UMLS:C0036572 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

Query: UMLS:C0036572 (seizures)
80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Severe myoclonic epilepsy of infancy (SMEI or Dravet syndrome) is a rare disorder occurring in young children often without a family history of a similar disorder. The earliest disease manifestations are usually fever-associated seizures. Later in life, patients display different types of afebrile seizures including myoclonic seizures. Arrest of psychomotor development occurs in the second year of life and most patients become ataxic. Patients are resistant to antiepileptic drug therapy. Recently, we described de novo mutations of the neuronal sodium channel alpha-subunit gene SCN1A in seven isolated SMEI patients. To investigate the contribution of SCN1A mutations to the etiology of SMEI, we examined nine additional SMEI patients. We observed eight coding and one noncoding mutation. In contrast to our previous study, most mutations are missense mutations clustering in the S4-S6 region of SCN1A. These findings demonstrate that de novo mutations in SCN1A are a major cause of isolated SMEI.
...
PMID:De novo SCN1A mutations are a major cause of severe myoclonic epilepsy of infancy. 1275 8

SCN1A is part of the SCN1A-SCN2A-SCN3A gene cluster on chromosome 2q24 that encodes for alpha pore forming subunits of sodium channels. The 26 exons of SCN1A are spread over 100 kb of genomic DNA. Genetic defects in the coding sequence lead to generalized epilepsy with febrile seizures plus (GEFS+) and a range of childhood epileptic encephalopathies of varied severity (e.g., SMEI). All published mutations are collated. More than 100 novel mutations are spread throughout the gene with the more debilitating usually de novo. Some clustering of mutations is observed in the C-terminus and the loops between segments 5 and 6 of the first three domains of the protein. Functional studies so far show no consistent relationship between changes to channel properties and clinical phenotype. Of all the known epilepsy genes SCN1A is currently the most clinically relevant, with the largest number of epilepsy related mutations so far characterized.
...
PMID:SCN1A mutations and epilepsy. 1588 Mar 51

A mutation in the voltage-gated sodium-channel Scn2a results in moderate epilepsy in transgenic Scn2a(Q54) mice maintained on a C57BL/6J strain background. The onset of progressive epilepsy begins in adults with short-duration partial seizures that originate in the hippocampus. The underlying abnormality is an increase in persistent sodium current in hippocampal neurons. The voltage-gated potassium channel Kcnq2 is responsible for generating M current (I(KM)) that is thought to control excitability and limit repetitive firing of hippocampal neurons. To determine whether impaired M current would exacerbate the seizure phenotype of Scn2a(Q54) mice, we carried out genetic crosses with two mutant alleles of Kcnq2. Szt1 mice carry a spontaneous deletion that removes the C-terminal domain of Kcnq2. A novel Kcnq2 missense mutation V182M was identified by screening the offspring of ENU-treated males for reduced threshold to electrically evoked minimal clonic seizures. Double mutant mice carrying the Scn2a(Q54) transgene together with either of the Kcnq2 mutations exhibited severe epilepsy with early onset, generalized tonic-clonic seizures and juvenile lethality by 3 weeks of age. This dramatic exacerbation of the sodium-channel mutant phenotype indicates that M current plays a critical role in preventing seizure initiation and spreading in this animal model. The genetic interaction between Scn2a and Kcnq2 demonstrates that combinations of mild alleles of monogenic epilepsy genes can result in severe disease and provides a model for complex inheritance of human epilepsy. The data suggest that interaction between these genes might contribute to the variable expressivity observed in human families with sodium-channel mutations. In a screen of 23 SMEI patients with missense mutations of SCN1A, no second-site mutations in KCNQ2 were identified.
...
PMID:Severe epilepsy resulting from genetic interaction between Scn2a and Kcnq2. 1646 83

Inherited or de novo mutations in at least a dozen genes encoding ion channels may present as paroxysmal disorders during the neonatal period or first year of life. These channelopathies include genes encoding voltage-gated channels specific for sodium (SCN1A, SCN2A, SCN1B, SCN9A) and potassium (KCNQ2, KCNQ3) which account for a variety of epilepsy phenotypes ranging from mild, such as Benign familial neonatal seizures (BFNS) to severe, such as Dravet syndrome (severe myoclonic epilepsy of infancy, SMEI) and the rare and unusual syndrome paroxysmal extreme pain disorder (PEPD). Ligand-gated channels involved include the GABA(A) receptor in a variety of epilepsy phenotypes and the human glycine receptor. Mutations in five genes encoding subunits of this receptor and accessory molecules underlie hyperekplexia or stiff-baby syndrome. All these conditions are rare but correct diagnosis is of value not only for genetic counselling but to allow the specific treatment which is available.
...
PMID:Molecular genetics of infantile nervous system channelopathies. 1704 61

Severe Myoclonic Epilepsy in infancy (SMEI, or Dravet syndrome) is a drug-resistant epilepsy that occurs in the first year of life of previously healthy children. The main clinical features are prolonged and repeated febrile and afebrile generalized or unilateral convulsive seizures. In the course of the epilepsy, cognitive deterioration becomes evident, and interictal myoclonus, clumsiness and ataxia appear. One third of the children with SMEI show de novo mutations of the SCN1A gene, and additional familial genes probably contribute to the phenotype. While the clinical picture of SMEI has been well studied, neuropsychological data remain scarce. Global mental retardation, attention deficit and psychotic behavior have been reported but the long-term outcome has not been evaluated. We conducted a longitudinal neuropsychological study of children with SMEI. Twenty children, aged 11 months to 16 years, were prospectively examined using standardized neuropsychological tests. Correlation analysis with other clinical features was performed in 12 cases. Marked slowing or stagnation of psychomotor development, accompanied by psychotic or autistic traits and hyperactivity, was observed between the ages of one and four years. In the later stages (at ages 5 to 16 years), cognitive function stabilized but remained below normal. In children with a more favorable course, language capacities were better preserved than visuospatial functions, and behavior improved. The cognitive and behavioral impairment tended to correlate with the frequency of convulsive seizures (>5 per month). The data suggest that SMEI can be considered as a prototype of an epileptic encephalopathy.
...
PMID:Severe myoclonic epilepsy of infants (Dravet syndrome): natural history and neuropsychological findings. 1710 60

The purpose of this article is to present a short review of the natural history of myoclonic astatic epilepsy (MAE; Doose syndrome) and the Lennox-Gastaut syndrome (LGS). In the 1989 classification of the International League Against Epilepsy (ILAE, 1989), MAE and LGS were initially included in group 2.2: "Cryptogenic or symptomatic generalized epilepsies and syndromes." The subsequent classification of the Proposed Diagnostic Scheme for People with Epileptic Seizures and with Epilepsy (see Ref. 8) placed MAE in axis 3 in the "generalized epilepsy" group and LGS, severe myoclonic epilepsy of infancy (SMEI or Dravet syndrome) and atypical benign partial epilepsy/pseudo-Lennox syndrome (ABPE/PLS) in the "epileptic encephalopathy" group. The semiology of MAE and LGS and their differential diagnosis from SMEI and ABPE/PLS are described. Before the onset of SMEI, MAE, and ABPE/PLS, the development of the child is usually normal. In contrast, in LGS, development is frequently retarded at the onset, depending on the etiopathogenesis of the underlying brain disease. The course of MAE is highly variable with regard to seizure outcome (complete remission in some cases, persistent epilepsy in others) and cognitive development (normal or delayed). The course of LGS and SMEI is generally poor, both with regard to the epilepsy and to the cognitive development whereas the course and seizure outcome of ABPE/PLS is favorable; the patients will be seizure-free at puberty. However, the neuropsychological outcome is less favorable; most patients remain mentally retarded.
...
PMID:The natural history of myoclonic astatic epilepsy (Doose syndrome) and Lennox-Gastaut syndrome. 1710 62

The relationship between severe myoclonic epilepsy of infancy (SMEI or Dravet syndrome) and the related syndrome SMEI-borderland (SMEB) with mutations in the sodium channel alpha 1 subunit gene SCN1A is well established. To explore the phenotypic variability associated with SCN1A mutations, 188 patients with a range of epileptic encephalopathies were examined for SCN1A sequence variations by denaturing high performance liquid chromatography and sequencing. All patients had seizure onset within the first 2 years of life. A higher proportion of mutations were identified in patients with SMEI (52/66; 79%) compared to patients with SMEB (25/36; 69%). By studying a broader spectrum of infantile epileptic encephalopathies, we identified mutations in other syndromes including cryptogenic generalized epilepsy (24%) and cryptogenic focal epilepsy (22%). Within the latter group, a distinctive subgroup designated as severe infantile multifocal epilepsy had SCN1A mutations in three of five cases. This phenotype is characterized by early onset multifocal seizures and later cognitive decline. Knowledge of an expanded spectrum of epileptic encephalopathies associated with SCN1A mutations allows earlier diagnostic confirmation for children with these devastating disorders.
...
PMID:The spectrum of SCN1A-related infantile epileptic encephalopathies. 1833 Apr 64

Mutations in the SCN 1 A gene, encoding the neuronal voltage-gated sodium channel alpha1 subunit, cause SMEI, GEFS+, and related epileptic syndromes. We herein report the R1575C-SCN 1 A mutation identified in a patient with Rasmussen encephalitis. R1575C were constructed in a recombinant human SCN 1 A and then heterologously expressed in HEK293 cells along with the human beta1 and beta2 sodium channel accessory subunits. Whole-cell patch-clamp recording was used to define biophysical properties. The R1575C channels exhibited increased channel availability and an increased persistent sodium current in comparison to the wild-type. These defects of electrophysiological properties can result in neuronal hyperexitability. The seizure susceptibility allele may influence the pathogenesis of Rasmussen encephalitis in this case.
...
PMID:Rasmussen encephalitis associated with SCN 1 A mutation. 1803 52

PRO: In the past decade, genotyping has started to help the neurologic practitioner treat patients with three types of epilepsy causing mutations, namely (1) SCN1A, a sodium channel gene mutated in Dravet's sporadic severe myoclonic epilepsy of infancy (SMEI and SMEB); (2) laforin (dual specificity protein phosphatase) and malin (ubiquitin E3 ligase) in Lafora progressive myoclonic epilepsy (PME); and (3) cystatin B in Unverricht-Lundborg type of PME. Laforin, malin, and cystatin B are non-ion channel gene mutations that cause PME. Genotyping ensures accurate diagnosis, helps treatment and genetic counseling, psychological and social help for patients and families, and directs families to organizations devoted to finding cures for specific epilepsy diseases. In SCN1A and cystatin B mutations, treatment with sodium channel blockers (phenytoin, carbamazepine, oxcarbazepine, lamotrigine) should be avoided. Because of early and correct diagnosis by genotyping of SCN1A mutations, the avoidance of sodium channel blockers, and aggressive treatment of prolonged convulsive status, there is hope that Dravet's syndrome may not be as severe as observed in all past reports. Genotyping also identifies nonsense mutations in Lafora PME. Nonsense mutations can be corrected by premature stop codon readthrough drugs such as gentamicin. The community practitioner together with epilepsy specialists in PME can work together and acquire gentamicin (Barton-Davis et al., 1999) for "compassionate use" in Lafora PME, a generalized lysosome multiorgan storage disorder that is invariably fatal. In Unverricht-Lundborg PME, new cohorts with genotyped cystatin B mutations have led to the chronic use of antioxidant N-acetylcysteine and combination valproate clobazam or clonazepam plus antimyoclonic drugs topiramate, zonisamide, piracetam, levetiracetam, or brivaracetam. These cohorts have minimal ataxia and no dementia, questioning whether the syndrome is truly progressive. In conclusion, not only is genotyping a prerequisite in the diagnosis of Dravet's syndrome and the progressive myoclonus epilepsies, but it also helps us choose the correct antiepileptic drugs to treat seizures in Dravet's syndrome and Unverricht-Lundborg PME. Genotyping also portends a brighter future, helping us to reassess the true course, severity, and progressive nature of Dravet's syndrome and Unverricht-Lundborg PME and helping us craft a future curative treatment for Dravet's syndrome and Lafora disease. Without the genotyping diagnosis of epilepsy causing mutations we are stuck with imprecise diagnosis and symptomatic treatment of seizures. CON: Genotyping of epilepsy may help to better understand the genetics of epilepsy, to establish an etiology in a patient with epilepsy, to provide genetic counseling, and to confirm a clinical diagnosis. However, critical analysis reveals that genotyping does not contribute to an improved treatment for the patients. In order to improve treatment, genotyping would have to (1) improve our ability to select the drug of choice for a given epilepsy or epileptic syndrome; (2) improve our ability to predict the individual risk of adverse reactions to certain drugs; (3) improve our ability to avoid unnecessary treatments or treatments that could aggravate seizures. Many example illustrate the lack of impact of genetic information on the treatment outcome: we do not treat Dravet syndrome more successfully since SCN1A testing became available; we do not treat Lafora disease more successfully since testing for laforin and malin became available; we do not need to know the genetic nature of Unverricht-Lundborg disease or test for the cystatin B mutation in order to select or avoid certain drugs; we do not treat Rett syndrome more successfully since MECP2 testing became available; we do not treat JME more successfully since we know its genetic origin; we do not treat autosomal dominant nocturnal frontal lobe epilepsy more successfully since we know its genetic origin and can test for its mutation. The clinical characteristics as well as the response to treatment of these epilepsy syndromes have been well established before genotyping became available. It can not be argued that genotyping is necessary for establishing a diagnosis or ensure accurate diagnosis. Since not all individuals with given syndromes have been shown to have the corresponding mutation, the clinical diagnosis must have been based on well-established clinical criteria. In addition, the presence or absence of the mutation in a given patient has never been shown to specifically predict the response to any form of treatment, positive or negative. Finally, the appropriate psychological and social help in a given patient will not depend on the identification of a mutation. This does not leave any role for genotyping in epilepsy for the sole reason of improving treatment of the patient. Claiming that the result of genotyping predicts optimal treatment in certain epilepsies is equivalent to stating that genotyping for diabetes has become available and that, based on this breakthrough, insulin can now be selected as the treatment of choice in those who test positive.
...
PMID:Debate: Does genetic information in humans help us treat patients? PRO--genetic information in humans helps us treat patients. CON--genetic information does not help at all. 1908 13

Aims of our study were to describe the early clinical features of Dravet syndrome (SMEI) and the neurological, cognitive and behavioral outcome. The clinical history of 37 patients with clinical diagnosis of SMEI, associated with a point mutation of SCN1A gene in 84% of cases, were reviewed with particular attention to the symptoms of onset. All the patients received at least one formal cognitive and behavior evaluation. Epilepsy started at a mean age of 5.7 months; the onset was marked by isolated seizure in 25 infants, and by status epilepticus in 12; the first seizure had been triggered by fever, mostly of low degree in 22 infants; the first EEG was normal in all cases. During the second year of life difficult-to-treat seizures recurred, mostly triggered by fever, hot bath, and intermittent lights and delay in psychomotor development became evident. At the last evaluation, performed at a mean age of 16+/-6.9 years, mental retardation was present in 33 patients, associated with behavior disorders in 21. Our data indicate that the most striking features of SMEI are: the early onset of seizures in a previously healthy child, the long duration of the first seizure, the presence of focal ictal symptoms, and sensitivity to low-grade fever. Diagnosis of SMEI may be proposed by the end of the first year of life, and a definite diagnosis can be established during the second year based on the peculiar seizure-favoring factors, EEG photosensitivity and psychomotor slowing. The temporal correlation between high seizure frequency and cognitive impairment support the role of epilepsy in the clinical outcome, even if a role of channelopathy cannot be ruled out.
...
PMID:Dravet syndrome: early clinical manifestations and cognitive outcome in 37 Italian patients. 1985

1 2 Next >>