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Elkhateeb N, Issa MY, Elbendary HM, Elnaggar W, Ramadan A, Rafat K, Kamel M, Abdel-Ghafar SF, Amer F, Hassaan HM, Trunzo R, Pereira C, Abdel-Hamid MS, D'Arco F, Bauer P, Bertoli-Avella AM, Girgis M, Gleeson JG, Zaki MS, Selim L. The clinical and genetic landscape of developmental and epileptic encephalopathies in Egyptian children. Clin Genet 2024; 105:510-522. [PMID: 38221827 DOI: 10.1111/cge.14481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/28/2023] [Accepted: 01/03/2024] [Indexed: 01/16/2024]
Abstract
Developmental and epileptic encephalopathies (DEEs) are a heterogeneous group of epilepsies characterized by early-onset, refractory seizures associated with developmental regression or impairment, with a heterogeneous genetic landscape including genes implicated in various pathways and mechanisms. We retrospectively studied the clinical and genetic data of patients with genetic DEE who presented at two tertiary centers in Egypt over a 10-year period. Exome sequencing was used for genetic testing. We report 74 patients from 63 unrelated Egyptian families, with a high rate of consanguinity (58%). The most common seizure type was generalized tonic-clonic (58%) and multiple seizure types were common (55%). The most common epilepsy syndrome was early infantile DEE (50%). All patients showed variable degrees of developmental impairment. Microcephaly, hypotonia, ophthalmological involvement and neuroimaging abnormalities were common. Eighteen novel variants were identified and the phenotypes of five DEE genes were expanded with novel phenotype-genotype associations. Obtaining a genetic diagnosis had implications on epilepsy management in 17 patients with variants in 12 genes. In this study, we expand the phenotype and genotype spectrum of DEE in a large single ethnic cohort of patients. Reaching a genetic diagnosis guided precision management of epilepsy in a significant proportion of patients.
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Affiliation(s)
- Nour Elkhateeb
- Department of Clinical Genetics, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Mahmoud Y Issa
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Hasnaa M Elbendary
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Walaa Elnaggar
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Areef Ramadan
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Karima Rafat
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Mona Kamel
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Sherif F Abdel-Ghafar
- Department of Medical Molecular Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Fawzia Amer
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Hebatallah M Hassaan
- Department of Pediatrics, Clinical Genetics Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | | | | | - Mohamed S Abdel-Hamid
- Department of Medical Molecular Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Felice D'Arco
- Radiology Department, Great Ormond Street Hospital for Children, London, UK
| | | | | | - Marian Girgis
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Joseph G Gleeson
- Department of Neurosciences, University of California, San Diego, La Jolla, USA
- Rady Children's Hospital, Rady Children's Institute for Genomic Medicine, San Diego, La Jolla, USA
| | - Maha S Zaki
- Department of Clinical Genetics, Human Genetics and Genome Research Institute, National Research Centre, Cairo, Egypt
| | - Laila Selim
- Department of Pediatrics, Pediatric Neurology and Metabolic Medicine Unit, Kasr Al-Ainy School of Medicine, Cairo University, Cairo, Egypt
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2
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Frewer V, Gilchrist CP, Collins SE, Williams K, Seal ML, Leventer RJ, Amor DJ. A systematic review of brain MRI findings in monogenic disorders strongly associated with autism spectrum disorder. J Child Psychol Psychiatry 2021; 62:1339-1352. [PMID: 34426966 DOI: 10.1111/jcpp.13510] [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] [Accepted: 07/06/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Research on monogenic forms of autism spectrum disorder (autism) can inform our understanding of genetic contributions to the autism phenotype; yet, there is much to be learned about the pathways from gene to brain structure to behavior. This systematic review summarizes and evaluates research on brain magnetic resonance imaging (MRI) findings in monogenic conditions that have strong association with autism. This will improve understanding of the impact of genetic variability on brain structure and related behavioral traits in autism. METHODS The search strategy for this systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Risk of bias (ROB) assessment was completed on included studies using the Newcastle-Ottawa Scales. RESULTS Of 4,287 studies screened, 69 were included pertaining to 13 of the top 20 genes with the strongest association with autism. The greatest number of studies related to individuals with PTEN variants and autism. Brain MRI abnormalities were reported for 12 of the 13 genes studied, and in 51.7% of participants across all 13 genes, including 100% of participants with ARID1B variants. Specific MRI findings were highly variable, with no clear patterns emerging within or between the 13 genes, although white matter abnormalities were the most common. Few studies reported specific details about methods for acquisition and processing of brain MRI, and descriptors for brain abnormalities were variable. ROB assessment indicated high ROB for all studies, largely due to small sample sizes and lack of comparison groups. CONCLUSIONS Brain abnormalities are common in this population of individuals, in particular, children; however, a range of different brain abnormalities were reported within and between genes. Directions for future neuroimaging research in monogenic autism are suggested.
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Affiliation(s)
- Veronica Frewer
- Murdoch Children's Research Institute, Parkville, Vic., Australia.,Department of Paediatrics, The University of Melbourne, Parkville, Vic., Australia
| | - Courtney P Gilchrist
- Murdoch Children's Research Institute, Parkville, Vic., Australia.,Neurodevelopment in Health and Disease, RMIT University, Bundoora, Vic., Australia
| | - Simonne E Collins
- Murdoch Children's Research Institute, Parkville, Vic., Australia.,School of Psychological Sciences, Turner Institute for Brain & Mental Health, Monash University, Melbourne, Vic., Australia
| | - Katrina Williams
- Monash University, Melbourne, Vic., Australia.,Monash Children's Hospital, Melbourne, Vic., Australia
| | - Marc L Seal
- Murdoch Children's Research Institute, Parkville, Vic., Australia.,Department of Paediatrics, The University of Melbourne, Parkville, Vic., Australia
| | - Richard J Leventer
- Murdoch Children's Research Institute, Parkville, Vic., Australia.,Department of Paediatrics, The University of Melbourne, Parkville, Vic., Australia.,Royal Children's Hospital, Parkville, Vic., Australia
| | - David J Amor
- Murdoch Children's Research Institute, Parkville, Vic., Australia.,Department of Paediatrics, The University of Melbourne, Parkville, Vic., Australia.,Royal Children's Hospital, Parkville, Vic., Australia
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3
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Neurological Disorders and Risk of Arrhythmia. Int J Mol Sci 2020; 22:ijms22010188. [PMID: 33375447 PMCID: PMC7795827 DOI: 10.3390/ijms22010188] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/19/2020] [Accepted: 12/24/2020] [Indexed: 01/08/2023] Open
Abstract
Neurological disorders including depression, anxiety, post-traumatic stress disorder (PTSD), schizophrenia, autism and epilepsy are associated with an increased incidence of cardiovascular disorders and susceptibility to heart failure. The underlying molecular mechanisms that link neurological disorders and adverse cardiac function are poorly understood. Further, a lack of progress is likely due to a paucity of studies that investigate the relationship between neurological disorders and cardiac electrical activity in health and disease. Therefore, there is an important need to understand the spatiotemporal behavior of neurocardiac mechanisms. This can be advanced through the identification and validation of neurological and cardiac signaling pathways that may be adversely regulated. In this review we highlight how dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, autonomic nervous system (ANS) activity and inflammation, predispose to psychiatric disorders and cardiac dysfunction. Moreover, antipsychotic and antidepressant medications increase the risk for adverse cardiac events, mostly through the block of the human ether-a-go-go-related gene (hERG), which plays a critical role in cardiac repolarization. Therefore, understanding how neurological disorders lead to adverse cardiac ion channel remodeling is likely to have significant implications for the development of effective therapeutic interventions and helps improve the rational development of targeted therapeutics with significant clinical implications.
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4
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Masini E, Loi E, Vega-Benedetti AF, Carta M, Doneddu G, Fadda R, Zavattari P. An Overview of the Main Genetic, Epigenetic and Environmental Factors Involved in Autism Spectrum Disorder Focusing on Synaptic Activity. Int J Mol Sci 2020; 21:ijms21218290. [PMID: 33167418 PMCID: PMC7663950 DOI: 10.3390/ijms21218290] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 12/11/2022] Open
Abstract
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that affects social interaction and communication, with restricted interests, activity and behaviors. ASD is highly familial, indicating that genetic background strongly contributes to the development of this condition. However, only a fraction of the total number of genes thought to be associated with the condition have been discovered. Moreover, other factors may play an important role in ASD onset. In fact, it has been shown that parental conditions and in utero and perinatal factors may contribute to ASD etiology. More recently, epigenetic changes, including DNA methylation and micro RNA alterations, have been associated with ASD and proposed as potential biomarkers. This review aims to provide a summary of the literature regarding ASD candidate genes, mainly focusing on synapse formation and functionality and relevant epigenetic and environmental aspects acting in concert to determine ASD onset.
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Affiliation(s)
- Elena Masini
- Department of Biomedical Sciences, Unit of Biology and Genetics, University of Cagliari, 09042 Cagliari, Italy; (E.M.); (E.L.); (A.F.V.-B.)
| | - Eleonora Loi
- Department of Biomedical Sciences, Unit of Biology and Genetics, University of Cagliari, 09042 Cagliari, Italy; (E.M.); (E.L.); (A.F.V.-B.)
| | - Ana Florencia Vega-Benedetti
- Department of Biomedical Sciences, Unit of Biology and Genetics, University of Cagliari, 09042 Cagliari, Italy; (E.M.); (E.L.); (A.F.V.-B.)
| | - Marinella Carta
- Center for Pervasive Developmental Disorders, Azienda Ospedaliera Brotzu, 09121 Cagliari, Italy;
| | - Giuseppe Doneddu
- Centro per l’Autismo e Disturbi correlati (CADc), Nuovo Centro Fisioterapico Sardo, 09131 Cagliari, Italy;
| | - Roberta Fadda
- Department of Pedagogy, Psychology, Philosophy, University of Cagliari, 09123 Cagliari, Italy;
| | - Patrizia Zavattari
- Department of Biomedical Sciences, Unit of Biology and Genetics, University of Cagliari, 09042 Cagliari, Italy; (E.M.); (E.L.); (A.F.V.-B.)
- Correspondence:
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5
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Quantitative genome-wide association study of six phenotypic subdomains identifies novel genome-wide significant variants in autism spectrum disorder. Transl Psychiatry 2020; 10:215. [PMID: 32624584 PMCID: PMC7335742 DOI: 10.1038/s41398-020-00906-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 05/17/2020] [Accepted: 05/26/2020] [Indexed: 11/09/2022] Open
Abstract
Autism spectrum disorders (ASD) are highly heritable and are characterized by deficits in social communication and restricted and repetitive behaviors. Twin studies on phenotypic subdomains suggest a differing underlying genetic etiology. Studying genetic variation explaining phenotypic variance will help to identify specific underlying pathomechanisms. We investigated the effect of common variation on ASD subdomains in two cohorts including >2500 individuals. Based on the Autism Diagnostic Interview-Revised (ADI-R), we identified and confirmed six subdomains with a SNP-based genetic heritability h2SNP = 0.2-0.4. The subdomains nonverbal communication (NVC), social interaction (SI), and peer interaction (PI) shared genetic risk factors, while the subdomains of repetitive sensory-motor behavior (RB) and restricted interests (RI) were genetically independent of each other. The polygenic risk score (PRS) for ASD as categorical diagnosis explained 2.3-3.3% of the variance of SI, joint attention (JA), and PI, 4.5% for RI, 1.2% of RB, but only 0.7% of NVC. We report eight genome-wide significant hits-partially replicating previous findings-and 292 known and novel candidate genes. The underlying biological mechanisms were related to neuronal transmission and development. At the SNP and gene level, all subdomains showed overlap, with the exception of RB. However, no overlap was observed at the functional level. In summary, the ADI-R algorithm-derived subdomains related to social communication show a shared genetic etiology in contrast to restricted and repetitive behaviors. The ASD-specific PRS overlapped only partially, suggesting an additional role of specific common variation in shaping the phenotypic expression of ASD subdomains.
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6
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AlSaif S, Umair M, Alfadhel M. Biallelic SCN2A Gene Mutation Causing Early Infantile Epileptic Encephalopathy: Case Report and Review. J Cent Nerv Syst Dis 2019; 11:1179573519849938. [PMID: 31205438 PMCID: PMC6537489 DOI: 10.1177/1179573519849938] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 04/20/2019] [Indexed: 01/13/2023] Open
Abstract
The voltage-gated sodium channel neuronal type 2 alpha subunit (Navα1.2) encoded by the SCN2A gene causes early infantile epileptic encephalopathy (EIEE) inherited in an autosomal dominant manner. Clinically, it has variable presentations, ranging from benign familial infantile seizures (BFIS) to severe EIEE. Diagnosis is achieved through molecular DNA testing of the SCN2A gene. Herein, we report on a 30-month-old Saudi girl who presented on the fourth day of life with EIEE, normal brain magnetic resonance imaging (MRI), normal electroencephalography (EEG), and well-controlled seizures. Genetic investigation revealed a novel homozygous missense mutation (c.5242A > G; p.Asn1748Asp) in the SCN2A gene (NM_001040142.1). This is the first reported autosomal recessive inheritance of a disease allele in the SCN2A and therefore expands the molecular and inheritance spectrum of the SCN2A gene defects.
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Affiliation(s)
- Shahad AlSaif
- College of Medicine, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Muhammad Umair
- Medical Genomics Research Department, King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
| | - Majid Alfadhel
- Medical Genomics Research Department, King Abdullah International Medical Research Center (KAIMRC), King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia.,Division of Genetics, Department of Pediatrics, King Saud bin Abdulaziz University for Health Science, King Abdulaziz Medical City, Ministry of National Guard-Health Affairs (NGHA), Riyadh, Saudi Arabia
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7
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Karoglan A, Schanze D, Bär C, Muschke P, Zenker M, Schanze I. A 2q24.2 microdeletion containingTANKas novel candidate gene for intellectual disability. Am J Med Genet A 2019; 179:832-836. [DOI: 10.1002/ajmg.a.61093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/09/2019] [Accepted: 02/04/2019] [Indexed: 12/27/2022]
Affiliation(s)
- Ante Karoglan
- Department of Dermatology; University Hospital Magdeburg, University of Magdeburg; Magdeburg Germany
- Institute of Human Genetics; Otto-von-Guericke University; Magdeburg Germany
| | - Denny Schanze
- Institute of Human Genetics; Otto-von-Guericke University; Magdeburg Germany
| | - Claudia Bär
- Department of Dermatology; University Hospital Magdeburg, University of Magdeburg; Magdeburg Germany
- Institute of Human Genetics; Otto-von-Guericke University; Magdeburg Germany
| | - Petra Muschke
- Institute of Human Genetics; Otto-von-Guericke University; Magdeburg Germany
| | - Martin Zenker
- Institute of Human Genetics; Otto-von-Guericke University; Magdeburg Germany
| | - Ina Schanze
- Institute of Human Genetics; Otto-von-Guericke University; Magdeburg Germany
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8
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Nickel K, Tebartz van Elst L, Domschke K, Gläser B, Stock F, Endres D, Maier S, Riedel A. Heterozygous deletion of SCN2A and SCN3A in a patient with autism spectrum disorder and Tourette syndrome: a case report. BMC Psychiatry 2018; 18:248. [PMID: 30071822 PMCID: PMC6090917 DOI: 10.1186/s12888-018-1822-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 07/19/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Mutations in voltage-gated sodium channel (SCN) genes are supposed to be of importance in the etiology of psychiatric and neurological diseases, in particular in the etiology of seizures. Previous studies report a potential susceptibility region at the chromosomal locus 2q including SCN1A, SCN2A and SCN3A genes for autism spectrum disorder (ASD). To date, there is no previous description of a patient with comorbid ASD and Tourette syndrome showing a deletion containing SCN2A and SCN3A. CASE PRESENTATION We present the unique complex case of a 28-year-old male patient suffering from developmental retardation and exhibiting a range of behavioral traits since birth. He received the diagnoses of ASD (in early childhood) and of Tourette syndrome (in adulthood) according to ICD-10 and DSM-5 criteria. Investigations of underlying genetic factors yielded a heterozygous microdeletion of approximately 719 kb at 2q24.3 leading to a deletion encompassing the five genes SCN2A (exon 1 to intron 14-15), SCN3A, GRB14 (exon 1 to intron 2-3), COBLL1 and SCL38A11. CONCLUSIONS We discuss the association of SCN2A, SCN3A, GRB14, COBLL1 and SCL38A11 deletions with ASD and Tourette syndrome and possible implications for treatment.
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Affiliation(s)
- Kathrin Nickel
- Section for Experimental Neuropsychiatry, Department of Psychiatry and Psychotherapy, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Hauptstraße 5, D-79104, Freiburg, Germany.
| | - Ludger Tebartz van Elst
- grid.5963.9Section for Experimental Neuropsychiatry, Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Hauptstraße 5, D-79104 Freiburg, Germany
| | - Katharina Domschke
- grid.5963.9Section for Experimental Neuropsychiatry, Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Hauptstraße 5, D-79104 Freiburg, Germany
| | - Birgitta Gläser
- grid.5963.9Institute of Human Genetics, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Straße 33, D-79106 Freiburg, Germany
| | - Friedrich Stock
- grid.5963.9Institute of Human Genetics, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Straße 33, D-79106 Freiburg, Germany
| | - Dominique Endres
- grid.5963.9Section for Experimental Neuropsychiatry, Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Hauptstraße 5, D-79104 Freiburg, Germany
| | - Simon Maier
- grid.5963.9Section for Experimental Neuropsychiatry, Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Hauptstraße 5, D-79104 Freiburg, Germany
| | - Andreas Riedel
- grid.5963.9Section for Experimental Neuropsychiatry, Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Hauptstraße 5, D-79104 Freiburg, Germany
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9
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Chong PF, Saitsu H, Sakai Y, Imagi T, Nakamura R, Matsukura M, Matsumoto N, Kira R. Deletions of SCN2A and SCN3A genes in a patient with West syndrome and autistic spectrum disorder. Seizure 2018; 60:91-93. [PMID: 29929112 DOI: 10.1016/j.seizure.2018.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 05/11/2018] [Accepted: 06/13/2018] [Indexed: 10/28/2022] Open
Abstract
SCN2A encodes the alpha-subunit of voltage-gated sodium channel, Nav1.2, which is highly expressed at an early stage of the postnatal brain. Genetic studies revealed that de novo heterozygous mutations of SCN2A caused severe developmental disorders in childhood, such as autism and epileptic encephalopathy. However, few reports have demonstrated the cases carrying segmental deletions at the SCN2A locus for those with epileptic disorders. In this study, we report a 1.8-year-old boy, who presented with West syndrome in infancy and developed the sequelae of psychomotor delay and autism. Since whole-exome sequencing did not detect pathogenic mutations, we extensively searched for microdeletions and duplications by applying the eXome Hidden Markov Model (XHMM) for read depths of sequenced intervals. Using this approach, we identified a de novo deletion spanning the 1.1-Mb region of chromosome 2q24.3. We found that the deleted interval included the SCN2A and SCN3A loci. These data validate the utility of XHMM and support that SCN2A is involved in the pathogenic processes underlying epileptic encephalopathy in childhood.
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Affiliation(s)
- Pin Fee Chong
- Department of Pediatric Neurology, Fukuoka Children's Hospital, Fukuoka, Japan.
| | - Hirotomo Saitsu
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Yasunari Sakai
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Toru Imagi
- Department of Pediatric Neurology, Fukuoka Children's Hospital, Fukuoka, Japan
| | - Ryoko Nakamura
- Department of Pediatric Neurology, Fukuoka Children's Hospital, Fukuoka, Japan
| | - Masaru Matsukura
- Department of Pediatric Neurology, Fukuoka Children's Hospital, Fukuoka, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Ryutaro Kira
- Department of Pediatric Neurology, Fukuoka Children's Hospital, Fukuoka, Japan
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10
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Wang X, Kery R, Xiong Q. Synaptopathology in autism spectrum disorders: Complex effects of synaptic genes on neural circuits. Prog Neuropsychopharmacol Biol Psychiatry 2018; 84:398-415. [PMID: 28986278 DOI: 10.1016/j.pnpbp.2017.09.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 09/05/2017] [Accepted: 09/26/2017] [Indexed: 01/03/2023]
Affiliation(s)
- Xinxing Wang
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794, USA
| | - Rachel Kery
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794, USA; Medical Scientist Training Program (MSTP), Stony Brook University, Stony Brook, NY 11794, USA
| | - Qiaojie Xiong
- Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY 11794, USA.
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11
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Zhao P, Mao B, Cai X, Jiang J, Liu Z, Lin J, He X. 2q24 deletion in a 9-month old girl with anal atresia, hearing impairment, and hypotonia. Int J Pediatr Otorhinolaryngol 2018; 109:96-100. [PMID: 29728193 DOI: 10.1016/j.ijporl.2018.03.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 12/21/2022]
Abstract
Deletion of 2q24.2 is a rare cytogenetic aberration in patients, exhibiting heterogeneous clinical features, and common phenotypes included developmental delay, intellectual disability, hypotonia, and mild dysmorphic features. Hearing impairment and anal atresia are rarely described. Here we described a 9-month-old female patient with hypotonia in all four limbs, developmental delay, and intellectual disability. In addition, congenital anal atresia was diagnosed and treated after birth, and hearing impairment was found in right ear. Single nucleotide polymorphisms (SNP) array detected a 5.2 Mb deletion on 2q24.2q24.3, including 19 genes (ITGB6; TBR1; SLC4A10; KCNH7 SCN3A; SCN2A et al.). Among these genes, it is affirmative that TBR1 is a causative gene for intellectual disability; however, the pathogenic genes of other phenotypes remain unclear. We briefly review the knowledge of genes likely involved in these clinical features, including hearing impairment, anal atresia, and developmental delay.
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Affiliation(s)
- Peiwei Zhao
- Clinical Research Center, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, China
| | - Bing Mao
- Department of Neurology, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, China; Department of Neurology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, 430016, China
| | - Xiaonan Cai
- Clinical Research Center, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, China
| | - Jun Jiang
- Department of Rehabilitation, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, China; Department of Rehabilitation, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, 430016, China
| | - Zhisheng Liu
- Department of Neurology, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, China; Department of Neurology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, 430016, China.
| | - Jun Lin
- EEG Room, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, 430016, China.
| | - Xuelian He
- Clinical Research Center, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology, China.
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12
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Liang JS, Lin LJ, Yang MT, Wang JS, Lu JF. The therapeutic implication of a novel SCN2A mutation associated early-onset epileptic encephalopathy with Rett-like features. Brain Dev 2017; 39:877-881. [PMID: 28709814 DOI: 10.1016/j.braindev.2017.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/07/2017] [Accepted: 06/14/2017] [Indexed: 01/06/2023]
Abstract
Epileptic encephalopathies are highly heterogeneous and phenotypical disorders with different underlying genetic defects. Mutations in the SCN2A gene cause different epilepsy syndromes, including epilepsy of infancy with migrating focal seizures, Ohtahara syndrome, and West syndrome. We utilized a targeted next generation sequencing (NGS) approach on a girl with early-onset seizures and Rett-like features, including autistic behavior, limited hand function with chorea, and profound intellectual disability, to identify novel missense mutation (c.1270G>A; p.V424M) in the SCN2A gene, which encodes the αII-subunit of the voltage-gated Na+ channel (Nav1.2). The identified SCN2A mutation responsible for the development of the disease is confirmed to be de novo for the proband. Our findings broaden the clinical spectrum of SCN2A mutations, which resembles clinical phenotypes of SCN1A mutations by manifesting as fever sensitive seizures, and highlights that SCN2A mutations are an important cause of early-onset epileptic encephalopathies with movement disorders. In addition, the use of levetiracetam to treat SCN2A epileptic encephalopathy, when Na+ channel-blocking anticonvulsants are ineffective, is also recommended.
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Affiliation(s)
- Jao-Shwann Liang
- Department of Pediatrics, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Li-Ju Lin
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Ming-Tao Yang
- Department of Pediatrics, Far Eastern Memorial Hospital, New Taipei City, Taiwan; Department of Chemical Engineering and Material Science, Yuan Ze University, Taoyuan, Taiwan
| | - Jinn-Shyan Wang
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Jyh-Feng Lu
- School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan.
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13
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Lee BH, Smith T, Paciorkowski AR. Autism spectrum disorder and epilepsy: Disorders with a shared biology. Epilepsy Behav 2015; 47:191-201. [PMID: 25900226 PMCID: PMC4475437 DOI: 10.1016/j.yebeh.2015.03.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/17/2022]
Abstract
There is an increasing recognition of clinical overlap in patients presenting with epilepsy and autism spectrum disorder (ASD), and a great deal of new information regarding the genetic causes of both disorders is available. Several biological pathways appear to be involved in both disease processes, including gene transcription regulation, cellular growth, synaptic channel function, and maintenance of synaptic structure. We review several genetic disorders where ASD and epilepsy frequently co-occur, and we discuss the screening tools available for practicing neurologists and epileptologists to help determine which patients should be referred for formal ASD diagnostic evaluation. Finally, we make recommendations regarding the workflow of genetic diagnostic testing available for children with both ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".
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Affiliation(s)
- Bo Hoon Lee
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Tristram Smith
- Division of Neurodevelopmental and Behavioral Pediatrics, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Alex R Paciorkowski
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA; Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA; Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA; Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY, USA.
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14
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A de novo 2.3 Mb deletion in 2q24.2q24.3 in a 20-month-old developmentally delayed girl. Gene 2014; 539:168-72. [PMID: 24508274 DOI: 10.1016/j.gene.2014.01.060] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 01/16/2014] [Accepted: 01/23/2014] [Indexed: 12/21/2022]
Abstract
We report a 20-month-old girl ascertained at the age of 11 months for developmental delay. She presented with hypotonia and delayed motor development. The patient had severe language impairment and showed behaviour consistent with autism spectrum disorder. She was microcephalic with mild dysmorphic features and had joint hyperlaxity. We detected a 2.3 Mb de novo deletion in 2q24.2q24.3 on her paternal chromosome. We compare the clinical features of our patient to six previously published patients with a deletion in 2q24.2q24.3, and one patient reported in the ECARUCA database. Although the clinical presentation of these patients is not highly consistent, likely due to the different deletion size and gene content, the following features seem to be recurrent: disturbance in the central nervous system, poor growth, hypotonia, and joint hyperlaxity. The region deleted in our patient contains 13 genes including PSMD14, TBR1, SLC4A10, DPP4, KCNH7, and FIGN. We briefly review the knowledge of these genes and their possible involvement in the aetiology of this developmental delay syndrome.
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15
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Matsunami N, Hensel CH, Baird L, Stevens J, Otterud B, Leppert T, Varvil T, Hadley D, Glessner JT, Pellegrino R, Kim C, Thomas K, Wang F, Otieno FG, Ho K, Christensen GB, Li D, Prekeris R, Lambert CG, Hakonarson H, Leppert MF. Identification of rare DNA sequence variants in high-risk autism families and their prevalence in a large case/control population. Mol Autism 2014; 5:5. [PMID: 24467814 PMCID: PMC4098669 DOI: 10.1186/2040-2392-5-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 12/24/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Genetics clearly plays a major role in the etiology of autism spectrum disorders (ASDs), but studies to date are only beginning to characterize the causal genetic variants responsible. Until recently, studies using multiple extended multi-generation families to identify ASD risk genes had not been undertaken. METHODS We identified haplotypes shared among individuals with ASDs in large multiplex families, followed by targeted DNA capture and sequencing to identify potential causal variants. We also assayed the prevalence of the identified variants in a large ASD case/control population. RESULTS We identified 584 non-conservative missense, nonsense, frameshift and splice site variants that might predispose to autism in our high-risk families. Eleven of these variants were observed to have odds ratios greater than 1.5 in a set of 1,541 unrelated children with autism and 5,785 controls. Three variants, in the RAB11FIP5, ABP1, and JMJD7-PLA2G4B genes, each were observed in a single case and not in any controls. These variants also were not seen in public sequence databases, suggesting that they may be rare causal ASD variants. Twenty-eight additional rare variants were observed only in high-risk ASD families. Collectively, these 39 variants identify 36 genes as ASD risk genes. Segregation of sequence variants and of copy number variants previously detected in these families reveals a complex pattern, with only a RAB11FIP5 variant segregating to all affected individuals in one two-generation pedigree. Some affected individuals were found to have multiple potential risk alleles, including sequence variants and copy number variants (CNVs), suggesting that the high incidence of autism in these families could be best explained by variants at multiple loci. CONCLUSIONS Our study is the first to use haplotype sharing to identify familial ASD risk loci. In total, we identified 39 variants in 36 genes that may confer a genetic risk of developing autism. The observation of 11 of these variants in unrelated ASD cases further supports their role as ASD risk variants.
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Affiliation(s)
- Nori Matsunami
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | | | - Lisa Baird
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Jeff Stevens
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Brith Otterud
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Tami Leppert
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Tena Varvil
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
| | - Dexter Hadley
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Joseph T Glessner
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Renata Pellegrino
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Cecilia Kim
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kelly Thomas
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Fengxiang Wang
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Frederick G Otieno
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Karen Ho
- Lineagen, Inc, Salt Lake City, UT, USA
| | | | - Dongying Li
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Rytis Prekeris
- Department of Cell and Developmental Biology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | - Hakon Hakonarson
- Center for Applied Genomics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Mark F Leppert
- Department of Human Genetics, University of Utah, Salt Lake City, UT, USA
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16
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Celle ME, Cuoco C, Porta S, Gimelli G, Tassano E. Interstitial 2q24.3 deletion including SCN2A and SCN3A genes in a patient with autistic features, psychomotor delay, microcephaly and no history of seizures. Gene 2013; 532:294-6. [DOI: 10.1016/j.gene.2013.09.073] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/16/2013] [Accepted: 09/19/2013] [Indexed: 10/26/2022]
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17
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Schmunk G, Gargus JJ. Channelopathy pathogenesis in autism spectrum disorders. Front Genet 2013; 4:222. [PMID: 24204377 PMCID: PMC3817418 DOI: 10.3389/fgene.2013.00222] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 10/09/2013] [Indexed: 01/12/2023] Open
Abstract
Autism spectrum disorder (ASD) is a syndrome that affects normal brain development and is characterized by impaired social interaction as well as verbal and non-verbal communication and by repetitive, stereotypic behavior. ASD is a complex disorder arising from a combination of multiple genetic and environmental factors that are independent from racial, ethnic and socioeconomical status. The high heritability of ASD suggests a strong genetic basis for the disorder. Furthermore, a mounting body of evidence implies a role of various ion channel gene defects (channelopathies) in the pathogenesis of autism. Indeed, recent genome-wide association, and whole exome- and whole-genome resequencing studies linked polymorphisms and rare variants in calcium, sodium and potassium channels and their subunits with susceptibility to ASD, much as they do with bipolar disorder, schizophrenia and other neuropsychiatric disorders. Moreover, animal models with these genetic variations recapitulate endophenotypes considered to be correlates of autistic behavior seen in patients. An ion flux across the membrane regulates a variety of cell functions, from generation of action potentials to gene expression and cell morphology, thus it is not surprising that channelopathies have profound effects on brain functions. In the present work, we summarize existing evidence for the role of ion channel gene defects in the pathogenesis of autism with a focus on calcium signaling and its downstream effects.
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Affiliation(s)
- Galina Schmunk
- Department of Physiology and Biophysics, University of California Irvine, CA, USA ; UCI Center for Autism Research and Treatment, School of Medicine, University of California Irvine, CA, USA
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18
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Imbrici P, Camerino DC, Tricarico D. Major channels involved in neuropsychiatric disorders and therapeutic perspectives. Front Genet 2013; 4:76. [PMID: 23675382 PMCID: PMC3646240 DOI: 10.3389/fgene.2013.00076] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/16/2013] [Indexed: 12/11/2022] Open
Abstract
Voltage-gated ion channels are important mediators of physiological functions in the central nervous system. The cyclic activation of these channels influences neurotransmitter release, neuron excitability, gene transcription, and plasticity, providing distinct brain areas with unique physiological and pharmacological response. A growing body of data has implicated ion channels in the susceptibility or pathogenesis of psychiatric diseases. Indeed, population studies support the association of polymorphisms in calcium and potassium channels with the genetic risk for bipolar disorders (BPDs) or schizophrenia. Moreover, point mutations in calcium, sodium, and potassium channel genes have been identified in some childhood developmental disorders. Finally, antibodies against potassium channel complexes occur in a series of autoimmune psychiatric diseases. Here we report recent studies assessing the role of calcium, sodium, and potassium channels in BPD, schizophrenia, and autism spectrum disorders, and briefly summarize promising pharmacological strategies targeted on ion channels for the therapy of mental illness and related genetic tests.
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Affiliation(s)
- Paola Imbrici
- Section of Pharmacology, Department of Pharmacy - Drug Science, University of Bari Bari, Italy
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19
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Burrage LC, Eble TN, Hixson PM, Roney EK, Cheung SW, Franco LM. A mosaic 2q24.2 deletion narrows the critical region to a 0.4 Mb interval that includes TBR1, TANK, and PSMD14. Am J Med Genet A 2013; 161A:841-4. [PMID: 23444363 DOI: 10.1002/ajmg.a.35751] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 10/11/2012] [Indexed: 11/11/2022]
Abstract
Interstitial deletions involving 2q24 have been associated with a wide range of phenotypes including intellectual disability and short stature. To date, the smallest common region among reported cases of deletions in this region is approximately 2.65 Mb and contains 15 genes. In the present case report, we describe an 18-year-old male with mild intellectual disability, short stature, and mosaicism for a 0.422 Mb deletion on 2q24.2 that was diagnosed by comparative genomic hybridization and confirmed with fluorescent in situ hybridization (FISH). This deletion, which is present in approximately 61% of cells, includes three genes: TBR1, TANK, and PSMD14. The findings suggest that the critical region for intellectual disability and short stature in 2q24.2 can be narrowed to a 0.422 Mb segment. TBR1, a transcription factor involved in early cortical development, is a strong candidate for the intellectual disability phenotype seen in our patient and in patients with larger deletions in this region of the genome.
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Affiliation(s)
- Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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20
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Nimmakayalu M, Noble N, Horton VK, Willing M, Copeland S, Sheffield V, Nagy PL, Wassink T, Patil S, Shchelochkov OA. 2q24 deletions: Further characterization of clinical findings and their relation to the SCN cluster. Am J Med Genet A 2012; 158A:2767-74. [DOI: 10.1002/ajmg.a.35362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Accepted: 02/06/2012] [Indexed: 12/31/2022]
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21
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Traylor RN, Dobyns WB, Rosenfeld JA, Wheeler P, Spence JE, Bandholz AM, Bawle EV, Carmany EP, Powell CM, Hudson B, Schultz RA, Shaffer LG, Ballif BC. Investigation of TBR1 Hemizygosity: Four Individuals with 2q24 Microdeletions. Mol Syndromol 2012; 3:102-112. [PMID: 23112752 DOI: 10.1159/000342008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2012] [Indexed: 12/19/2022] Open
Abstract
TBR1 encodes a transcription factor with critical roles in corticogenesis, including cortical neuron migration and axon pathfinding, establishment of regional and laminar identity of cortical neurons, and control of glutamatergic neuronal cell fate. Based upon TBR1's role in cortical development, we sought to investigate TBR1 hemizygosity in individuals referred for genetic evaluation of intellectual disability and developmental delay. We describe 4 patients with microdeletions identified by molecular cytogenetic techniques, encompassing TBR1 and spanning 2q24.1q31.1, ranging in size from 2.17 to 12.34 Mb. Only the patient with the largest deletion had a possible cortical malformation. Mild ventriculomegaly is the only common brain anomaly, present in all patients; a Chiari I malformation is seen in 2 patients, and mega cisterna magna is seen in a third. Our findings are consistent with Tbr1 mouse models showing that hemizygosity of the gene requires additional genetic factors for the manifestation of severe structural brain malformations. Other syndromic features are present in these patients, including autism spectrum disorders, ocular colobomas, and craniosynostosis, features that are likely affected by the deletion of genes other than TBR1.
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Affiliation(s)
- R N Traylor
- Signature Genomic Laboratories, PerkinElmer Inc., Spokane, Wash., USA
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22
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Need AC, Shashi V, Hitomi Y, Schoch K, Shianna KV, McDonald MT, Meisler MH, Goldstein DB. Clinical application of exome sequencing in undiagnosed genetic conditions. J Med Genet 2012; 49:353-61. [PMID: 22581936 PMCID: PMC3375064 DOI: 10.1136/jmedgenet-2012-100819] [Citation(s) in RCA: 321] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Background There is considerable interest in the use of next-generation sequencing to help diagnose unidentified genetic conditions, but it is difficult to predict the success rate in a clinical setting that includes patients with a broad range of phenotypic presentations. Methods The authors present a pilot programme of whole-exome sequencing on 12 patients with unexplained and apparent genetic conditions, along with their unaffected parents. Unlike many previous studies, the authors did not seek patients with similar phenotypes, but rather enrolled any undiagnosed proband with an apparent genetic condition when predetermined criteria were met. Results This undertaking resulted in a likely genetic diagnosis in 6 of the 12 probands, including the identification of apparently causal mutations in four genes known to cause Mendelian disease (TCF4, EFTUD2, SCN2A and SMAD4) and one gene related to known Mendelian disease genes (NGLY1). Of particular interest is that at the time of this study, EFTUD2 was not yet known as a Mendelian disease gene but was nominated as a likely cause based on the observation of de novo mutations in two unrelated probands. In a seventh case with multiple disparate clinical features, the authors were able to identify homozygous mutations in EFEMP1 as a likely cause for macular degeneration (though likely not for other features). Conclusions This study provides evidence that next-generation sequencing can have high success rates in a clinical setting, but also highlights key challenges. It further suggests that the presentation of known Mendelian conditions may be considerably broader than currently recognised.
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Affiliation(s)
- Anna C Need
- Center for Human Genome Variation, Duke University School of Medicine, Box 91009, Durham, NC 27708, USA.
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23
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Boone PM, Bacino CA, Shaw CA, Eng PA, Hixson PM, Pursley AN, Kang SHL, Yang Y, Wiszniewska J, Nowakowska BA, del Gaudio D, Xia Z, Simpson-Patel G, Immken LL, Gibson JB, Tsai ACH, Bowers JA, Reimschisel TE, Schaaf CP, Potocki L, Scaglia F, Gambin T, Sykulski M, Bartnik M, Derwinska K, Wisniowiecka-Kowalnik B, Lalani SR, Probst FJ, Bi W, Beaudet AL, Patel A, Lupski JR, Cheung SW, Stankiewicz P. Detection of clinically relevant exonic copy-number changes by array CGH. Hum Mutat 2010; 31:1326-42. [PMID: 20848651 DOI: 10.1002/humu.21360] [Citation(s) in RCA: 201] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 09/02/2010] [Indexed: 12/22/2022]
Abstract
Array comparative genomic hybridization (aCGH) is a powerful tool for the molecular elucidation and diagnosis of disorders resulting from genomic copy-number variation (CNV). However, intragenic deletions or duplications--those including genomic intervals of a size smaller than a gene--have remained beyond the detection limit of most clinical aCGH analyses. Increasing array probe number improves genomic resolution, although higher cost may limit implementation, and enhanced detection of benign CNV can confound clinical interpretation. We designed an array with exonic coverage of selected disease and candidate genes and used it clinically to identify losses or gains throughout the genome involving at least one exon and as small as several hundred base pairs in size. In some patients, the detected copy-number change occurs within a gene known to be causative of the observed clinical phenotype, demonstrating the ability of this array to detect clinically relevant CNVs with subkilobase resolution. In summary, we demonstrate the utility of a custom-designed, exon-targeted oligonucleotide array to detect intragenic copy-number changes in patients with various clinical phenotypes.
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Affiliation(s)
- Philip M Boone
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
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24
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Bartnik M, Chun-Hui Tsai A, Xia Z, Cheung SW, Stankiewicz P. Disruption of the SCN2A and SCN3A genes in a patient with mental retardation, neurobehavioral and psychiatric abnormalities, and a history of infantile seizures. Clin Genet 2010; 80:191-5. [PMID: 20807223 DOI: 10.1111/j.1399-0004.2010.01526.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutations in genes encoding voltage-gated sodium channels are significant factors in the etiology of neurological diseases and psychiatric disorders, including various types of idiopathic epilepsy. Using a clinical exon-targeted oligonucleotide array comparative genomic hybridization (aCGH), we have identified a de novo ~110-kb deletion involving exons 1-2 of SCN2A and non-coding exon 1a of SCN3A in a 25-year-old female with mental retardation, neurobehavioral and psychiatric abnormalities, and a history of infantile seizures with abnormal EEG. We propose that haploinsufficiency of SCN2A may play an important role in the genetic basis of neurodevelopmental and neurobehavioral disorders and emphasize the efficacy of detecting exonic copy-number variation (CNV) by exon-targeted oligo aCGH.
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Affiliation(s)
- M Bartnik
- Department of Medical Genetics, Institute of Mother and Child, Warsaw, Poland
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