Benigne familiäre Neugeborenenkrämpfe Molekulare Pathogenese und Diagnostik

Benign familial neonatal convulsions are a rare monogenic form of idiopathic epilepsy characterized by the onset of frequent brief seizures after the second day of life. The seizures disappear spontaneously within a few weeks, but recurrent seizures later in life are common. Linkage studies located genes to chromosome 20q13.3 and 8q24, and the voltage-gated potassium channels KCNQ2 and KCNQ3 were recently identified. Since then, several mutations have been found leading to haplosufficiency of the ion channel. Functional studies showed that KCNQ2 and KCNQ3 are able to contribute to a heteromeric channel exhibiting kinetic and pharmacological properties similar to those of the native M current, the latter playing an important role in the regulation of neuronal excitability. This overview presents a summary of the molecular, genetic, and electrophysiological findings and discusses them with respect to their clinical relevance.     

Nicotinic acetylcholine receptors and epilepsy

The neuronal nicotinic acetylcholine receptors (nAChRs) have multiple roles in the brain: they are involved in signal transduction by fast synaptic transmission, axo-axonic transmission, and in the modulation of presynaptic transmitter release. Presynaptic nAChRs can increase the release of excitatory as well as of inhibitory transmitters, and can thereby control neuronal excitability. Furthermore, nAChRs which are expressed in fetal brain might also be involved in brain morphogenesis. Thus, the genes coding for the different nAChR subunits are likely candidates for several neurological disorders. The CHRNA4- or CHRNB2 subunits of the nAChR are associated with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), a rare monogenic type of idiopathic epilepsy. Electrophysiological studies demonstrated that ADNFLE mutations are causing both a loss-of-function and a gain-of-function in alpha4/beta2-heteropentameric nAChRs.     

A Korean kindred with autosomal dominant nocturnal frontal lobe epilepsy and mental retardation

BACKGROUND: A Korean family had distinctive clinical and neuroimaging features and carried the same genetic mutation that was found in a previously described Japanese kindred with autosomal dominant nocturnal frontal lobe epilepsy. OBJECTIVE: To describe the first Korean family with autosomal dominant nocturnal frontal lobe epilepsy. METHODS: Members of a large family, including 9 affected individuals from 3 generations, underwent a comprehensive genetic, clinical, electroencephalographic, neuropsychological, and neuroimaging evaluation. Affected members were tested for possible mutations in transmembrane regions 1 through 3 of the neuronal nicotinic acetylcholine receptor alpha4 subunit (CHRNA4) by direct sequencing and subsequent restriction analysis. RESULTS: Seizures began in childhood, presenting as nocturnal episodes of staring, confusion, shouting, perioral movements, unintelligible speech, and hand waving. Some patients had ictal or interictal epileptiform activity in the temporal and/or frontocentral areas. Neurological examination and brain magnetic resonance imaging results showed no abnormalities, except that all patients available for testing had mild to moderate mental retardation. Fluorodeoxyglucose F 18 with positron emission tomography showed mild decreased glucose uptake in the superior and middle frontal regions, more so on the left than on the right. Patient response to carbamazepine was poor. All affected members were heterozygous for the CHRNA4 Ser252Leu mutation. CONCLUSIONS: Disorders associated with mutations in the transmembrane region 2 of CHRNA4 are genetically and phenotypically heterogeneous. Distinctive features of this kindred include (1) mental retardation in all affected members available for testing, (2) abnormal brain findings on fluorodeoxyglucose F 18 with positron emission tomography, (3) poor response to carbamazepine, and (4) full penetrance.     

The CHRNB2 mutation I312M is associated with epilepsy and distinct memory deficits

Mutations in nAChRs are found in a rare form of nocturnal frontal lobe epilepsy (ADNFLE). Previously, some nAChR mutations have been described that are associated with additional neurological features such as psychiatric disorders or cognitive defects. Here, we report a new CHRNB2 mutation located in transmembrane region 3 (M3), outside the known ADNFLE mutation cluster. The CHRNB2 mutation I312M, which occurred de novo in twins, markedly increases the receptor's sensitivity to acetylcholine. Phenotypically, the mutation is associated not only with typical ADNFLE, but also with distinct deficits in memory. The cognitive problems are most obvious in tasks requiring the organization and storage of verbal information.     

Speech-induced aphasic seizures in epilepsy caused by LGI1 mutation

Summary:  Purpose: Patients with autosomal dominant lateral temporal lobe epilepsy (ADTLE) may have seizures precipitated by sound or speech. We have examined a patient with speech-induced seizures caused by an LGI1 mutation (C46R).
Methods: A clinical study and a video-EEG recording using interrogative speech as the activation procedure was performed in a 23-year-old man.
Results: He had experienced short episodes of sensory aphasia in situations in which he was suddenly verbally addressed. Voices became distorted, and he could not comprehend despite hearing words. The day after a late party, his girlfriend unexpectedly spoke to him. Her speech became unintelligible to him. He did not reply and had a generalized tonic–clonic (GTC) seizure. During an EEG, he was suddenly asked for the names of his siblings. He answered, but lost understanding of the further conversation and described how syllables floated together with an echoing character. With a versive movement to the right, another GTC occurred. In the EEG, rhythmic 6-Hz activity built up in the frontotemporal areas starting on the left side with bilateral and posterior spreading. Postictal slowing was symmetrical, and no aphasia was noted on awakening.
Conclusions: To our knowledge, this is the first video-EEG recorded seizure in LGI1 -caused ADTLE. This peculiar seizure semiology and precipitating effect of speech may serve as a marker for identifying further individuals with this particular phenotype and genotype and may indicate that the LGI1 gene may have a physiologic function connected to the human capacity for speech and language.     

Genotypic association of exonic LGI4 polymorphisms and childhood absence epilepsy

The LGI4 gene is located in a region linked to benign familial infantile convulsions (BFIC) and idiopathic generalized epilepsy. Screening of the LGI4 coding region in BFIC and childhood absence epilepsy (CAE) revealed several frequent exonic polymorphisms. A genotypic association was found for the c.1914GCAT polymorphism in 42 CAE patients compared with 110 population controls (²=6.66, df=1, P=0.01), providing evidence for a so far undetected susceptibility allele for CAE in the LGI4 region.     

Early glial cell reactivity in experimental retinal detachment: effect of suramin

PURPOSE: In a rabbit model of retinal detachment, early Müller glial cell reactivity was monitored-specifically, changes in membrane features-to determine whether these changes involve an upregulation of purinergic P2 receptor-mediated responses and whether all or some of these alterations could be blocked by suramin or pyridoxal phosphate 6-azophenyl-2',4'-disulfonic acid (PPADS). In addition, the immune cell reactivity (microglial cells and blood-derived immune cells) was monitored. METHODS: A local retinal detachment was induced by subretinal injection of a sodium hyaluronate solution. Three, 24, 48, and 72 hours after surgery, Müller cells were acutely isolated, and patch-clamp records of the whole-cell potassium currents were made. The presence of P2 receptor-mediated responses was determined by measuring extracellular adenosine triphosphate (ATP)-induced membrane current increases, and by recording of ATP-induced calcium responses at the vitreal surface of retinal wholemounts. The density of isolectin B(4)-labeled immune cells was determined in the nerve fiber layer of retinal wholemounts. RESULTS: Within 24 hours of detachment, Müller cell reactivity was evident. The cells downregulated the density of their inwardly rectifying potassium currents to 60% and 47% of the control value at 48 hours and 72 hours of detachment, respectively. This downregulation was accompanied by an enhanced incidence of cells which showed calcium and current responses after ATP application (control: 14%; 24 hours of detachment: 42%; 72 hours of detachment: 80%). Müller cell hypertrophy was apparent at 48 and 72 hours of detachment. Application of suramin during surgery inhibited the downregulation of potassium currents, but not the elevated responsiveness to extracellular ATP; PPADS had no effect. Suramin also inhibited the inflammatory response that was induced by the surgical procedure and that was apparent by the increased number of immune cells. CONCLUSIONS: Reactive responses of Müller cells occur within 24 hours of detachment. Suramin inhibits several (but not all) reactive glial alterations and therefore may represent one candidate for further investigations in the search for drugs that limit detrimental effects of immune cell activation and Müller cell gliosis during retinal detachment.     

Untersuchungen über die Sonderstellung des Alkohols als Desinfiziens und über die Rolle der Adsorption bei Desinfektionsversuchen,insbesondere bei der Händedesinfektion

Ohne ZusammenfassungAus dem Institut Robert Koch.Herrn Prof.Doerr zum 70. Geburtstag gewidmet.