1
|
Huang H, Shakkottai VG. Targeting Ion Channels and Purkinje Neuron Intrinsic Membrane Excitability as a Therapeutic Strategy for Cerebellar Ataxia. Life (Basel) 2023; 13:1350. [PMID: 37374132 DOI: 10.3390/life13061350] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/03/2023] [Accepted: 06/06/2023] [Indexed: 06/29/2023] Open
Abstract
In degenerative neurological disorders such as Parkinson's disease, a convergence of widely varying insults results in a loss of dopaminergic neurons and, thus, the motor symptoms of the disease. Dopamine replacement therapy with agents such as levodopa is a mainstay of therapy. Cerebellar ataxias, a heterogeneous group of currently untreatable conditions, have not been identified to have a shared physiology that is a target of therapy. In this review, we propose that perturbations in cerebellar Purkinje neuron intrinsic membrane excitability, a result of ion channel dysregulation, is a common pathophysiologic mechanism that drives motor impairment and vulnerability to degeneration in cerebellar ataxias of widely differing genetic etiologies. We further propose that treatments aimed at restoring Purkinje neuron intrinsic membrane excitability have the potential to be a shared therapy in cerebellar ataxia akin to levodopa for Parkinson's disease.
Collapse
Affiliation(s)
- Haoran Huang
- Medical Scientist Training Program, The Ohio State University College of Medicine, Columbus, OH 43210, USA
| | - Vikram G Shakkottai
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| |
Collapse
|
2
|
He Z, Li Y, Zhao X, Li B. Dravet Syndrome: Advances in Etiology, Clinical Presentation, and Treatment. Epilepsy Res 2022; 188:107041. [DOI: 10.1016/j.eplepsyres.2022.107041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/08/2022] [Accepted: 10/26/2022] [Indexed: 11/16/2022]
|
3
|
Genetic therapeutic advancements for Dravet Syndrome. Epilepsy Behav 2022; 132:108741. [PMID: 35653814 DOI: 10.1016/j.yebeh.2022.108741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/05/2022] [Accepted: 05/11/2022] [Indexed: 11/03/2022]
Abstract
Dravet Syndrome is a genetic epileptic syndrome characterized by severe and intractable seizures associated with cognitive, motor, and behavioral impairments. The disease is also linked with increased mortality mainly due to sudden unexpected death in epilepsy. Over 80% of cases are due to a de novo mutation in one allele of the SCN1A gene, which encodes the α-subunit of the voltage-gated ion channel NaV1.1. Dravet Syndrome is usually refractory to antiepileptic drugs, which only alleviate seizures to a small extent. Viral, non-viral genetic therapy, and gene editing tools are rapidly enhancing and providing new platforms for more effective, alternative medicinal treatments for Dravet syndrome. These strategies include gene supplementation, CRISPR-mediated transcriptional activation, and the use of antisense oligonucleotides. In this review, we summarize our current knowledge of novel genetic therapies that are currently under development for Dravet syndrome.
Collapse
|
4
|
Jin N, Gureviciene I, Atalay AN, Häkli S, Ziyatdinova S, Tanila H. Preclinical evaluation of drug treatment options for sleep‐related epileptiform spiking in Alzheimer's disease. ALZHEIMER'S & DEMENTIA: TRANSLATIONAL RESEARCH & CLINICAL INTERVENTIONS 2022; 8:e12291. [PMID: 35415205 PMCID: PMC8982322 DOI: 10.1002/trc2.12291] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 02/20/2022] [Accepted: 03/03/2022] [Indexed: 11/29/2022]
Abstract
Introduction There are no published data on prospective clinical studies on drug treatment options for sleep‐related epileptiform spiking in Alzheimer's disease (AD). Methods Using video‐EEG with hippocampal electrodes in 17 APP/PS1 transgenic male mice we assessed the effects of donepezil and memantine, anti‐seizure drugs levetiracetam and lamotrigine, gamma‐secretase inhibitor semagacestat, anti‐inflammatory minocycline and adenosine receptor antagonist istradephylline on density of cortical and hippocampal spikes during sleep. Results Levetiracetam decreased the density of hippocampal giant spikes and cortical spikes. Lamotrigine reduced cortical single spikes and spike‐wave discharges but dramatically increased hippocampal giant spikes. Memantine increased cortical single spikes and spike‐wave discharges dose‐dependently. Memantine and istradephylline decreased total sleep time while levetiracetam increased it. Lamotrigine decreased REM sleep duration. Other drugs had no significant effects. Discussion Levetiracetam appears promising for treating sleep‐related epileptiform spiking in AD while lamotrigine should be used with caution. Donepezil at low doses appeared neutral but the memantine effects warrant further studies.
Collapse
Affiliation(s)
- Nanxiang Jin
- A. I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
| | - Irina Gureviciene
- A. I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
| | - Aysu Naz Atalay
- A. I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
| | - Sara Häkli
- A. I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
| | - Sofya Ziyatdinova
- A. I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
| | - Heikki Tanila
- A. I. Virtanen Institute for Molecular Sciences University of Eastern Finland Kuopio Finland
| |
Collapse
|
5
|
Comparative structural analysis of human Na v1.1 and Na v1.5 reveals mutational hotspots for sodium channelopathies. Proc Natl Acad Sci U S A 2021; 118:2100066118. [PMID: 33712547 DOI: 10.1073/pnas.2100066118] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Among the nine subtypes of human voltage-gated sodium (Nav) channels, the brain and cardiac isoforms, Nav1.1 and Nav1.5, each carry more than 400 missense mutations respectively associated with epilepsy and cardiac disorders. High-resolution structures are required for structure-function relationship dissection of the disease variants. We report the cryo-EM structures of the full-length human Nav1.1-β4 complex at 3.3 Å resolution here and the Nav1.5-E1784K variant in the accompanying paper. Up to 341 and 261 disease-related missense mutations in Nav1.1 and Nav1.5, respectively, are resolved. Comparative structural analysis reveals several clusters of disease mutations that are common to both Nav1.1 and Nav1.5. Among these, the majority of mutations on the extracellular loops above the pore domain and the supporting segments for the selectivity filter may impair structural integrity, while those on the pore domain and the voltage-sensing domains mostly interfere with electromechanical coupling and fast inactivation. Our systematic structural delineation of these mutations provides important insight into their pathogenic mechanism, which will facilitate the development of precise therapeutic interventions against various sodium channelopathies.
Collapse
|
6
|
Abstract
PURPOSE OF REVIEW This review will illustrate the electroclinical description of Dravet syndrome, highlighting the difficulty to understand the correlation between the SCN1A mutation and clinical characteristics, including the frequent comorbidities. Therefore, the efficacy of the new treatment options, which now become available, should not only focus on seizure frequency reduction but also on the long-term effects on these comorbidities, such as intellectual disability, motor and sleep problems. RECENT FINDINGS Comprehensive guidelines for a more standardized treatment in children with Dravet syndrome have been published. First-line and second-line treatments actually include only a few antiseizure medications, such as valproate, clobazam, stiripentol, topiramate and bromide. Cannabidiol and fenfluramine were shown to be very effective drugs and will become standard second-line drugs in Dravet syndrome. There are preliminary data showing that both drugs also have a positive effect on quality of life and on cognitive functioning. Genetic treatments in Dravet syndrome most likely will dramatically change the natural course of this refractory epilepsy syndrome. SUMMARY A better understanding of the full clinical picture is necessary to understand the potential value of new treatment options in Dravet syndrome. Treatment nowadays with the newer drugs becomes much more standardized and effective, and this will have a positive effect on long-term overall outcome.
Collapse
|
7
|
Wang ZJ, Kim ES, Noh BH, Liang JG, Lee D, Hur YJ, Kim NY, Kim HD. Alteration in brain connectivity in patients with Dravet syndrome after vagus nerve stimulation (VNS): exploration of its effectiveness using graph theory analysis with electroencephalography. J Neural Eng 2020; 17:036014. [PMID: 32380482 DOI: 10.1088/1741-2552/ab914f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Vagus nerve stimulation (VNS) is a nonpharmacologic therapeutic option for patients who have pharmaco-resistant Dravet syndrome (DS). Plentiful efforts have been made for delivering VNS to DS patients, but its effectiveness still requires further verification. We investigated the effectiveness of the VNS treatment of DS patients using brain connectivity analysis with electroencephalography (EEG). APPROACH Twenty pharmaco-resistant DS patients were selected to undergo VNS implantation and classified into responder and non-responder groups after 24 months post-VNS. The effect of VNS between 6 months pre- and 6, 12, and 24 months post-VNS in all patients, responders, and non-responders on four different frequency categories of four brain parameters were compared using resting-state EEG. MAIN RESULTS In alpha and beta bands, all patients showed positive results for characteristic path length (CPL), global efficiency (GE), and transitivity after VNS treatment, and changes in betweenness centrality (BC) were not significant. The difference in transitivity between responders and non-responders is more pronounced than those in CPL and GE are, in both the alpha (p < 0.015) and beta (p < 0.001) bands. There was an obvious change in BC, especially in the alpha band, as the hubs tended to move from frontal lobe to parietal lobe for responders; however, there was no change for the non-responders. SIGNIFICANCE We investigated the alteration in brain connectivity of DS patients in alpha and beta bands during a long-term follow-up and found the responders have a decreased transitivity after the VNS treatment. Moreover, the hubs with high values in the alpha band tended to move from frontal lobe to parietal lobe for responders after VNS treatment.
Collapse
Affiliation(s)
- Zhi-Ji Wang
- RFIC Center, Kwangwoon University, 447-1 Wolgye-Dong, Nowon-Ku, Seoul 139-701, Republic of Korea. These authors contributed equally to this work
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Frimat JP, Luttge R. The Need for Physiological Micro-Nanofluidic Systems of the Brain. Front Bioeng Biotechnol 2019; 7:100. [PMID: 31134196 PMCID: PMC6514106 DOI: 10.3389/fbioe.2019.00100] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 04/18/2019] [Indexed: 01/09/2023] Open
Abstract
In this article, we review brain-on-a-chip models and associated underlying technologies. Micro-nanofluidic systems of the brain can utilize the entire spectrum of organoid technology. Notably, there is an urgent clinical need for a physiologically relevant microfluidic platform that can mimic the brain. Brain diseases affect millions of people worldwide, and this number will grow as the size of elderly population increases, thus making brain disease a serious public health problem. Brain disease modeling typically involves the use of in vivo rodent models, which is time consuming, resource intensive, and arguably unethical because many animals are required for a single study. Moreover, rodent models may not accurately predict human diseases, leading to erroneous results, thus rendering animal models poor predictors of human responses to treatment. Various clinical researchers have highlighted this issue, showing that initial physiological descriptions of animal models rarely encompass all the desired human features, including how closely the model captures what is observed in patients. Consequently, such animal models only mimic certain disease aspects, and they are often inadequate for studying how a certain molecule affects various aspects of a disease. Thus, there is a great need for the development of the brain-on-a-chip technology based on which a human brain model can be engineered by assembling cell lines to generate an organ-level model. To produce such a brain-on-a-chip device, selection of appropriate cells lines is critical because brain tissue consists of many different neuronal subtypes, including a plethora of supporting glial cell types. Additionally, cellular network bio-architecture significantly varies throughout different brain regions, forming complex structures and circuitries; this needs to be accounted for in the chip design process. Compartmentalized microenvironments can also be designed within the microphysiological cell culture system to fulfill advanced requirements of a given application. On-chip integration methods have already enabled advances in Parkinson's disease, Alzheimer's disease, and epilepsy modeling, which are discussed herein. In conclusion, for the brain model to be functional, combining engineered microsystems with stem cell (hiPSC) technology is specifically beneficial because hiPSCs can contribute to the complexity of tissue architecture based on their level of differentiation and thereby, biology itself.
Collapse
Affiliation(s)
- Jean-Philippe Frimat
- Neuro-Nanoscale Engineering Group, Microsystems Section & ICMS Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
- Department of Neurosurgery, Maastricht University Medical Centre, School for Mental Health and Neuroscience, Eindhoven, Netherlands
| | - Regina Luttge
- Neuro-Nanoscale Engineering Group, Microsystems Section & ICMS Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands
| |
Collapse
|
9
|
Shi X, He W, Guo S, Zhang B, Ren S, Liu K, Sun T, Cui J. RNA-seq Analysis of the SCN1A-KO Model based on CRISPR/Cas9 Genome Editing Technology. Neuroscience 2018; 398:1-11. [PMID: 30529264 DOI: 10.1016/j.neuroscience.2018.11.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 01/14/2023]
Abstract
Dravet syndrome (DS) is a disease that is primarily caused by the inactivation of the SCN1A-encoded voltage-gated sodium channel alpha subunit (Nav1.1). In this study, we constructed an SCN1A gene knockout model using CRISPR/Cas9 genome editing technology to deprive the Nav1.1 function in vitro. With mRNA-seq analysis we found abundant gene changes after SCN1A knockout, which associated with various signaling pathways, such as cancer pathways, the PI3K-AKT signaling pathway, the MAPK signaling pathway, and pathways involved in HTLV-I infection. We also noticed changes in the spliceosome, decreased glycolytic capacity, disturbances in calcium signaling pathways, and changes in the potassium, sodium, chloride, and calcium plasma channels after SCN1A knockout. In this study, we have been the first time to discover these changes and summarize them here and hope it would provide some clue for the study of Nav1.1 in the nervous system.
Collapse
Affiliation(s)
- Xiaoguang Shi
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Wenxin He
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Shanshan Guo
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Bingying Zhang
- Department of Biochemistry and Molecular Biology, The School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China
| | - Shuanglai Ren
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Kunmei Liu
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Tao Sun
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Jianqi Cui
- The Ningxia Key Laboratory of Cerebrocranial Diseases, Incubation Base of the National Key Laboratory, Ningxia Medical University, Yinchuan, China; Department of Biochemistry and Molecular Biology, The School of Basic Medical Sciences, Ningxia Medical University, Yinchuan, China.
| |
Collapse
|
10
|
de Lange IM, Koudijs MJ, van ‘t Slot R, Sonsma ACM, Mulder F, Carbo EC, van Kempen MJA, Nijman IJ, Ernst RF, Savelberg SMC, Knoers NVAM, Brilstra EH, Koeleman BPC. Assessment of parental mosaicism in SCN1A-related epilepsy by single-molecule molecular inversion probes and next-generation sequencing. J Med Genet 2018; 56:75-80. [DOI: 10.1136/jmedgenet-2018-105672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/24/2018] [Accepted: 09/30/2018] [Indexed: 01/08/2023]
Abstract
BackgroundDravet syndrome is a severe genetic encephalopathy, caused by pathogenic variants in SCN1A. Low-grade parental mosaicism occurs in a substantial proportion of families (7%–13%) and has important implications for recurrence risks. However, parental mosaicism can remain undetected by methods regularly used in diagnostics. In this study, we use single-molecule molecular inversion probes (smMIP), a technique with high sensitivity for detecting low-grade mosaic variants and high cost-effectiveness, to investigate the incidence of parental mosaicism of SCN1A variants in a cohort of 90 families and assess the feasibility of this technique.MethodsDeep sequencing of SCN1A was performed using smMIPs. False positive rates for each of the proband’s pathogenic variants were determined in 145 unrelated samples. If parents showed corresponding variant alleles at a significantly higher rate than the established noise ratio, mosaicism was confirmed by droplet digital PCR (ddPCR).ResultsSequence coverage of at least 100× at the location of the corresponding pathogenic variant was reached for 80 parent couples. The variant ratio was significantly higher than the established noise ratio in eight parent couples, of which four (5%) were regarded as true mosaics, based on ddPCR results. The false positive rate of smMIP analysis without ddPCR was therefore 50%. Three of these variants had previously been considered de novo in the proband by Sanger sequencing.ConclusionsmMIP technology combined withnext generation sequencing (NGS) performs better than Sanger sequencing in the detection of parental mosaicism. Because parental mosaicism has important implications for genetic counselling and recurrence risks, we stress the importance of implementing high-sensitivity NGS-based assays in standard diagnostics.
Collapse
|
11
|
Myers KA, Johnstone DL, Dyment DA. Epilepsy genetics: Current knowledge, applications, and future directions. Clin Genet 2018; 95:95-111. [PMID: 29992546 DOI: 10.1111/cge.13414] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2018] [Revised: 07/03/2018] [Accepted: 07/06/2018] [Indexed: 12/12/2022]
Abstract
The rapid pace of disease gene discovery has resulted in tremendous advances in the field of epilepsy genetics. Clinical testing with comprehensive gene panels, exomes, and genomes are now available and have led to higher diagnostic rates and insights into the underlying disease processes. As such, the contribution to the care of patients by medical geneticists, neurogeneticists and genetic counselors are significant; the dysmorphic examination, the necessary pre- and post-test counseling, the selection of the appropriate next-generation sequencing-based test(s), and the interpretation of sequencing results require a care provider to have a comprehensive working knowledge of the strengths and limitations of the available testing technologies. As the underlying mechanisms of the encephalopathies and epilepsies are better understood, there may be opportunities for the development of novel therapies based on an individual's own specific genotype. Drug screening with in vitro and in vivo models of epilepsy can potentially facilitate new treatment strategies. The future of epilepsy genetics will also probably include other-omic approaches such as transcriptomes, metabolomes, and the expanded use of whole genome sequencing to further improve our understanding of epilepsy and provide better care for those with the disease.
Collapse
Affiliation(s)
- K A Myers
- Department of Pediatrics, University of McGill, Montreal, Canada.,Research Institute of the McGill University Health Centre, Montreal, Canada
| | - D L Johnstone
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - D A Dyment
- Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada.,Department of Genetics, Children's Hospital of Eastern Ontario, Ottawa, Canada
| |
Collapse
|
12
|
de Lange IM, Koudijs MJ, van 't Slot R, Gunning B, Sonsma ACM, van Gemert LJJM, Mulder F, Carbo EC, van Kempen MJA, Verbeek NE, Nijman IJ, Ernst RF, Savelberg SMC, Knoers NVAM, Brilstra EH, Koeleman BPC. Mosaicism of de novo pathogenic SCN1A
variants in epilepsy is a frequent phenomenon that correlates with variable phenotypes. Epilepsia 2018; 59:690-703. [DOI: 10.1111/epi.14021] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Iris M. de Lange
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Marco J. Koudijs
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Ruben van 't Slot
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | | | - Anja C. M. Sonsma
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | | | - Flip Mulder
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Ellen C. Carbo
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Marjan J. A. van Kempen
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Nienke E. Verbeek
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Isaac J. Nijman
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Robert F. Ernst
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Sanne M. C. Savelberg
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Nine V. A. M. Knoers
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Eva H. Brilstra
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| | - Bobby P. C. Koeleman
- Department of Genetics; Center for Molecular Medicine; University Medical Center Utrecht; Utrecht the Netherlands
| |
Collapse
|
13
|
Kissoon NR, Cutrer FM. Aura and Other Neurologic Dysfunction in or with Migraine. Headache 2017; 57:1179-1194. [DOI: 10.1111/head.13101] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Narayan R. Kissoon
- Division of Headache, Department of Neurology; Mayo Clinic; Rochester MN USA
| | - Fred Michael Cutrer
- Division of Headache, Department of Neurology; Mayo Clinic; Rochester MN USA
| |
Collapse
|
14
|
Sharkia R, Hengel H, Schöls L, Athamna M, Bauer P, Mahajnah M. Parental mosaicism in another case of Dravet syndrome caused by a novel SCN1A deletion: a case report. J Med Case Rep 2016; 10:67. [PMID: 27021235 PMCID: PMC4810572 DOI: 10.1186/s13256-016-0854-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 02/26/2016] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Dravet syndrome, a rare genetic disorder with early-onset epileptic encephalopathy, was first described by Dravet in 1978. Dravet syndrome is most frequently caused by various mutations of the SCN1A gene encoding the type 1 subunit of the neuronal voltage-gated sodium channel. CASE PRESENTATION Two sisters of a non-consanguineous Palestinian family from the Arab community in Israel attended our child development and pediatric neurology clinic due to recurrent seizures and developmental delay. Genomic DNA was extracted from peripheral blood lymphocytes of all family members and a SCN1A mutation in exon 10 was revealed by Sanger sequencing in both affected siblings but not in the parents. Our data present a case of Dravet syndrome caused by a novel heterozygous SCN1A deletion (c.1458_1465delCTCTAAGT) in two affected siblings. Our findings add to the spectrum of mutations known in the SCN1A gene and confirm parental mosaicism as a mechanism relevant for transmission of this disease. CONCLUSIONS These cases confirm parental mosaicism in the transmission of Dravet syndrome and add to the spectrum of known mutations of the SCN1A gene. Repeated reports on parental mosaicism should remind us that there is a risk of recurrence even if the mutation is apparently de novo.
Collapse
Affiliation(s)
- Rajech Sharkia
- />The Triangle Regional Research and Development Center, P. O. Box-2167, Kfar Qari’, 30075 Israel
- />Beit-Berl Academic College, Beit-Berl, 44905 Israel
| | - Holger Hengel
- />German Research Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
- />Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler Str. 3, 72076 Tübingen, Germany
| | - Ludger Schöls
- />German Research Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
- />Department of Neurodegenerative Diseases and Hertie-Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler Str. 3, 72076 Tübingen, Germany
| | - Muhammad Athamna
- />The Triangle Regional Research and Development Center, P. O. Box-2167, Kfar Qari’, 30075 Israel
| | - Peter Bauer
- />Institute of Medical Genetics and Applied Genomics, University of Tübingen, 72076 Tübingen, Germany
| | - Muhammad Mahajnah
- />Child Neurology and Development Center, Hillel-Yaffe Medical Center, 38100 Hadera, Israel
- />Bruce and Ruth Rappaprt Faculty of Medicine, Technion, 31096 Haifa Israel
| |
Collapse
|
15
|
Polypharmacology Shakes Hands with Complex Aetiopathology. Trends Pharmacol Sci 2015; 36:802-821. [PMID: 26434643 DOI: 10.1016/j.tips.2015.08.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 08/13/2015] [Accepted: 08/18/2015] [Indexed: 02/07/2023]
Abstract
Chronic diseases are due to deviations of fundamental physiological systems, with different pathologies being characterised by similar malfunctioning biological networks. The ensuing compensatory mechanisms may weaken the body's dynamic ability to respond to further insults and reduce the efficacy of conventional single target treatments. The multitarget, systemic, and prohomeostatic actions emerging for plant cannabinoids exemplify what might be needed for future medicines. Indeed, two combined cannabis extracts were approved as a single medicine (Sativex(®)), while pure cannabidiol, a multitarget cannabinoid, is emerging as a treatment for paediatric drug-resistant epilepsy. Using emerging cannabinoid medicines as an example, we revisit the concept of polypharmacology and describe a new empirical model, the 'therapeutic handshake', to predict efficacy/safety of compound combinations of either natural or synthetic origin.
Collapse
|
16
|
Xu X, Yang X, Wu Q, Liu A, Yang X, Ye AY, Huang AY, Li J, Wang M, Yu Z, Wang S, Zhang Z, Wu X, Wei L, Zhang Y. Amplicon Resequencing Identified Parental Mosaicism for Approximately 10% of "de novo" SCN1A Mutations in Children with Dravet Syndrome. Hum Mutat 2015; 36:861-72. [PMID: 26096185 PMCID: PMC5034833 DOI: 10.1002/humu.22819] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 05/28/2015] [Indexed: 12/13/2022]
Abstract
The majority of children with Dravet syndrome (DS) are caused by de novo SCN1A mutations. To investigate the origin of the mutations, we developed and applied a new method that combined deep amplicon resequencing with a Bayesian model to detect and quantify allelic fractions with improved sensitivity. Of 174 SCN1A mutations in DS probands which were considered "de novo" by Sanger sequencing, we identified 15 cases (8.6%) of parental mosaicism. We identified another five cases of parental mosaicism that were also detectable by Sanger sequencing. Fraction of mutant alleles in the 20 cases of parental mosaicism ranged from 1.1% to 32.6%. Thirteen (65% of 20) mutations originated paternally and seven (35% of 20) maternally. Twelve (60% of 20) mosaic parents did not have any epileptic symptoms. Their mutant allelic fractions were significantly lower than those in mosaic parents with epileptic symptoms (P = 0.016). We identified mosaicism with varied allelic fractions in blood, saliva, urine, hair follicle, oral epithelium, and semen, demonstrating that postzygotic mutations could affect multiple somatic cells as well as germ cells. Our results suggest that more sensitive tools for detecting low-level mosaicism in parents of families with seemingly "de novo" mutations will allow for better informed genetic counseling.
Collapse
Affiliation(s)
- Xiaojing Xu
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Xiaoxu Yang
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
| | - Qixi Wu
- National Institute of Biological SciencesBeijingChina
| | - Aijie Liu
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Xiaoling Yang
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Adam Yongxin Ye
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
- Peking‐Tsinghua Center for Life SciencesBeijingChina
- Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijingChina
| | | | - Jiarui Li
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
| | - Meng Wang
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
| | - Zhe Yu
- National Institute of Biological SciencesBeijingChina
| | - Sheng Wang
- National Institute of Biological SciencesBeijingChina
- College of Biological SciencesChina Agricultural UniversityBeijingChina
| | - Zhichao Zhang
- Andrology CenterPeking University First HospitalBeijingChina
| | - Xiru Wu
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Liping Wei
- Center for BioinformaticsState Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking UniversityBeijingChina
- National Institute of Biological SciencesBeijingChina
| | - Yuehua Zhang
- Department of PediatricsPeking University First HospitalBeijingChina
| |
Collapse
|
17
|
Meng H, Xu HQ, Yu L, Lin GW, He N, Su T, Shi YW, Li B, Wang J, Liu XR, Tang B, Long YS, Yi YH, Liao WP. TheSCN1AMutation Database: Updating Information and Analysis of the Relationships among Genotype, Functional Alteration, and Phenotype. Hum Mutat 2015; 36:573-80. [PMID: 25754450 DOI: 10.1002/humu.22782] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/25/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Heng Meng
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
- Department of Neurology; The First Affiliated Hospital of Jinan University; Guangzhou China
| | - Hai-Qing Xu
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Lu Yu
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Guo-Wang Lin
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Na He
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Tao Su
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Yi-Wu Shi
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Bin Li
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Jie Wang
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Xiao-Rong Liu
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Bin Tang
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Yue-Sheng Long
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Yong-Hong Yi
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| | - Wei-Ping Liao
- Institute of Neuroscience and The Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China; Guangzhou China
| |
Collapse
|
18
|
Simons C, Rash LD, Crawford J, Ma L, Cristofori-Armstrong B, Miller D, Ru K, Baillie GJ, Alanay Y, Jacquinet A, Debray FG, Verloes A, Shen J, Yesil G, Guler S, Yuksel A, Cleary JG, Grimmond SM, McGaughran J, King GF, Gabbett MT, Taft RJ. Mutations in the voltage-gated potassium channel gene KCNH1 cause Temple-Baraitser syndrome and epilepsy. Nat Genet 2014; 47:73-7. [PMID: 25420144 DOI: 10.1038/ng.3153] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 10/31/2014] [Indexed: 12/15/2022]
Abstract
Temple-Baraitser syndrome (TBS) is a multisystem developmental disorder characterized by intellectual disability, epilepsy, and hypoplasia or aplasia of the nails of the thumb and great toe. Here we report damaging de novo mutations in KCNH1 (encoding a protein called ether à go-go, EAG1 or KV10.1), a voltage-gated potassium channel that is predominantly expressed in the central nervous system (CNS), in six individuals with TBS. Characterization of the mutant channels in both Xenopus laevis oocytes and human HEK293T cells showed a decreased threshold of activation and delayed deactivation, demonstrating that TBS-associated KCNH1 mutations lead to deleterious gain of function. Consistent with this result, we find that two mothers of children with TBS, who have epilepsy but are otherwise healthy, are low-level (10% and 27%) mosaic carriers of pathogenic KCNH1 mutations. Consistent with recent reports, this finding demonstrates that the etiology of many unresolved CNS disorders, including epilepsies, might be explained by pathogenic mosaic mutations.
Collapse
Affiliation(s)
- Cas Simons
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Lachlan D Rash
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Joanna Crawford
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Linlin Ma
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Ben Cristofori-Armstrong
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - David Miller
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia. [2] Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Kelin Ru
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Gregory J Baillie
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Yasemin Alanay
- Pediatric Genetics, Department of Pediatrics, Acibadem University School of Medicine, Istanbul, Turkey
| | - Adeline Jacquinet
- Center for Human Genetics, Centre Hospitalier Universitaire and University of Liège, Liège, Belgium
| | | | - Alain Verloes
- 1] Department of Genetics, Assistance Publique des Hôpitaux de Paris (AP-HP), Robert Debré Hospital, Paris, France. [2] INSERM UMR 1141, Robert Debré Hospital, Paris, France
| | - Joseph Shen
- Medical Genetics and Metabolism, Children's Hospital Central California, Madera, California, USA
| | - Gözde Yesil
- Department of Medical Genetics, Bezmialem Vakif University School of Medicine, Istanbul, Turkey
| | - Serhat Guler
- Department of Medical Genetics, Bezmialem Vakif University School of Medicine, Istanbul, Turkey
| | - Adnan Yuksel
- Department of Medical Genetics, Bezmialem Vakif University School of Medicine, Istanbul, Turkey
| | | | - Sean M Grimmond
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia. [2] Wolfson Wohl Cancer Research Centre, Institute for Cancer Sciences, University of Glasgow, Glasgow, UK
| | - Julie McGaughran
- 1] Genetic Health Queensland, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia. [2] School of Medicine, The University of Queensland, Brisbane, Queensland, Australia
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Michael T Gabbett
- 1] Genetic Health Queensland, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia. [2] School of Medicine, Griffith University, Gold Coast, Queensland, Australia
| | - Ryan J Taft
- 1] Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia. [2] Department of Integrated Systems Biology, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA. [3] Department of Pediatrics, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA. [4] Illumina, Inc., San Diego, California, USA
| |
Collapse
|
19
|
Steinlein OK. Mechanisms underlying epilepsies associated with sodium channel mutations. PROGRESS IN BRAIN RESEARCH 2014; 213:97-111. [DOI: 10.1016/b978-0-444-63326-2.00005-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
20
|
Abstract
Voltage-gated sodium channels (VGSCs) are integral membrane proteins. They are essential for normal neurologic function and are, currently, the most common recognized cause of genetic epilepsy. This review summarizes the neurobiology of VGSCs, their association with different epilepsy syndromes, and the ways in which we can experimentally interrogate their function. The most important sodium channel subunit of relevance to epilepsy is SCN1A, in which over 650 genetic variants have been discovered. SCN1A mutations are associated with a variety of epilepsy syndromes; the more severe syndromes are associated with truncation or complete loss of function of the protein. SCN2A is another important subtype associated with epilepsy syndromes, across a range of severe and less severe epilepsies. This subtype is localized primarily to excitatory neurons, and mutations have a range of functional effects on the channel. SCN8A is the other main adult subtype found in the brain and has recently emerged as an epilepsy gene, with the first human mutation discovered in a severe epilepsy syndrome. Mutations in the accessory β subunits, thought to modulate trafficking and function of the α subunits, have also been associated with epilepsy. Genome sequencing is continuing to become more affordable, and as such, the amount of incoming genetic data is continuing to increase. Current experimental approaches have struggled to keep pace with functional analysis of these mutations, and it has proved difficult to build associations between disease severity and the precise effect on channel function. These mutations have been interrogated with a range of experimental approaches, from in vitro, in vivo, to in silico. In vitro techniques will prove useful to scan mutations on a larger scale, particularly with the advance of high-throughput automated patch-clamp techniques. In vivo models enable investigation of mutation in the context of whole brains with connected networks and more closely model the human condition. In silico models can help us incorporate the impact of multiple genetic factors and investigate epistatic interactions and beyond.
Collapse
Affiliation(s)
- Megan Oliva
- Florey Neuroscience Institutes, University of Melbourne, Melbourne, Victoria, Australia
| | | | | |
Collapse
|
21
|
Abstract
OBJECTIVES To assess delay in diagnosis and clinical characteristics of Dravet syndrome based on the Dravet register at The National Centre for Epilepsy in Norway. MATERIAL AND METHODS Medical records of patients diagnosed with Dravet syndrome since 2007 were analysed. RESULTS Twenty-two patients were identified. In 15, genetic screening disclosed mutations/deletions in the SCN1A gene. Average time from seizure onset to diagnosis was 7.4 years. Mean age at seizure onset was 6.7 months, nine had hemiconvulsions and 13 had generalized tonic-clonic seizures. The seizures were precipitated by fever in 17, by external heating in three. During second year of life, multiple seizure types and cognitive and motoric stagnation occurred. No patients became seizure-free with antiepileptic drugs. The effect of vagal nerve stimulation was disappointing. CONCLUSIONS By making an early diagnosis, an extensive presurgical evaluation may be avoided, and the patient and their parents may be offered genetic guidance.
Collapse
Affiliation(s)
- A Bremer
- Division of Surgery and Neuroscience, National Centre for Epilepsy, Oslo University Hospital, Norway.
| | | | | |
Collapse
|
22
|
Shi YW, Yu MJ, Long YS, Qin B, He N, Meng H, Liu XR, Deng WY, Gao MM, Yi YH, Li BM, Liao WP. Mosaic SCN1A mutations in familial partial epilepsy with antecedent febrile seizures. GENES BRAIN AND BEHAVIOR 2011; 11:170-6. [PMID: 22151702 DOI: 10.1111/j.1601-183x.2011.00756.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
SCN1A is the most relevant epilepsy gene. Mutations of SCN1A generate phenotypes ranging from the extremely severe form of Dravet syndrome (DS) to a mild form of generalized epilepsy with febrile seizures plus (GEFS+). Mosaic SCN1A mutations have been identified in rare familial DS. It is suspected that mosaic mutations of SCN1A may cause other types of familial epilepsies with febrile seizures (FS), which are more common clinically. Thus, we screened SCN1A mutations in 13 families with partial epilepsy with antecedent febrile seizures (PEFS+) using denaturing high-performance liquid chromatography and sequencing. The level of mosaicism was further quantified by pyrosequencing. Two missense SCN1A mutations with mosaic origin were identified in two unrelated families, accounting for 15.4% (2/13) of the PEFS+ families tested. One of the mosaic carriers with ~25.0% mutation of c.5768A>G/p.Q1923R had experienced simple FS; another with ~12.5% mutation of c.4847T>C/p.I1616T was asymptomatic. Their heterozygous children had PEFS+. Recurrent transmission occurred in both families, as noted in most of the families with germline mosaicism reported previously. The two mosaic mutations identified in this study are less destructive missense, compared with the more destructive truncating and splice-site mutations identified in the majority of previous studies. This is the first report of mosaic SCN1A mutations in families with probands that do not exhibit DS, but manifest only a milder phenotype. Therefore, such families with mild cases should be approached with caution in genetic counseling and the possibility of mosaicism origin associated with high recurrence risk should be excluded.
Collapse
Affiliation(s)
- Y-W Shi
- Institute of Neuroscience, The Second Affiliated Hospital of Guangzhou Medical University, Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangdong, China
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Abstract
Before the advent of molecular genetics, the nature of Dravet syndrome remained largely obscure, and arguments in favour of either an acquired origin, such as the occurrence of Dravet syndrome after vaccination, or an inherited origin, such as the occurrence of epilepsy in relatives, were formulated. In 2001 we demonstrated that the majority of Dravet patients have a genetic cause due to loss-of-function mutations in the SCN1A gene. Understandably, since this syndrome severely affects reproductive fitness, these mutations almost exclusively arise de novo, with the rare exceptions of mosaic mutations in a non-affected transmitting parent. Besides classical Sanger sequencing, mutation analysis of the SCN1A gene also requires a method that allows the detection of genomic rearrangements (MAQ, MLPA), since microdeletions or whole gene deletions also result in Dravet syndromes. Depending on the series reported and their recruitment strategies, the yield of SCN1A mutations detected varied from 50 to 80%, implying that other genes or factors must be involved in these 'SCN1A-negative Dravet patients'. Recently mutations in some other genes have been described in these genuine Dravet patients who do not carry an SCN1A mutation. The second most important Dravet-associated gene is PCDH19.These patients initially may have all characteristics of Dravet syndrome but may later run a somewhat different course.
Collapse
Affiliation(s)
- Peter De Jonghe
- Neurogenetic Group, VIB Department of Molecular Genetics, University of Antwerp, Belgium.
| |
Collapse
|
24
|
Nicita F, Spalice A, Papetti L, Ursitti F, Parisi P, Gennaro E, Zara F, Iannetti P. Genotype-phenotype correlations in a group of 15 SCN1A-mutated Italian patients with GEFS+ spectrum (seizures plus, classical and borderline severe myoclonic epilepsy of infancy). J Child Neurol 2010; 25:1369-76. [PMID: 20729507 DOI: 10.1177/0883073810365737] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mutations in SCN1A gene have been associated with the spectrum of generalized/genetic epilepsy with febrile seizures plus. Recently, databases reporting SCN1A mutations and clinical details of patients have been created to facilitate genotype- phenotype correlations, actually not completely defined, particularly if a specific mutation underlies phenotypes. We report on a group of 15 patients with clinical features of GEFS+ (3), classical (7), or borderline severe myoclonic epilepsy of infancy (5), in whom genetic analysis of patients and parents and follow-up period were performed to establish genotype-phenotype correlations, to enrich literature and databases data. We found 11 pathogenic mutations (5 novel: c.80 G>C exon 1; c.187 T>C exon 1; c.3061 G>T exon 16; c.4297 G>A exon 22; c.5579 delA ins TCTCC exon 26) and 4 novel nucleotidic variants (IVS5+38 C>T intron 5; IVS8-19 C>T intron 18; c.4945 C>T exon 25; c.5127 C>A exon 26). Paternal inheritance was observed in 4/4 cases.
Collapse
Affiliation(s)
- Francesco Nicita
- Child Neurology, Paediatric Department, I Faculty of Medicine, Sapienza University c/o Policlinico Umberto I, Rome, Italy
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Vadlamudi L, Dibbens LM, Lawrence KM, Iona X, McMahon JM, Murrell W, Mackay-Sim A, Scheffer IE, Berkovic SF. Timing of de novo mutagenesis--a twin study of sodium-channel mutations. N Engl J Med 2010; 363:1335-40. [PMID: 20879882 DOI: 10.1056/nejmoa0910752] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
De novo mutations are a cause of sporadic disease, but little is known about the developmental timing of such mutations. We studied concordant and discordant monozygous twins with de novo mutations in the sodium channel α1 subunit gene (SCN1A) causing Dravet's syndrome, a severe epileptic encephalopathy. On the basis of our findings and the literature on mosaic cases, we conclude that de novo mutations in SCN1A may occur at any time, from the premorula stage of the embryo (causing disease in the subject) to adulthood (with mutations in the germ-line cells of parents causing disease in offspring).
Collapse
Affiliation(s)
- Lata Vadlamudi
- Epilepsy Research Center, Austin Health, University of Melbourne, Melbourne, VIC, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|