Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The role of neuronal acetylcholine receptors (nAChRs) in epilepsy has been clearly established by the finding of mutations in a subset of genes coding for subunits of the nAChRs in a form of sleep-related epilepsy with familial occurrence in about 30% of probands and dominant inheritance, named autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Sporadic and familial forms have similar clinical and EEG features. Seizures begin in middle childhood as clusters of sleep-related attacks with prominent motor activity, and sustained dystonic posturing. In addition to nocturnal seizures, psychosis or schizophrenia, behavioral disorders, memory deficits and mental retardation were described in some individuals. Although over hundred families are on record, only a minority of them have been linked to mutations in the genes coding for the alpha4, alpha2 and beta2 (CHRNA4, CHRNA2, and CHRNB2) subunits of the nAChRs, indicating that ADNFLE is genetically heterogeneous despite a relatively homogeneous clinical picture. Functional characterization of some mutations suggests that gain of the receptor function might be the basis for epileptogenesis. In vitro and in vivo studies have shown high density of nAChRs in the thalamus, over activated brainstem ascending cholinergic pathway and enhanced GABAergic function, reinforcing the hypothesis that cortico-subcortical networks, regulating arousal from sleep, play a central role in seizure precipitation in ADNFLE.
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PMID:The role of the nicotinic acetylcholine receptors in sleep-related epilepsy. 1766 53

Ring chromosome 20 (r(20)) syndrome is a rare disease characterized by refractory epilepsy, moderate mental retardation and particular electroencephalographic disorder with non-convulsive status epilepticus. Here, we report a new case of r(20) syndrome in a 12 year old female who presented minimal dysmorphism, generalised tonic-clonic and absence seizures refractory to medical therapy and behavioural troubles. Among 20 cytogenetically analysed cells, 14 (70%) exhibited a 46,XX,r(20)(p13q13.3) karyotype and 6 (30%) showed a normal 46,XX caryotype. Interphasic FISH using centromeric probe of chromosome 20 detects the presence of a chromosome 20 monosomy in 7% and a duplicated ring chromosome 20 in 8% of studied cells. Metaphase FISH using chromosome 20 telomeric probes and specific probes of CHRNA4 and KCNQ2 genes detects the absence of any deletion in the ring chromosome 20. Clinical symptoms of r(20) syndrome are attributed to telomeric partial monosomy generated by ring chromosome and causing an haploinsufficiency of two epilepsy genes CHRNA4 and KCNQ2. However, our patient presents the typical epilepsy disorder but no detectable deletion in the ring chromosome 20. We speculate that clinical features of ring chromosome 20 syndrome are caused by low mosaicism of chromosome 20 monosomy caused by the loss of the ring chromosome 20.
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PMID:Ring chromosome 20 syndrome without deletions of the subtelomeric and CHRNA4--KCNQ2 genes loci. 1785 Nov 50

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE; MIM 600513) has been associated with mutations in the genes coding for the alfa-4 (CHRNA4), beta-2 (CHRNB2), and alpha-2 (CHRNA2) subunits of the neuronal nicotinic acetylcholine receptor (nAChR) and for the corticotropin-releasing hormone (CRH). A four-generation ADNFLE family with six affected members was identified. All affected members presented the clinical characteristics of ADNFLE. Interictal awake and sleep EEG recordings showed no epileptiform abnormalities. Ictal video-EEG recordings showed focal seizures with frontal lobe semiology. Mutation analysis of the CHRNB2 gene revealed a c.859G>A transition (Val287Met) within the second transmembrane domain, identical to that previously described in a Scottish ADNFLE family. To our knowledge, this is the third family reported presenting a mutation in CHRNB2. The clinical phenotype appears similar to that described with mutations in CHRNA4, suggesting that mutations in these two subunits lead to similar functional alterations of the nAChR.
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PMID:Autosomal dominant nocturnal frontal lobe epilepsy with a mutation in the CHRNB2 gene. 1790 Feb 92

Mutations of genes encoding alpha4, beta2, or alpha2 subunits (CHRNA4, CHRNB2, or CHRNA2, respectively) of nAChR [neuronal nicotinic ACh (acetylcholine) receptor] cause nocturnal frontal lobe epilepsy (NFLE) in human. NFLE-related seizures are seen exclusively during sleep and are characterized by three distinct seizure phenotypes: "paroxysmal arousals," "paroxysmal dystonia," and "episodic wandering." We generated transgenic rat strains that harbor a missense mutation S284L, which had been identified in CHRNA4 in NFLE. The transgenic rats were free of biological abnormalities, such as dysmorphology in the CNS, and behavioral abnormalities. The mRNA level of the transgene (mutant Chrna4) was similar to the wild type, and no distorted expression was detected in the brain. However, the transgenic rats showed epileptic seizure phenotypes during slow-wave sleep (SWS) similar to those in NFLE exhibiting three characteristic seizure phenotypes and thus fulfilled the diagnostic criteria of human NFLE. The therapeutic response of these rats to conventional antiepileptic drugs also resembled that of NFLE patients with the S284L mutation. The rats exhibited two major abnormalities in neurotransmission: (1) attenuation of synaptic and extrasynaptic GABAergic transmission and (2) abnormal glutamate release during SWS. The currently available genetically engineered animal models of epilepsy are limited to mice; thus, our transgenic rats offer another dimension to the epilepsy research field.
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PMID:Rats harboring S284L Chrna4 mutation show attenuation of synaptic and extrasynaptic GABAergic transmission and exhibit the nocturnal frontal lobe epilepsy phenotype. 1902 39

The alpha4 subunit gene (CHRNA4) of the neuronal nicotinic acetylcholine receptor (nAChR), linked to an idiopathic partial epilepsy, autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), may also play a key role in the development of the idiopathic generalized epilepsy syndrome (IGE), juvenile myoclonic epilepsy (JME). This study was designed to explore an association of four polymorphisms of the CHRNA4 with JME in Polish children and young patients. The study included 92 JME patients and 222 unrelated healthy individuals. In each group the frequencies of the CHRNA4 c.555C>T, c.594C>T, 1674(+11)C>T, and 1674(+14)A>G polymorphisms were determined using PCR-RFLP analyses. An association between the 1674(+11)C>T polymorphism of the CHRNA4 and JME was evidenced. Allele T (the risk factor) appeared with a significantly higher frequency in the JME patients than in the controls (p=0.0299). The patients harboring the 1674(+11)CT+TT genotypes showed an increased risk of JME (CT+TT versus CC: OR=1.925; 95% CI=1.021-3.629; p=0.0408). No association was found for the other CHRNA4 polymorphisms tested. The CHRNA4 1674(+11)C>T polymorphism may be a susceptibility factor for epilepsy, and its higher frequency in patients with juvenile myoclonic epilepsy suggests that the CHRNA4 may be one of the candidate genes for this epileptic syndrome.
Seizure 2009 Oct
PMID:The 1674+11C>T polymorphism of CHRNA4 is associated with juvenile myoclonic epilepsy. 1957 88

Genetic factors play an increasingly recognized role in idiopathic epilepsies. Since 1995, positional cloning strategies in multi-generational families with autosomal dominant transmission have revealed 11 genes (KCNQ2, KCNQ3, CHRNA4, CHRNA2, CHRNB2, SCN1B, SCN1A, SCN2A, GABRG2, GABRA1, and LGI1) and numerous loci for febrile seizures and epilepsies. To date, all genes with the exception of LGI1 (leucine-rich glioma inactivated 1), encode neuronal ion channel or neurotransmitter receptor subunits. Molecular approaches have revealed great genetic heterogeneity, with the vast majority of genes remaining to be identified. One of the major challenges is now to understand phenotype-genotype correlations. This review focuses on the current knowledge on the molecular basis of these rare Mendelian autosomal dominant forms of idiopathic epilepsies.
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PMID:Advances on the genetics of mendelian idiopathic epilepsies. 1985 23

Characterized by sudden episodes called seizures, epilepsy was recognized long ago as a neurological disorder that can have multiple forms ranging from benign to life threatening depending upon its severity. Although several evidences indicated that genes play an important role in at least half of the patients, it is only with the advances in molecular biology and genetics that the puzzle about oligogenic and monogenic epilepsies slowly starts to unfold. The finding of an association between a monogenic form of epilepsy and a mutation in the gene encoding the neuronal nicotinic acetylcholine receptor subunit CHRNA4 marked, in 1995, a turning point in our understanding of epilepsy. It also marked the first step towards the today widely acknowledged concept of epilepsies as channelopathies. Several mutations in nicotinic acetylcholine receptor genes have, since then, been identified, and the functional properties of these mutated receptors were characterized. In this work, we review, in the light of the latest discoveries, the effects caused by the mutations on the physiological properties of the receptors and the impact of such mutations on neuronal network functions.
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PMID:Nicotinic receptor channelopathies and epilepsy. 2001 90

Nocturnal frontal lobe epilepsy is seen exclusively during sleep and is characterized by three distinct seizure phenotypes: paroxysmal arousals, paroxysmal dystonia, and episodic wandering. Mutations of CHRNA4, CHRNB2, or CHRNA2 genes encoding alpha4, beta2 or alpha2 subunits of neuronal nicotinic ACh receptor (nAChR) have been identified in the individuals with sporadic type NFLE and pedigrees with autosomal dominant type of NFLE (ADNFLE). In the past decade, various electrophysiological studies have analyzed the functional abnormalities of ADNFLE/NFLE mutant nAChR; however, the detailed pathogenesis of ADNFLE/NFLE has remained to be clarified. Therefore, to explore the pathogenesis of ADNFLE/NFLE, genetic animal models harboring ADNFLE mutant Chrna4 genes have recently been established. The face, construct and predictive validities have been demonstrated in a transgenic rat strain bearing the S284L mutant Chrna4 gene. The in vivo analyses of the functional abnormalities using genetic ADNFLE/NFLE animal models suggest the putative mechanisms of the ADNFLE/NFLE seizure onset during slow wave sleep.
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PMID:[Generation of epilepsy animal model bearing a genetic abnormality identified in autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) of humans]. 2029 37

Genetic factors play an increasingly recognized role in idiopathic epilepsies. Since 1995, positional cloning strategies in multigenerational families with autosomal dominant transmission have revealed 11 genes (KCNQ2, KCNQ3, CHRNA4, CHRNA2, CHRNB2, SCN1B, SCN1A, SCN2A, GABRG2, GABRA1, and LGI1) and numerous loci for febrile seizures and epilepsies. To date, all genes with the exception of LGI1, encode neuronal ion channel or neurotransmitter receptor subunits. Molecular approaches have revealed great genetic heterogeneity, with most genes remaining to be identified. One of the major challenges is now to understand phenotype-genotype correlations. This review focuses on the current knowledge on the molecular basis of these rare mendelian autosomal dominant forms of idiopathic epilepsies.
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PMID:Advances on the genetics of Mendelian idiopathic epilepsies. 2083 59

Ring chromosome 20 syndrome combines epilepsy with varying levels of mental retardation, behavioral disorders, and malformations. Epilepsy is generally serious, with frequent drug resistance. The pathophysiology of seizures remains unclear. Rearrangements of two epilepsy genes, CHRNA4 and KCNQ2, have been raised as the cause. We report the observation of one child, with a telomeric deletion 20p13, with no epileptic symptoms. Preservation of CHRNA4 and KCNQ2 gene activity could explain this distinctive feature.
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PMID:[Polymorphic expression of epilepsy and cognitive impairment in ring chromosome 20 syndrome]. 2139 68


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