Polygenic risk scores as a marker for epilepsy risk across lifetime and after unspecified seizure events.

A diagnosis of epilepsy has significant consequences for an individual but is often challenging in clinical practice. Novel biomarkers are thus greatly needed. Here, we investigated how common genetic factors (epilepsy polygenic risk scores, [PRSs]) influence epilepsy risk in detailed longitudinal electronic health records (EHRs) of > 700k Finns and Estonians. We found that a high genetic generalized epilepsy PRS (PRSGGE) increased risk for genetic generalized epilepsy (GGE) (hazard ratio [HR] 1.73 per PRSGGE standard deviation [SD]) across lifetime and within 10 years after an unspecified seizure event. The effect of PRSGGE was significantly larger on idiopathic generalized epilepsies, in females and for earlier epilepsy onset. Analogously, we found significant but more modest focal epilepsy PRS burden associated with non-acquired focal epilepsy (NAFE). Here, we outline the potential of epilepsy specific PRSs to serve as biomarkers after a first seizure event.

Clustered de novo start-loss variants in GLUL result in a developmental and epileptic encephalopathy via stabilization of glutamine synthetase.

Glutamine synthetase (GS), encoded by GLUL, catalyzes the conversion of glutamate to glutamine. GS is pivotal for the generation of the neurotransmitters glutamate and gamma-aminobutyric acid and is the primary mechanism of ammonia detoxification in the brain. GS levels are regulated post-translationally by an N-terminal degron that enables the ubiquitin-mediated degradation of GS in a glutamine-induced manner. GS deficiency in humans is known to lead to neurological defects and death in infancy, yet how dysregulation of the degron-mediated control of GS levels might affect neurodevelopment is unknown. We ascertained nine individuals with severe developmental delay, seizures, and white matter abnormalities but normal plasma and cerebrospinal fluid biochemistry with de novo variants in GLUL. Seven out of nine were start-loss variants and two out of nine disrupted 5' UTR splicing resulting in splice exclusion of the initiation codon. Using transfection-based expression systems and mass spectrometry, these variants were shown to lead to translation initiation of GS from methionine 18, downstream of the N-terminal degron motif, resulting in a protein that is stable and enzymatically competent but insensitive to negative feedback by glutamine. Analysis of human single-cell transcriptomes demonstrated that GLUL is widely expressed in neuro- and glial-progenitor cells and mature astrocytes but not in post-mitotic neurons. One individual with a start-loss GLUL variant demonstrated periventricular nodular heterotopia, a neuronal migration disorder, yet overexpression of stabilized GS in mice using in utero electroporation demonstrated no migratory deficits. These findings underline the importance of tight regulation of glutamine metabolism during neurodevelopment in humans.

Perampanel for the treatment of epilepsy with genetic aetiology: Real-world evidence from the PERMIT Extension study.

Genetic factors contribute to the aetiology of epilepsy in >50% of cases, and information on the use of antiseizure medications in people with specific aetiologies will help guide treatment decisions. The PERMIT Extension study pooled data from two real-world studies (PERMIT and PROVE) to investigate the effectiveness and safety/tolerability of perampanel (PER) when used to treat people with focal and generalised epilepsy in everyday clinical practice. This post-hoc analysis of PERMIT Extension explored the use of PER when used to treat individuals presumed to have epilepsy with a genetic aetiology. Assessments included retention rate (evaluated at 3, 6 and 12 months), effectiveness (responder and seizure freedom rates; evaluated at 3, 6, 12 months and the last visit [last observation carried forward) and tolerability (adverse events [AEs]). Of the 6822 people with epilepsy included in PERMIT Extension, 1012 were presumed to have a genetic aetiology. The most common genetic aetiologies were idiopathic generalised epilepsy (IGE; 58.2%), tuberous sclerosis (1.1%), Dravet syndrome (0.8%) and genetic epilepsy with febrile seizures plus (GEFS+; 0.5%). Retention rates at 3, 6 and 12 months in the total genetic aetiology population were 89.3%, 79.7% and 65.9%, respectively. In the total genetic aetiology population, responder rates at 12 months and the last visit were 74.8% and 68.3%, respectively, and corresponding seizure freedom rates were 48.9% and 46.5%, respectively. For the specific aetiology subgroups, responder rates at 12 months and the last visit were, respectively: 90.4% and 84.4% (IGE), 100% and 57.1% (tuberous sclerosis), 100% and 71.4% (Dravet syndrome), and 33.3% and 20.0% (GEFS+). Corresponding seizure freedom rates were, respectively: 73.1% and 64.6% (IGE), 33.3% and 22.2% (tuberous sclerosis), 20.0% and 28.6% (Dravet syndrome), and 0% and 0% (GEFS+). The incidence of AEs was 46.5% for the total genetic aetiology population, 48.8% for IGE, 27.3% for tuberous sclerosis, 62.5% for Dravet syndrome, and 20% for GEFS+. Tolerability findings were consistent with PER's known safety profile. PER was effective and generally well tolerated when used in individuals with a presumed genetic epilepsy aetiology in clinical practice. PER was effective across a wide range of genetic aetiologies.

Clearance for Driving in Genetic Generalized Epilepsy.

A key aspect of management of genetic generalized epilepsy involves assessing seizure control and deciding suitability for driving motor vehicles. We surveyed child neurologists and pediatric epileptologists on key questions that practitioners should ask prior to providing clearance for driving. The results showed a wide variability of practice among responders. We propose a likely appropriate process necessary to determine seizure control.

Gene-gene interaction network analysis indicates CNTN2 is a candidate gene for idiopathic generalized epilepsy.

Twin and family studies have established the genetic contribution to idiopathic generalized epilepsy (IGE). The genetic architecture of IGE is generally complex and heterogeneous, and the majority of the genetic burden in IGE remains unsolved. We hypothesize that gene-gene interactions contribute to the complex inheritance of IGE. CNTN2 (OMIM* 615,400) variants have been identified in cases with familial adult myoclonic epilepsy and other epilepsies. To explore the gene-gene interaction network in IGE, we took the CNTN2 gene as an example and investigated its co-occurrent genetic variants in IGE cases. We performed whole-exome sequencing in 114 unrelated IGE cases and 296 healthy controls. Variants were qualified with sequencing quality, minor allele frequency, in silico prediction, genetic phenotype, and recurrent case numbers. The STRING_TOP25 gene interaction network analysis was introduced with the bait gene CNTN2 (denoted as A). The gene-gene interaction pair mode was presumed to be A + c, A + d, A + e, with a leading gene A, or A + B + f, A + B + g, A + B + h, with a double-gene A + B, or other combinations. We compared the number of gene interaction pairs between the case and control groups. We identified three pairs in the case group, CNTN2 + PTPN18, CNTN2 + CNTN1 + ANK2 + ANK3 + SNTG2, and CNTN2 + PTPRZ1, while we did not discover any pairs in the control group. The number of gene interaction pairs in the case group was much more than in the control group (p = 0.021). Taking together the genetic bioinformatics, reported epilepsy cases, and statistical evidence in the study, we supposed CNTN2 as a candidate pathogenic gene for IGE. The gene interaction network analysis might help screen candidate genes for IGE or other complex genetic disorders.

Idiopathic generalized epilepsy in a family with SCN4A-related myotonia.

OBJECTIVES: Myotonia is a clinical sign typical of a group of skeletal muscle channelopathies, the non-dystrophic myotonias. These disorders are electrophysiologically characterized by altered membrane excitability, due to specific genetic variants in known causative genes (CLCN1 and SCN4A). Juvenile Myoclonic Epilepsy (JME) is an epileptic syndrome identified as idiopathic generalized epilepsy, its genetics is complex and still unclarified. The co-occurrence of these two phenotypes is rare and the causes likely have a genetic background. In this study, we have genetically investigated an Italian family in which co-segregates myotonia, JME, or abnormal EEG without seizures was observed. METHODS: All six individuals of the family, 4 affected and 2 unaffected, were clinically evaluated; EMG and EEG examinations were performed. For genetic testing, Exome Sequencing was performed for the six family members and Sanger sequencing was used to confirm the candidate variant. RESULTS: Four family members, the mother and three siblings, were affected by myotonia. Moreover, EEG recordings revealed interictal generalized sharp-wave discharges in all affected individuals, and two siblings were affected by JME. All four affected members share the same identified variant, c.644 T > C, p.Ile215Thr, in SCN4A gene. Variants that could account for the epileptic phenotype alone, separately from the myotonic one, were not identified. SIGNIFICANCE: These results provide supporting evidence that both myotonic and epileptic phenotypes could share a common genetic background, due to variants in SCN4A gene. SCN4A pathogenic variants, already known to be causative of myotonia, likely increase the susceptibility to epilepsy in our family. PLAIN LANGUAGE SUMMARY: This study analyzed all members of an Italian family, in which the mother and three siblings had myotonia and epilepsy. Genetic analysis allowed to identify a variant in the SCN4A gene, which appears to be the cause of both clinical signs in this family.

High-density electroencephalographic functional networks in genetic generalized epilepsy: Preserved whole-brain topology hides local reorganization.

OBJECTIVE: Genetic generalized epilepsy (GGE) accounts for approximately 20% of adult epilepsy cases and is considered a disorder of large brain networks, involving both hemispheres. Most studies have not shown any difference in functional whole-brain network topology when compared to healthy controls. Our objective was to examine whether this preserved global network topology could hide local reorganizations that balance out at the global network level. METHODS: We recorded high-density electroencephalograms from 20 patients and 20 controls, and reconstructed the activity of 118 regions. We computed functional connectivity in windows free of interictal epileptiform discharges in broad, delta, theta, alpha, and beta frequency bands, characterized the network topology, and used the Hub Disruption Index (HDI) to quantify the topological reorganization. We examined the generalizability of our results by reproducing a 25-electrode clinical system. RESULTS: Our study did not reveal any significant change in whole-brain network topology among GGE patients. However, the HDI was significantly different between patients and controls in all frequency bands except alpha (p < .01, false discovery rate [FDR] corrected, d < -1), and accompanied by an increase in connectivity in the prefrontal regions and default mode network. This reorganization suggests that regions that are important in transferring the information in controls were less so in patients. Inversely, the crucial regions in patients are less so in controls. These findings were also found in delta and theta frequency bands when using 25 electrodes (p < .001, FDR corrected, d < -1). SIGNIFICANCE: In GGE patients, the overall network topology is similar to that of healthy controls but presents a balanced local topological reorganization. This reorganization causes the prefrontal areas and default mode network to be more integrated and segregated, which may explain executive impairment associated with GGE. Additionally, the reorganization distinguishes patients from controls even when using 25 electrodes, suggesting its potential use as a diagnostic tool.

Functional Characteristics of the Nav1.1 p.Arg1596Cys Mutation Associated with Varying Severity of Epilepsy Phenotypes.

Mutations of the SCN1A gene, which encodes the voltage-dependent Na+ channel's α subunit, are associated with diverse epileptic syndromes ranging in severity, even intra-family, from febrile seizures to epileptic encephalopathy. The underlying cause of this variability is unknown, suggesting the involvement of additional factors. The aim of our study was to describe the properties of mutated channels and investigate genetic causes for clinical syndromes' variability in the family of five SCN1A gene p.Arg1596Cys mutation carriers. The analysis of additional genetic factors influencing SCN1A-associated phenotypes was conducted through exome sequencing (WES). To assess the impact of mutations, we used patch clamp analysis of mutated channels expressed in HEK cells and in vivo neural excitability studies (NESs). In cells expressing the mutant channel, sodium currents were reduced. NESs indicated increased excitability of peripheral motor neurons in mutation carriers. WES showed the absence of non-SCA1 pathogenic variants that could be causative of disease in the family. Variants of uncertain significance in three genes, as potential modifiers of the most severe phenotype, were identified. The p.Arg1596Cys substitution inhibits channel function, affecting steady-state inactivation kinetics. Its clinical manifestations involve not only epileptic symptoms but also increased excitability of peripheral motor fibers. The role of Nav1.1 in excitatory neurons cannot be ruled out as a significant factor of the clinical phenotype.

A Homozygous PTRHD1 Missense Variant (p.Arg122Gln) in an Individual with Intellectual Disability, Generalized Epilepsy, and Juvenile Parkinsonism.

Biallelic variants in PTRHD1 have been associated with autosomal recessive intellectual disability, spasticity, and juvenile parkinsonism, with few reported cases. Here, we present the clinical and genetic findings of a female of Austrian origin exhibiting infantile neurodevelopmental abnormalities, intellectual disability, and childhood-onset parkinsonian features, consistent with the established phenotypic spectrum. Notably, she developed genetic generalized epilepsy at age 4, persisting into adulthood. Using diagnostic exome sequencing, we identified a homozygous missense variant (c.365G > A, p.(Arg122Gln)) in PTRHD1 (NM_001013663). In summary, our findings not only support the existing link between biallelic PTRHD1 variants and parkinsonism with neurodevelopmental abnormalities but also suggest a potential extension of the phenotypic spectrum to include generalized epilepsy.

Molecular and Phenotypic Characterization of the RORB-Related Disorder.

BACKGROUND AND OBJECTIVES: Heterozygous variants in RAR-related orphan receptor B (RORB) have recently been associated with susceptibility to idiopathic generalized epilepsy. However, few reports have been published so far describing pathogenic variants of this gene in patients with epilepsy and intellectual disability (ID). In this study, we aimed to delineate the epilepsy phenotype associated with RORB pathogenic variants and to provide arguments in favor of the pathogenicity of variants. METHODS: Through an international collaboration, we analyzed seizure characteristics, EEG data, and genotypes of a cohort of patients with heterozygous variants in RORB. To gain insight into disease mechanisms, we performed ex vivo cortical electroporation in mouse embryos of 5 selected variants, 2 truncating and 3 missense, and evaluated on expression and quantified changes in axonal morphology. RESULTS: We identified 35 patients (17 male, median age 10 years, range 2.5-23 years) carrying 32 different heterozygous variants in RORB, including 28 single-nucleotide variants or small insertions/deletions (12 missense, 12 frameshift or nonsense, 2 splice-site variants, and 2 in-frame deletions), and 4 microdeletions; de novo in 18 patients and inherited in 10. Seizures were reported in 31/35 (89%) patients, with a median age at onset of 3 years (range 4 months-12 years). Absence seizures occurred in 25 patients with epilepsy (81%). Nineteen patients experienced a single seizure type: absences, myoclonic absences, or absences with eyelid myoclonia and focal seizures. Nine patients had absence seizures combined with other generalized seizure types. One patient had presented with absences associated with photosensitive occipital seizures. Three other patients had generalized tonic-clonic seizures without absences. ID of variable degree was observed in 85% of the patients. Expression studies in cultured neurons showed shorter axons for the 5 tested variants, both truncating and missense variants, supporting an impaired protein function. DISCUSSION: In most patients, the phenotype of the RORB-related disorder associates absence seizures with mild-to-moderate ID. In silico and in vitro evaluation of the variants in our cohort, including axonal morphogenetic experiments in cultured neurons, supports their pathogenicity, showing a hypomorphic effect.

Coexistence of temporal lobe epilepsy and idiopathic generalized epilepsy.

OBJECTIVE: We investigated the frequency of coexistence of temporal lobe epilepsy (TLE) and idiopathic generalized epilepsy (IGE) in a retrospective database study. We also explored the underlying pathomechanisms of the coexistence of TLE and IGE based on the available information, using bioinformatics tools. METHODS: The first phase of the investigation was a retrospective study. All patients with an electro-clinical diagnosis of epilepsy were studied at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2023. In the second phase, we searched the following databases for genetic variations (epilepsy-associated genetic polymorphisms) that are associated with TLE or syndromes of IGE: DisGeNET, genome-wide association study (GWAS) Catalog, epilepsy genetic association database (epiGAD), and UniProt. We also did a separate literature search using PubMed. RESULTS: In total, 3760 patients with epilepsy were registered at our clinic; four patients with definitely mixed TLE and IGE were identified; 0.1% of all epilepsies. We could identify that rs1883415 of ALDH5A1, rs137852779 of EFHC1, rs211037 of GABRG2, rs1130183 of KCNJ10, and rs1045642 of ABCB1 genes are shared between TLE and syndromes of IGE. CONCLUSION: While coexistence of TLE and IGE is a rare phenomenon, this could be explained by shared genetic variations.

Gen SCN1A, Epilepsias Genéticas (Sindrome de DRAVET), Correlato Genotipo / Fenotipo / The SCN1A gene, congenital epilepsies (Dravet syndrome), genotype/phenotype correlations

Las mutaciones del Gen SCN1A están asociadas a varios síndromes epilépticos con presentaciones clínicas superpuestas y de variable severidad a saber: Epilepsia Severa Mioclonica de la Infancia o Síndrome de Dravet,Epilepsia Generalizada con Convulsiones Febriles Plus, formas más leves de Sindrome de Dravet, la Epilepsia Intratable con Convulsiones Generalizadas Tonico-Clonicas y raros casos de Migraña familiar. Todas estas formas clínicas representan el 90% de los casos de mutación del gen SCN1A; recientemente se han incluido la Epilepsia Focal y Generalizada Criptogenética, la Mioclónica–Astática, formas del Síndrome de Lennox-Gastaut y la forma severa de Epilepsia Multifocal Infantil (Epilepsia Migratoria o Multifocal Severa de la Infancia). El objetivo de la presentación de estos tres casos de Epilepsia Refractaria Precoz es enfatizar los Fenotipos variables en la evolución de la semiología convulsiva, y del compromiso cognitivo, asociado a genotipos variables (compromiso de alelos diferentes en el mismo Gen). Se debe sospechar compromiso del Gen SCN1A en toda Encefalopatía Epiléptica con convulsiones febriles de comienzo en el 1er año de vida repetidas, en muchas ocasiones, prolongadas o en ramilletes, refractarias al tratamiento médico, con neuroimagenes y EEG normales en el inicio del trastorno convulsivo aunque la regresión psicomotora ocurra años después o las mioclonias estén ausentes y en quienes la vulnerabilidad a la fiebre o a los estados infecciosos leves precipitan convulsiones

Mutations in the SCN1A gene are associated with different epi-lepsy syndromes with overlapping clinical presentations and of variable severity, such as severe myoclonic epilepsy in infancy or Dravet syndrome, generalized epilepsy with febrile seizures plus, milder forms of Dravet syndrome, refractory epilepsy with generalized tonic-clonic seizures, and rare cases of familial migraine. In 90% of all these clinical presentations SCN1A mutations are found. More recently, cryptogenic focal and ge-neralized epilepsy, myoclonic–astatic epilepsy, different types of Lennox-Gastaut syndrome, and the severe form of infantile multifocal epilepsy (migrating partial seizures or severe infanti-le multifocal epilepsy) have also been included. The aim of the presentation of these three cases of early refractory epilepsy was to emphasize the variable phenotypes in the evolution of seizure semiology and the cognitive involvement associated with variable genotypes (involvement of different alleles of the same gene). SCN1A-gene involvement should be suspected in the face of all epileptic encephalopathies...

Crisis febriles simples y complejas, epilepsia generalizada con crisis febriles plus, FIRES y nuevos síndromes / [Simple febrile seizure, complex seizure, generalized epilepsy with febrile seizure plus, FIRES and new syndromes].

Febrile seizures are the most common seizures in childhood. They have been observed in 2-5

of children before the age of 5, but in some populations this figure may increase to 15

. It is a common cause of pediatric hospital admissions and cause of anxiety for parents. Febrile seizures could be the first manifestation of epilepsy. About 13

of epileptic patients have a history of febrile seizure, and 30

have had recurrent febrile seizures. Their phenotypic characteristics allow, in the majority of cases, a classification of the seizure, an elaboration of a prognosis and to assume a specific therapeutic attitude. It is possible to describe a spectrum according to their severity, from the benign simple seizure to the more complex, febrile seizure plus, Dravet’syndrome, and FIRES. During the past decade, molecular genetic studies have contributed to the identification of genetic factors involved in febrile seizure and related disorders, making the necessity of a careful follow up of these patients in order to detect risk factors earlier. We have reviewed the medical literature to update current knowledge of febrile seizures, their prognosis and their relation to new epileptic syndromes.

A genética das epilepsias: [revisão] / The genetics of epilepsies: [review]

OBJETIVO: Discutir alguns dos aspectos genéticos clínicos e moleculares de novas descobertas no campo da genética das epilepsias e relacioná-las com indicações importantes para a melhor compreensão dos mecanismos subjacentes a algumas síndromes epilépticas monogênicas. FONTES DOS DADOS: Muitos desenhos de estudo foram usados através dos anos, incluindo estudos familiares e pesquisas genético-epidemiológicas. Mais recentemente, estudos de genética molecular e estratégias de descoberta de genes foram usados para revelar os mecanismos moleculares e celulares envolvidas em diversas síndromes epilépticas mendelianas. SÍNTESE DOS DADOS: A importância dos fatores genéticos em epilepsias é reconhecida desde os tempos de Hipócrates. CONCLUSÕES: Nos tempos modernos, muitos estudos demonstraram a existência de um componente hereditário nas epilepsias generalizadas e focais. Nas últimas duas décadas, diversas famílias segregando diferentes tipos de epilepsia monogência foram descritas, o que levou ao progresso na caracterização dos defeitos moleculares nestas famílias.

OBJECTIVES: To discuss some of the clinical and molecular genetic aspects of new discoveries in the field of the genetics of the epilepsies and relate these with relevant clues for a better understanding of the mechanisms underlying some of the monogenic epilepsy syndromes. SOURCES: Many study designs have been performed over the years and these include family-based studies, genetic-epidemiology surveys. More recently, molecular genetics studies and gene discovery strategies have been used to unravel the molecular and cell mechanisms involved in several Mendelian epilepsy syndromes. SUMMARY OF THE FINDINGS: The importance of genetic factors in the epilepsies has been recognized since the time of Hippocrates. CONCLUSIONS: In the modern era, many studies have demonstrated the existence of an inherited component in the generalized and focal epilepsies and in the last 2 decades a number of families segregating different types of monogenic epilepsy have been described, leading to progresses in the characterization of the molecular defects in these families.