Mutations in the Neuronal Vesicular SNARE VAMP2 Affect Synaptic Membrane Fusion and Impair Human Neurodevelopment

VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved residues within the C terminus of the VAMP2 SNARE motif. Affected individuals carrying de novo non-synonymous variants involving the C-terminal region presented a more severe phenotype with additional neurological features, including central visual impairment, hyperkinetic movement disorder, and epilepsy or electroencephalography abnormalities. Reconstituted fusion involving a lipid-mixing assay indicated impairment in vesicle fusion as one of the possible associated disease mechanisms. The genetic synaptopathy caused by VAMP2 de novo mutations highlights the key roles of this gene in human brain development and function

The Genetic Landscape of Complex Childhood-Onset Hyperkinetic Movement Disorders

Background and Objective: The objective of this study was to better delineate the genetic landscape and key clinical characteristics of complex, early-onset, monogenic hyperkinetic movement disorders. Methods: Patients were recruited from 14 international centers. Participating clinicians completed standardized proformas capturing demographic, clinical, and genetic data. Two pediatric movement disorder experts reviewed available video footage, classifying hyperkinetic movements according to published criteria. Results: One hundred forty patients with pathogenic variants in 17 different genes (ADCY5, ATP1A3, DDC, DHPR, FOXG1, GCH1, GNAO1, KMT2B, MICU1, NKX2.1, PDE10A, PTPS, SGCE, SLC2A1, SLC6A3, SPR, and TH) were identified. In the majority, hyperkinetic movements were generalized (77%), with most patients (69%) manifesting combined motor semiologies. Parkinsonism-dystonia was characteristic of primary neurotransmitter disorders (DDC, DHPR, PTPS, SLC6A3, SPR, TH); chorea predominated in ADCY5-, ATP1A3-, FOXG1-, NKX2.1-, SLC2A1-, GNAO1-, and PDE10A-related disorders; and stereotypies were a prominent feature in FOXG1- and GNAO1-related disease. Those with generalized hyperkinetic movements had an earlier disease onset than those with focal/segmental distribution (2.5 +/- 0.3 vs. 4.7 +/- 0.7 years; P = 0.007). Patients with developmental delay also presented with hyperkinetic movements earlier than those with normal neurodevelopment (1.5 +/- 2.9 vs. 4.7 +/- 3.8 years; P < 0.001). Effective disease-specific therapies included dopaminergic agents for neurotransmitters disorders, ketogenic diet for glucose transporter deficiency, and deep brain stimulation for SGCE-, KMT2B-, and GNAO1-related hyperkinesia. Conclusions: This study highlights the complex phenotypes observed in children with genetic hyperkinetic movement disorders that can lead to diagnostic difficulty. We provide a comprehensive analysis of motor semiology to guide physicians in the genetic investigation of these patients, to facilitate early diagnosis, precision medicine treatments, and genetic counseling. (C) 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder SocietyNIHR Professorship; Sir Jules Thorn Award for Biomedical Research and Wellcome Trust; Instituto de Salud Carlos III [PI 18/01319, PI21/00248]; MRC Clinician-Scientist Fellowship [511015]; Dystonia Medical Research Foundation; Fight for Sight; Winston Churchill Memorial trust and Cerebral Palsy Alliance; Beca Jose Castillejos [CAS14/00328]This work was supported by an NIHR Professorship (to M.A.K.). M.A.K. has received funding from the Sir Jules Thorn Award for Biomedical Research and Wellcome Trust. B.P.-D. was supported by Instituto de Salud Carlos III, PI 18/01319 and PI21/00248, and has received funding from Beca Jose Castillejos (CAS14/00328). K.J.P. was supported by an MRC Clinician-Scientist Fellowship (511015) and was supported by the Dystonia Medical Research Foundation and Fight for Sight. S.S.M. has received funding from the Winston Churchill Memorial trust and Cerebral Palsy Alliance

Mutations in the Neuronal Vesicular SNARE VAMP2 Affect Synaptic Membrane Fusion and Impair Human Neurodevelopment

VAMP2 encodes the vesicular SNARE protein VAMP2 (also called synaptobrevin-2). Together with its partners syntaxin-1A and synaptosomal-associated protein 25 (SNAP25), VAMP2 mediates fusion of synaptic vesicles to release neurotransmitters. VAMP2 is essential for vesicular exocytosis and activity-dependent neurotransmitter release. Here, we report five heterozygous de novo mutations in VAMP2 in unrelated individuals presenting with a neurodevelopmental disorder characterized by axial hypotonia (which had been present since birth), intellectual disability, and autistic features. In total, we identified two single-amino-acid deletions and three non-synonymous variants affecting conserved residues within the C terminus of the VAMP2 SNARE motif. Affected individuals carrying de novo non-synonymous variants involving the C-terminal region presented a more severe phenotype with additional neurological features, including central visual impairment, hyperkinetic movement disorder, and epilepsy or electroencephalography abnormalities. Reconstituted fusion involving a lipid-mixing assay indicated impairment in vesicle fusion as one of the possible associated disease mechanisms. The genetic synaptopathy caused by VAMP2 de novo mutations highlights the key roles of this gene in human brain development and function.Fil: Salpietro, Vincenzo. Università degli Studi di Genova; Italia. University College London; Estados UnidosFil: Malintan, Nancy T.. Università degli Studi di Genova; ItaliaFil: Llano Rivas, Isabel. Hospital Universitario Cruces; EspañaFil: Spaeth, Christine G.. University of Cincinnati; Estados UnidosFil: Efthymiou, Stephanie. University College London; Estados UnidosFil: Striano, Pasquale. Istituto Giannina Gaslini; Italia. University of Genoa; ItaliaFil: Vandrovcova, Jana. University College London; Estados UnidosFil: Cutrupi, Maria Concetta. University of Messina; ItaliaFil: Chimenz, Roberto. University of Messina; ItaliaFil: David, Emanuele. Papardo University Hospital; ItaliaFil: Di Rosa, Gabriella. University of Messina; ItaliaFil: Marce Grau, Anna. University Hospital Vall d’Hebron; EspañaFil: Raspall Chaure, Miquel. University Hospital Vall d’Hebron; EspañaFil: Martin Hernandez, Elena. Hospital 12 de Octubre; EspañaFil: Zara, Federico. Istituto Giannina Gaslini; ItaliaFil: Minetti, Carlo. Istituto Giannina Gaslini; ItaliaFil: Bello, Oscar Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; ArgentinaFil: De Zorzi, Rita. Università degli Studi di Trieste; ItaliaFil: Fortuna, Sara. Università degli Studi di Trieste; ItaliaFil: Dauber, Andrew. Cincinnati Children's Hospital Medical Center; Estados UnidosFil: Alkhawaja, Mariam. No especifíca;Fil: Sultan, Tipu. Institute of Child Health and The Children’s Hospital Lahore; PakistánFil: Mankad, Kshitij. Great Ormond Street Hospital for Children; Reino UnidoFil: Vitobello, Antonio. Center Hospitalier Universitaire Dijon Bourgogne; FranciaFil: Thomas, Quentin. Center Hospitalier Universitaire Dijon Bourgogne; FranciaFil: Tran Mau Them, Frederic. Center Hospitalier Universitaire Dijon Bourgogne; FranciaFil: Faivre, Laurence. Hospital d’Enfants, Dijon; Francia. Center Hospitalier Universitaire Dijon Bourgogne; FranciaFil: Martinez Azorin, Francisco. No especifíca;Fil: Prada, Carlos E.. University of Cincinnati; Estados UnidosFil: Macaya, Alfons. University Hospital Vall d’Hebron; Españ