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Epilepsy & Behavior : E&B Jul 2022Dravet Syndrome is a genetic epileptic syndrome characterized by severe and intractable seizures associated with cognitive, motor, and behavioral impairments. The... (Review)
Review
Dravet Syndrome is a genetic epileptic syndrome characterized by severe and intractable seizures associated with cognitive, motor, and behavioral impairments. The disease is also linked with increased mortality mainly due to sudden unexpected death in epilepsy. Over 80% of cases are due to a de novo mutation in one allele of the SCN1A gene, which encodes the α-subunit of the voltage-gated ion channel Na1.1. Dravet Syndrome is usually refractory to antiepileptic drugs, which only alleviate seizures to a small extent. Viral, non-viral genetic therapy, and gene editing tools are rapidly enhancing and providing new platforms for more effective, alternative medicinal treatments for Dravet syndrome. These strategies include gene supplementation, CRISPR-mediated transcriptional activation, and the use of antisense oligonucleotides. In this review, we summarize our current knowledge of novel genetic therapies that are currently under development for Dravet syndrome.
Topics: Epilepsies, Myoclonic; Epilepsy; Epileptic Syndromes; Humans; Mutation; NAV1.1 Voltage-Gated Sodium Channel; Seizures; Spasms, Infantile
PubMed: 35653814
DOI: 10.1016/j.yebeh.2022.108741 -
Brain : a Journal of Neurology Nov 2022Brain voltage-gated sodium channel NaV1.1 (SCN1A) loss-of-function variants cause the severe epilepsy Dravet syndrome, as well as milder phenotypes associated with...
Brain voltage-gated sodium channel NaV1.1 (SCN1A) loss-of-function variants cause the severe epilepsy Dravet syndrome, as well as milder phenotypes associated with genetic epilepsy with febrile seizures plus. Gain of function SCN1A variants are associated with familial hemiplegic migraine type 3. Novel SCN1A-related phenotypes have been described including early infantile developmental and epileptic encephalopathy with movement disorder, and more recently neonatal presentations with arthrogryposis. Here we describe the clinical, genetic and functional evaluation of affected individuals. Thirty-five patients were ascertained via an international collaborative network using a structured clinical questionnaire and from the literature. We performed whole-cell voltage-clamp electrophysiological recordings comparing sodium channels containing wild-type versus variant NaV1.1 subunits. Findings were related to Dravet syndrome and familial hemiplegic migraine type 3 variants. We identified three distinct clinical presentations differing by age at onset and presence of arthrogryposis and/or movement disorder. The most severely affected infants (n = 13) presented with congenital arthrogryposis, neonatal onset epilepsy in the first 3 days of life, tonic seizures and apnoeas, accompanied by a significant movement disorder and profound intellectual disability. Twenty-one patients presented later, between 2 weeks and 3 months of age, with a severe early infantile developmental and epileptic encephalopathy and a movement disorder. One patient presented after 3 months with developmental and epileptic encephalopathy only. Associated SCN1A variants cluster in regions of channel inactivation associated with gain of function, different to Dravet syndrome variants (odds ratio = 17.8; confidence interval = 5.4-69.3; P = 1.3 × 10-7). Functional studies of both epilepsy and familial hemiplegic migraine type 3 variants reveal alterations of gating properties in keeping with neuronal hyperexcitability. While epilepsy variants result in a moderate increase in action current amplitude consistent with mild gain of function, familial hemiplegic migraine type 3 variants induce a larger effect on gating properties, in particular the increase of persistent current, resulting in a large increase of action current amplitude, consistent with stronger gain of function. Clinically, 13 out of 16 (81%) gain of function variants were associated with a reduction in seizures in response to sodium channel blocker treatment (carbamazepine, oxcarbazepine, phenytoin, lamotrigine or lacosamide) without evidence of symptom exacerbation. Our study expands the spectrum of gain of function SCN1A-related epilepsy phenotypes, defines key clinical features, provides novel insights into the underlying disease mechanisms between SCN1A-related epilepsy and familial hemiplegic migraine type 3, and identifies sodium channel blockers as potentially efficacious therapies. Gain of function disease should be considered in early onset epilepsies with a pathogenic SCN1A variant and non-Dravet syndrome phenotype.
Topics: Humans; Arthrogryposis; Epilepsies, Myoclonic; Epilepsy; Gain of Function Mutation; Migraine with Aura; Movement Disorders; NAV1.1 Voltage-Gated Sodium Channel; Phenotype; Spasms, Infantile; Infant, Newborn; Infant
PubMed: 35696452
DOI: 10.1093/brain/awac210 -
Epilepsia Jul 2022This study was undertaken to gain consensus from experienced physicians and caregivers regarding optimal diagnosis and management of Dravet syndrome (DS), in the context...
OBJECTIVE
This study was undertaken to gain consensus from experienced physicians and caregivers regarding optimal diagnosis and management of Dravet syndrome (DS), in the context of recently approved, DS-specific therapies and emerging disease-modifying treatments.
METHODS
A core working group was convened consisting of six physicians with recognized expertise in DS and two representatives of the Dravet Syndrome Foundation. This core group summarized the current literature (focused on clinical presentation, comorbidities, maintenance and rescue therapies, and evolving disease-modifying therapies) and nominated the 31-member expert panel (ensuring international representation), which participated in two rounds of a Delphi process to gain consensus on diagnosis and management of DS.
RESULTS
There was strong consensus that infants 2-15 months old, presenting with either a first prolonged hemiclonic seizure or first convulsive status epilepticus with fever or following vaccination, in the absence of another cause, should undergo genetic testing for DS. Panelists agreed on evolution of specific comorbidities with time, but less agreement was achieved on optimal management. There was also agreement on appropriate first- to third-line maintenance therapies, which included the newly approved agents. Whereas there was agreement for recommendation of disease-modifying therapies, if they are proven safe and efficacious for seizures and/or reduction of comorbidities, there was less consensus for when these should be started, with caregivers being more conservative than physicians.
SIGNIFICANCE
This International DS Consensus, informed by both experienced global caregiver and physician voices, provides a strong overview of the impact of DS, therapeutic goals and optimal management strategies incorporating the recent therapeutic advances in DS, and evolving disease-modifying therapies.
Topics: Consensus; Epilepsies, Myoclonic; Epileptic Syndromes; Humans; Infant; Seizures; Spasms, Infantile
PubMed: 35490361
DOI: 10.1111/epi.17274 -
Developmental Medicine and Child... Nov 2010Doose syndrome, otherwise traditionally known as myoclonic-astatic epilepsy, was first described as a unique epilepsy syndrome by Dr Hermann Doose in 1970. In 1989, the... (Review)
Review
Doose syndrome, otherwise traditionally known as myoclonic-astatic epilepsy, was first described as a unique epilepsy syndrome by Dr Hermann Doose in 1970. In 1989, the International League Against Epilepsy classified it formally as a symptomatic generalized epilepsy, and 20 years later it was renamed 'epilepsy with myoclonic-atonic seizures'. In this review, we discuss the components of this unique disorder including its incidence, clinical features, and electroencephalographic findings. Recent evidence has suggested possible genetic links to the GEFS+ (generalized epilepsy with febrile seizures plus) family, and, additionally, some children with structural brain lesions can mimic the Doose syndrome phenotype. Treatment strategies such as corticosteroids, ethosuximide, and valproate have been described as only partially effective, but newer anticonvulsants, such as levetiracetam and zonisamide, may provide additional seizure control. The most effective treatment reported to date appears to be the ketogenic diet. Prognosis is quite varied in this disorder; however, many children can have a remarkably normal neurodevelopmental outcome.
Topics: Anticonvulsants; Electroencephalography; Epilepsies, Myoclonic; History, 20th Century; History, 21st Century; Humans; Mutation; NAV1.9 Voltage-Gated Sodium Channel; Neuropeptides; Prognosis; Receptors, GABA-A; Sodium Channels
PubMed: 20722665
DOI: 10.1111/j.1469-8749.2010.03744.x -
Epilepsia Open Mar 2022Dravet syndrome (DS) is a severe, rare, and complex developmental and epileptic encephalopathy affecting 1 in 16 000 live births and characterized by a drug-resistant... (Review)
Review
Dravet syndrome (DS) is a severe, rare, and complex developmental and epileptic encephalopathy affecting 1 in 16 000 live births and characterized by a drug-resistant epilepsy, cognitive, psychomotor, and language impairment, and behavioral disorders. Evidence suggests that optimal treatment of seizures in DS may improve outcomes, even though neurodevelopmental impairments are the likely result of both the underlying genetic variant and the epilepsy. We present an updated guideline for DS diagnosis and treatment, taking into consideration care of the adult patient and nonpharmaceutical therapeutic options for this disease. This up-to-date guideline, which is based on an extensive review of the literature and culminates with a new treatment algorithm for DS, is a European consensus developed through a survey involving 29 European clinical experts in DS. This guideline will serve professionals in their clinical practice and, as a consequence, will benefit DS patients and their families.
Topics: Adult; Epilepsies, Myoclonic; Epilepsy; Epileptic Syndromes; Europe; Humans; Infant; Spasms, Infantile
PubMed: 34882995
DOI: 10.1002/epi4.12569 -
Epilepsia Jul 2021CSNK2B has recently been implicated as a disease gene for neurodevelopmental disability (NDD) and epilepsy. Information about developmental outcomes has been limited by...
CSNK2B has recently been implicated as a disease gene for neurodevelopmental disability (NDD) and epilepsy. Information about developmental outcomes has been limited by the young age and short follow-up for many of the previously reported cases, and further delineation of the spectrum of associated phenotypes is needed. We present 25 new patients with variants in CSNK2B and refine the associated NDD and epilepsy phenotypes. CSNK2B variants were identified by research or clinical exome sequencing, and investigators from different centers were connected via GeneMatcher. Most individuals had developmental delay and generalized epilepsy with onset in the first 2 years. However, we found a broad spectrum of phenotypic severity, ranging from early normal development with pharmacoresponsive seizures to profound intellectual disability with intractable epilepsy and recurrent refractory status epilepticus. These findings suggest that CSNK2B should be considered in the diagnostic evaluation of patients with a broad range of NDD with treatable or intractable seizures.
Topics: Adolescent; Adult; Age of Onset; Child; Child, Preschool; Developmental Disabilities; Epilepsies, Myoclonic; Epilepsy, Generalized; Exome; Female; Genetic Variation; Humans; Infant; Intellectual Disability; Male; Mutation; Phenotype; Status Epilepticus; Young Adult
PubMed: 34041744
DOI: 10.1111/epi.16931 -
British Medical Journal (Clinical... Apr 1982
Topics: Child; Child, Preschool; Diagnosis, Differential; Epilepsies, Myoclonic; Epilepsies, Partial; Epilepsy; Epilepsy, Absence; Epilepsy, Tonic-Clonic; Humans; Infant
PubMed: 6803925
DOI: 10.1136/bmj.284.6324.1247 -
Seizure Oct 2019Progressive Myoclonus Epilepsies (PMEs) are a group of uncommon clinically and genetically heterogeneous disorders characterised by myoclonus, generalized epilepsy, and... (Review)
Review
Progressive Myoclonus Epilepsies (PMEs) are a group of uncommon clinically and genetically heterogeneous disorders characterised by myoclonus, generalized epilepsy, and neurological deterioration, including dementia and ataxia. PMEs may have infancy, childhood, juvenile or adult onset, but usually present in late childhood or adolescence, at variance from epileptic encephalopathies, which start with polymorphic seizures in early infancy. Neurophysiologic recordings are suited to describe faithfully the time course of the shock-like muscle contractions which characterize myoclonus. A combination of positive and negative myoclonus is typical of PMEs. The gene defects for most PMEs (Unverricht-Lundborg disease, Lafora disease, several forms of neuronal ceroid lipofuscinoses, myoclonus epilepsy with ragged-red fibers [MERRF], and type 1 and 2 sialidoses) have been identified. PMEs are uncommon disorders, difficult to diagnose in the absence of extensive experience. Thus, aetiology is undetermined in many patients, despite the advance in molecular medicine. Treatment of PMEs remains essentially symptomaticof seizures and myoclonus, together with palliative, supportive, and rehabilitative measures. The response to therapy may initially be relatively favourable, afterwards however, seizures may become more frequent, and progressive neurologic decline occurs. The prognosis of a PME depends on the specific disease. The history of PMEs revealed that the international collaboration and sharing experience is the right way to proceed. This emerging picture and biological insights will allow us to find ways to provide the patients with meaningful treatment.
Topics: Humans; Myoclonic Epilepsies, Progressive; Precision Medicine
PubMed: 31476531
DOI: 10.1016/j.seizure.2019.08.012 -
Developmental Medicine and Child... Apr 2011Severe myoclonic epilepsy of infancy (SMEI) is a complex form of epilepsy that was first described in France in 1978. Because the myoclonic component of this epilepsy is... (Review)
Review
Severe myoclonic epilepsy of infancy (SMEI) is a complex form of epilepsy that was first described in France in 1978. Because the myoclonic component of this epilepsy is not always present and because some variability has been observed in the symptomatology, the name was changed to Dravet syndrome in 1989. The genetic aetiology of this epilepsy was discovered in 2001, and since then numerous studies have contributed to a better knowledge of the disease. Around 70% of affected patients are carriers of a mutation on the alpha subunit of the SCN1A gene. An accurate analysis of the clinical features leads to the distinction between typical and atypical forms, both with the same unfavourable prognosis and the same genetic background. However, many studies are being conducted in order to establish correlations between phenotypes and genotypes, and to understand the factors underlying the cognitive impairment of the affected patients.
Topics: Brain; Child, Preschool; Diagnosis, Differential; Electroencephalography; Epilepsies, Myoclonic; Genetic Predisposition to Disease; Humans; Infant; NAV1.1 Voltage-Gated Sodium Channel; Nerve Tissue Proteins; Sodium Channels; Syndrome
PubMed: 21504424
DOI: 10.1111/j.1469-8749.2011.03964.x -
Paediatric Drugs Apr 2020The progressive myoclonic epilepsies (PMEs) represent a rare but devastating group of syndromes characterized by epileptic myoclonus, typically action-induced seizures,... (Review)
Review
The progressive myoclonic epilepsies (PMEs) represent a rare but devastating group of syndromes characterized by epileptic myoclonus, typically action-induced seizures, neurological regression, medically refractory epilepsy, and a variety of other signs and symptoms depending on the specific syndrome. Most of the PMEs begin in children who are developing as expected, with the onset of the disorder heralded by myoclonic and other seizure types. The conditions are considerably heterogenous, but medical intractability to epilepsy, particularly myoclonic seizures, is a core feature. With the increasing use of molecular genetic techniques, mutations and their abnormal protein products are being delineated, providing a basis for disease-based therapy. However, genetic and enzyme replacement or substrate removal are in the nascent stage, and the primary therapy is through antiepileptic drugs. Epilepsy in children with progressive myoclonic seizures is notoriously difficult to treat. The disorder is rare, so few double-blinded, placebo-controlled trials have been conducted in PME, and drugs are chosen based on small open-label trials or extrapolation of data from drug trials of other syndromes with myoclonic seizures. This review discusses the major PME syndromes and their neurogenetic basis, pathophysiological underpinning, electroencephalographic features, and currently available treatments.
Topics: Child; Humans; Myoclonic Epilepsies, Progressive; Research Design
PubMed: 31939107
DOI: 10.1007/s40272-019-00378-y