1
|
Cuccurullo C, Cerulli Irelli E, Ugga L, Riva A, D'Amico A, Cabet S, Lesca G, Bilo L, Zara F, Iliescu C, Barca D, Fung F, Helbig K, Ortiz-Gonzalez X, Schelhaas HJ, Willemsen MH, van der Linden I, Canafoglia L, Courage C, Gommaraschi S, Gonzalez-Alegre P, Bardakjian T, Syrbe S, Schuler E, Lemke JR, Vari S, Roende G, Bak M, Huq M, Powis Z, Johannesen KM, Hammer TB, Møller RS, Rabin R, Pappas J, Zupanc ML, Zadeh N, Cohen J, Naidu S, Krey I, Saneto R, Thies J, Licchetta L, Tinuper P, Bisulli F, Minardi R, Bayat A, Villeneuve N, Molinari F, Salimi Dafsari H, Moller B, Le Roux M, Houdayer C, Vecchi M, Mammi I, Fiorini E, Proietti J, Ferri S, Cantalupo G, Battaglia DI, Gambardella ML, Contaldo I, Brogna C, Trivisano M, De Dominicis A, Bova SM, Gardella E, Striano P, Coppola A. Clinical features and genotype-phenotype correlations in epilepsy patients with de novo DYNC1H1 variants. Epilepsia 2024. [PMID: 38953796 DOI: 10.1111/epi.18054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 06/17/2024] [Accepted: 06/18/2024] [Indexed: 07/04/2024]
Abstract
OBJECTIVE DYNC1H1 variants are involved on a disease spectrum from neuromuscular disorders to neurodevelopmental disorders. DYNC1H1-related epilepsy has been reported in small cohorts. We dissect the electroclinical features of 34 patients harboring de novo DYNC1H1 pathogenic variants, identify subphenotypes on the DYNC1H1-related epilepsy spectrum, and compare the genotype-phenotype correlations observed in our cohort with the literature. METHODS Patients harboring de novo DYNC1H1 pathogenic variants were recruited through international collaborations. Clinical data were retrospectively collected. Latent class analysis was performed to identify subphenotypes. Multivariable binary logistic regression analysis was applied to investigate the association with DYNC1H1 protein domains. RESULTS DYNC1H1-related epilepsy presented with infantile epileptic spasms syndrome (IESS) in 17 subjects (50%), and in 25% of these individuals the epileptic phenotype evolved into Lennox-Gastaut syndrome (LGS). In 12 patients (35%), focal onset epilepsy was defined. In two patients, the epileptic phenotype consisted of generalized myoclonic epilepsy, with a progressive phenotype in one individual harboring a frameshift variant. In approximately 60% of our cohort, seizures were drug-resistant. Malformations of cortical development were noticed in 79% of our patients, mostly on the lissencephaly-pachygyria spectrum, particularly with posterior predominance in a half of them. Midline and infratentorial abnormalities were additionally reported in 45% and 27% of subjects. We have identified three main classes of subphenotypes on the DYNC1H1-related epilepsy spectrum. SIGNIFICANCE We propose a classification in which pathogenic de novo DYNC1H1 variants feature drug-resistant IESS in half of cases with potential evolution to LGS (Class 1), developmental and epileptic encephalopathy other than IESS and LGS (Class 2), or less severe focal or genetic generalized epilepsy including a progressive phenotype (Class 3). We observed an association between stalk domain variants and Class 1 phenotypes. The variants p.Arg309His and p.Arg1962His were common and associated with Class 1 subphenotype in our cohort. These findings may aid genetic counseling of patients with DYNC1H1-related epilepsy.
Collapse
Affiliation(s)
- Claudia Cuccurullo
- Epilepsy Center, Department of Neuroscience, Reproductive and Odontostomatological Sciences, Federico II University of Naples, Naples, Italy
- Neurology and Stroke Unit, Ospedale del Mare Hospital, Naples, Italy
| | | | - Lorenzo Ugga
- Department of Advanced Biomedical Sciences, University Federico II, Naples, Italy
| | - Antonella Riva
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
- Medical Genetic Unit, Istituti di Ricovero e Cura a Carattere Scientifico Istituto Giannina Gaslini, Genoa, Italy
| | | | - Sara Cabet
- Pediatric and Fetal Imaging, Hôpital Femme-Mère-Enfant, Hospices Civils de Lyon, Lyon, France
| | - Gaetan Lesca
- Service de Génétique, Hospices Civils de Lyon, Bron, France
- Institut NeuroMyoGene, CNRS UMR5310, INSERM U1217, Université Claude Bernard Lyon 1, Lyon, France
| | - Leonilda Bilo
- Epilepsy Center, Department of Neuroscience, Reproductive and Odontostomatological Sciences, Federico II University of Naples, Naples, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
- Medical Genetic Unit, Istituti di Ricovero e Cura a Carattere Scientifico Istituto Giannina Gaslini, Genoa, Italy
| | - Catrinel Iliescu
- Department of Clinical Neurosciences, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - Diana Barca
- Department of Pediatric Neurology, Expertise Center for Rare Diseases in Pediatric Neurology, member of the EpiCARE European Reference Network, "Prof. Dr. Alex. Obregia" Clinical Hospital, Bucharest, Romania
| | - France Fung
- Department of Pediatrics and Neurology, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Katherine Helbig
- Department of Pediatrics and Neurology, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | - Xilma Ortiz-Gonzalez
- Department of Pediatrics and Neurology, Children's Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
| | | | - Marjolein H Willemsen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Inge van der Linden
- Department of Neurology, Epilepsy Center Kempenhaeghe, Heeze, the Netherlands
| | - Laura Canafoglia
- Integrated Diagnostics for Epilepsy, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Carolina Courage
- Folkhälsan Research Center, Helsinki, Finland
- Department of Biomedical and Clinical Science, University of Milan, Milan, Italy
| | - Samuele Gommaraschi
- Department of Biomedical and Clinical Science, University of Milan, Milan, Italy
| | - Pedro Gonzalez-Alegre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, Philadelphia, USA
| | - Tanya Bardakjian
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Pennsylvania, Philadelphia, USA
| | - Steffen Syrbe
- Division of Paediatric Epileptology, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Elisabeth Schuler
- Division of Paediatric Epileptology, Center for Pediatrics and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Johannes R Lemke
- Center for Rare Diseases, University of Leipzig Medical Center, Leipzig, Germany
| | - Stella Vari
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, "G. Gaslini" Institute, University of Genoa, Genoa, Italy
| | - Gitte Roende
- Department of Pediatrics and Adolescent Medicine, University Hospital Rigshopitalet, Copenhagen, Denmark
| | - Mads Bak
- Department of Clinical Genetics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Mahbulul Huq
- Department of Pediatrics, Wayne State University, Detroit, Michigan, USA
| | - Zoe Powis
- Ambry Genetics, Department of Emerging Genetic Medicine, CGC 15 Argonaut, Aliso Viejo, California, USA
| | - Katrine M Johannesen
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
| | - Trine Bjørg Hammer
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
| | - Rachel Rabin
- Clinical Genetic Services, Department of Pediatrics, NYU Grossman School of Medicine, New York, New York, USA
| | - John Pappas
- Clinical Genetic Services, Department of Pediatrics, NYU Grossman School of Medicine, New York, New York, USA
| | - Mary L Zupanc
- Children's Health of Orange County, Orange, California, USA
| | - Neda Zadeh
- Genetics Center and Division of Medical Genetics, Children's Hospital of Orange County, Orange, California, USA
| | - Julie Cohen
- Department of Neurology, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Sakkubai Naidu
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland, USA
| | - Ilona Krey
- Institute of Human Genetics, University of Leipzig Medical Center, Leipzig, Germany
| | - Russell Saneto
- Department of Neurology, Seattle Children's Hospital, University of Washington, Seattle, Washington, USA
- Department of Pediatrics, Seattle Children's Hospital, University of Washington, Seattle, Washington, USA
| | - Jenny Thies
- Seattle Children's Research Institute, University of Washington, Seattle, Washington, USA
| | - Laura Licchetta
- IRCCS, Istituto Delle Scienze Neurologiche di Bologna, full member of the EpiCARE European Reference Network, Bologna, Italy
| | - Paolo Tinuper
- IRCCS, Istituto Delle Scienze Neurologiche di Bologna, full member of the EpiCARE European Reference Network, Bologna, Italy
| | - Francesca Bisulli
- IRCCS, Istituto Delle Scienze Neurologiche di Bologna, full member of the EpiCARE European Reference Network, Bologna, Italy
| | - Raffaella Minardi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Allan Bayat
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
- Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | | | - Florence Molinari
- Biolab, PolitoBIOMedLab, Department of Electronics and Telecommunications, Politecnico di Torino, Turin, Italy
| | - Hormos Salimi Dafsari
- Department of Pediatrics, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
- Max Planck Institute for Biology of Ageing, Cologne, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases, University of Cologne, Cologne, Germany
- Department of Paediatric Neurology, Evelina's Children Hospital, Guy's & St. Thomas' Hospital NHS Foundation Trust, London, UK
- Randall Division of Cell and Molecular Biophysics, Muscle Signaling Section, King's College London, London, UK
| | - Birk Moller
- Department of Pediatrics, Faculty of Medicine, University of Cologne and University Hospital Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Marie Le Roux
- Department of Pediatric Neurology and Neurosurgery, CHU, Angers, France
| | - Clara Houdayer
- Service de Génétique Médicale, Université d'Angers, CHU d'Angers, Inserm, CNRS, MITOVASC, SFR ICAT, Angers, France
| | | | | | - Elena Fiorini
- Child Neuropsychiatry Unit, University Hospital of Verona, full member of the EpiCARE European Reference Network, Verona, Italy
- Center for Research on Epilepsy in Pediatric Age, University Hospital of Verona, Verona, Italy
| | - Jacopo Proietti
- Child Neuropsychiatry Unit, University Hospital of Verona, full member of the EpiCARE European Reference Network, Verona, Italy
- Center for Research on Epilepsy in Pediatric Age, University Hospital of Verona, Verona, Italy
| | - Sofia Ferri
- Child Neuropsychiatry Unit, University Hospital of Verona, full member of the EpiCARE European Reference Network, Verona, Italy
| | - Gaetano Cantalupo
- Child Neuropsychiatry Unit, University Hospital of Verona, full member of the EpiCARE European Reference Network, Verona, Italy
- Center for Research on Epilepsy in Pediatric Age, University Hospital of Verona, Verona, Italy
- Innovation Biomedicine Section, Department of Engineering for Innovation Medicine, University of Verona, Verona, Italy
| | - Domenica Immacolata Battaglia
- Pediatric Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
- Università Cattolica del Sacro Cuore, Rome, Italy
| | | | - Ilaria Contaldo
- Pediatric Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Claudia Brogna
- Pediatric Neurology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
- Neuropsychiatric Unit, ASL Avellino, Avellino, Italy
| | - Marina Trivisano
- Neurology, Epilepsy, and Movement Disorders, Bambino Gesù Children's Hospital, IRCCS, full member of the EpiCARE European Reference Network, Rome, Italy
| | | | | | - Elena Gardella
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Dianalund, Denmark
| | - Pasquale Striano
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, "G. Gaslini" Institute, University of Genoa, Genoa, Italy
| | - Antonietta Coppola
- Epilepsy Center, Department of Neuroscience, Reproductive and Odontostomatological Sciences, Federico II University of Naples, Naples, Italy
| |
Collapse
|
2
|
Wang L, Pan P, Ma H, He C, Qin Z, He W, Huang J, Tan S, Meng D, Wei H, Yin A. Malformations of cortical development: Fetal imaging and genetics. Mol Genet Genomic Med 2024; 12:e2440. [PMID: 38634212 PMCID: PMC11024634 DOI: 10.1002/mgg3.2440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 03/04/2024] [Accepted: 03/28/2024] [Indexed: 04/19/2024] Open
Abstract
BACKGROUND Malformations of cortical development (MCD) are a group of congenital disorders characterized by structural abnormalities in the brain cortex. The clinical manifestations include refractory epilepsy, mental retardation, and cognitive impairment. Genetic factors play a key role in the etiology of MCD. Currently, there is no curative treatment for MCD. Phenotypes such as epilepsy and cerebral palsy cannot be observed in the fetus. Therefore, the diagnosis of MCD is typically based on fetal brain magnetic resonance imaging (MRI), ultrasound, or genetic testing. The recent advances in neuroimaging have enabled the in-utero diagnosis of MCD using fetal ultrasound or MRI. METHODS The present study retrospectively reviewed 32 cases of fetal MCD diagnosed by ultrasound or MRI. Then, the chromosome karyotype analysis, single nucleotide polymorphism array or copy number variation sequencing, and whole-exome sequencing (WES) findings were presented. RESULTS Pathogenic copy number variants (CNVs) or single-nucleotide variants (SNVs) were detected in 22 fetuses (three pathogenic CNVs [9.4%, 3/32] and 19 SNVs [59.4%, 19/32]), corresponding to a total detection rate of 68.8% (22/32). CONCLUSION The results suggest that genetic testing, especially WES, should be performed for fetal MCD, in order to evaluate the outcomes and prognosis, and predict the risk of recurrence in future pregnancies.
Collapse
Affiliation(s)
- Lin‐Lin Wang
- Department of Obstetrics and GynecologyThe First Affiliated Hospital of Jinan UniversityGuangzhouGuangdongChina
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Ping‐Shan Pan
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Hui Ma
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Chun He
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Zai‐Long Qin
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Wei He
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Jing Huang
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Shu‐Yin Tan
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Da‐Hua Meng
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Hong‐Wei Wei
- Prenatal Diagnosis CenterMaternal & Child Health Hospital of Guangxi Zhuang Autonomous RegionNanningGuangxiChina
| | - Ai‐Hua Yin
- Department of Obstetrics and GynecologyThe First Affiliated Hospital of Jinan UniversityGuangzhouGuangdongChina
- Medical Genetic CenterGuangdong Women and Children HospitalGuangzhouGuangdongChina
| |
Collapse
|
3
|
Puri D, Barry BJ, Engle EC. TUBB3 and KIF21A in neurodevelopment and disease. Front Neurosci 2023; 17:1226181. [PMID: 37600020 PMCID: PMC10436312 DOI: 10.3389/fnins.2023.1226181] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/17/2023] [Indexed: 08/22/2023] Open
Abstract
Neuronal migration and axon growth and guidance require precise control of microtubule dynamics and microtubule-based cargo transport. TUBB3 encodes the neuronal-specific β-tubulin isotype III, TUBB3, a component of neuronal microtubules expressed throughout the life of central and peripheral neurons. Human pathogenic TUBB3 missense variants result in altered TUBB3 function and cause errors either in the growth and guidance of cranial and, to a lesser extent, central axons, or in cortical neuronal migration and organization, and rarely in both. Moreover, human pathogenic missense variants in KIF21A, which encodes an anterograde kinesin motor protein that interacts directly with microtubules, alter KIF21A function and cause errors in cranial axon growth and guidance that can phenocopy TUBB3 variants. Here, we review reported TUBB3 and KIF21A variants, resulting phenotypes, and corresponding functional studies of both wildtype and mutant proteins. We summarize the evidence that, in vitro and in mouse models, loss-of-function and missense variants can alter microtubule dynamics and microtubule-kinesin interactions. Lastly, we highlight additional studies that might contribute to our understanding of the relationship between specific tubulin isotypes and specific kinesin motor proteins in health and disease.
Collapse
Affiliation(s)
- Dharmendra Puri
- Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
- F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA, United States
- Howard Hughes Medical Institute, Chevy Chase, MD, United States
| | - Brenda J. Barry
- Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
- F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA, United States
- Howard Hughes Medical Institute, Chevy Chase, MD, United States
| | - Elizabeth C. Engle
- Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
- F. M. Kirby Neurobiology Center, Boston Children’s Hospital, Boston, MA, United States
- Howard Hughes Medical Institute, Chevy Chase, MD, United States
- Department of Ophthalmology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, United States
| |
Collapse
|
4
|
Chung IH, Huang YS, Fang TH, Chen CH. Whole Genome Sequencing Revealed Inherited Rare Oligogenic Variants Contributing to Schizophrenia and Major Depressive Disorder in Two Families. Int J Mol Sci 2023; 24:11777. [PMID: 37511534 PMCID: PMC10380944 DOI: 10.3390/ijms241411777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/12/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Schizophrenia and affective disorder are two major complex mental disorders with high heritability. Evidence shows that rare variants with significant clinical impacts contribute to the genetic liability of these two disorders. Also, rare variants associated with schizophrenia and affective disorders are highly personalized; each patient may carry different variants. We used whole genome sequencing analysis to study the genetic basis of two families with schizophrenia and major depressive disorder. We did not detect de novo, autosomal dominant, or recessive pathogenic or likely pathogenic variants associated with psychiatric disorders in these two families. Nevertheless, we identified multiple rare inherited variants with unknown significance in the probands. In family 1, with singleton schizophrenia, we detected four rare variants in genes implicated in schizophrenia, including p.Arg1627Trp of LAMA2, p.Pro1338Ser of CSMD1, p.Arg691Gly of TLR4, and Arg182X of AGTR2. The p.Arg691Gly of TLR4 was inherited from the father, while the other three were inherited from the mother. In family 2, with two affected sisters diagnosed with major depressive disorder, we detected three rare variants shared by the two sisters in three genes implicated in affective disorders, including p.Ala4551Gly of FAT1, p.Val231Leu of HOMER3, and p.Ile185Met of GPM6B. These three rare variants were assumed to be inherited from their parents. Prompted by these findings, we suggest that these rare inherited variants may interact with each other and lead to psychiatric conditions in these two families. Our observations support the conclusion that inherited rare variants may contribute to the heritability of psychiatric disorders.
Collapse
Affiliation(s)
- I-Hang Chung
- Department of Psychiatry, Chang Gung Memorial Hospital-Linkou, Taoyuan 333, Taiwan
| | - Yu-Shu Huang
- Department of Psychiatry, Chang Gung Memorial Hospital-Linkou, Taoyuan 333, Taiwan
- Department of Psychiatry, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan
| | - Ting-Hsuan Fang
- Department of Psychiatry, Chang Gung Memorial Hospital-Linkou, Taoyuan 333, Taiwan
| | - Chia-Hsiang Chen
- Department of Psychiatry, Chang Gung Memorial Hospital-Linkou, Taoyuan 333, Taiwan
| |
Collapse
|
5
|
Falcicchio G, Riva A, La Neve A, Iacomino M, Lastella P, Suppressa P, Sciruicchio V, Trojano M, Striano P. Case report: LAMC3-associated cortical malformations: Case report of a novel stop-gain variant and literature review. Front Genet 2023; 13:990350. [PMID: 36685914 PMCID: PMC9852726 DOI: 10.3389/fgene.2022.990350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 12/01/2022] [Indexed: 01/09/2023] Open
Abstract
Background: Malformations of cortical development (MCDs) can lead to peculiar neuroradiological patterns and clinical presentations (i.e., seizures, cerebral palsy, and intellectual disability) according to the specific genetic pathway of the brain development involved; and yet a certain degree of phenotypic heterogeneity exists even when the same gene is affected. Here we report a man with an malformations of cortical development extending beyond occipital lobes associated with a novel stop-gain variant in LAMC3. Case presentation: The patient is a 28-year-old man suffering from drug-resistant epilepsy and moderate intellectual disability. He underwent a brain magnetic resonance imaging showing polymicrogyria involving occipital and temporal lobes bilaterally. After performing exome sequencing, a novel stop-gain variant in LAMC3 (c.3871C>T; p. Arg1291*) was identified. According to the cortical alteration of the temporal regions, temporal seizures were detected; instead, the patient did not report occipital seizures. Different pharmacological and non-pharmacological interventions (i.e., vagus nerve stimulation) were unsuccessful, even though a partial seizure reduction was obtained after cenobamate administration. Conclusion: Our case report confirms that variants of a gene known to be related to specific clinical and neuroradiological pictures can unexpectedly lead to new phenotypes involving different areas of the brain.
Collapse
Affiliation(s)
- Giovanni Falcicchio
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Antonella Riva
- Paediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy
| | - Angela La Neve
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Michele Iacomino
- Unit of Medical Genetics, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Patrizia Lastella
- Department of Internal Medicine and Rare Diseases Centre “C. Frugoni”, University Hospital of Bari, Bari, Italy
| | - Patrizia Suppressa
- Department of Internal Medicine and Rare Diseases Centre “C. Frugoni”, University Hospital of Bari, Bari, Italy
| | | | - Maria Trojano
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari, Bari, Italy
| | - Pasquale Striano
- Paediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy,Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genoa, Italy,*Correspondence: Pasquale Striano,
| |
Collapse
|
6
|
Chung CT, Lee NC, Fan SP, Hung MZ, Lin YH, Chen CH, Jao T. DYNC1H1 variant associated with epilepsy: Expanding the phenotypic spectrum. Epilepsy Behav Rep 2022; 21:100580. [PMID: 36636459 PMCID: PMC9829698 DOI: 10.1016/j.ebr.2022.100580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/16/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022] Open
Abstract
DYNC1H1 variants are associated with peripheral neuronal dysfunction and brain morphology abnormalities resulting in neurodevelopmental delay. However, few studies have focused on the association between DYNC1H1 variants and epilepsy. Herein, we report a case of drug-resistant focal epilepsy associated with a pathogenic variant of DYNC1H1. We further summarized the clinical, genetic, and neuroimaging characteristics of patients with DYNC1H1 variant-associated epilepsy from the relevant literature. This report expands the phenotypic spectrum of DYNC1H1-related disorder to include early-onset epilepsy, which is frequently associated with neurodevelopmental delay and intellectual disability, malformations of cortical development, and neuromuscular, ophthalmic, and orthopedic involvement.
Collapse
Affiliation(s)
- Chi-Ting Chung
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan,Department of Neurology, National Taiwan University, Taipei, Taiwan
| | - Ni-Chung Lee
- Department of Pediatrics and Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan,Department of Medical Genetics, National Taiwan University, Taipei, Taiwan,Corresponding authors at: Room 12, 15F, Clinical Research Building, National Taiwan University Hospital, No.7, Chung-Shan S. Rd., Taipei 100225, Taiwan (Tun Jao). Department of Pediatrics, National Taiwan University Hospital, 8 Chung-Shan South Road, Taipei, 10041, Taiwan, (Ni-Chung Lee).
| | - Sung-Pin Fan
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan,Department of Neurology, National Taiwan University, Taipei, Taiwan
| | - Miao-Zi Hung
- Department of Medical Genetics, National Taiwan University, Taipei, Taiwan
| | - Yen-Heng Lin
- Department of Medical Imaging, National Taiwan University, Taipei, Taiwan
| | - Chih-Hao Chen
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan,Department of Neurology, National Taiwan University, Taipei, Taiwan
| | - Tun Jao
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan,Department of Neurology, National Taiwan University, Taipei, Taiwan,Corresponding authors at: Room 12, 15F, Clinical Research Building, National Taiwan University Hospital, No.7, Chung-Shan S. Rd., Taipei 100225, Taiwan (Tun Jao). Department of Pediatrics, National Taiwan University Hospital, 8 Chung-Shan South Road, Taipei, 10041, Taiwan, (Ni-Chung Lee).
| |
Collapse
|
7
|
Naim A, Accogli A, Amadori E, D'Onofrio G, Madia F, Tortora D, Zara F, Striano P, Salpietro V, Severino M. Abnormal course of the corticospinal tracts in KIF5C-related encephalopathy. Eur J Med Genet 2022; 65:104622. [PMID: 36122673 DOI: 10.1016/j.ejmg.2022.104622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 08/14/2022] [Accepted: 09/12/2022] [Indexed: 11/03/2022]
Abstract
KIF5C encodes a protein belonging to the kinesin family and involved in cellular transport. Variants in KIF5C were first associated a decade ago with microcephaly and malformations of cortical development, with a phenotypic spectrum ranging from polymicrogyria to pachygyria. Currently, eight patients have been reported so far. Here we describe a new paediatric patient carrying the recurrent p.(Glu237Lys) KIF5C variant associated with a distinctive neuroradiological pattern of abnormal posterior course of the corticospinal tract at the level of the pons with a thickened anterior component of the transverse pontine fibers. This finding is likely related to altered axonal guidance and requires further evidence in other patients with KIF5C-related disorder.
Collapse
Affiliation(s)
- Alessandro Naim
- Pediatric Neurology and Muscular Diseases Unit, IRCCS "G. Gaslini" Institute, Genova, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Unit of Medical Genetics, IRCCS Giannina Gaslini Institute, Genova, Italy
| | - Andrea Accogli
- Division of Medical Genetics, Department of Specialized Medicine, Montreal Children's Hospital, McGill University Health Centre (MUHC), Montreal, QC, H4A 3J1, Canada; Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Elisabetta Amadori
- Pediatric Neurology and Muscular Diseases Unit, IRCCS "G. Gaslini" Institute, Genova, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Unit of Medical Genetics, IRCCS Giannina Gaslini Institute, Genova, Italy
| | - Gianluca D'Onofrio
- Pediatric Neurology and Muscular Diseases Unit, IRCCS "G. Gaslini" Institute, Genova, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Unit of Medical Genetics, IRCCS Giannina Gaslini Institute, Genova, Italy
| | - Francesca Madia
- UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, University of Genoa, 16147, Genoa, Italy
| | - Domenico Tortora
- Neuroradiology Unit IRCCS, Istituto Giannina Gaslini, Genoa, Italy
| | - Federico Zara
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Unit of Medical Genetics, IRCCS Giannina Gaslini Institute, Genova, Italy; UOC Genetica Medica, IRCCS Istituto Giannina Gaslini, University of Genoa, 16147, Genoa, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, IRCCS "G. Gaslini" Institute, Genova, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Unit of Medical Genetics, IRCCS Giannina Gaslini Institute, Genova, Italy
| | - Vincenzo Salpietro
- Pediatric Neurology and Muscular Diseases Unit, IRCCS "G. Gaslini" Institute, Genova, Italy; Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Unit of Medical Genetics, IRCCS Giannina Gaslini Institute, Genova, Italy.
| | | |
Collapse
|
8
|
De Novo ACTG1 Variant Expands the Phenotype and Genotype of Partial Deafness and Baraitser-Winter Syndrome. Int J Mol Sci 2022; 23:ijms23020692. [PMID: 35054877 PMCID: PMC8776155 DOI: 10.3390/ijms23020692] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/02/2022] [Accepted: 01/05/2022] [Indexed: 02/04/2023] Open
Abstract
Actin molecules are fundamental for embryonic structural and functional differentiation; γ-actin is specifically required for the maintenance and function of cytoskeletal structures in the ear, resulting in hearing. Baraitser–Winter Syndrome (B-WS, OMIM #243310, #614583) is a rare, multiple-anomaly genetic disorder caused by mutations in either cytoplasmically expressed actin gene, ACTB (β-actin) or ACTG1 (γ-actin). The resulting actinopathies cause characteristic cerebrofrontofacial and developmental traits, including progressive sensorineural deafness. Both ACTG1-related non-syndromic A20/A26 deafness and B-WS diagnoses are characterized by hypervariable penetrance in phenotype. Here, we identify a 28th patient worldwide carrying a mutated γ-actin ACTG1 allele, with mildly manifested cerebrofrontofacial B-WS traits, hypervariable penetrance of developmental traits and sensorineural hearing loss. This patient also displays brachycephaly and a complete absence of speech faculty, previously unreported for ACTG1-related B-WS or DFNA20/26 deafness, representing phenotypic expansion. The patient’s exome sequence analyses (ES) confirms a de novo ACTG1 variant previously unlinked to the pathology. Additional microarray analysis uncover no further mutational basis for dual molecular diagnosis in our patient. We conclude that γ-actin c.542C > T, p.Ala181Val is a dominant pathogenic variant, associated with mildly manifested facial and cerebral traits typical of B-WS, hypervariable penetrance of developmental traits and sensorineural deafness. We further posit and present argument and evidence suggesting ACTG1-related non-syndromic DFNA20/A26 deafness is a manifestation of undiagnosed ACTG1-related B-WS.
Collapse
|
9
|
Dekker J, Diderich KEM, Schot R, Husen SC, Dremmen MHG, Go ATJI, Weerts MJA, van Slegtenhorst MA, Mancini GMS. A novel family illustrating the mild phenotypic spectrum of TUBB2B variants. Eur J Paediatr Neurol 2021; 35:35-39. [PMID: 34592644 DOI: 10.1016/j.ejpn.2021.09.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
TUBB2B codes for one of the isotypes of β-tubulin and dominant negative variants in this gene result in distinctive malformations of cortical development (MCD), including dysgyria, dysmorphic basal ganglia and cerebellar anomalies. We present a novel family with a heterozygous missense variant in TUBB2B and an unusually mild phenotype. First, at 21 37 weeks of gestation ultrasonography revealed a fetus with a relatively small head, enlarged lateral ventricles, borderline hypoplastic cerebellum and a thin corpus callosum. The couple opted for pregnancy termination. Exome sequencing on fetal material afterwards identified a heterozygous maternally inherited variant in TUBB2B (NM_178012.4 (TUBB2B):c.530A > T, p.(Asp177Val)), not present in GnomAD and predicted as damaging. The healthy mother had only a language delay in childhood. This inherited TUBB2B variant prompted re-evaluation of the older son of the couple, who presented with a mild delay in motor skills and speech. His MRI revealed mildly enlarged lateral ventricles, a thin corpus callosum, mild cortical dysgyria, and dysmorphic vermis and basal ganglia, a pattern typical of tubulinopathies. This son finally showed the same TUBB2B variant, supporting pathogenicity of the TUBB2B variant. These observations illustrate the wide phenotypic heterogeneity of tubulinopathies, including reduced penetrance and mild expressivity, that require careful evaluation in pre- and postnatal counseling.
Collapse
Affiliation(s)
- Jordy Dekker
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Karin E M Diderich
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Rachel Schot
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Sofie C Husen
- Department of Obstetrics and Prenatal Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjolein H G Dremmen
- Department of Radiology and Nuclear Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Attie T J I Go
- Department of Obstetrics and Prenatal Medicine, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjolein J A Weerts
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Marjon A van Slegtenhorst
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC University Medical Center, 3015, GD Rotterdam, the Netherlands.
| |
Collapse
|
10
|
Mancini GMS, Smits DJ, Dekker J, Schot R, de Wit MCY, Lequin MH, Dremmen M, Brooks AS, van Ham T, Verheijen FW, Fornerod M, Dobyns WB, Wilke M. Multidisciplinary interaction and MCD gene discovery. The perspective of the clinical geneticist. Eur J Paediatr Neurol 2021; 35:27-34. [PMID: 34592643 DOI: 10.1016/j.ejpn.2021.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/18/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022]
Abstract
The increasing pace of gene discovery in the last decade has brought a major change in the way the genetic causes of brain malformations are being diagnosed. Unbiased genomic screening has gained the first place in the diagnostic protocol of a child with congenital (brain) anomalies and the detected variants are matched with the phenotypic presentation afterwards. This process is defined as "reverse phenotyping". Screening of DNA, through copy number variant analysis of microarrays and analysis of exome data on different platforms, obtained from the index patient and both parents has become a routine approach in many centers worldwide. Clinicians are used to multidisciplinary team interaction in patient care and disease management and this explains why the majority of research that has led to the discovery of new genetic disorders nowadays proceeds from clinical observations to genomic analysis and to data exchange facilitated by open access sharing databases. However, the relevance of multidisciplinary team interaction has not been object of systematic research in the field of brain malformations. This review will illustrate some examples of how diagnostically driven questions through multidisciplinary interaction, among clinical and preclinical disciplines, can be successful in the discovery of new genes related to brain malformations. The first example illustrates the setting of interaction among neurologists, geneticists and neuro-radiologists. The second illustrates the importance of interaction among clinical dysmorphologists for pattern recognition of syndromes with multiple congenital anomalies. The third example shows how fruitful it can be to step out of the "clinical comfort zone", and interact with basic scientists in applying emerging technologies to solve the diagnostic puzzles.
Collapse
Affiliation(s)
- Grazia M S Mancini
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands; ENCORE Expertise Center for Genetic Neurocognitive Developmental Disorders, Erasmus, MC, Rotterdam.
| | - Daphne J Smits
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands
| | - Jordy Dekker
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands
| | - Rachel Schot
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands; ENCORE Expertise Center for Genetic Neurocognitive Developmental Disorders, Erasmus, MC, Rotterdam
| | - Marie Claire Y de Wit
- Department of Child Neurology, Sophia Children's Hospital, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, Rotterdam, NL, the Netherlands; ENCORE Expertise Center for Genetic Neurocognitive Developmental Disorders, Erasmus, MC, Rotterdam
| | - Maarten H Lequin
- Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Marjolein Dremmen
- Department of Radiology, Sophia Children's Hospital, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands; ENCORE Expertise Center for Genetic Neurocognitive Developmental Disorders, Erasmus, MC, Rotterdam
| | - Alice S Brooks
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands
| | - Tjakko van Ham
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands
| | - Frans W Verheijen
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands; ENCORE Expertise Center for Genetic Neurocognitive Developmental Disorders, Erasmus, MC, Rotterdam
| | - Maarten Fornerod
- Department of Cell Biology, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands
| | - William B Dobyns
- Department of Pediatrics (Genetics), University of Minnesota, 420 Delaware Street SE, MMC75, Minneapolis, MN, 55454, USA
| | - Martina Wilke
- Department of Clinical Genetics, ErasmusMC University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, the Netherlands; ENCORE Expertise Center for Genetic Neurocognitive Developmental Disorders, Erasmus, MC, Rotterdam
| |
Collapse
|
11
|
DFNA20/26 and Other ACTG1-Associated Phenotypes: A Case Report and Review of the Literature. Audiol Res 2021; 11:582-593. [PMID: 34698053 PMCID: PMC8544197 DOI: 10.3390/audiolres11040052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/10/2021] [Accepted: 10/13/2021] [Indexed: 02/08/2023] Open
Abstract
Since the early 2000s, an ever-increasing subset of missense pathogenic variants in the ACTG1 gene has been associated with an autosomal-dominant, progressive, typically post-lingual non-syndromic hearing loss (NSHL) condition designed as DFNA20/26. ACTG1 gene encodes gamma actin, the predominant actin protein in the cytoskeleton of auditory hair cells; its normal expression and function are essential for the stereocilia maintenance. Different gain-of-function pathogenic variants of ACTG1 have been associated with two major phenotypes: DFNA20/26 and Baraitser-Winter syndrome, a multiple congenital anomaly disorder. Here, we report a novel ACTG1 variant [c.625G>A (p. Val209Met)] in an adult patient with moderate-severe NSHL characterized by a downsloping audiogram. The patient, who had a clinical history of slowly progressive NSHL and tinnitus, was referred to our laboratory for the analysis of a large panel of NSHL-associated genes by next generation sequencing. An extensive review of previously reported ACTG1 variants and their associated phenotypes was also performed.
Collapse
|
12
|
Excitatory/Inhibitory Synaptic Ratios in Polymicrogyria and Down Syndrome Help Explain Epileptogenesis in Malformations. Pediatr Neurol 2021; 116:41-54. [PMID: 33450624 DOI: 10.1016/j.pediatrneurol.2020.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 12/25/2022]
Abstract
BACKGROUND The ratio between excitatory (glutamatergic) and inhibitory (GABAergic) inputs into maturing individual cortical neurons influences their epileptic potential. Structural factors during development that alter synaptic inputs can be demonstrated neuropathologically. Increased mitochondrial activity identifies neurons with excessive discharge rates. METHODS This study focuses on the neuropathological examinaion of surgical resections for epilepsy and at autopsy, in fetuses, infants, and children, using immunocytochemical markers, and electron microscopy in selected cases. Polymicrogyria and Down syndrome are highlighted. RESULTS Factors influencing afferent synaptic ratios include the following: (1) synaptic short-circuitry in fused molecular zones of adjacent gyri (polymicrogyria); (2) impaired development of dendritic spines decreasing excitation (Down syndrome); (3) extracellular keratan sulfate proteoglycan binding to somatic membranes but not dendritic spines may be focally diminished (cerebral atrophy, schizencephaly, lissencephaly, polymicrogyria) or augmented, ensheathing individual axons (holoprosencephaly), or acting as a barrier to axonal passage in the U-fiber layer. If keratan is diminished, glutamate receptors on the neuronal soma enable ectopic axosomatic excitatory synapses to form; (4) dysplastic, megalocytic neurons and balloon cells in mammalian target of rapamycin disorders; (5) satellitosis of glial cells displacing axosomatic synapses; (6) peri-neuronal inflammation (tuberous sclerosis) and heat-shock proteins. CONCLUSIONS Synaptic ratio of excitatory/inhibitory afferents is a major fundamental basis of epileptogenesis at the neuronal level. Neuropathology can demonstrate subcellular changes that help explain either epilepsy or lack of seizures in immature brains. Synaptic ratios in malformations influence postnatal epileptogenesis. Single neurons can be hypermetabolic and potentially epileptogenic.
Collapse
|