124 research outputs found
Bi-allelic GAD1 variants cause a neonatal onset syndromic developmental and epileptic encephalopathy.
Developmental and epileptic encephalopathies are a heterogeneous group of early-onset epilepsy syndromes dramatically impairing neurodevelopment. Modern genomic technologies have revealed a number of monogenic origins and opened the door to therapeutic hopes. Here we describe a new syndromic developmental and epileptic encephalopathy caused by bi-allelic loss-of-function variants in GAD1, as presented by 11 patients from six independent consanguineous families. Seizure onset occurred in the first 2 months of life in all patients. All 10 patients, from whom early disease history was available, presented with seizure onset in the first month of life, mainly consisting of epileptic spasms or myoclonic seizures. Early EEG showed suppression-burst or pattern of burst attenuation or hypsarrhythmia if only recorded in the post-neonatal period. Eight patients had joint contractures and/or pes equinovarus. Seven patients presented a cleft palate and two also had an omphalocele, reproducing the phenotype of the knockout Gad1-/- mouse model. Four patients died before 4 years of age. GAD1 encodes the glutamate decarboxylase enzyme GAD67, a critical actor of the Îł-aminobutyric acid (GABA) metabolism as it catalyses the decarboxylation of glutamic acid to form GABA. Our findings evoke a novel syndrome related to GAD67 deficiency, characterized by the unique association of developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele
KCNQ2 R144 variants cause neurodevelopmental disability with language impairment and autistic features without neonatal seizures through a gain-of-function mechanism
Prior studies have revealed remarkable phenotypic heterogeneity in KCNQ2-related disorders, correlated with effects on biophysical features of heterologously expressed channels. Here, we assessed phenotypes and functional properties associated with KCNQ2 missense variants R144W, R144Q, and R144G. We also explored in vitro blockade of channels carrying R144Q mutant subunits by amitriptyline
Mutations in GABRB3
Objective: To examine the role of mutations in GABRB3 encoding the b3 subunit of the GABAA receptor in individual patients with epilepsy with regard to causality, the spectrum of genetic variants, their pathophysiology, and associated phenotypes. Methods: We performed massive parallel sequencing of GABRB3 in 416 patients with a range of epileptic encephalopathies and childhood-onset epilepsies and recruited additional patients with epilepsy with GABRB3 mutations from other research and diagnostic programs. Results: We identified 22 patients with heterozygous mutations in GABRB3, including 3 probands frommultiplex families. The phenotypic spectrum of the mutation carriers ranged from simple febrile seizures, genetic epilepsies with febrile seizures plus, and epilepsy withmyoclonic-atonic seizures to West syndrome and other types of severe, early-onset epileptic encephalopathies. Electrophysiologic analysis of 7 mutations in Xenopus laevis oocytes, using coexpression of wild-type or mutant beta(3), together with alpha(5) and gamma(2s) subunits and an automated 2-microelectrode voltage-clamp system, revealed reduced GABA-induced current amplitudes or GABA sensitivity for 5 of 7 mutations. Conclusions: Our results indicate that GABRB3 mutations are associated with a broad phenotypic spectrum of epilepsies and that reduced receptor function causing GABAergic disinhibition represents the relevant disease mechanism
Visual motion with pink noise induces predation behaviour
Visual motion cues are one of the most important factors for eliciting animal behaviour, including predator-prey interactions in aquatic environments. To understand the elements of motion that cause such selective predation behaviour, we used a virtual plankton system where the predation behaviour in response to computer-generated prey was analysed. First, we performed motion analysis of zooplankton (Daphnia magna) to extract mathematical functions for biologically relevant motions of prey. Next, virtual prey models were programmed on a computer and presented to medaka (Oryzias latipes), which served as predatory fish. Medaka exhibited predation behaviour against several characteristic virtual plankton movements, particularly against a swimming pattern that could be characterised as pink noise motion. Analysing prey-predator interactions via pink noise motion will be an interesting research field in the future
<i>GRIN2A</i>-related disorders:genotype and functional consequence predict phenotype
Alterations of the N-methyl-d-aspartate receptor (NMDAR) subunit GluN2A, encoded by GRIN2A, have been associated with a spectrum of neurodevelopmental disorders with prominent speech-related features, and epilepsy. We performed a comprehensive assessment of phenotypes with a standardized questionnaire in 92 previously unreported individuals with GRIN2A-related disorders. Applying the criteria of the American College of Medical Genetics and Genomics to all published variants yielded 156 additional cases with pathogenic or likely pathogenic variants in GRIN2A, resulting in a total of 248 individuals. The phenotypic spectrum ranged from normal or near-normal development with mild epilepsy and speech delay/apraxia to severe developmental and epileptic encephalopathy, often within the epilepsy-aphasia spectrum. We found that pathogenic missense variants in transmembrane and linker domains (misTMD+Linker) were associated with severe developmental phenotypes, whereas missense variants within amino terminal or ligand-binding domains (misATD+LBD) and null variants led to less severe developmental phenotypes, which we confirmed in a discovery (P = 10-6) as well as validation cohort (P = 0.0003). Other phenotypes such as MRI abnormalities and epilepsy types were also significantly different between the two groups. Notably, this was paralleled by electrophysiology data, where misTMD+Linker predominantly led to NMDAR gain-of-function, while misATD+LBD exclusively caused NMDAR loss-of-function. With respect to null variants, we show that Grin2a+/- cortical rat neurons also had reduced NMDAR function and there was no evidence of previously postulated compensatory overexpression of GluN2B. We demonstrate that null variants and misATD+LBD of GRIN2A do not only share the same clinical spectrum (i.e. milder phenotypes), but also result in similar electrophysiological consequences (loss-of-function) opposing those of misTMD+Linker (severe phenotypes; predominantly gain-of-function). This new pathomechanistic model may ultimately help in predicting phenotype severity as well as eligibility for potential precision medicine approaches in GRIN2A-related disorders
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Le systÚme budgétaire du Royaume-Uni
International audienceA lâorigine du Parlement il y a lâimpĂŽt. Câest pour donner son consentement Ă lâimpĂŽt quâest apparu, au cours du Moyen-Age, en Angleterre, le Commun conseil. Plus tard, il se transformera en Parlement et Ă©tendra son contrĂŽle aux dĂ©penses. Lâhistoire aurait pu sâarrĂȘter lĂ . Mais lâAngleterre, « voisine dâaucun par la terre est devenue, au fil du temps, voisine de tous par la mer ». Son modĂšle, autant dire celui de la Grande-Bretagne puis du Royaume-Uni, qui unit indissolublement budget et parlement, a essaimĂ© Ă travers le monde. Il a Ă©tĂ© copiĂ©, adoptĂ©, imposĂ©, sur prĂšs dâun quart de la surface de la terre, aussi bien dans lâhĂ©misphĂšre borĂ©al (par ex. Canada) que dans lâhĂ©misphĂšre austral (par ex. Afrique du Sud). Mais ce modĂšle, dont lâoriginalitĂ© en matiĂšre constitutionnelle est indĂ©niable, se singularise-t-il aussi en matiĂšre budgĂ©taire ? Existe-t-il rĂ©ellement un modĂšle budgĂ©taire britannique comme il existe un modĂšle parlementaire britannique ? La rĂ©ponse est oui. Des spĂ©cificitĂ©s existent. Assez tout au moins, pour apporter la preuve de « la possibilitĂ© dâune Ăźle ». Ou plutĂŽt de la possibilitĂ© dâun archipel, tant ce systĂšme budgĂ©taire sâest diffusĂ© dans le monde
GĂ©rard Nicoud et la rĂ©volte des indĂ©pendants contre lâinjustice fiscale
International audienceLe mouvement de GĂ©rard Nicoud naĂźt en dĂ©cembre 1968, dâunerĂ©volte antifiscale. Il se caractĂ©rise par la lutte contre lâinquisitionfiscale et la dĂ©fiance Ă lâĂ©gard du systĂšme politique. Il remporteplusieurs victoires parmi lesquelles la crĂ©ation du Conseil des impĂŽts,de la charte du contribuable vĂ©rifiĂ©, des centres de gestion agrĂ©Ă©s, ainsique la suppression de la patente.GĂ©rard Nicoudâs movement was born in December 1968, of an anti-taxrevolt. It is characterized by the fight against tax inquisition and mistrustof the political system. The movement won several victories including thecreation of the Tax Council, the charter of the inspected taxpayer, thechartered management centers, and the abolition of the patent
Le financement public du bicamérisme du Royaume-Uni
International audienceLe 12 juin 1215 une Grande Charte, la MagnaCarta, est arrachĂ©e au roi Jean Sans Terre. Lesbarons anglais profitent de plusieurs dĂ©faites, dontcelle de Bouvines et de La-Roche-aux-Moines,pour imposer Ă Jean sans Terre la reconnaissancede franchises ecclĂ©siastiques, le respect de rĂšglesspĂ©cifiques Ă la noblesse ainsi que le consentementĂ lâimpĂŽt du Grand Conseil. Au fil des siĂšcles,le Grand Conseil va devenir le Parlement britannique.Câest tout au moins ce que dit la lĂ©gende.Le Parlement britannique serait ainsi lâun des plusanciens du monde. Le modĂšle parlementaire va sediffuser avec dâautant plus de facilitĂ© que lâempirecolonial britannique est Ă©tendu.Le Parlement, câest lâune des originalitĂ©s dusystĂšme constitutionnel britannique, comprend laReine, la Chambre des lords et la Chambre descommunes. Il siĂšge au Palais de Westminster, Ă Londres. Par convention, le Premier ministre duRoyaume-Uni et les membres du gouvernementsont tous membres du Parlement, gĂ©nĂ©ralementde la Chambre des communes, mais pas obligatoirement.Dans cet exposĂ© nous ne nous intĂ©resseronsquâau financement du parlement strictosensu, au sens oĂč on lâentend en France, câest-Ă direĂ la Chambre des communes et Ă la Chambredes Lords.Ă travers la question du financement du parlementbritannique, câest toute la question de lasĂ©paration des pouvoirs qui est posĂ©e. Un par -lement fonctionnant exclusivement avec desrecettes propres paraĂźt difficilement concevable.Dans le mĂȘme temps, un parlement trop dĂ©pendantde lâexĂ©cutif cesse dâĂȘtre un vrai contrepouvoir.DâoĂč lâimportance de cette questionrelative au financement du parlement du Royaume-Uni. Cette autonomie financiĂšre du parlementbritannique existe. Elle nâest pas complĂšte, lebudget du parlement Ă©tant adoptĂ© dans les loisdâappropriation votĂ©es par le Parlement. Or,celles-ci sont prĂ©parĂ©es par le gouvernement etne peuvent ĂȘtre modifiĂ©es en cours de discussionparlementaire, quâavec lâaccord du gouvernement
Le conflit budgétaire, moteur de la démocratie américaine
International audienceIl nây a pas un mais deux projets de budget qui se font face. Chaque pouvoir, exĂ©cutif et lĂ©gislatif arrive avec son projet. En fonction de lâĂ©tat des forces politiques, le budget qui sera finalement adoptĂ© penchera davantage vers le projet du prĂ©sident ou vers celui du CongrĂšs. Pour prĂ©parer ces deux budgets chaque pouvoir dispose dâun « office », une administration des finances autonome, en quelque sorte.Toute la singularitĂ© du droit budgĂ©taire des Etats-Unis rĂ©side dans le fait dâavoir laissĂ© le budget dans le champ du dĂ©bat dĂ©mocratique. Les crises que traversent rĂ©guliĂšrement les Etats-Unis lors de lâadoption du budget en sont le prix Ă payer. Ce prix est celui dâun conflit entre les diffĂ©rents pouvoirs qui concourent Ă son Ă©laboration, câest Ă dire essentiellement entre lâexĂ©cutif et le lĂ©gislatif. La procĂ©dure budgĂ©taire sâapparente Ă un chemin sinueux dont le but est de favoriser lâĂ©mergence dâun compromis entre les protagonistes. Ce chemin est jalonnĂ© de rĂšgles permettant la rĂ©solution du conflit. Les protagonistes ont intĂ©rĂȘt Ă le suivre : ils savent quâĂ la fin il faudra trouver un accord. Dans les moments les plus conflictuels, le budget se transforme alors en acte dâarmistice entre les combattants budgĂ©taires. Il est lâaboutissement de la rĂ©solution du conflit. Sâil nây a pas dâarmistice, il nây a pas de budget. Câest le shutdown : le CongrĂšs refuse de voter le budget et, faute de financement, une grande partie de lâadministration doit sâarrĂȘter. Mais le shutdown ne peut-ĂȘtre que temporaire. Il est une Ă©tape, douloureuse certes, vers la rĂ©solution du conflit. Les belligĂ©rants ne peuvent pas se permettre de prolonger la guerre qui les oppose. Ou bien, avec la fermeture des administrations, câest le pays entier qui risque dâĂȘtre transformĂ© en champ de bataille. Lâordre budgĂ©taire, le droit qui en dĂ©coule, a pour objet de faciliter le rĂšglement du conflit. Il est lĂ pour aider les protagonistes Ă marcher vers un accord
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