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Traverso M, Baratto S, Iacomino M, Di Duca M, Panicucci C, Casalini S, Grandis M, Falace A, Torella A, Picillo E, Onore ME, Politano L, Nigro V, Innes AM, Barresi R, Bruno C, Zara F, Fiorillo C, Scala M. DAG1 haploinsufficiency is associated with sporadic and familial isolated or pauci-symptomatic hyperCKemia. Eur J Hum Genet 2024; 32:342-349. [PMID: 38177406 PMCID: PMC10923780 DOI: 10.1038/s41431-023-01516-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 10/31/2023] [Accepted: 11/27/2023] [Indexed: 01/06/2024] Open
Abstract
DAG1 encodes for dystroglycan, a key component of the dystrophin-glycoprotein complex (DGC) with a pivotal role in skeletal muscle function and maintenance. Biallelic loss-of-function DAG1 variants cause severe muscular dystrophy and muscle-eye-brain disease. A possible contribution of DAG1 deficiency to milder muscular phenotypes has been suggested. We investigated the genetic background of twelve subjects with persistent mild-to-severe hyperCKemia to dissect the role of DAG1 in this condition. Genetic testing was performed through exome sequencing (ES) or custom NGS panels including various genes involved in a spectrum of muscular disorders. Histopathological and Western blot analyses were performed on muscle biopsy samples obtained from three patients. We identified seven novel heterozygous truncating variants in DAG1 segregating with isolated or pauci-symptomatic hyperCKemia in all families. The variants were rare and predicted to lead to nonsense-mediated mRNA decay or the formation of a truncated transcript. In four cases, DAG1 variants were inherited from similarly affected parents. Histopathological analysis revealed a decreased expression of dystroglycan subunits and Western blot confirmed a significantly reduced expression of beta-dystroglycan in muscle samples. This study supports the pathogenic role of DAG1 haploinsufficiency in isolated or pauci-symptomatic hyperCKemia, with implications for clinical management and genetic counseling.
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Affiliation(s)
- Monica Traverso
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Serena Baratto
- Centre of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Michele Iacomino
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Marco Di Duca
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Chiara Panicucci
- Centre of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Sara Casalini
- Centre of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | | | - Antonio Falace
- Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Annalaura Torella
- Department of Precision Medicine, University "Luigi Vanvitelli", Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Esther Picillo
- Department of Precision Medicine, University "Luigi Vanvitelli", Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Maria Elena Onore
- Department of Precision Medicine, University "Luigi Vanvitelli", Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Luisa Politano
- Department of Precision Medicine, University "Luigi Vanvitelli", Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Vincenzo Nigro
- Department of Precision Medicine, University "Luigi Vanvitelli", Naples, Italy
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - A Micheil Innes
- Department of Medical Genetics and Pediatrics, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | | | - Claudio Bruno
- Centre of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Genoa, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Federico Zara
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.
| | - Chiara Fiorillo
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.
| | - Marcello Scala
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy.
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy.
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2
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Romano F, Amadori E, Madia F, Severino M, Capra V, Rizzo R, Barone R, Corradi B, Maragliano L, Shams Nosrati MS, Falace A, Striano P, Zara F, Scala M. Case Report: Novel biallelic moderately damaging variants in RTTN in a patient with cerebellar dysplasia. Front Pediatr 2023; 11:1326552. [PMID: 38178912 PMCID: PMC10764497 DOI: 10.3389/fped.2023.1326552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 12/05/2023] [Indexed: 01/06/2024] Open
Abstract
Rotatin, encoded by the RTTN gene, is a centrosomal protein with multiple, emerging functions, including left-right specification, ciliogenesis, and neuronal migration. Recessive variants in RTTN are associated with a neurodevelopmental disorder with microcephaly and malformations of cortical development known as "Microcephaly, short stature, and polymicrogyria with seizures" (MSSP, MIM #614833). Affected individuals show a wide spectrum of clinical manifestations like intellectual disability, poor/absent speech, short stature, microcephaly, and congenital malformations. Here, we report a subject showing a distinctive neuroradiological phenotype and harboring novel biallelic variants in RTTN: the c.5500A>G, p.(Asn1834Asp), (dbSNP: rs200169343, ClinVar ID:1438510) and c.19A>G, p.(Ile7Val), (dbSNP: rs201165599, ClinVar ID:1905275) variants. In particular brain magnetic resonance imaging (MRI) showed a peculiar pattern, with cerebellar hypo-dysplasia, and multiple arachnoid cysts in the lateral cerebello-medullary cisterns, in addition to left Meckel cave. Thus, we compare his phenotypic features with current literature, speculating a possible role of newly identified RTTN variants in his clinical picture, and supporting a relevant variability in this emerging condition.
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Affiliation(s)
- Ferruccio Romano
- Genomics and Clinical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Elisabetta Amadori
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy
- Child Neuropsichiatry Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Francesca Madia
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | | | - Valeria Capra
- Genomics and Clinical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Renata Rizzo
- Child Neuropsychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Rita Barone
- Child Neuropsychiatry Unit, Department of Clinical and Experimental Medicine, University of Catania, Catania, Italy
| | - Beatrice Corradi
- Department of Experimental Medicine, University of Genova, Genova, Italy
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
| | - Luca Maragliano
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | | | - Antonio Falace
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy
- Pediatric Neurology and Muscular Diseases Unit, IRCCS, Genoa, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy
- Medical Genetics Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
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3
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Clausing RJ, De La Fuente G, Falace A, Chiantore M. Accounting for environmental stress in restoration of intertidal foundation species. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- R. J. Clausing
- Department of Ecology and Evolutionary Biology University of California Los Angeles CA USA
- Department of Earth, Environment and Life Sciences University of Genoa Genoa Italy
| | - G. De La Fuente
- Department of Earth, Environment and Life Sciences University of Genoa Genoa Italy
| | - A. Falace
- Department of Life Sciences University of Trieste Trieste Italy
| | - M. Chiantore
- Department of Earth, Environment and Life Sciences University of Genoa Genoa Italy
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4
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Michetti C, Falace A, Benfenati F, Fassio A. Synaptic genes and neurodevelopmental disorders: From molecular mechanisms to developmental strategies of behavioral testing. Neurobiol Dis 2022; 173:105856. [PMID: 36070836 DOI: 10.1016/j.nbd.2022.105856] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 10/14/2022] Open
Abstract
Synaptopathies are a class of neurodevelopmental disorders caused by modification in genes coding for synaptic proteins. These proteins oversee the process of neurotransmission, mainly controlling the fusion and recycling of synaptic vesicles at the presynaptic terminal, the expression and localization of receptors at the postsynapse and the coupling between the pre- and the postsynaptic compartments. Murine models, with homozygous or heterozygous deletion for several synaptic genes or knock-in for specific pathogenic mutations, have been developed. They have proved to be extremely informative for understanding synaptic physiology, as well as for clarifying the patho-mechanisms leading to developmental delay, epilepsy and motor, cognitive and social impairments that are the most common clinical manifestations of neurodevelopmental disorders. However, the onset of these disorders emerges during infancy and adolescence while the behavioral phenotyping is often conducted in adult mice, missing important information about the impact of synaptic development and maturation on the manifestation of the behavioral phenotype. Here, we review the main achievements obtained by behavioral testing in murine models of synaptopathies and propose a battery of behavioral tests to improve classification, diagnosis and efficacy of potential therapeutic treatments. Our aim is to underlie the importance of studying behavioral development and better focusing on disease onset and phenotypes.
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Affiliation(s)
- Caterina Michetti
- Department of Experimental Medicine, University of Genoa, Genoa, Italy; Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, Genoa, Italy.
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience, Istituto Italiano di Tecnologia, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy; IRCCS Ospedale Policlinico San Martino, Genoa, Italy.
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5
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Fassio A, Falace A, Esposito A, Aprile D, Guerrini R, Benfenati F. Emerging Role of the Autophagy/Lysosomal Degradative Pathway in Neurodevelopmental Disorders With Epilepsy. Front Cell Neurosci 2020; 14:39. [PMID: 32231521 PMCID: PMC7082311 DOI: 10.3389/fncel.2020.00039] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/10/2020] [Indexed: 01/08/2023] Open
Abstract
Autophagy is a highly conserved degradative process that conveys dysfunctional proteins, lipids, and organelles to lysosomes for degradation. The post-mitotic nature, complex and highly polarized morphology, and high degree of specialization of neurons make an efficient autophagy essential for their homeostasis and survival. Dysfunctional autophagy occurs in aging and neurodegenerative diseases, and autophagy at synaptic sites seems to play a crucial role in neurodegeneration. Moreover, a role of autophagy is emerging for neural development, synaptogenesis, and the establishment of a correct connectivity. Thus, it is not surprising that defective autophagy has been demonstrated in a spectrum of neurodevelopmental disorders, often associated with early-onset epilepsy. Here, we discuss the multiple roles of autophagy in neurons and the recent experimental evidence linking neurodevelopmental disorders with epilepsy to genes coding for autophagic/lysosomal system-related proteins and envisage possible pathophysiological mechanisms ranging from synaptic dysfunction to neuronal death.
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Affiliation(s)
- Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | - Alessandro Esposito
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy.,IRCCS Fondazione Stella Maris, Pisa, Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
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6
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Felline S, Del Coco L, Kaleb S, Guarnieri G, Fraschetti S, Terlizzi A, Fanizzi FP, Falace A. The response of the algae Fucus virsoides (Fucales, Ochrophyta) to Roundup® solution exposure: A metabolomics approach. Environ Pollut 2019; 254:112977. [PMID: 31377326 DOI: 10.1016/j.envpol.2019.112977] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/28/2019] [Accepted: 07/27/2019] [Indexed: 06/10/2023]
Abstract
Glyphosate, as a broad-spectrum herbicide, is frequently detected in water and several studies have investigated its effects on several freshwater aquatic organisms. Yet, only few investigations have been performed on marine macroalgae. Here, we studied both the metabolomics responses and the effect on primary production in the endemic brown algae Fucus virsoides exposed to different concentration (0, 0.5, 1.5 and 2.5 mg L-1) of a commercial glyphosate-based herbicide, namely Roundup®. Our results show that Roundup® significantly reduced quantum yield of photosynthesis (Fv/Fm) and caused alteration in the metabolomic profiles of exposed thalli compared to controls. Together with the decrease in the aromatic amino acids (phenylalanine and tyrosine), an increase in shikimate content was detected. The branched-amino acids differently varied according to levels of herbicide exposure, as well as observed for the content of choline, formate, glucose, malonate and fumarate. Our results suggest that marine primary producers could be largely affected by the agricultural land use, this asking for further studies addressing the ecosystem-level effects of glyphosate-based herbicides in coastal waters.
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Affiliation(s)
- S Felline
- CoNISMa, Piazzale Flaminio 9, 00196, Roma, Italy
| | - L Del Coco
- Department of Biology, Environmental Sciences and Technologies, University of Salento, 73100, Lecce, Italy
| | - S Kaleb
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy
| | - G Guarnieri
- CoNISMa, Piazzale Flaminio 9, 00196, Roma, Italy; Department of Biology, Environmental Sciences and Technologies, University of Salento, 73100, Lecce, Italy
| | - S Fraschetti
- Department of Biology, University of Naples Federico II, 80926, Napoli, Italy; Stazione Zoologica Anton Dohrn, 80121, Napoli, Italy
| | - A Terlizzi
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy; Stazione Zoologica Anton Dohrn, 80121, Napoli, Italy
| | - F P Fanizzi
- Department of Biology, Environmental Sciences and Technologies, University of Salento, 73100, Lecce, Italy.
| | - A Falace
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy
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Abstract
The development of the cerebral cortex requires complex sequential processes that have to be precisely orchestrated. The localization and timing of neuronal progenitor proliferation and of neuronal migration define the identity, laminar positioning, and specific connectivity of each single cortical neuron. Alterations at any step of this organized series of events—due to genetic mutations or environmental factors—lead to defined brain pathologies collectively known as malformations of cortical development (MCDs), which are now recognized as a leading cause of drug-resistant epilepsy and intellectual disability. In this heterogeneous group of disorders, macroscopic alterations of brain structure (eg, heterotopic nodules, small or absent gyri, double cortex) can be recognized and probably subtend a general reorganization of neuronal circuits. In this review, we provide an overview of the molecular mechanisms that are implicated in the generation of genetic MCDs associated with aberrations at various steps of neurogenesis and cortical development.
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Affiliation(s)
| | | | - Antonio Falace
- Aix-Marseille University, INSERM U1249, INMED, Marseille 13009, France
| | - Carlos Cardoso
- Aix-Marseille University, INSERM U1249, INMED, Marseille 13009, France
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Aprile D, Fruscione F, Baldassari S, Fadda M, Ferrante D, Falace A, Buhler E, Sartorelli J, Represa A, Baldelli P, Benfenati F, Zara F, Fassio A. TBC1D24 regulates axonal outgrowth and membrane trafficking at the growth cone in rodent and human neurons. Cell Death Differ 2019; 26:2464-2478. [PMID: 30858606 DOI: 10.1038/s41418-019-0313-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 01/25/2019] [Accepted: 02/20/2019] [Indexed: 01/04/2023] Open
Abstract
Mutations in TBC1D24 are described in patients with a spectrum of neurological diseases, including mild and severe epilepsies and complex syndromic phenotypes such as Deafness, Onycodystrophy, Osteodystrophy, Mental Retardation and Seizure (DOORS) syndrome. The product of TBC1D24 is a multifunctional protein involved in neuronal development, regulation of synaptic vesicle trafficking, and protection from oxidative stress. Although pathogenic mutations in TBC1D24 span the entire coding sequence, no clear genotype/phenotype correlations have emerged. However most patients bearing predicted loss of function mutations exhibit a severe neurodevelopmental disorder. Aim of the study is to investigate the impact of TBC1D24 knockdown during the first stages of neuronal differentiation when axonal specification and outgrowth take place. In rat cortical primary neurons silenced for TBC1D24, we found defects in axonal specification, the maturation of axonal initial segment and action potential firing. The axonal phenotype was accompanied by an impairment of endocytosis at the growth cone and an altered activation of the TBC1D24 molecular partner ADP ribosylation factor 6. Accordingly, acute knockdown of TBC1D24 in cerebrocortical neurons in vivo analogously impairs callosal projections. The axonal defect was also investigated in human induced pluripotent stem cell-derived neurons from patients carrying TBC1D24 mutations. Reprogrammed neurons from a patient with severe developmental encephalopathy show significant axon formation defect that were absent from reprogrammed neurons of a patient with mild early onset epilepsy. Our data reveal that alterations of membrane trafficking at the growth cone induced by TBC1D24 loss of function cause axonal and excitability defects. The axonal phenotype correlates with the disease severity and highlight an important role for TBC1D24 in connectivity during brain development.
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Affiliation(s)
- Davide Aprile
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Floriana Fruscione
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Simona Baldassari
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Manuela Fadda
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Daniele Ferrante
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Antonio Falace
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Children's Hospital A. Meyer-University of Florence, Florence, Italy
| | | | - Jacopo Sartorelli
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Alfonso Represa
- INMED, Aix-Marseille University, INSERM U1249, Marseille, France
| | - Pietro Baldelli
- Department of Experimental Medicine, University of Genoa, Genoa, Italy.,IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Fabio Benfenati
- IRCCS Ospedale Policlinico San Martino, Genoa, Italy.,Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Federico Zara
- Laboratory of Neurogenetics and Neuroscience, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Anna Fassio
- Department of Experimental Medicine, University of Genoa, Genoa, Italy. .,IRCCS Ospedale Policlinico San Martino, Genoa, Italy.
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9
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Conti V, Carabalona A, Pallesi-Pocachard E, Leventer RJ, Schaller F, Parrini E, Deparis AA, Watrin F, Buhler E, Novara F, Lise S, Pagnamenta AT, Kini U, Taylor JC, Zuffardi O, Represa A, Keays DA, Guerrini R, Falace A, Cardoso C. A Novel Strategy Combining Array-CGH, Whole-exome Sequencing and In Utero Electroporation in Rodents to Identify Causative Genes for Brain Malformations. J Vis Exp 2017. [PMID: 29286390 DOI: 10.3791/53570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Birth defects that involve the cerebral cortex - also known as malformations of cortical development (MCD) - are important causes of intellectual disability and account for 20-40% of drug-resistant epilepsy in childhood. High-resolution brain imaging has facilitated in vivo identification of a large group of MCD phenotypes. Despite the advances in brain imaging, genomic analysis and generation of animal models, a straightforward workflow to systematically prioritize candidate genes and to test functional effects of putative mutations is missing. To overcome this problem, an experimental strategy enabling the identification of novel causative genes for MCD was developed and validated. This strategy is based on identifying candidate genomic regions or genes via array-CGH or whole-exome sequencing and characterizing the effects of their inactivation or of overexpression of specific mutations in developing rodent brains via in utero electroporation. This approach led to the identification of the C6orf70 gene, encoding for a putative vesicular protein, to the pathogenesis of periventricular nodular heterotopia, a MCD caused by defective neuronal migration.
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Affiliation(s)
| | | | | | - Richard J Leventer
- Royal Children's Hospital; Murdoch Children's Research Institute; University of Melbourne
| | - Fabienne Schaller
- INSERM INMED; Aix-Marseille University; Plateforme postgenomique INMED
| | | | | | | | - Emmanuelle Buhler
- INSERM INMED; Aix-Marseille University; Plateforme postgenomique INMED
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10
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Balestrini S, Milh M, Castiglioni C, Lüthy K, Finelli MJ, Verstreken P, Cardon A, Stražišar BG, Holder JL, Lesca G, Mancardi MM, Poulat AL, Repetto GM, Banka S, Bilo L, Birkeland LE, Bosch F, Brockmann K, Cross JH, Doummar D, Félix TM, Giuliano F, Hori M, Hüning I, Kayserili H, Kini U, Lees MM, Meenakshi G, Mewasingh L, Pagnamenta AT, Peluso S, Mey A, Rice GM, Rosenfeld JA, Taylor JC, Troester MM, Stanley CM, Ville D, Walkiewicz M, Falace A, Fassio A, Lemke JR, Biskup S, Tardif J, Ajeawung NF, Tolun A, Corbett M, Gecz J, Afawi Z, Howell KB, Oliver KL, Berkovic SF, Scheffer IE, de Falco FA, Oliver PL, Striano P, Zara F, Campeau PM, Sisodiya SM. TBC1D24 genotype-phenotype correlation: Epilepsies and other neurologic features. Neurology 2016; 87:77-85. [PMID: 27281533 PMCID: PMC4932231 DOI: 10.1212/wnl.0000000000002807] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 03/28/2016] [Indexed: 11/15/2022] Open
Abstract
Objective: To evaluate the phenotypic spectrum associated with mutations in TBC1D24. Methods: We acquired new clinical, EEG, and neuroimaging data of 11 previously unreported and 37 published patients. TBC1D24 mutations, identified through various sequencing methods, can be found online (http://lovd.nl/TBC1D24). Results: Forty-eight patients were included (28 men, 20 women, average age 21 years) from 30 independent families. Eighteen patients (38%) had myoclonic epilepsies. The other patients carried diagnoses of focal (25%), multifocal (2%), generalized (4%), and unclassified epilepsy (6%), and early-onset epileptic encephalopathy (25%). Most patients had drug-resistant epilepsy. We detail EEG, neuroimaging, developmental, and cognitive features, treatment responsiveness, and physical examination. In silico evaluation revealed 7 different highly conserved motifs, with the most common pathogenic mutation located in the first. Neuronal outgrowth assays showed that some TBC1D24 mutations, associated with the most severe TBC1D24-associated disorders, are not necessarily the most disruptive to this gene function. Conclusions: TBC1D24-related epilepsy syndromes show marked phenotypic pleiotropy, with multisystem involvement and severity spectrum ranging from isolated deafness (not studied here), benign myoclonic epilepsy restricted to childhood with complete seizure control and normal intellect, to early-onset epileptic encephalopathy with severe developmental delay and early death. There is no distinct correlation with mutation type or location yet, but patterns are emerging. Given the phenotypic breadth observed, TBC1D24 mutation screening is indicated in a wide variety of epilepsies. A TBC1D24 consortium was formed to develop further research on this gene and its associated phenotypes.
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11
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Tagliatti E, Fadda M, Falace A, Benfenati F, Fassio A. Arf6 regulates the cycling and the readily releasable pool of synaptic vesicles at hippocampal synapse. eLife 2016; 5. [PMID: 26731518 PMCID: PMC4764570 DOI: 10.7554/elife.10116] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 01/04/2016] [Indexed: 01/29/2023] Open
Abstract
Recycling of synaptic vesicles (SVs) is a fundamental step in the process of neurotransmission. Endocytosed SV can travel directly into the recycling pool or recycle through endosomes but little is known about the molecular actors regulating the switch between these SV recycling routes. ADP ribosylation factor 6 (Arf6) is a small GTPase known to participate in constitutive trafficking between plasma membrane and early endosomes. Here, we have morphologically and functionally investigated Arf6-silenced hippocampal synapses and found an activity dependent accumulation of synaptic endosome-like organelles and increased release-competent docked SVs. These features were phenocopied by pharmacological blockage of Arf6 activation. The data reveal an unexpected role for this small GTPase in reducing the size of the readily releasable pool of SVs and in channeling retrieved SVs toward direct recycling rather than endosomal sorting. We propose that Arf6 acts at the presynapse to define the fate of an endocytosed SV. DOI:http://dx.doi.org/10.7554/eLife.10116.001 Communication between neurons takes place at cell-to-cell contacts called synapses. Each synapse is formed between one neuron that sends the message, and another neuron that receives it. The neuron before the synapse – called the presynaptic neuron – contains packets called synaptic vesicles, which are full of chemical messengers ready to be released upon activity. Accurate communication between neurons relies on the exact composition, and organized trafficking, of the synaptic vesicles when the neuron is active. Synapses also contain bigger structures, called endosomal structures, which may represent an intermediate station in which synaptic vesicle composition is controlled. However, the trafficking of synaptic vesicles through the endosomal structures is poorly understood. Now, Tagliatti, Fadda et al. have revealed that a protein called Arf6 plays an important role in presynaptic neurons. The experiments involved rat neurons grown in the laboratory, and showed that Arf6 controls both the number of synaptic vesicles ready to be released and the trafficking of synaptic vesicles via endosomal structures in active neurons. The next step following on from these findings is to understand how Arf6 exerts its effects and how this protein is regulated in the presynaptic neuron. DOI:http://dx.doi.org/10.7554/eLife.10116.002
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Affiliation(s)
- Erica Tagliatti
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Manuela Fadda
- Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Antonio Falace
- Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Fabio Benfenati
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
| | - Anna Fassio
- Center of Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genova, Italy.,Department of Experimental Medicine, University of Genova, Genova, Italy
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12
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Mosca-Boidron AL, Gueneau L, Huguet G, Goldenberg A, Henry C, Gigot N, Pallesi-Pocachard E, Falace A, Duplomb L, Thevenon J, Duffourd Y, St-Onge J, Chambon P, Rivière JB, Thauvin-Robinet C, Callier P, Marle N, Payet M, Ragon C, Goubran Botros H, Buratti J, Calderari S, Dumas G, Delorme R, Lagarde N, Pinoit JM, Rosier A, Masurel-Paulet A, Cardoso C, Mugneret F, Saugier-Veber P, Campion D, Faivre L, Bourgeron T. A de novo microdeletion of SEMA5A in a boy with autism spectrum disorder and intellectual disability. Eur J Hum Genet 2015; 24:838-43. [PMID: 26395558 PMCID: PMC4867450 DOI: 10.1038/ejhg.2015.211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 07/14/2015] [Accepted: 08/14/2015] [Indexed: 12/13/2022] Open
Abstract
Semaphorins are a large family of secreted and membrane-associated proteins necessary for wiring of the brain. Semaphorin 5A (SEMA5A) acts as a bifunctional guidance cue, exerting both attractive and inhibitory effects on developing axons. Previous studies have suggested that SEMA5A could be a susceptibility gene for autism spectrum disorders (ASDs). We first identified a de novo translocation t(5;22)(p15.3;q11.21) in a patient with ASD and intellectual disability (ID). At the translocation breakpoint on chromosome 5, we observed a 861-kb deletion encompassing the end of the SEMA5A gene. We delineated the breakpoint by NGS and observed that no gene was disrupted on chromosome 22. We then used Sanger sequencing to search for deleterious variants affecting SEMA5A in 142 patients with ASD. We also identified two independent heterozygous variants located in a conserved functional domain of the protein. Both variants were maternally inherited and predicted as deleterious. Our genetic screens identified the first case of a de novo SEMA5A microdeletion in a patient with ASD and ID. Although our study alone cannot formally associate SEMA5A with susceptibility to ASD, it provides additional evidence that Semaphorin dysfunction could lead to ASD and ID. Further studies on Semaphorins are warranted to better understand the role of this family of genes in susceptibility to neurodevelopmental disorders.
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Affiliation(s)
- Anne-Laure Mosca-Boidron
- Laboratoire de Cytogénétique, Plateau technique de Biologie, CHU Dijon, Dijon, France.,Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Lucie Gueneau
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Guillaume Huguet
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | | | - Céline Henry
- Centre Resource Autisme Bourgogne, CHU Dijon, Dijon, France
| | - Nadège Gigot
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | | | - Antonio Falace
- Institut de Neurobiologie de la Méditerranée INSERM UMR901, Marseille, France
| | - Laurence Duplomb
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Julien Thevenon
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France.,Centre de Génétique et Centre de Référence «Anomalies du Développement et Syndromes Malformatifs», Hôpital d'Enfants, CHU Dijon, Dijon, France
| | - Yannis Duffourd
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Judith St-Onge
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France.,Laboratoire de Génétique Moléculaire, Plateau Technique de Biologie, CHU Dijon, Dijon, France
| | | | - Jean-Baptiste Rivière
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France.,Laboratoire de Génétique Moléculaire, Plateau Technique de Biologie, CHU Dijon, Dijon, France
| | - Christel Thauvin-Robinet
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France.,Centre de Génétique et Centre de Référence «Anomalies du Développement et Syndromes Malformatifs», Hôpital d'Enfants, CHU Dijon, Dijon, France
| | - Patrick Callier
- Laboratoire de Cytogénétique, Plateau technique de Biologie, CHU Dijon, Dijon, France.,Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Nathalie Marle
- Laboratoire de Cytogénétique, Plateau technique de Biologie, CHU Dijon, Dijon, France.,Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Muriel Payet
- Laboratoire de Cytogénétique, Plateau technique de Biologie, CHU Dijon, Dijon, France.,Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Clemence Ragon
- Laboratoire de Cytogénétique, Plateau technique de Biologie, CHU Dijon, Dijon, France.,Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France
| | - Hany Goubran Botros
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Julien Buratti
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France.,Fondation FondaMental, Créteil, France
| | - Sophie Calderari
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France.,Fondation FondaMental, Créteil, France
| | - Guillaume Dumas
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France
| | - Richard Delorme
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France.,Psychiatrie de l'enfance et de l'adolescence - Hôpital Robert-Debré, Paris, France
| | | | | | - Antoine Rosier
- Centre de Ressources Autisme de Haute Normandie, Saint Etienne du Rouvray, France
| | - Alice Masurel-Paulet
- Centre de Génétique et Centre de Référence «Anomalies du Développement et Syndromes Malformatifs», Hôpital d'Enfants, CHU Dijon, Dijon, France
| | - Carlos Cardoso
- Institut de Neurobiologie de la Méditerranée INSERM UMR901, Marseille, France
| | - Francine Mugneret
- Laboratoire de Cytogénétique, Plateau technique de Biologie, CHU Dijon, Dijon, France
| | | | | | - Laurence Faivre
- Equipe Génétique et Anomalies du Développement, Faculté de Médecine, Université de Bourgogne, Dijon, France.,Centre de Génétique et Centre de Référence «Anomalies du Développement et Syndromes Malformatifs», Hôpital d'Enfants, CHU Dijon, Dijon, France
| | - Thomas Bourgeron
- Institut Pasteur, Human Genetics and Cognitive Functions Unit, Paris, France.,CNRS UMR 3571: Genes, Synapses and Cognition, Institut Pasteur, Paris, France.,Université Paris Diderot, Sorbonne Paris Cité, Human Genetics and Cognitive Functions, Paris, France.,Fondation FondaMental, Créteil, France
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13
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Vanni N, Fruscione F, Ferlazzo E, Striano P, Robbiano A, Traverso M, Sander T, Falace A, Gazzerro E, Bramanti P, Bielawski J, Fassio A, Minetti C, Genton P, Zara F. Impairment of ceramide synthesis causes a novel progressive myoclonus epilepsy. Ann Neurol 2014; 76:206-12. [PMID: 24782409 DOI: 10.1002/ana.24170] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 04/28/2014] [Accepted: 04/28/2014] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Alterations of sphingolipid metabolism are implicated in the pathogenesis of many neurodegenerative disorders. METHODS We identified a homozygous nonsynonymous mutation in CERS1, the gene encoding ceramide synthase 1, in 4 siblings affected by a progressive disorder with myoclonic epilepsy and dementia. CerS1, a transmembrane protein of the endoplasmic reticulum (ER), catalyzes the biosynthesis of C18-ceramides. RESULTS We demonstrated that the mutation decreases C18-ceramide levels. In addition, we showed that downregulation of CerS1 in a neuroblastoma cell line triggers ER stress response and induces proapoptotic pathways. INTERPRETATION This study demonstrates that impairment of ceramide biosynthesis underlies neurodegeneration in humans.
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Affiliation(s)
- Nicola Vanni
- Department of Neuroscience, Institute G. Gaslini, Genoa, Italy
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14
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Milh M, Falace A, Villeneuve N, Vanni N, Cacciagli P, Assereto S, Nabbout R, Benfenati F, Zara F, Chabrol B, Villard L, Fassio A. Novel compound heterozygous mutations in TBC1D24 cause familial malignant migrating partial seizures of infancy. Hum Mutat 2013; 34:869-72. [PMID: 23526554 DOI: 10.1002/humu.22318] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 03/07/2013] [Indexed: 11/08/2022]
Abstract
Early-onset epileptic encephalopathies (EOEEs) are a group of rare devastating epileptic syndromes of infancy characterized by severe drug-resistant seizures and electroencephalographic abnormalities. The current study aims to determine the genetic etiology of a familial form of EOEE fulfilling the diagnosis criteria for malignant migrating partial seizures of infancy (MMPSI). We identified two inherited novel mutations in TBC1D24 in two affected siblings. Mutations severely impaired TBC1D24 expression and function, which is critical for maturation of neuronal circuits. The screening of TBC1D24 in an additional set of eight MMPSI patients was negative. TBC1D24 loss of function has been associated to idiopathic infantile myoclonic epilepsy, as well as to drug-resistant early-onset epilepsy with intellectual disability. Here, we describe a familial form of MMPSI due to mutation in TBC1D24, revealing a devastating epileptic phenotype associated with TBC1D24 dysfunction.
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15
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Striano P, Coppola A, Paravidino R, Malacarne M, Gimelli S, Robbiano A, Traverso M, Pezzella M, Belcastro V, Bianchi A, Elia M, Falace A, Gazzerro E, Ferlazzo E, Freri E, Galasso R, Gobbi G, Molinatto C, Cavani S, Zuffardi O, Striano S, Ferrero GB, Silengo M, Cavaliere ML, Benelli M, Magi A, Piccione M, Dagna Bricarelli F, Coviello DA, Fichera M, Minetti C, Zara F. Clinical significance of rare copy number variations in epilepsy: a case-control survey using microarray-based comparative genomic hybridization. ACTA ACUST UNITED AC 2011; 69:322-30. [PMID: 22083797 DOI: 10.1001/archneurol.2011.1999] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To perform an extensive search for genomic rearrangements by microarray-based comparative genomic hybridization in patients with epilepsy. DESIGN Prospective cohort study. SETTING Epilepsy centers in Italy. PATIENTS Two hundred seventy-nine patients with unexplained epilepsy, 265 individuals with nonsyndromic mental retardation but no epilepsy, and 246 healthy control subjects were screened by microarray-based comparative genomic hybridization. MAIN OUTCOME MEASURES Identification of copy number variations (CNVs) and gene enrichment. RESULTS Rare CNVs occurred in 26 patients (9.3%) and 16 healthy control subjects (6.5%) (P = .26). The CNVs identified in patients were larger (P = .03) and showed higher gene content (P = .02) than those in control subjects. The CNVs larger than 1 megabase (P = .002) and including more than 10 genes (P = .005) occurred more frequently in patients than in control subjects. Nine patients (34.6%) among those harboring rare CNVs showed rearrangements associated with emerging microdeletion or microduplication syndromes. Mental retardation and neuropsychiatric features were associated with rare CNVs (P = .004), whereas epilepsy type was not. The CNV rate in patients with epilepsy and mental retardation or neuropsychiatric features is not different from that observed in patients with mental retardation only. Moreover, significant enrichment of genes involved in ion transport was observed within CNVs identified in patients with epilepsy. CONCLUSIONS Patients with epilepsy show a significantly increased burden of large, rare, gene-rich CNVs, particularly when associated with mental retardation and neuropsychiatric features. The limited overlap between CNVs observed in the epilepsy group and those observed in the group with mental retardation only as well as the involvement of specific (ion channel) genes indicate a specific association between the identified CNVs and epilepsy. Screening for CNVs should be performed for diagnostic purposes preferentially in patients with epilepsy and mental retardation or neuropsychiatric features.
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Affiliation(s)
- Pasquale Striano
- Laboratory of Neurogenetics, Department of Neuroscience, Institute G. Gaslini, Largo Gaslini 5, Genoa, Italy
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16
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Falace A, Filipello F, La Padula V, Vanni N, Madia F, De Pietri Tonelli D, de Falco FA, Striano P, Dagna Bricarelli F, Minetti C, Benfenati F, Fassio A, Zara F. TBC1D24, an ARF6-interacting protein, is mutated in familial infantile myoclonic epilepsy. Am J Hum Genet 2010; 87:365-70. [PMID: 20727515 DOI: 10.1016/j.ajhg.2010.07.020] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 07/19/2010] [Accepted: 07/22/2010] [Indexed: 12/28/2022] Open
Abstract
Idiopathic epilepsies (IEs) are a group of disorders characterized by recurrent seizures in the absence of detectable brain lesions or metabolic abnormalities. IEs include common disorders with a complex mode of inheritance and rare Mendelian traits suggesting the occurrence of several alleles with variable penetrance. We previously described a large family with a recessive form of idiopathic epilepsy, named familial infantile myoclonic epilepsy (FIME), and mapped the disease locus on chromosome 16p13.3 by linkage analysis. In the present study, we found that two compound heterozygous missense mutations (D147H and A509V) in TBC1D24, a gene of unknown function, are responsible for FIME. In situ hybridization analysis revealed that Tbc1d24 is mainly expressed at the level of the cerebral cortex and the hippocampus. By coimmunoprecipitation assay we found that TBC1D24 binds ARF6, a Ras-related family of small GTPases regulating exo-endocytosis dynamics. The main recognized function of ARF6 in the nervous system is the regulation of dendritic branching, spine formation, and axonal extension. TBC1D24 overexpression resulted in a significant increase in neurite length and arborization and the FIME mutations significantly reverted this phenotype. In this study we identified a gene mutation involved in autosomal-recessive idiopathic epilepsy, unveiled the involvement of ARF6-dependent molecular pathway in brain hyperexcitability and seizures, and confirmed the emerging role of subtle cytoarchitectural alterations in the etiology of this group of common epileptic disorders.
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Affiliation(s)
- Antonio Falace
- Department of Neuroscience, Institute G. Gaslini and University of Genova, Italy.
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17
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Biancheri R, Falace A, Tessa A, Pedemonte M, Scapolan S, Cassandrini D, Aiello C, Rossi A, Broda P, Zara F, Santorelli FM, Minetti C, Bruno C. POMT2 gene mutation in limb-girdle muscular dystrophy with inflammatory changes. Biochem Biophys Res Commun 2007; 363:1033-7. [PMID: 17923109 DOI: 10.1016/j.bbrc.2007.09.066] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2007] [Accepted: 09/12/2007] [Indexed: 01/06/2023]
Abstract
Defects in glycosylation of alpha-dystroglycan are associated with several forms of muscular dystrophies. Mutations in POMT2 gene have been identified in patients with congenital muscular dystrophy and brain involvement, either characterized by a Walker-Warburg/muscle-eye-brain phenotype, or by microcephaly, mental retardation, and cerebellar hypoplasia. We identified a POMT2 homozygous missense mutation in a girl with a mild limb-girdle muscular dystrophy (LGMD) phenotype, marked elevated serum creatine kinase levels, and absence of brain involvement. Muscle biopsy revealed myopathic and inflammatory changes and severe alpha-dystroglycan reduction. In view of the remarkable mild clinical picture, we propose to designate this phenotype as LGMD2N.
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Affiliation(s)
- Roberta Biancheri
- Muscular and Neurodegenerative Disease Unit, G. Gaslini Institute and University of Genova, Largo Gaslini 5, 16147 Genova, Italy.
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18
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Falace A, Striano P, Manganelli F, Coppola A, Striano S, Minetti C, Zara F. Inherited neuromyotonia: A clinical and genetic study of a family. Neuromuscul Disord 2007; 17:23-7. [PMID: 17140792 DOI: 10.1016/j.nmd.2006.09.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 09/11/2006] [Accepted: 09/20/2006] [Indexed: 10/23/2022]
Abstract
Neuromyotonia is a disorder of peripheral nerve hyperexcitability characterized by myokymia, muscle cramps and stiffness, delayed muscle relaxation after contraction (pseudomyotonia), and hyperhidrosis, associated with well described spontaneous electromyographic features. It is usually an acquired disorder associated with autoantibodies against neuronal voltage-gated potassium channels. However, mutations of KCNA1, encoding the K(+) channel subunit hKv1.1, have been reported in rare families with neuromyotonia, and mutations in KCNQ2, encoding voltage-gated potassium M channel subunit, in families with benign neonatal seizures and myokymia. We report a three-generation family with inherited neuromyotonia without evidence of immunological involvement. Genetic study excluded mutations in KCNA1, KCNA2, KCNA6 and KCNQ2 genes. Our study does not completely exclude the involvement of other genes encoding ion channels subunits in the pathogenesis of this disorder. Further studies of familial cases will shed light on the molecular basis of inherited neuromyotonia.
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Affiliation(s)
- Antonio Falace
- Neuromuscular and Neurodegenerative Disease Unit, University of Genova, G Gaslini Institute, Genova, Italy
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19
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Biancheri R, Bertini E, Falace A, Pedemonte M, Rossi A, D'Amico A, Scapolan S, Bergamino L, Petrini S, Cassandrini D, Broda P, Manfredi M, Zara F, Santorelli FM, Minetti C, Bruno C. POMGnT1 Mutations in Congenital Muscular Dystrophy. ACTA ACUST UNITED AC 2006; 63:1491-5. [PMID: 17030669 DOI: 10.1001/archneur.63.10.1491] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Muscle-eye-brain disease is a congenital muscular dystrophy with eye and brain involvement due to POMGnT1 mutations. OBJECTIVE To describe the clinical and molecular features of 3 Italian patients with POMGnT1 mutations. DESIGN Case reports. PATIENTS One patient had muscle and brain abnormalities without eye involvement. Two patients had a classic muscle-eye-brain disease phenotype with different levels of clinical severity. RESULTS Brain magnetic resonance imaging showed cortical malformation and posterior fossa involvement. Immunofluorescence for glycosylated alpha-dystroglycan performed on muscle biopsy specimens demonstrated an absent signal in 1 patient and reduced staining in 2 patients. Molecular analysis identified 5 mutations, 2 of which are novel. CONCLUSION This article adds to what is known about the genotype-phenotype correlation and expands our awareness of the clinical spectrum associated with POMGnT1 mutations.
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Affiliation(s)
- Roberta Biancheri
- Muscular and Neurodegenerative Disease Unit, Department of Neuroscience and Rehabilitation, University of Genova, Italy.
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20
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D'Amico A, Tessa A, Bruno C, Petrini S, Biancheri R, Pane M, Pedemonte M, Ricci E, Falace A, Rossi A, Mercuri E, Santorelli FM, Bertini E. Expanding the clinical spectrum of POMT1 phenotype. Neurology 2006; 66:1564-7; discussion 1461. [PMID: 16717220 DOI: 10.1212/01.wnl.0000216145.66476.36] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Mutations in POMT1 have been identified in Walker-Warburg syndrome and in patients with limb-girdle muscular dystrophy and mental retardation (LGMD2K). The authors report new POMT1 mutations in three unrelated children with severe motor impairment, leg hypertrophy, and mental retardation but without brain and ocular malformations. These patients are similar to LGMD2K but have earlier onset and more severe motor disability. The current findings expand the spectrum of POMT1-associated phenotypes.
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Affiliation(s)
- A D'Amico
- Department of Laboratory Medicine, IRCCS-Bambino Gesù Children's Hospital, Rome, Italy
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