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 γ-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

Inhibition of G-protein signalling in cardiac dysfunction of intellectual developmental disorder with cardiac arrhythmia (IDDCA) syndrome

BACKGROUND: Pathogenic variants of GNB5 encoding the β5 subunit of the guanine nucleotide-binding protein cause IDDCA syndrome, an autosomal recessive neurodevelopmental disorder associated with cognitive disability and cardiac arrhythmia, particularly severe bradycardia. METHODS: We used echocardiography and telemetric ECG recordings to investigate consequences of Gnb5 loss in mouse. RESULTS: We delineated a key role of Gnb5 in heart sinus conduction and showed that Gnb5-inhibitory signalling is essential for parasympathetic control of heart rate (HR) and maintenance of the sympathovagal balance. Gnb5-/- mice were smaller and had a smaller heart than Gnb5+/+ and Gnb5+/- , but exhibited better cardiac function. Lower autonomic nervous system modulation through diminished parasympathetic control and greater sympathetic regulation resulted in a higher baseline HR in Gnb5-/- mice. In contrast, Gnb5-/- mice exhibited profound bradycardia on treatment with carbachol, while sympathetic modulation of the cardiac stimulation was not altered. Concordantly, transcriptome study pinpointed altered expression of genes involved in cardiac muscle contractility in atria and ventricles of knocked-out mice. Homozygous Gnb5 loss resulted in significantly higher frequencies of sinus arrhythmias. Moreover, we described 13 affected individuals, increasing the IDDCA cohort to 44 patients. CONCLUSIONS: Our data demonstrate that loss of negative regulation of the inhibitory G-protein signalling causes HR perturbations in Gnb5-/- mice, an effect mainly driven by impaired parasympathetic activity. We anticipate that unravelling the mechanism of Gnb5 signalling in the autonomic control of the heart will pave the way for future drug screening

Inhibition of G-protein signalling in cardiac dysfunction of intellectual developmental disorder with cardiac arrhythmia (IDDCA) syndrome

Background: Pathogenic variants of GNB5 encoding the β5 subunit of the guanine nucleotide-binding protein cause IDDCA syndrome, an autosomal recessive neurodevelopmental disorder associated with cognitive disability and cardiac arrhythmia, particularly severe bradycardia. Methods: We used echocardiography and telemetric ECG recordings to investigate consequences of Gnb5 loss in mouse. Results: We delineated a key role of Gnb5 in heart sinus conduction and showed that Gnb5-inhibitory signalling is essential for parasympathetic control of heart rate (HR) and maintenance of the sympathovagal balance. Gnb5-/- mice were smaller and had a smaller heart than Gnb5+/+ and Gnb5+/-, but exhibited better cardiac function. Lower autonomic nervous system modulation through diminished parasympathetic control and greater sympathetic regulation resulted in a higher baseline HR in Gnb5-/- mice. In contrast, Gnb5-/- mice exhibited profound bradycardia on treatment with carbachol, while sympathetic modulation of the cardiac stimulation was not altered. Concordantly, transcriptome study pinpointed altered expression of genes involved in cardiac muscle contractility in atria and ventricles of knocked-out mice. Homozygous Gnb5 loss resulted in significantly higher frequencies of sinus arrhythmias. Moreover, we described 13 affected individuals, increasing the IDDCA cohort to 44 patients. Conclusions: Our data demonstrate that loss of negative regulation of the inhibitory G-protein signalling causes HR perturbations in Gnb5-/- mice, an effect mainly driven by impaired parasympathetic activity. We anticipate that unravelling the mechanism of Gnb5 signalling in the autonomic control of the heart will pave the way for future drug screening

NEXMIF encephalopathy: an X-linked disorder with male and female phenotypic patterns

Purpose: Pathogenic variants in the X-linked gene NEXMIF (previously KIAA2022) are associated with intellectual disability (ID), autism spectrum disorder, and epilepsy. We aimed to delineate the female and male phenotypic spectrum of NEXMIF encephalopathy. / Methods: Through an international collaboration, we analyzed the phenotypes and genotypes of 87 patients with NEXMIF encephalopathy. / Results: Sixty-three females and 24 males (46 new patients) with NEXMIF encephalopathy were studied, with 30 novel variants. Phenotypic features included developmental delay/ID in 86/87 (99%), seizures in 71/86 (83%) and multiple comorbidities. Generalized seizures predominated including myoclonic seizures and absence seizures (both 46/70, 66%), absence with eyelid myoclonia (17/70, 24%), and atonic seizures (30/70, 43%). Males had more severe developmental impairment; females had epilepsy more frequently, and varied from unaffected to severely affected. All NEXMIF pathogenic variants led to a premature stop codon or were deleterious structural variants. Most arose de novo, although X-linked segregation occurred for both sexes. Somatic mosaicism occurred in two males and a family with suspected parental mosaicism. / Conclusion: NEXMIF encephalopathy is an X-linked, generalized developmental and epileptic encephalopathy characterized by myoclonic–atonic epilepsy overlapping with eyelid myoclonia with absence. Some patients have developmental encephalopathy without epilepsy. Males have more severe developmental impairment. NEXMIF encephalopathy arises due to loss-of-function variants

Clinical and functional heterogeneity associated with the disruption of retinoic acid receptor beta.

PURPOSE: Dominant variants in the retinoic acid receptor beta (RARB) gene underlie a syndromic form of microphthalmia, known as MCOPS12, which is associated with other birth anomalies and global developmental delay with spasticity and/or dystonia. Here, we report 25 affected individuals with 17 novel pathogenic or likely pathogenic variants in RARB. This study aims to characterize the functional impact of these variants and describe the clinical spectrum of MCOPS12. METHODS: We used in vitro transcriptional assays and in silico structural analysis to assess the functional relevance of RARB variants in affecting the normal response to retinoids. RESULTS: We found that all RARB variants tested in our assays exhibited either a gain-of-function or a loss-of-function activity. Loss-of-function variants disrupted RARB function through a dominant-negative effect, possibly by disrupting ligand binding and/or coactivators' recruitment. By reviewing clinical data from 52 affected individuals, we found that disruption of RARB is associated with a more variable phenotype than initially suspected, with the absence in some individuals of cardinal features of MCOPS12, such as developmental eye anomaly or motor impairment. CONCLUSION: Our study indicates that pathogenic variants in RARB are functionally heterogeneous and associated with extensive clinical heterogeneity

Clinical spectrum of STX1B-related epileptic disorders

OBJECTIVE: The aim of this study was to expand the spectrum of epilepsy syndromes related to STX1B, encoding the presynaptic protein syntaxin-1B, and establish genotype-phenotype correlations by identifying further disease-related variants. METHODS: We used next-generation sequencing in the framework of research projects and diagnostic testing. Clinical data and EEGs were reviewed, including already published cases. To estimate the pathogenicity of the variants, we used established and newly developed in silico prediction tools. RESULTS: We describe 17 new variants in STX1B, which are distributed across the whole gene. We discerned 4 different phenotypic groups across the newly identified and previously published patients (49 patients in 23 families): (1) 6 sporadic patients or families (31 affected individuals) with febrile and afebrile seizures with a benign course, generally good drug response, normal development, and without permanent neurologic deficits; (2) 2 patients with genetic generalized epilepsy without febrile seizures and cognitive deficits; (3) 13 patients or families with intractable seizures, developmental regression after seizure onset and additional neuropsychiatric symptoms; (4) 2 patients with focal epilepsy. More often, we found loss-of-function mutations in benign syndromes, whereas missense variants in the SNARE motif of syntaxin-1B were associated with more severe phenotypes. CONCLUSION: These data expand the genetic and phenotypic spectrum of STX1B-related epilepsies to a diverse range of epilepsies that span the International League Against Epilepsy classification. Variants in STX1B are protean and contribute to many different epilepsy phenotypes, similar to SCN1A, the most important gene associated with fever-associated epilepsies

Clinical spectrum of STX1B-related epileptic disorders

Objective The aim of this study was to expand the spectrum of epilepsy syndromes related to STX1B, encoding the presynaptic protein syntaxin- 1B, and establish genotype-phenotype correlations by identifying further disease related variants. Methods We used next-generation sequencing in the framework of research projects and diagnostic testing. Clinical data and EEGs were reviewed, including already published cases. To estimate the pathogenicity of the variants, we used established and newly developed in silico prediction tools. Results We describe 17 new variants in STX1B, which are distributed across the whole gene. We discerned 4 different phenotypic groups across the newly identified and previously published patients (49 patients in 23 families): (1) 6 sporadic patients or families (31 affected individuals) with febrile and afebrile seizures with a benign course, generally good drug response, normal development, and without permanent neurologic deficits; (2) 2 patients with genetic generalized epilepsy without febrile seizures and cognitive deficits; (3) 13 patients or families with intractable seizures, developmental regression after seizure onset and additional neuropsychiatric symptoms; (4) 2 patients with focal epilepsy. More often, we found loss-of-function mutations in benign syndromes, whereas missense variants in the SNARE motif of syntaxin-1B were associated with more severe phenotypes. Conclusion These data expand the genetic and phenotypic spectrum of STX1B-related epilepsies to a diverse range of epilepsies that span the International League Against Epilepsy classification. Variants in STX1B are protean and contribute to many different epilepsy phenotypes, similar to SCN1A, the most important gene associated with fever-associated epilepsies

Utilisation du REMDÉSIVIR et impact potentiel sur divers paramètres biologiques.

CONTEXTE: Le Remdésivir (R), antiviral inhibant l’ARN polymérase du SARS-CoV-2, a été utilisé dans le cadre d’une Autorisation temporaire d’utilisation (ATU), puis de l’Autorisation de mise sur le marché (AMM) pour les pneumopathies à COVID-19 modérées à sévères. OBJECTIFS: Les objectifs de ce travail sont de décrire la population ayant reçu le R et les variations biologiques possiblement associées à son administration. PATIENTS ET MÉTHODES: Une étude rétrospective monocentrique incluant les patients ayant reçu du R entre le 15/09 et le 15/12/2020 a été menée. Les caractéristiques des patients, les modalités de leur Prise en charge (PEC), leur devenir et les paramètres biologiques incluant créatinine, ASAT, ALAT, CRP et D-dimères ont été recueillis dans les 48 heures avant et après l’administration de R via Crossway®, ICCA® et Cyberlab®. Les données étaient exploitables (DE) quand les deux valeurs avant et après R étaient disponibles pour chaque paramètre. RÉSULTATS: Au total, 88 patients ont été inclus (âge médian = 70 ans, sexe-ratio = 2/1, moy indice masse corporelle = 30,19 ± 6,38 kg/m(2)). Une comorbidité était présente chez 94,3 % des patients : antécédent cardiovasculaire (76,1 %), obésité (48,9 %), diabète (30,7 %), antécédent pulmonaire (13,6 %) et immunodépression (6,8 %). Le R était initié dans 62,5 % des cas en réanimation et 37,5 % en médecine, en moyenne 7,9 ± 3,7 jours (j) [1 ; 19] (médiane = 8 jours) après le début des symptômes ; la durée moyenne de traitement était de 6,2  ±  2,2 jours [1 ; 10] (médiane = 5 j). R a été arrêté prématurément pour 7 patients : 2 bilans biologiques altérés, 2 transferts vers d’autres hôpitaux, 2 améliorations et un décès. La durée moyenne de séjour des patients sous R était de 12,5 ± 8,3 jours [4 ; 55] (médiane = 10 jours). Après sortie d’hospitalisation, 47,7 % sont rentrés à domicile, 27,3 % sont sortis en soins de suite et de réadaptation, 14,8 % sont décédés et 10,2 % des patients ont été transférés vers d’autres hôpitaux. Une diminution du débit de filtration glomérulaire (77,3 % de DE) était relevée chez 54,4 % des patients. Le passage d’un stade d’insuffisance rénale légère à sévère a été noté chez 3 patients (dont 2 dialysés à la fin du R). Après R, 18,8 % avaient des ALAT > normale (N) (54,5 % DE) et 17,0 % ASAT supérieure à la normale (N) (53,4 % DE) pour une concentration initialement N. Les valeurs maximales d’ASAT ont atteint 4 fois la N. La moyenne des CRP avant R était de 115,4 ± 82,5 mg/L (66 patients) versus 31,9 ± 45,0 mg/L après (39 patients). Les D-dimères avant R étaient de 1728,5 ± 2101 ng/mL pour 79 patients. Aucun effet indésirable n’a été rapporté. DISCUSSION/CONCLUSION: L’échantillon présente des caractéristiques statistiquement comparables aux données de la littérature (p > 0,05). Les bilans biologiques ont été moins réalisés après que le R ait obtenu l’AMM. Aussi, le manque de données exploitables n’a pas permis d’établir de corrélation statistique de l’utilisation du R à la variation des paramètres étudiés. La pathologie, les comorbidités et la PEC pourraient être des facteurs confondants. Il serait intéressant d’effectuer une étude multicentrique sur un large échantillon et d’inclure des données supplémentaires

Identification of the functional states of human vitamin K epoxide reductase from molecular dynamics simulations

In mammalians, the enzymatic activity of vitamin K epoxide reductase (VKORC1) requires a protein conformational reorganisation that includes several transient enzymatic states involving a dynamic electron transfer. Regarding the structurally non-characterised human enzyme (hVKORC1), this process remains poorly explained and the different redox states of the enzyme generated by its biochemical transformation are unknown. Here, we report a 3D model of the fully reduced hVKORC1 at the atomistic level. By exploring this model through molecular dynamics (MD) simulations, we established the most probable intermediate states of the enzyme which were used for generation of the putative functionally related enzymatic states. Enzymatic functionality of each state was assigned by probing their recognition properties with respect to vitamin K in its quinone and hydroxyquinone forms. Two states were identified as contributing to the two-step vitamin K transformation. The state highly selective for native vitamin K was further validated through analyses of its free energy of binding with vitamin K agonists (VKAs) that showed a high correlation with the experimental inhibiting constants

STAG2 microduplication in a patient with eyelid myoclonia and absences and a review of EMA-related reported genes

International audienceXq25 microduplication involving exclusively STAG2 is a new distinctive cohesinopathy including mild to moderate intellectual disability, speech delay and facial dysmorphism. Seizures seem to be scarce, but detailed seizure type descriptions are missing. We report the case of an 8-year-old boy with mild intellectual disability and eyelid myoclonia with onset at age of 3 years, initially misinterpreted as tics. An ictal VIDEO-EEG documented eye closure elicited generalized 3 Hz spike-waves or polyspike-waves concomitant to eyelid myoclonia, sometimes associated to brief clinically observable absences. Intermittent photic stimulation revealed a photoparoxysmal response. Array CGH identified a 199 kb copy number gain in Xq25 including the whole STAG2 gene, inherited from his asymptomatic mother. To the best of our knowledge, this is the first case of STAG2 encephalopathy fulfilling all electroclinical criteria for epilepsy with eyelid myoclonia and absences (EMA), formally named Jeavons syndrome (JS). As for other Genetic Generalized Epilepsy syndromes, EMA/JS usually occurs in normally developing children. Intellectual disability of variable degree is occasionally reported. On the background of other genes responsible for Developmental and Epileptic Encephalopathies, linked to specific generalized seizure types or seizure combinations, we discuss the contribution of pathogenic variants in CHD2, SYNGAP1 and some other genes as, RORB, NEXMIF and KCNB1 to this peculiar EMA phenotype