiological mechanism. A video of six cases displaying multiple SAME with diverse outcomes is provided. We identified 50 different conditions that manifest SAME, some associated with developmental regression. Etiologies include disorders of metabolism: energy substrate, amino acids, complex molecules, vitamins/cofactors, minerals, and neurotransmitters/synaptic vesicle cycling. Non-metabolic neurodegenerative and genetic disorders that present with movement disorders and epilepsy can additionally manifest SAME. A limited number of triggers are grouped here, together with an approach to investigations and general management strategies. Several neurogenetic and neurometabolic disorders manifest SAME. Identifying triggers can help in certain cases narrow the differential diagnosis and guide the expeditious application of targeted therapies to minimize adverse developmental and neurological consequences. This process may inform pathogenesis and eventually improve our understanding of the mechanisms that lead to the development of SAME. © 2024 International Parkinson and Movement Disorder Society.

Utility of genome sequencing in exome-negative pediatric patients with neurodevelopmental phenotypes.

Exome sequencing (ES) has emerged as an essential tool in the evaluation of neurodevelopmental disorders (NDD) of unknown etiology. Genome sequencing (GS) offers advantages over ES due to improved detection of structural, copy number, repeat number and non-coding variants. However, GS is less commonly utilized due to higher cost and more intense analysis. Here, we present nine cases of pediatric NDD that were molecularly diagnosed with GS between 2017 and 2022, following non-diagnostic ES. All individuals presented with global developmental delay or regression. Other features present in our cohort included epilepsy, white matter abnormalities, brain malformation and dysmorphic features. Two cases were diagnosed on GS due to newly described gene-disease relationship or variant reclassification (MAPK8IP3, CHD3). Additional features missed on ES that were later detected on GS were: intermediate-size deletions in three cases who underwent ES that were not validated for CNV detection, pathogenic variants within the non-protein coding genes SNORD118 and RNU7-1, pathogenic variant within the promoter region of GJB1, and a coding pathogenic variant within BCAP31 which was not sufficiently covered on ES. GS following non-diagnostic ES led to the identification of pathogenic variants in this cohort of nine cases, four of which would not have been identified by reanalysis alone.

In Silico Methods for the Discovery of Kv7.2/7.3 Channels Modulators: A Comprehensive Review.

The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with developmental plateauing or regression. Nevertheless, there is a lack of available therapeutic options, considering that retigabine, the only molecule used in clinic as a broad-spectrum Kv7 agonist, has been withdrawn from the market in late 2016. This is why several efforts have been made both by both academia and industry in the search for suitable chemotypes acting as Kv7.2/7.3 agonists. In this context, in silico methods have played a major role, since the precise structures of different Kv7 homotetramers have been only recently disclosed. In the present review, the computational methods used for the design of Kv.7.2/7.3 small molecule agonists and the underlying medicinal chemistry are discussed in the context of their biological and structure-function properties.

Epilepsy and Cognition in GM2-Gangliosidosis B1 Variant – Experience of a Tertiary Hospital

Introduction: GM2 gangliosidosis B1 variant (GM2B1) is an autosomal recessive disorder due to deficiency of β-hexosaminidase A, leading to the lysosomal storage of GM2 gangliosides in neuronal tissue and neuronal death. Symptoms include progressive motor coordination impairment and neurodegeneration, in children with previously normal development, leading to early death. Objective: Clinical characterization of patients with GM2B1 with a focus on epileptic manifestations. Methods: A descriptive retrospective study was conducted, analyzing clinical records of patients diagnosed with GM2B1 and followed at our Hospital Neuropediatric Department in the decade 2013-2022. Results: Four patients (three female) from three families diagnosed with GM2B1 were identified. The median age at diagnosis was 70 months. The most frequent symptoms at presentation were developmental regression (all children), language impairment (three), and epileptic seizures (two). Enzymatic deficiency in leukocytes and pathogenic variants in the HEXA gene were demonstrated in all cases. The pathogenic variant c.533G&gt;A(p.R178H) in exon 5 was present in seven of the eight alleles. All patients experienced language impairment (Md=42 mos) with complete language loss (Md=78 mos). Loss of walking ability occurred in three patients (Md=96 mos). All patients experienced epileptic seizures during the course of the disease, with a median onset of seizures at 55 months. Initial seizures were classified as atypical absences (two), tonic seizures (one) and myoclonic seizures (one). Electroencephalographic evaluation revealed slow basal rhythm and focal paroxysmal activity in all cases. All were treated with antiseizure medication, two requiring a combination of three drugs. Conclusion: GM2B1 encompasses a wide clinical spectrum, with heterogenous age of symptom onset, clinical presentation and disease progression. Epilepsy is a common comorbidity in GM2B1, with variable seizure type and severity, and may be difficult to control. Timely diagnosis, coupled with multidisciplinary clinical follow-up, is crucial to improve quality of life of patients and enable genetic counseling.