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Contains fulltext : 231688.pdf (Publisher’s version ) (Closed access), PURPOSE: Pathogenic variants in the X-linked gene NEXMIF (previously KIAA2022) are associated with intellectual disability (ID), autism spectrum disorder, and epilepsy. We aimed to delineate the female and male phenotypic spectrum of NEXMIF encephalopathy. METHODS: Through an international collaboration, we analyzed the phenotypes and genotypes of 87 patients with NEXMIF encephalopathy. RESULTS: Sixty-three females and 24 males (46 new patients) with NEXMIF encephalopathy were studied, with 30 novel variants. Phenotypic features included developmental delay/ID in 86/87 (99%), seizures in 71/86 (83%) and multiple comorbidities. Generalized seizures predominated including myoclonic seizures and absence seizures (both 46/70, 66%), absence with eyelid myoclonia (17/70, 24%), and atonic seizures (30/70, 43%). Males had more severe developmental impairment; females had epilepsy more frequently, and varied from unaffected to severely affected. All NEXMIF pathogenic variants led to a premature stop codon or were deleterious structural variants. Most arose de novo, although X-linked segregation occurred for both sexes. Somatic mosaicism occurred in two males and a family with suspected parental mosaicism. CONCLUSION: NEXMIF encephalopathy is an X-linked, generalized developmental and epileptic encephalopathy characterized by myoclonic-atonic epilepsy overlapping with eyelid myoclonia with absence. Some patients have developmental encephalopathy without epilepsy. Males have more severe developmental impairment. NEXMIF encephalopathy arises due to loss-of-function variants.

Objective: To study the epilepsy syndromes among the severe epilepsies of infancy and assess their incidence, etiologies, and outcomes. Method(s): A population-based cohort study was undertaken of severe epilepsies with onset before age 18 months in Victoria, Australia. Two epileptologists reviewed clinical features, seizure videos, and electroencephalograms to diagnose International League Against Epilepsy epilepsy syndromes. Incidence, etiologies, and outcomes at age 2 years were determined. Result(s): Seventy-three of 114 (64%) infants fulfilled diagnostic criteria for epilepsy syndromes at presentation, and 16 (14%) had "variants" of epilepsy syndromes in which there was one missing or different feature, or where all classical features had not yet emerged. West syndrome (WS) and "WS-like" epilepsy (infantile spasms without hypsarrhythmia or modified hypsarrhythmia) were the most common syndromes, with a combined incidence of 32.7/100 000 live births/year. The incidence of epilepsy of infancy with migrating focal seizures (EIMFS) was 4.5/100 000 and of early infantile epileptic encephalopathy (EIEE) was 3.6/100 000. Structural etiologies were common in "WS-like" epilepsy (100%), unifocal epilepsy (83%), and WS (39%), whereas single gene disorders predominated in EIMFS, EIEE, and Dravet syndrome. Eighteen (16%) infants died before age 2 years. Development was delayed or borderline in 85 of 96 (89%) survivors, being severe-profound in 40 of 96 (42%). All infants with EIEE or EIMFS had severe-profound delay or were deceased, but only 19 of 64 (30%) infants with WS, "WS-like," or "unifocal epilepsy" had severe-profound delay, and only two of 64 (3%) were deceased. Significance: Three quarters of severe epilepsies of infancy could be assigned an epilepsy syndrome or "variant syndrome" at presentation. In this era of genomic testing and advanced brain imaging, diagnosing epilepsy syndromes at presentation remains clinically useful for guiding etiologic investigation, i

Currently there is no secured ongoing funding in Australia for next generation sequencing (NGS) such as exome sequencing (ES) for adult neurological disorders. Studies have focused on paediatric populations in research or highly specialised settings, utilised standard NGS pipelines focusing only on small insertions, deletions and single nucleotide variants, and not explored impacts on management in detail. This prospective multi-site study performed ES and an extended bioinformatics repeat expansion analysis pipeline, on patients with broad phenotypes (ataxia, dementia, dystonia, spastic paraparesis, motor neuron disease, Parkinson's disease and complex/not-otherwise-specified), with symptom onset between 2 and 60 years. Genomic data analysis was phenotype-driven, using virtual gene panels, reported according to American College of Medical Genetics and Genomics guidelines. One-hundred-and-sixty patients (51% female) were included, median age 52 years (range 14-79) and median 9 years of symptoms. 34/160 (21%) patients received a genetic diagnosis. Highest diagnostic rates were in spastic paraparesis (10/25, 40%), complex/not-otherwise-specified (10/38, 26%) and ataxia (7/28, 25%) groups. Findings were considered 'possible/uncertain' in 21/160 patients. Repeat expansion detection identified an unexpected diagnosis of Huntington disease in an ataxic patient with negative ES. Impacts on management, such as more precise and tailored care, were seen in most diagnosed patients (23/34, 68%). ES and a novel bioinformatics analysis pipepline had a substantial diagnostic yield (21%) and management impacts for most diagnosed patients, in heterogeneous, complex, mainly adult-onset neurological disorders in real-world settings in Australia, providing evidence for NGS and complementary multiple, new technologies as valuable diagnostic tools.Copyright © 2020 Elsevier B.V.

Objective: Febrile seizures may follow vaccination. Common variants in the sodium channel gene, SCN1A, are associated with febrile seizures, and rare pathogenic variants in SCN1A cause the severe developmental and epileptic encephalopathy Dravet syndrome. Following vaccination, febrile seizures may raise the specter of poor outcome and inappropriately implicate vaccination as the cause. We aimed to determine the prevalence of SCN1A variants in children having their first febrile seizure either proximal to vaccination or unrelated to vaccination compared to controls. Method(s): We performed SCN1A sequencing, blind to clinical category, in a prospective cohort of children presenting with their first febrile seizure as vaccine proximate (n = 69) or as non-vaccine proximate (n = 75), and children with no history of seizures (n = 90) recruited in Australian pediatric hospitals. Result(s): We detected 2 pathogenic variants in vaccine-proximate cases (p.R568X and p.W932R), both of whom developed Dravet syndrome, and 1 in a non-vaccine-proximate case (p.V947L) who had febrile seizures plus from 9 months. All had generalized tonic-clonic seizures lasting >15 minutes. We also found enrichment of a reported risk allele, rs6432860-T, in children with febrile seizures compared to controls (odds ratio = 1.91, 95% confidence interval = 1.31-2.81). Interpretation(s): Pathogenic SCN1A variants may be identified in infants with vaccine-proximate febrile seizures. As early diagnosis of Dravet syndrome is essential for optimal management and outcome, SCN1A sequencing in infants with prolonged febrile seizures, proximate to vaccination, should become routine. ANN NEUROL 2020;87:281-288.Copyright © 2019 American Neurological Association

Meeting abstract: 33rd International Epilepsy Congress Bangkok, Thailand 22 – 26 June 2019

Item does not contain fulltext, Developmental and epileptic encephalopathy (DEE) is a group of conditions characterized by the co-occurrence of epilepsy and intellectual disability (ID), typically with developmental plateauing or regression associated with frequent epileptiform activity. The cause of DEE remains unknown in the majority of cases. We performed whole-genome sequencing (WGS) in 197 individuals with unexplained DEE and pharmaco-resistant seizures and in their unaffected parents. We focused our attention on de novo mutations (DNMs) and identified candidate genes containing such variants. We sought to identify additional subjects with DNMs in these genes by performing targeted sequencing in another series of individuals with DEE and by mining various sequencing datasets. We also performed meta-analyses to document enrichment of DNMs in candidate genes by leveraging our WGS dataset with those of several DEE and ID series. By combining these strategies, we were able to provide a causal link between DEE and the following genes: NTRK2, GABRB2, CLTC, DHDDS, NUS1, RAB11A, GABBR2, and SNAP25. Overall, we established a molecular diagnosis in 63/197 (32%) individuals in our WGS series. The main cause of DEE in these individuals was de novo point mutations (53/63 solved cases), followed by inherited mutations (6/63 solved cases) and de novo CNVs (4/63 solved cases). De novo missense variants explained a larger proportion of individuals in our series than in other series that were primarily ascertained because of ID. Moreover, these DNMs were more frequently recurrent than those identified in ID series. These observations indicate that the genetic landscape of DEE might be different from that of ID without epilepsy.

Objective We evaluated seizure outcome in a large cohort of familial neonatal seizures (FNS), and examined phenotypic overlap with different molecular lesions. Methods Detailed clinical data were collected from 36 families comprising two or more individuals with neonatal seizures. The seizure course and occurrence of seizures later in life were analyzed. Families were screened for KCNQ2, KCNQ3, SCN2A, and PRRT2 mutations, and linkage studies were performed in mutation-negative families to exclude known loci. Results Thirty-three families fulfilled clinical criteria for benign familial neonatal epilepsy (BFNE); 27 of these families had KCNQ2 mutations, one had a KCNQ3 mutation, and two had SCN2A mutations. Seizures persisting after age 6 months were reported in 31% of individuals with KCNQ2 mutations; later seizures were associated with frequent neonatal seizures. Linkage mapping in two mutation-negative BFNE families excluded linkage to KCNQ2, KCNQ3, and SCN2A, but linkage to KCNQ2 could not be excluded in the third mutation-negative BFNE family. The three remaining families did not fulfill criteria of BFNE due to developmental delay or intellectual disability; a molecular lesion was identified in two; the other family remains unsolved. Significance Most families in our cohort of familial neonatal seizures fulfill criteria for BFNE; the molecular cause was identified in 91%. Most had KCNQ2 mutations, but two families had SCN2A mutations, which are normally associated with a mixed picture of neonatal and infantile onset seizures. Seizures later in life are more common in BFNE than previously reported and are associated with a greater number of seizures in the neonatal period. Linkage studies in two families excluded known loci, suggesting a further gene is involved in BFNE.Copyright © Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Objective Nocturnal frontal lobe epilepsy (NFLE) can be sporadic or autosomal dominant; some families have nicotinic acetylcholine receptor subunit mutations. We report a novel autosomal recessive phenotype in a single family and identify the causative gene. Methods Whole exome sequencing data was used to map the family, thereby narrowing exome search space, and then to identify the mutation. Results Linkage analysis using exome sequence data from two affected and two unaffected subjects showed homozygous linkage peaks on chromosomes 7, 8, 13, and 14 with maximum LOD scores between 1.5 and 1.93. Exome variant filtering under these peaks revealed that the affected siblings were homozygous for a novel splice site mutation (c.93+2T>C) in the PRIMA1 gene on chromosome 14. No additional PRIMA1 mutations were found in 300 other NFLE cases. The c.93+2T>C mutation was shown to lead to skipping of the first coding exon of the PRIMA1 mRNA using a minigene system. Interpretation PRIMA1 is a transmembrane protein that anchors acetylcholinesterase (AChE), an enzyme hydrolyzing acetycholine, to membrane rafts of neurons. PRiMA knockout mice have reduction of AChE and accumulation of acetylcholine at the synapse; our minigene analysis suggests that the c.93+2T>C mutation leads to knockout of PRIMA1. Mutations with gain of function effects in acetylcholine receptor subunits cause autosomal dominant NFLE. Thus, enhanced cholinergic responses are the likely cause of the severe NFLE and intellectual disability segregating in this family, representing the first recessive case to be reported and the first PRIMA1 mutation implicated in disease.

Item does not contain fulltext, We previously identified a homozygous mutation in the Golgi SNAP receptor complex 2 gene (GOSR2) in six patients with progressive myoclonus epilepsy. To define the syndrome better we analysed the clinical and electrophysiological phenotype in 12 patients with GOSR2 mutations, including six new unrelated subjects. Clinical presentation was remarkably similar with early onset ataxia (average 2 years of age), followed by myoclonic seizures at the average age of 6.5 years. Patients developed multiple seizure types, including generalized tonic clonic seizures, absence seizures and drop attacks. All patients developed scoliosis by adolescence, making this an important diagnostic clue. Additional skeletal deformities were present, including pes cavus in four patients and syndactyly in two patients. All patients had elevated serum creatine kinase levels (median 734 IU) in the context of normal muscle biopsies. Electroencephalography revealed pronounced generalized spike and wave discharges with a posterior predominance and photosensitivity in all patients, with focal EEG features seen in seven patients. The disease course showed a relentless decline; patients uniformly became wheelchair bound (mean age 13 years) and four had died during their third or early fourth decade. All 12 cases had the same variant (c.430G>T, G144W) and haplotype analyses confirmed a founder effect. The cases all came from countries bounding the North Sea, extending to the coastal region of Northern Norway. 'North Sea' progressive myoclonus epilepsy has a homogeneous clinical presentation and relentless disease course allowing ready identification from the other progressive myoclonus epilepsies.

Epileptic encephalopathies are a devastating group of epilepsies with poor prognosis, of which the majority are of unknown etiology. We perform targeted massively parallel resequencing of 19 known and 46 candidate genes for epileptic encephalopathy in 500 affected individuals (cases) to identify new genes involved and to investigate the phenotypic spectrum associated with mutations in known genes. Overall, we identified pathogenic mutations in 10% of our cohort. Six of the 46 candidate genes had 1 or more pathogenic variants, collectively accounting for 3% of our cohort. We show that de novo CHD2 and SYNGAP1 mutations are new causes of epileptic encephalopathies, accounting for 1.2% and 1% of cases, respectively. We also expand the phenotypic spectra explained by SCN1A, SCN2A and SCN8A mutations. To our knowledge, this is the largest cohort of cases with epileptic encephalopathies to undergo targeted resequencing. Implementation of this rapid and efficient method will change diagnosis and understanding of the molecular etiologies of these disorders. © 2013 Nature America, Inc. All rights reserved.

Purpose: Epileptic encephalopathies (EEs) are a devastating group of epilepsies characterized by refractory seizures, cognitive arrest or regression, associated with ongoing epileptic activity, and a poor prognosis. De novo mutations in a number of genes, as well as rare, de novo copy number changes, are known to cause EE. However, the vast majority of cases have an unknown etiology. Method(s): We performed targeted massively parallel resequencing of 18 known and 47 candidate EE genes in 500 patients to identify novel genes, and investigate the phenotypic spectrum of known genes. Result(s): Overall, we identify pathogenic mutations in 10% of our cohort. Pathogenic variants were found in seven of our 47 candidate genes, collectively accounting for 3% of EE in our cohort. Most notably, we identify mutations in 1.2% of our cohort in a novel gene that acts in the chromatin remodeling pathway. Also, de novo mutations were detected in 1% of the cohort in SYNGAP1, a gene identified in individuals with intellectual disability. The remaining pathogenic variants were detected in known EE genes. For some, including SCN1A, SCN2A, and SCN8A, we expand the phenotypic spectrum, presenting novel clinical features associated with these genes. Conclusion(s): We have developed a rapid, cost-effective ($1/gene/proband) and efficient targeted resequencing approach to define the molecular etiology of EE. These results will transform molecular diagnostic approaches and facilitate the management of families affected by this devastating disorder. Furthermore, we have identified the chromatin remodeling pathway as a novel biological process involved in epileptogenesis. Future studies of this pathway will provide new avenues for development of therapeutic interventions.

Multiple Symmetrical Lipomatosis (MSL) is an unusual disorder characterized by the development of axial lipomas in adulthood. The pathoetiology of lipoma tissue in MSL remains unresolved. Seven patients with MSL were followed for a mean period of 12. years (8-20 years). All patients had cervical lipomas ranging from subtle lesions to disfiguring masses; six patients had peripheral neuropathy and five had proximal myopathy. Myoclonus, cerebellar ataxia and additional lipomas were variably present. All patients showed clinical progression. Muscle histopathology was consistent with mitochondrial disease. Five patients were positive for mtDNA point mutation m.8344A. >. G, three of whom underwent lipoma resection - all samples were positive for uncoupling protein-1 mRNA (unique to brown fat). Lipoma from one case stained positive for adipocyte fatty-acid protein-2 (unique to brown fat and immature adipocytes). This long-term study hallmarks the phenotypic heterogeneity of MSL's associated clinical features. The clinical, genetic and molecular findings substantiate the hypothesis that lipomas in MSL are due to a mitochondrial disorder of brown fat. © 2013 Elsevier B.V. and Mitochondria Research Society.

Data from animal studies suggest that serotonin release promotes wakefulness and suppresses REM sleep, but there are dangers in extrapolating these findings to humans. Binding of the radioligand [18F]MPPF to 5HT1A receptors is sensitive to levels of endogenous serotonin. In this study, we aimed to demonstrate changes in serotonin receptor availability in the human brain in wakefulness and sleep using [18F]MPPF and positron emission tomography. 14 subjects with narcolepsy cataplexy underwent [18F]MPPF PET scans in wakefulness and in sleep. Subjects who used the stimulant methylphenidate took their normal medication for the wake scan but omitted it prior to the sleep scan. The change in binding potential (BP) between the sleep and wake scans was examined using paired t test. Methylphenidate is thought to have little or no effect on serotonergic neurotransmission, and in order to confirm the absence of an effect on [ 18F]MPPF binding, a concurrent study was performed using a beta-microprobe technique to examine the effect of methylphenidate administration on [18F]MPPF binding in Sprague-Dawley rats. The human study showed a significant increase in [18F]MPPF binding in sleep compared to wakefulness in the whole brain and all regions of interest examined (temporal cortex, mesial temporal region and cingulate cortex). The beta-microprobe study confirmed that methylphenidate administration had no effect on [18F]MPPF binding. These findings indicate that serotonin receptor availability is increased in sleep compared to wakefulness in narcoleptic humans. © 2005 Elsevier Inc. All rights reserved.

Purpose: Severe myoclonic epilepsy of infancy (SMEI) is an intractable epilepsy of early childhood of unknown etiology. It is often associated with a family history of seizure disorders, but epilepsy phenotypes have not been well described. We sought to characterize the seizure phenotypes of relatives to better understand to the genetic basis of SMEI. Method(s): Probands with SMEI were identified, and systematic family studies were performed. Epilepsy syndromes were characterized in affected family members. Result(s): Twelve probands with SMEI were identified. Eleven of the 12 probands with SMEI had a family history of seizures, and the twelfth was the result of a consanguineous marriage. We found that 16.7% of full siblings and 8.3% of parents had definite seizures. A total of 39 affected family members was identified. The most common phenotype was febrile seizures in 14, febrile seizures plus in seven, partial epilepsy in two, and there were single individuals with SMEI, myoclonic-astatic epilepsy, Lennox-Gastaut syndrome, and 13 cases with unclassified or unconfirmed seizures. Conclusion(s): The family history of seizures in SMEI is in keeping with the spectrum of seizure phenotypes seen in generalized epilepsy with febrile seizures plus (GEFS+). Our findings suggest that SMEI is the most severe phenotype in the GEFS+ spectrum.

Background: Abnormal paroxysmal events in sleep may be parasomnias or epileptic seizures. In nocturnal frontal lobe epilepsy (NFLE), the unusual seizure features often lead to diagnostic confusion with nonepileptic parasomnias; video-electroencephalography monitoring is usually required to make the diagnosis. Objective(s): To examine the reliability of the clinical history in diagnosing NFLE, using the Frontal Lobe Epilepsy and Parasomnias (FLEP) scale. Design(s): The FLEP scale, comprising specific questions reflecting the diagnostic features of NFLE and parasomnias, was developed by an expert panel following review of the literature. It was then validated in a sample of individuals with firmly diagnosed nocturnal events. Setting(s): Patients were recruited after appropriate diagnostic workup in tertiary sleep and epilepsy referral centers in Melbourne, Australia. Participant(s): Sixty-two patients (45 men) with paroxysmal nocturnal events. Intervention(s): Two independent interviews were conducted in each case, with the patient and a witness, by researchers blinded to the diagnosis. Main Outcome Measure(s): The diagnosis obtained from scores on the FLEP scale was compared with the confirmed diagnosis in each patient. Result(s): Nocturnal frontal lobe epilepsy was correctly diagnosed from the FLEP score in 31 of 31 patients, with a sensitivity of 1.0 (95% confidence interval [CI], 0.85-1.00), specificity of 0.90 (95% CI, 0.73-0.97), positive predictive value of 0.91 (95% CI, 0.75-0.97), and negative predictive value of 1.00 (95% CI, 0.85-1.00). Conclusion(s): A diagnosis of NFLE can be made reliably using the clinical features identified in the FLEP scale. This may reduce the requirement for tertiary referral and extensive inpatient monitoring. ©2006 American Medical Association. All rights reserved.

Photosensitive seizures occur most commonly in childhood and adolescence, usually as a manifestation of complex idiopathic generalized epilepsies (IGEs). Molecular mechanisms underlying this condition are yet to be determined because no susceptibility genes have been identified. The NEDD4-2 (Neuronally Expressed Developmentally Downregulated 4) gene encodes a ubiquitin protein ligase proposed to regulate cell surface levels of several ion channels, receptors and transporters involved in regulating neuronal excitability, including voltage-gated sodium channels (VGSCs), the most clinically relevant of the epilepsy genes. The regulation of NEDD4-2 in vivo involves complex interactions with accessory proteins in a cell type specific manner. We screened NEDD4-2 for mutations in a cohort of 253 families with IGEs. We identified three NEDD4-2 missense changes in highly conserved residues; S233L, E271A and H515P in families with photosensitive generalized epilepsy. The NEDD4-2 variants were as effective as wild-type NEDD4-2 in downregulating the VGSC subtype Na v1.2 when assessed in the Xenopus oocyte heterologous expression system showing that the direct interaction with the ion channel was not altered by these variants. These data raise the possibility that photosensitive epilepsy may arise from defective interaction of NEDD4-2 with as yet unidentified accessory or target proteins. © 2007 Blackwell Publishing Ltd.

Recent molecular insights into the human idiopathic epilepsies have suggested the central role of ligand-gated and voltage-gated ion channels in their etiology. So far, genes coding for sodium and potassium channel subunits as well as a nicotinic cholinergic receptor subunit have been identified for Mendelian idiopathic epilepsies. In vitro and in vivo studies of mutations demonstrate functional changes, allowing new insights in mechanisms underlying hyperexcitability. Similarly, spontaneous murine epilepsy models have been associated with calcium channel molecular defects. The major challenge before us in understanding the genetics of the epilepsies is to identify genes for common forms of epilepsy following complex inheritance. Once such genes are discovered, the gene-gene-environmental interactions producing specific epilepsy syndromes can be explored. (C) 2000 Lippincott Williams and Wilkins, Inc.

Two novel mutations (R85C and R85H) on the extracellular immunoglobulin-like domain of the sodium channel beta1 subunit have been identified in individuals from two families with generalized epilepsy with febrile seizures plus (GEFS+). The functional consequences of these two mutations were determined by co-expression of the human brain NaV1.2 alpha subunit with wild type or mutant beta1 subunits in human embryonic kidney (HEK)-293T cells. Patch clamp studies confirmed the regulatory role of beta1 in that relative to NaV1.2 alone the NaV1.2+beta1 currents had right-shifted voltage dependence of activation, fast and slow inactivation and reduced use dependence. In addition, the NaV1.2+beta1 current entered fast inactivation slightly faster than NaV1.2 channels alone. The beta1(R85C) subunit appears to be a complete loss of function in that none of the modulating effects of the wild type beta1 were observed when it was co-expressed with NaV1.2. Interestingly, the beta1(R85H) subunit also failed to modulate fast kinetics, however, it shifted the voltage dependence of steady state slow inactivation in the same way as the wild type beta1 subunit. Immunohistochemical studies revealed cell surface expression of the wild type beta1 subunit and undetectable levels of cell surface expression for both mutants. The functional studies suggest association of the beta1(R85H) subunit with the alpha subunit where its influence is limited to modulating steady state slow inactivation. In summary, the mutant beta1 subunits essentially fail to modulate alpha subunits which could increase neuronal excitability and underlie GEFS+ pathogenesis. © 2007 IBRO.

We identified two large French-Canadian families segregating a familial partial epilepsy syndrome with variable foci (FPEVF) characterized by mostly nocturnal seizures arising from frontal, temporal, and occasionally occipital epileptic foci. There is no evidence for structural brain damage or permanent neurological dysfunction. The syndrome is inherited as an autosomal dominant trait with incomplete penetrance. We mapped the disease locus to a 3.8-cM interval on chromosome 22q11-q12, between markers D22S1144 and D22S685. Using the most conservative diagnostic scheme, the maximum cumulative LOD score was 6.53 at recombination fraction (theta) 0 with D22S689. The LOD score in the larger family was 5.34 at theta = 0 with the same marker. The two families share an identical linked haplotype for >=10 cM, including the candidate interval, indicating a recent founder effect. A severe phenotype in one of the probands may be caused by homozygosity for the causative mutation, as suggested by extensive homozygosity for the linked haplotype and a bilineal family history of epilepsy. An Australian family with a similar phenotype was not found to link to chromosome 22, indicating genetic heterogeneity of FPEVF.

The majority of severe epileptic encephalopathies of early childhood are symptomatic where a clear etiology is apparent. There is a small subgroup, however, where no etiology is found on imaging and metabolic studies, and genetic factors are important. Myoclonic-astatic epilepsy (MAE) and severe myoclonic epilepsy in infancy (SMEI), also known as Dravet syndrome, are epileptic encephalopathies where multiple seizure types begin in the first few years of life associated with developmental slowing. Clinical and molecular genetic studies of the families of probands with MAE and SMEI suggest a genetic basis. MAE was originally identified as part of the genetic epilepsy syndrome generalized epilepsy with febrile seizures plus (GEFS+). Recent clinical genetic studies suggest that SMEI forms the most severe end of the spectrum of the GEFS+. GEFS+ has now been associated with molecular defects in three sodium channel subunit genes and a GABA subunit gene. Molecular defects of these genes have been identified in patients with MAE and SMEI. Interestingly, the molecular defects in MAE have been found in the setting of large GEFS+ pedigrees, whereas, more severe truncation mutations arising de novo have been identified in patients with SMEI. It is likely that future molecular studies will shed light on the interaction of a number of genes, possibly related to the same or different ion channels, which result in a severe phenotype such as MAE and SMEI. Copyright © 2001 Elsevier Science B.V.

Rare GABAA receptor gamma2 and alpha1 subunit mutations of pathogenic effect have been described segregating in families with "monogenic" epilepsies. We now report globally on the genetic variation contained within all 16 neuronal GABAA receptor subunit genes from the one patient cohort. The cohort consists of GEFS+, FS, and IGE subgroups as either sporadic cases or index cases from small families, with one index case from one large IGE family. The rarity of mutations and coding variation in general across all of the subunits suggests a low tolerance for mutations affecting GABA mediated neuronal inhibition. Characterization of the broader channelopathy load associated with susceptibility to these common epilepsies mostly with complex genetics will need to be expanded beyond the family of GABAA receptor subunits to all families of neuronal ion channels and their interacting molecules by systematic mutation detection associated with functional investigation of their naturally occurring genetic variations. © 2009.

Although epileptic photosensitivity is well known, its genetics and syndromic associations are incompletely understood. Seizures triggered by photic stimulation are usually a manifestation of the idiopathic generalized epilepsies, especially juvenile myoclonic epilepsy (JME), or of the occipital epilepsies. Idiopathic photosensitive occipital epilepsy (IPOE) is a focal epilepsy with colourful elementary visual auras, often with conscious tonic head and eye version; myoclonus is not a feature. All seizures are induced by photic stimuli. We describe four families with phenotypic overlap between JME and IPOE. Families were identified if two or more affected individuals had visual auras and electro-clinical features of an idiopathic epilepsy. Family members underwent detailed electro-clinical assessment. In addition, 40 unrelated JME probands were investigated systematically for unrecognized features of IPOE (visual aura and conscious head version). There were 12 affected individuals in four families; 11 were female. Clinical onset was at 8-21 years of age. Of 10 patients with visual auras, six had conscious head version and five also experienced myoclonic jerks; eight had non-photic induced tonic-clonic seizures (TCS). Of the remaining individuals, one had myoclonic jerks and occipital spikes; the other had TCS without visual aura or myoclonic jerks. Of 10 patients with EEG studies, eight had generalized spike and wave (GSW) and six had occipital spikes. All had photosensitivity with GSW and four had additional occipital spikes. Of the 40 JME probands, six had visual aura and/or conscious head version; five of these were photosensitive. There is overlap between the clusters of clinical features used to diagnose IPOE and JME. Half of the affected individuals in our families with visual aura had myoclonic jerks; the former is characteristic of IPOE and the latter of JME. Importantly, visual aura is not regarded as part of JME, nor myoclonus part of IPOE, but our data emp

Objective: To examine the genetic relationships among epilepsies with different seizure types-myoclonic, absence, and generalized tonic-clonic-within the idiopathic generalized epilepsies (IGEs). Background(s): Careful phenotype definition in the epilepsies may allow division into groups that share susceptibility genes. Examination of seizure type, a phenotypic characteristic less complex than IGE syndrome, may help to define more homogeneous subgroups. Method(s): Using the approach that found evidence of distinct genetic effects on myoclonic vs absence seizures in families from the Epilepsy Family Study of Columbia University, the authors examined an independent sample of families from Australia and Israel. They also examined the familial clustering of generalized tonic-clonic seizures (GTCs) within the IGEs in two combined data sets. Families were defined as concordant if all affected members had the same type of seizure or IGE syndrome, as appropriate for the analysis performed. Result(s): The proportion of families concordant for myoclonic vs absence seizures was greater than expected by chance in the Australian families. In addition, GTCs clustered in families with IGEs to a degree greater than expected by chance. Conclusion(s): These results provide additional evidence for distinct genetic effects on myoclonic vs absence seizures in an independent set of families and suggest that there is a genetic influence on the occurrence of generalized tonic-clonic seizures within the idiopathic generalized epilepsies. Copyright © 2005 by AAN Enterprises, Inc.

Purpose: We analyzed databases on chromosomal anomalies and epilepsy to identify chromosomal regions where abnormalities are associated with clinically recognizable epilepsy syndromes. The expectation was that these regions could then be offered as targets in the search for epilepsy genes. Method(s): The cytogenetic program of the Oxford Medical Database, and the PubMed database were used to identify chromosomal aberrations associated with seizures and/or EEG abnormalities. The literature on selected small anomalies thus identified was reviewed from a clinical and electroencephalographic viewpoint, to classify the seizures and syndromes according to the current International League Against Epilepsy (ILAE) classification. Result(s): There were 400 different chromosomal imbalances described with seizures or EEG abnormalities. Eight chromosomal disorders had a high association with epilepsy. These comprised: the Wolf-Hirschhorn (4p-) syndrome, Miller-Dieker syndrome (del 17p13.3), Angelman syndrome (del 15q11-q13), the inversion duplication 15 syndrome, terminal deletions of chromosome 1q and 1p, and ring chromosomes 14 and 20. Many other segments had a weaker association with seizures. The poor quality of description of the epileptology in many reports thwarted an attempt to make precise karyotype-phenotype correlations. Conclusion(s): We identified certain chromosomal regions where aberrations had an evident association with seizures, and these regions may be useful targets for gene hunters. New correlations with specific epilepsy syndromes were not revealed. Clinicians should continue to search for small chromosomal abnormalities associated with specific epilepsy syndromes that could provide important clues for finding epilepsy genes, and the epileptology should be rigorously characterized.

A missense mutation of the gamma2 subunit of the gamma-aminobutyric acid A (GABAA) receptor has been linked to an inherited human generalized epilepsy. As synaptic inhibition in the human brain is largely mediated by the GABAA receptor, we tested the hypothesis that the GABRG2(R43Q) mutation alters cortical excitability. Fourteen subjects affected by the GABRG2(R43Q) mutation (5 males, mean age: 44 +/- 15 years) and 24 controls (11 males, mean age: 38 +/- 11 years) were studied with transcranial magnetic stimulation (TMS). To assess the specificity of the effect of the mutation, 4 additional family members unaffected by the GABRG2(R43Q) mutation (2 males, mean age: 41 +/- 16 years) were included. Subjects affected by the GABRG2(R43Q) mutation demonstrated reduced net short-interval intracortical inhibition and increased intracortical facilitation assessed with paired-pulse stimulation. Subjects with the mutation had similar motor thresholds to controls both at rest and with weak voluntary activation. No significant differences were noted between groups in the cortical silent period. Our findings provide in vivo evidence for increased intracortical excitability in subjects affected by the GABRG2(R43Q) mutation. These findings are also likely to represent an important clue to the mechanisms linking this gene defect and the epilepsy phenotype. © The Author 2007. Published by Oxford University Press. All rights reserved.

Febrile seizures affect approximately 3% of all children under six years of age and are by far the most common seizure disorder. A small proportion of children with febrile seizures later develop ongoing epilepsy with afebrile seizures. Segregation analysis suggests the majority of cases have complex inheritance but rare families show apparent autosomal dominant inheritance. Two putative loci have been mapped (FEB1 and FEB2), but specific genes have not yet been identified. We recently described a clinical subset, termed generalized epilepsy with febrile seizures plus (GEFS+), in which many family members have seizures with fever that may persist beyond six years of age or be associated with afebrile generalized seizures. We now report linkage, in another large GEFS+ family, to chromosome region 19q13.1 and identification of a mutation in the voltage-gated sodium (Na+)-channel beta1 subunit gene (SCN1B). The mutation changes a conserved cysteine residue disrupting a putative disulfide bridge which normally maintains an extracellular immunoglobulin-like fold. Co-expression of the mutant beta1 subunit with a brain Na+-channel alpha subunit in Xenopus laevis oocytes demonstrates that the mutation interferes with the ability of the subunit to modulate channel-gating kinetics consistent with a loss-of-function allele. This observation develops the theme that idiopathic epilepsies are a family of channelopathies and raises the possibility of involvement of other Na+- channel subunit genes in febrile seizures and generalized epilepsies with complex inheritance patterns.

Background: Pulsatile GH secretion from the anterior pituitary is a key mediator of human growth regulation and is affected by a number of genetic and environmental factors. Activation of neuronal nicotinic acetylcholine (nACh) receptors promotes GH release, but the role of these receptors in growth regulation is unknown. Aim(s): Our aim was to assess the effect of a mutation in the alpha4 subunit of the nACh receptor on cholinergic-mediated GH release. Method(s): Forty-one healthy volunteers (24 male, age 36.2 +/- 12.2 yr, mean +/- SD) and 13 subjects with the alpha4-Ser248Phe mutation (four male, age 43.2 +/- 16.8 yr) were studied. Serum levels of GH, LH, FSH, prolactin, TSH, free T4, and cortisol were measured at baseline and at regular intervals after infusion of physostigmine. Height and weight were recorded in all participants as well as from additional family members with (n = 11, four male) and without (n = 16, seven male) the mutation. Result(s): Subjects with the mutation were shorter (1.62 +/- 0.08 vs. 1.72 +/- 0.09 m, P < 0.05) and had a greater body mass index (31 +/- 6 vs. 24 +/- 3kg/m 2, P < 0.05) than healthy volunteers and unaffected members of the pedigree. In controls, physostigmine markedly increased the serum levels of GH (mean increase, +732%). In contrast, the response to physostigmine was markedly blunted in subjects with the mutation (+104%, P > 0.2 vs. control). Conclusion(s): These findings suggest a role of the nACh receptor in human growth regulation. Copyright © 2008 by The Endocrine Society.

We examined the phenotypic variation and clinical genetics in nine families with generalized epilepsy with febrile seizures plus (GEFS+). This genetic epilepsy syndrome with heterogeneous phenotypes was hitherto described in only one family. We obtained genealogical information on 799 individuals and conducted detailed evaluation of 272 individuals. Ninety-one individuals had a history of seizures and 63 had epilepsy consistent with the GEFS+ syndrome. Epilepsy phenotypes were febrile seizures (FS) in 31, febrile seizures plus (FS+) in 15, FS+ with other seizure types (atonic, myoclonic, absence, or complex partial) in 8, and myoclonic-astatic epilepsy in 9 individuals. Inheritance was autosomal dominant with approximately 60% penetrance. This study confirms and expands the spectrum of GEFS+ and provides new insights into the phenotypic relationships and genetics of FS and the generalized epilepsies of childhood. Moreover, the ability to identify large families with this newly recognized common, childhood-onset, generalized genetic epilepsy syndrome suggests that it should be a prime target for attempts to identify genes relevant to FS and generalized epilepsy.