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Background and Objectives: KCNC2 encodes Kv3.2, a member of the Shaw-related (Kv3) voltage-gated potassium channel subfamily, which is important for sustained high-frequency firing and optimized energy efficiency of action potentials in the brain. The objective of this study was to analyze the clinical phenotype, genetic background, and biophysical function of disease-associated Kv3.2 variants., Methods: Individuals with KCNC2 variants detected by exome sequencing were selected for clinical, further genetic, and functional analysis. Cases were referred through clinical and research collaborations. Selected de novo variants were examined electrophysiologically in Xenopus laevis oocytes., Results: We identified novel KCNC2 variants in 18 patients with various forms of epilepsy, including genetic generalized epilepsy (GGE), developmental and epileptic encephalopathy (DEE) including early-onset absence epilepsy, focal epilepsy, and myoclonic-atonic epilepsy. Of the 18 variants, 10 were de novo and 8 were classified as modifying variants. Eight drug-responsive patients became seizure-free using valproic acid as monotherapy or in combination, including severe DEE cases. Functional analysis of 4 variants demonstrated gain of function in 3 severely affected DEE cases and loss of function in 1 case with a milder phenotype (GGE) as the underlying pathomechanisms., Discussion: These findings implicate KCNC2 as a novel causative gene for epilepsy and emphasize the critical role of K V 3.2 in the regulation of brain excitability., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Background: Acquired visual agnosia in the context of continuous spikes and waves during slow sleep (CSWS) is rarely described. We present a case of an almost 7-year-old boy who lost his ability to name pictures and recognize familiar faces. Initial encephalography (EEG) revealed sleep induced epileptiform activity with a spike-wave index (SWI) of 100%, predominanting in the left posterior head region., Methods: Serial neuropsychological testing with concomitant EEG was done during the first 18 months of treatment with intravenous methylprednisolone. We administered intelligence scales, verbal tasks (memory, fluency), visual tasks (drawings, search, face recognition), and tasks requiring visual-verbal integration (picture naming, visual closure)., Analyses: Neuropsychological recovery studied with reliable cognitive change cut-offs and 95% confidence intervals., Results: With treatment, there was an improvement of the EEG pattern (SWI reduction to 45%), followed by a relapse (SWI 82%). Neuropsychological measures in part synchronized with improvement, stability, and fluctuating values. Significant increases were seen on Verbal Comprehension Index and semantic memory. Visual Spatial Index remained unchanged (67 to 73). Naming pictures showed only limited change. Interpreting degraded pictures remained extremely difficult., Discussion: Acquired visual agnosia may be seen in children with CSWS. Early recognition, prompt accurate treatment and tailored neuropsychological assessment remain crucial., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Author(s).)

Pathogenic variants in the PCDH19 gene are associated with epilepsy, intellectual disability (ID) and behavioural disturbances. Only heterozygous females and mosaic males are affected, likely due to a disease mechanism named cellular interference. Until now, only four affected mosaic male patients have been described in literature. Here, we report five additional male patients, of which four are older than the oldest patient reported so far. All reported patients were selected for genetic testing because of developmental delay and/or epilepsy. Custom-targeted next generation sequencing gene panels for epilepsy genes were used. Clinical data were collected from medical records. All patients were mosaic in blood for likely pathogenic variants in the PCDH19 gene. In most, clinical features were very similar to the female phenotype, with normal development before seizure onset, which occurred between 5 and 10 months of age, clustering of seizures and sensitivity to fever. Four out of five patients had mild to severe ID and behavioural problems. We reaffirm the similarity between male and female PCDH19-related phenotypes, now also in a later phase of the disorder (ages 10-14 years).

Objective: To study the effect of vaccination-associated seizure onset on disease course and estimate the risk of subsequent seizures after infant pertussis combination and measles, mumps, and rubella (MMR) vaccinations in Dravet syndrome (DS)., Methods: We retrospectively analyzed data from hospital medical files, child health clinics, and the vaccination register for children with DS and pathogenic SCN1A mutations. Seizures within 24 hours after infant whole-cell, acellular, or nonpertussis combination vaccination or within 5 to 12 days after MMR vaccination were defined as "vaccination-associated." Risks of vaccination-associated seizures for the different vaccines were analyzed in univariable and in multivariable logistic regression for pertussis combination vaccines and by a self-controlled case series analysis using parental seizure registries for MMR vaccines. Disease courses of children with and without vaccination-associated seizure onset were compared., Results: Children who had DS (n = 77) with and without vaccination-associated seizure onset (21% and 79%, respectively) differed in age at first seizure (median 3.7 vs 6.1 months, p < 0.001) but not in age at first nonvaccination-associated seizure, age at first report of developmental delay, or cognitive outcome. The risk of subsequent vaccination-associated seizures was significantly lower for acellular pertussis (9%; odds ratio 0.18, 95% confidence interval [CI] 0.05-0.71) and nonpertussis (8%; odds ratio 0.11, 95% CI 0.02-0.59) than whole-cell pertussis (37%; reference) vaccines. Self-controlled case series analysis showed an increased incidence rate ratio of seizures of 2.3 (95% CI 1.5-3.4) within the risk period of 5 to 12 days following MMR vaccination., Conclusions: Our results suggest that vaccination-associated earlier seizure onset does not alter disease course in DS, while the risk of subsequent vaccination-associated seizures is probably vaccine-specific., (© 2015 American Academy of Neurology.)

Objective: To study the pattern of cognitive development in relation to duration of epilepsy., Methods: Participants were 113 children with epilepsy referred because of concerns about their cognitive development and tested at least twice at tertiary epilepsy settings. Verbal, Performance, and Full Scale IQ were measured with Wechsler Intelligence Scales. Various epilepsy and demographic variables were included. Change over time was modeled with multilevel analysis for longitudinal data with variable measurement occasion., Results: The Verbal and Full Scales could be fitted best as a downward progressing function. Earlier in time, decline was likely to be largest; later in time, decline followed a continuous, dwindling course. A similar trend was seen for the Performance Scale. Initially, Verbal IQ was higher than Performance IQ but this discrepancy decreased over time. Later onset of epilepsy was associated with an attenuated decline of the Verbal Scale. None of the other epilepsy variables were related to the course of cognitive development. Higher parental education was associated with higher IQ, but was not protective against decline., Conclusions: Verbal IQ, though initially spared, drops. The Performance IQ, which may have shown its vulnerability earlier in the course of the epilepsy, shows overall smaller changes. It is suggested that seizures impact synergistically on an affected brain, which leads to progressive cognitive decline. Earlier onset of epilepsy is associated with relatively higher VIQ, larger VIQ > PIQ discrepancies and more decline., (PsycINFO Database Record (c) 2014 APA, all rights reserved.)

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is an autosomal recessive inborn error of metabolism, most frequently associated with developmental delay and/or epilepsy. Most SCADD patients carry common SCAD-encoding gene ( ACADS) variants or these variants in combination with a rare ACADS mutation, in the Netherlands predominantly the c.1058C>T. Epilepsy in childhood often remains unexplained and patients with epilepsy related to SCADD may remain undiagnosed because studies for SCADD are often not performed. To test this hypothesis and to further estimate the extent of the Dutch SCADD population, we performed a study on blood spot samples in 131 paediatric patients with epilepsy and 909 anonymous newborns and investigated the presence of the 2 common ACADS variants and the rare c.1058C>T mutation. Overall, the 2 common ACADS variants and the rare c.1058C>T mutation were detected in either homozygous or compound heterozygous forms in 9.2% of the epilepsy and 7.5% of the reference group. A birth prevalence of SCADD with a mutation/variant genotype in the Netherlands as high as >1:1,000 was calculated. This is in contrast with the low number of patients diagnosed clinically and supports the hypothesis that SCADD is clinically irrelevant. Furthermore our study does not support an association between SCADD and epilepsy., (© Georg Thieme Verlag KG Stuttgart · New York.)

Purpose: Univerricht-Lundborg disease (ULD), with its major symptom of action myoclonus, is supposed to be very rare in the Netherlands and western Europe. We hypothesized that the syndrome may be underdiagnosed in patients with myoclonus epilepsy., Methods: Mutation analysis of the cystatin B gene was performed in 21 cases with uncontrolled myoclonus., Results: Seven of the 21 evaluated cases carried mutations in the cystatin B gene. Diagnosis of ULD was made with a mean delay of 20 years from symptom onset., Conclusions: This study from a country without previous reports of ULD suggests that underdiagnosis of the syndrome is likely. These findings also indicate that persons with juvenile-onset myoclonus epilepsy with action myoclonus should be analyzed for ULD., (Copyright 2004 International League Against Epilepsy)

Ring chromosome 20 mosaicism is associated with dysmorphic features, mental retardation, and intractable seizures, including recurrent episodes of nonconvulsive status epilepticus. The authors' findings in four children, all without dysmorphic features, indicate that mental deterioration and frequent subtle nocturnal frontal lobe seizures, associated with a characteristic EEG pattern, represent prominent additional clinical features not previously described in this syndrome. This emphasizes the importance of full-night video-EEG in children with frontal lobe seizures and cognitive deterioration.

Purpose: Extensive experience with video-EEG seizure monitoring, notably in the setting of epilepsy surgery programs, has exposed the limited value of the current International Classification of Epileptic Seizures (ICES) for providing relevant localizing information. To overcome this limitation, a Semiologic Seizure Classification (SSC) has recently been proposed. This study aimed to assess and to compare the usefulness and reliability of both systems in the setting of a tertiary epilepsy center., Methods: Three epileptologists independently reviewed video-taped seizures, randomly selected from the archive of the Epilepsy Monitoring Unit. They were blinded to the EEG findings and final diagnosis and classified all seizures according to both classifications., Results: One hundred thirty-eight seizures from 60 patients (age range, 2-59 years) were reviewed (maximum, three seizures per patient). Fifty-five seizures from 20 patients were recorded in the setting of presurgical evaluations, and the remainder as part of regular diagnostic evaluations. The average interobserver agreement was higher for SSC (63.3%, kappa = 0. 56) than for ICES (38.6%, kappa = 0.41). Some categories of SSC, such as hypermotor or automotor, had the best interobserver agreement, and were strongly correlated with the anatomic localization of the seizures (frontal and temporal lobe, respectively). All reviewers agreed that SSC provided a better description of the seizures than did ICES, in 60% of the patients., Conclusions: SSC provides a more comprehensive picture of epileptic seizures than does ICES, notably in patients with localized epilepsy syndromes, and appears to be very useful and reliable, particularly in the setting of specialized epilepsy centers.

Progressive myoclonus epilepsy of the Lafora type or Lafora disease (EPM2; McKusick no. 254780) is an autosomal recessive disorder characterized by epilepsy, myoclonus, progressive neurological deterioration and glycogen-like intracellular inclusion bodies (Lafora bodies). A gene for EPM2 previously has been mapped to chromosome 6q23-q25 using linkage analysis and homozygosity mapping. Here we report the positional cloning of the 6q EPM2 gene. A microdeletion within the EPM2 critical region, present inhomozygosis in an affected individual, was found to disrupt a novel gene encoding a putative protein tyrosine phosphatase (PTPase). The gene, denoted EPM2, presents alternative splicing in the 5' and 3' end regions. Mutational analysis revealed that EPM2 patients are homozygous for loss-of-function mutations in EPM2. These findings suggest that Lafora disease results from the mutational inactivation of a PTPase activity that may be important in the control of glycogen metabolism.

Isolated mineralocorticoid deficiency is described in a 5-week-old boy. The deficiency progressed to general adrenal insufficiency during the boy's first year of life. The family history suggested X-linked inheritance. At 18 months of age the patient developed acute bilateral infantile striatal necrosis, which might suggest a possible relationship between both entities.

Two half-sisters aged 14 and 18 years are described with a rigid spine syndrome as the cardinal clinical feature of an autosomal dominant neuromuscular disorder. Ten years previously, a diagnosis of multicore disease had been made from the clinical signs and muscle biopsy findings. Long term follow-up revealed a non-specific muscular dystrophy with axial predominance and a rigid spine in the younger girl; the older sister presented at the age of 18 with a rigid spine as the only myopathic sign. Computed tomography of the muscles showed severe involvement of the paraspinal musculature, in contrast with either less or no involvement of the other muscles.