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Elhawary NA, AlJahdali IA, Abumansour IS, Azher ZA, Falemban AH, Madani WM, Alosaimi W, Alghamdi G, Sindi IA. Phenotypic variability to medication management: an update on fragile X syndrome. Hum Genomics 2023; 17:60. [PMID: 37420260 DOI: 10.1186/s40246-023-00507-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 07/03/2023] [Indexed: 07/09/2023] Open
Abstract
This review discusses the discovery, epidemiology, pathophysiology, genetic etiology, molecular diagnosis, and medication-based management of fragile X syndrome (FXS). It also highlights the syndrome's variable expressivity and common comorbid and overlapping conditions. FXS is an X-linked dominant disorder associated with a wide spectrum of clinical features, including but not limited to intellectual disability, autism spectrum disorder, language deficits, macroorchidism, seizures, and anxiety. Its prevalence in the general population is approximately 1 in 5000-7000 men and 1 in 4000-6000 women worldwide. FXS is associated with the fragile X messenger ribonucleoprotein 1 (FMR1) gene located at locus Xq27.3 and encodes the fragile X messenger ribonucleoprotein (FMRP). Most individuals with FXS have an FMR1 allele with > 200 CGG repeats (full mutation) and hypermethylation of the CpG island proximal to the repeats, which silences the gene's promoter. Some individuals have mosaicism in the size of the CGG repeats or in hypermethylation of the CpG island, both produce some FMRP and give rise to milder cognitive and behavioral deficits than in non-mosaic individuals with FXS. As in several monogenic disorders, modifier genes influence the penetrance of FMR1 mutations and FXS's variable expressivity by regulating the pathophysiological mechanisms related to the syndrome's behavioral features. Although there is no cure for FXS, prenatal molecular diagnostic testing is recommended to facilitate early diagnosis. Pharmacologic agents can reduce some behavioral features of FXS, and researchers are investigating whether gene editing can be used to demethylate the FMR1 promoter region to improve patient outcomes. Moreover, clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 and developed nuclease defective Cas9 (dCas9) strategies have promised options of genome editing in gain-of-function mutations to rewrite new genetic information into a specified DNA site, are also being studied.
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Affiliation(s)
- Nasser A Elhawary
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia.
| | - Imad A AlJahdali
- Department of Community Medicine, College of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Iman S Abumansour
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Zohor A Azher
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Alaa H Falemban
- Department of Pharmacology and Toxicology, College of Medicine, Umm Al-Qura University, Mecca, 24382, Saudi Arabia
| | - Wefaq M Madani
- Department of Hematology and Immunology, Faculty of Medicine, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Ghydda Alghamdi
- Department of Medical Genetics, College of Medicine, Umm Al-Qura University, Mecca, 21955, Saudi Arabia
| | - Ikhlas A Sindi
- Department of Biology, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
- Preparatory Year Program, Batterjee Medical College, Jeddah, 21442, Saudi Arabia
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Talvio K, Minkeviciene R, Townsley KG, Achuta VS, Huckins LM, Corcoran P, Brennand KJ, Castrén ML. Reduced LYNX1 expression in transcriptome of human iPSC-derived neural progenitors modeling fragile X syndrome. Front Cell Dev Biol 2022; 10:1034679. [PMID: 36506088 PMCID: PMC9731341 DOI: 10.3389/fcell.2022.1034679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/04/2022] [Indexed: 11/22/2022] Open
Abstract
Lack of FMR1 protein results in fragile X syndrome (FXS), which is the most common inherited intellectual disability syndrome and serves as an excellent model disease to study molecular mechanisms resulting in neuropsychiatric comorbidities. We compared the transcriptomes of human neural progenitors (NPCs) generated from patient-derived induced pluripotent stem cells (iPSCs) of three FXS and three control male donors. Altered expression of RAD51C, PPIL3, GUCY1A2, MYD88, TRAPPC4, LYNX1, and GTF2A1L in FXS NPCs suggested changes related to triplet repeat instability, RNA splicing, testes development, and pathways previously shown to be affected in FXS. LYNX1 is a cholinergic brake of tissue plasminogen activator (tPA)-dependent plasticity, and its reduced expression was consistent with augmented tPA-dependent radial glial process growth in NPCs derived from FXS iPSC lines. There was evidence of human iPSC line donor-dependent variation reflecting potentially phenotypic variation. NPCs derived from an FXS male with concomitant epilepsy expressed differently several epilepsy-related genes, including genes shown to cause the auditory epilepsy phenotype in the murine model of FXS. Functional enrichment analysis highlighted regulation of insulin-like growth factor pathway in NPCs modeling FXS with epilepsy. Our results demonstrated potential of human iPSCs in disease modeling for discovery and development of therapeutic interventions by showing early gene expression changes in FXS iPSC-derived NPCs consistent with the known pathophysiological changes in FXS and by revealing disturbed FXS progenitor growth linked to reduced expression of LYNX1, suggesting dysregulated cholinergic system.
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Affiliation(s)
- Karo Talvio
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Rimante Minkeviciene
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Kayla G. Townsley
- Pamela Sklar Division of Psychiatric Genomics, Department of Genetics and Genomics, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, United States,Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States,Graduate School of Biomedical Science, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | | | - Laura M. Huckins
- Pamela Sklar Division of Psychiatric Genomics, Department of Genetics and Genomics, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, United States,Division of Molecular Psychiatry, Department of Psychiatry, Yale University, New Haven, CT, United States
| | - Padraic Corcoran
- Array and Analysis Facility, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Kristen J. Brennand
- Pamela Sklar Division of Psychiatric Genomics, Department of Genetics and Genomics, Icahn Institute of Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY, United States,Nash Family Department of Neuroscience, Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States,Division of Molecular Psychiatry, Department of Psychiatry, Yale University, New Haven, CT, United States,Department of Genetics, Yale University, New Haven, CT, United States
| | - Maija L. Castrén
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland,*Correspondence: Maija L. Castrén,
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Peteri UK, Pitkonen J, de Toma I, Nieminen O, Utami KH, Strandin TM, Corcoran P, Roybon L, Vaheri A, Ethell I, Casarotto P, Pouladi MA, Castrén ML. Urokinase plasminogen activator mediates changes in human astrocytes modeling fragile X syndrome. Glia 2021; 69:2947-2962. [PMID: 34427356 DOI: 10.1002/glia.24080] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 12/25/2022]
Abstract
The function of astrocytes intertwines with the extracellular matrix, whose neuron and glial cell-derived components shape neuronal plasticity. Astrocyte abnormalities have been reported in the brain of the mouse model for fragile X syndrome (FXS), the most common cause of inherited intellectual disability, and a monogenic cause of autism spectrum disorder. We compared human FXS and control astrocytes generated from human induced pluripotent stem cells and we found increased expression of urokinase plasminogen activator (uPA), which modulates degradation of extracellular matrix. Several pathways associated with uPA and its receptor function were activated in FXS astrocytes. Levels of uPA were also increased in conditioned medium collected from FXS hiPSC-derived astrocyte cultures and correlated inversely with intracellular Ca2+ responses to activation of L-type voltage-gated calcium channels in human astrocytes. Increased uPA augmented neuronal phosphorylation of TrkB within the docking site for the phospholipase-Cγ1 (PLCγ1), indicating effects of uPA on neuronal plasticity. Gene expression changes during neuronal differentiation preceding astrogenesis likely contributed to properties of astrocytes with FXS-specific alterations that showed specificity by not affecting differentiation of adenosine triphosphate (ATP)-responsive astrocyte population. To conclude, our studies identified uPA as an important regulator of astrocyte function and demonstrated that increased uPA in human FXS astrocytes modulated astrocytic responses and neuronal plasticity.
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Affiliation(s)
- Ulla-Kaisa Peteri
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Juho Pitkonen
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Ilario de Toma
- Systems Neurobiology Laboratory, Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Otso Nieminen
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Kagistia Hana Utami
- Department of Physiology, National University of Singapore (NUS), Singapore, Singapore
| | - Tomas M Strandin
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Padraic Corcoran
- Array and Analysis Facility, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Laurent Roybon
- iPSC Laboratory for CNS Disease Modeling, Department of Experimental Medical Science, BMC D10, and MultiPark and the Lund Stem Cell Center, Lund University, Lund, Sweden
| | - Antti Vaheri
- Department of Virology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Iryna Ethell
- Biomedical Sciences, University of California Riverside School of Medicine, Riverside, California, USA
| | | | - Mahmoud A Pouladi
- Department of Physiology, National University of Singapore (NUS), Singapore, Singapore.,British Columbia Children's Hospital Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maija L Castrén
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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Payán-Gómez C, Ramirez-Cheyne J, Saldarriaga W. Variable Expressivity in Fragile X Syndrome: Towards the Identification of Molecular Characteristics That Modify the Phenotype. Appl Clin Genet 2021; 14:305-312. [PMID: 34262328 PMCID: PMC8273740 DOI: 10.2147/tacg.s265835] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 06/21/2021] [Indexed: 12/18/2022] Open
Abstract
Fragile X syndrome (FXS), is an X-linked inherited genetic disease. FXS is the leading cause of inherited intellectual disability and autism in the world. Those affected are characterized by intellectual disability, language deficit, typical facies, and macroorchidism. Alterations in the FMR1 gene have been associated with FXS. The majority of people with this condition have an allele with an expansion of more than 200 repeats in a tract of CGGs within the 5' untranslated region, and this expansion is associated with a hypermethylated state of the gene promoter. FXS has incomplete penetrance and variable expressivity. Intellectual disability is present in 100% of males and 60% of females. Autism spectrum disorder symptoms appear in 50% to 60% of males and 20% of females. Other characteristics such as behavioral and physical alterations have significant variations in presentation frequency. The molecular causes of the variable phenotype in FXS patients are becoming clear: these causes are related to the FMR1 gene itself and to secondary, modifying gene effects. In FXS patients, size and methylation mosaicisms are common. Secondary to mosaicism, there is a variation in the quantity of FMR1 mRNA and the protein coded by the gene Fragile Mental Retardation Protein (FMRP). Potential modifier genes have also been proposed, with conflicting results. Characterizing patients according to CGG expansion, methylation status, concentration of mRNA and FMRP, and genotypification for possible modifier genes in a clinical setting offers an opportunity to identify predictors for treatment response evaluation. When intervention strategies become available to modulate the course of the disease they could be crucial for selecting patients and identifying the best therapeutic intervention. The purpose of this review is to present the information available about the molecular causes of the variability of the expression incomplete penetrance and variable expressivity in FXS and their potential clinical applications.
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Affiliation(s)
- César Payán-Gómez
- Deparment of Biology, Faculty of Natural Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Julian Ramirez-Cheyne
- Health Faculty, Universidad del Valle, Cali, Colombia
- Hospital Universitario del Valle, Cali, Colombia
| | - Wilmar Saldarriaga
- Health Faculty, Universidad del Valle, Cali, Colombia
- Hospital Universitario del Valle, Cali, Colombia
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Genotype-expression interactions for BDNF across human brain regions. BMC Genomics 2021; 22:207. [PMID: 33757426 PMCID: PMC7989003 DOI: 10.1186/s12864-021-07525-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 03/11/2021] [Indexed: 01/20/2023] Open
Abstract
Background Genetic variations in brain-derived neurotrophic factor (BDNF) are associated with various psychiatric disorders including depression, obsessive-compulsive disorder, substance use disorders, and schizophrenia; altered gene expression triggered by these genetic variants may serve to create these phenotypes. But genotype-expression interactions for this gene have not been well-studied across brain regions relevant for psychiatric disorders. Results At false discovery rate (FDR) of 10% (q < 0.1), a total of 61 SNPs were associated with BDNF expression in cerebellum (n = 209), 55 SNPs in cortex (n = 205), 48 SNPs in nucleus accumbens (n = 202), 47 SNPs in caudate (n = 194), and 58 SNPs in cerebellar hemisphere (n = 175). We identified a set of 30 SNPs in 2 haplotype blocks that were associated with alterations in expression for each of these 5 regions. The first haplotype block included variants associated in the literature with panic disorders (rs16917204), addiction (rs11030104), bipolar disorder (rs16917237/rs2049045), and obsessive-compulsive disorder (rs6265). Likewise, variants in the second haplotype block have been previously associated with disorders such as nicotine addiction, major depressive disorder (rs988748), and epilepsy (rs6484320/rs7103411). Conclusions This work supports the association of variants within BDNF for expression changes in these key brain regions that may contribute to common behavioral phenotypes for disorders of compulsion, impulsivity, and addiction. These SNPs should be further investigated as possible therapeutic and diagnostic targets to aid in management of these and other psychiatric disorders. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07525-1.
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Ivanov R, Zamyatin V, Klimenko A, Matushkin Y, Savostyanov A, Lashin S. Reconstruction and Analysis of Gene Networks of Human Neurotransmitter Systems Reveal Genes with Contentious Manifestation for Anxiety, Depression, and Intellectual Disabilities. Genes (Basel) 2019; 10:genes10090699. [PMID: 31514272 PMCID: PMC6770977 DOI: 10.3390/genes10090699] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/06/2019] [Accepted: 09/09/2019] [Indexed: 12/28/2022] Open
Abstract
Background: The study of the biological basis of anxiety, depression, and intellectual disabilities in humans is one of the most actual problems of modern neurophysiology. Of particular interest is the study of complex interactions between molecular genetic factors, electrophysiological properties of the nervous system, and the behavioral characteristics of people. The neurobiological understanding of neuropsychiatric disorders requires not only the identification of genes that play a role in the molecular mechanisms of the occurrence and course of diseases, but also the understanding of complex interactions that occur between these genes. A systematic study of such interactions obviously contributes to the development of new methods of diagnosis, prevention, and treatment of disorders, as the orientation to allele variants of individual loci is not reliable enough, because the literature describes a number of genes, the same alleles of which can be associated with different, sometimes extremely different variants of phenotypic traits, depending on the genetic background, of their carriers, habitat, and other factors. Results: In our study, we have reconstructed a series of gene networks (in the form of protein–protein interactions networks, as well as networks of transcription regulation) to build a model of the influence of complex interactions of environmental factors and genetic risk factors for intellectual disability, depression, and other disorders in human behavior. Conclusion: A list of candidate genes whose expression is presumably associated with environmental factors and has potentially contentious manifestation for behavioral and neurological traits is identified for further experimental verification.
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Affiliation(s)
- Roman Ivanov
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Vladimir Zamyatin
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Aleksandra Klimenko
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Yury Matushkin
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
| | - Alexander Savostyanov
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
- Institute of Physiology and Basic Medicine SB RAMS, 630117 Novosibirsk, Russia.
| | - Sergey Lashin
- Institute of Cytology and Genetics SB RAS, 630090 Novosibirsk, Russia.
- Novosibirsk State University, 630090 Novosibirsk, Russia.
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Zafarullah M, Tassone F. Molecular Biomarkers in Fragile X Syndrome. Brain Sci 2019; 9:E96. [PMID: 31035599 PMCID: PMC6562871 DOI: 10.3390/brainsci9050096] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/22/2019] [Accepted: 04/24/2019] [Indexed: 01/01/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common inherited form of intellectual disability (ID) and a known monogenic cause of autism spectrum disorder (ASD). It is a trinucleotide repeat disorder, in which more than 200 CGG repeats in the 5' untranslated region (UTR) of the fragile X mental retardation 1 (FMR1) gene causes methylation of the promoter with consequent silencing of the gene, ultimately leading to the loss of the encoded fragile X mental retardation 1 protein, FMRP. FMRP is an RNA binding protein that plays a primary role as a repressor of translation of various mRNAs, many of which are involved in the maintenance and development of neuronal synaptic function and plasticity. In addition to intellectual disability, patients with FXS face several behavioral challenges, including anxiety, hyperactivity, seizures, repetitive behavior, and problems with executive and language performance. Currently, there is no cure or approved medication for the treatment of the underlying causes of FXS, but in the past few years, our knowledge about the proteins and pathways that are dysregulated by the loss of FMRP has increased, leading to clinical trials and to the path of developing molecular biomarkers for identifying potential targets for therapies. In this paper, we review candidate molecular biomarkers that have been identified in preclinical studies in the FXS mouse animal model and are now under validation for human applications or have already made their way to clinical trials.
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Affiliation(s)
- Marwa Zafarullah
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, Sacramento, 95817 CA, USA.
| | - Flora Tassone
- Department of Biochemistry and Molecular Medicine, University of California Davis, School of Medicine, Sacramento, 95817 CA, USA.
- MIND Institute, University of California Davis Medical Center, Sacramento, 95817 CA, USA.
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Danesi C, Keinänen K, Castrén ML. Dysregulated Ca 2+-Permeable AMPA Receptor Signaling in Neural Progenitors Modeling Fragile X Syndrome. Front Synaptic Neurosci 2019; 11:2. [PMID: 30800064 PMCID: PMC6375879 DOI: 10.3389/fnsyn.2019.00002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 01/23/2019] [Indexed: 12/11/2022] Open
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder that represents a common cause of intellectual disability and is a variant of autism spectrum disorder (ASD). Studies that have searched for similarities in syndromic and non-syndromic forms of ASD have paid special attention to alterations of maturation and function of glutamatergic synapses. Copy number variations (CNVs) in the loci containing genes encoding alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs) subunits are associated with ASD in genetic studies. In FXS, dysregulated AMPAR subunit expression and trafficking affect neural progenitor differentiation and synapse formation and neuronal plasticity in the mature brain. Decreased expression of GluA2, the AMPAR subunit that critically controls Ca2+-permeability, and a concomitant increase in Ca2+-permeable AMPARs (CP-AMPARs) in human and mouse FXS neural progenitors parallels changes in expression of GluA2-targeting microRNAs (miRNAs). Thus, posttranscriptional regulation of GluA2 by miRNAs and subsequent alterations in calcium signaling may contribute to abnormal synaptic function in FXS and, by implication, in some forms of ASD.
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Affiliation(s)
- Claudia Danesi
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Kari Keinänen
- Research Program in Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Maija L Castrén
- Department of Physiology, Faculty of Medicine, University of Helsinki, Helsinki, Finland
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Torres CM, Siebert M, Bock H, Mota SM, Krammer BR, Duarte JÁ, Bragatti JA, Castan JU, de Castro LA, Saraiva-Pereira ML, Bianchin MM. NTRK2 (TrkB gene) variants and temporal lobe epilepsy: A genetic association study. Epilepsy Res 2017; 137:1-8. [PMID: 28863320 DOI: 10.1016/j.eplepsyres.2017.08.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 08/14/2017] [Accepted: 08/19/2017] [Indexed: 12/12/2022]
Abstract
OBJECTIVE The NTRK2 gene encodes a member of the neurotrophic tyrosine kinase receptor family known as TrkB. It is a membrane-associated receptor with signaling and cellular differentiation properties that has been involved in neuropsychiatric disorders, including epilepsy. We report here the frequencies of NTRK2 allele variants in patients with temporal lobe epilepsy (TLE) compared to controls without epilepsy and explore the impact of these polymorphisms on major clinical variables in TLE. METHODS A case-control study comparing the frequencies of the NTRK2 gene polymorphisms beween 198 TLE Caucasian patients and 200 matching controls without epilepsy. In a second step, the impact of allelic variation on major clinical and electroencephalographic epilepsy variables was evaluated in the group of TLE patients. The following polymorphisms were determined by testing different regions of the NTRK2 gene: rs1867283, rs10868235, rs1147198, rs11140800, rs1187286, rs2289656, rs1624327, rs1443445, rs3780645, and rs2378672. To correct for multiple correlations the level of significance was set at p<0.01. RESULTS Patients with TLE showed a statistical trend for increase of the T/T genotype in rs10868235 compared to control (O.R.=1.90; 95%CI=1.17-3.09; p=0.01). Homozygous patients for the A allele in rs1443445 had earlier mean age at onset of seizures, p=0.009 (mean age of 16.6 versus 22.4years). We also observed that the T allele in rs3780645 was more frequent in patients who needed polytheraphy for seizure control than in patients on monotherapy, (O.R.=4.13; 95%CI=1.68-10.29; p=0.001). This finding may reflect an increased difficulty to obtain seizure control in this group of patients. No additional differences were observed in this study. CONCLUSIONS Patients with epilepsy showed a trend for a difference in rs10868235 allelic distribution compared to controls without epilepsy. NTRK2 variability influenced age at seizure onset and the pharmacological response to seizure control. As far as we know, this is the first study showing an association between NTKR2 allelic variants in human epilepsy. We believe that further studies in this venue will shade some light on the molecular mechanisms involved in epileptogenesis and in the clinical characteristics of epilepsy.
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Affiliation(s)
- Carolina Machado Torres
- Graduate Program in Medical Science, Universidade Federal do Rio Grande do Sul, Brazil; Basic Research and Advanced Investigations in Neurology (BRAIN), Experimental Research Centre, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Tratamento de Epilepsia Refratária (CETER), Hospital de Clínicas de Porto Alegre, Brazil; Division of Neurology, Hospital de Clínicas de Porto Alegre, Brazil
| | - Marina Siebert
- Laboratory of Genetic Identification, Experimental Research Centre, Hospital de Clinicas de Porto Alegre, Brazil
| | - Hugo Bock
- Laboratory of Genetic Identification, Experimental Research Centre, Hospital de Clinicas de Porto Alegre, Brazil
| | - Suelen Mandelli Mota
- Basic Research and Advanced Investigations in Neurology (BRAIN), Experimental Research Centre, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil
| | - Bárbara Reis Krammer
- Basic Research and Advanced Investigations in Neurology (BRAIN), Experimental Research Centre, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil
| | - Juliana Ávila Duarte
- Graduate Program in Medical Science, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Tratamento de Epilepsia Refratária (CETER), Hospital de Clínicas de Porto Alegre, Brazil
| | - José Augusto Bragatti
- Centro de Tratamento de Epilepsia Refratária (CETER), Hospital de Clínicas de Porto Alegre, Brazil; Division of Neurology, Hospital de Clínicas de Porto Alegre, Brazil
| | - Juliana Unis Castan
- Centro de Tratamento de Epilepsia Refratária (CETER), Hospital de Clínicas de Porto Alegre, Brazil; Division of Neurology, Hospital de Clínicas de Porto Alegre, Brazil
| | - Luiza Amaral de Castro
- Graduate Program in Medical Science, Universidade Federal do Rio Grande do Sul, Brazil; Basic Research and Advanced Investigations in Neurology (BRAIN), Experimental Research Centre, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil
| | - Maria Luiza Saraiva-Pereira
- Graduate Program in Medical Science, Universidade Federal do Rio Grande do Sul, Brazil; Basic Research and Advanced Investigations in Neurology (BRAIN), Experimental Research Centre, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil; Laboratory of Genetic Identification, Experimental Research Centre, Hospital de Clinicas de Porto Alegre, Brazil
| | - Marino Muxfeldt Bianchin
- Graduate Program in Medical Science, Universidade Federal do Rio Grande do Sul, Brazil; Basic Research and Advanced Investigations in Neurology (BRAIN), Experimental Research Centre, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Brazil; Centro de Tratamento de Epilepsia Refratária (CETER), Hospital de Clínicas de Porto Alegre, Brazil; Division of Neurology, Hospital de Clínicas de Porto Alegre, Brazil.
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Cowley B, Kirjanen S, Partanen J, Castrén ML. Epileptic Electroencephalography Profile Associates with Attention Problems in Children with Fragile X Syndrome: Review and Case Series. Front Hum Neurosci 2016; 10:353. [PMID: 27462212 PMCID: PMC4941803 DOI: 10.3389/fnhum.2016.00353] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 06/28/2016] [Indexed: 01/18/2023] Open
Abstract
Fragile X syndrome (FXS) is the most common cause of inherited intellectual disability and a variant of autism spectrum disorder (ASD). The FXS population is quite heterogeneous with respect to comorbidities, which implies the need for a personalized medicine approach, relying on biomarkers or endophenotypes to guide treatment. There is evidence that quantitative electroencephalography (EEG) endophenotype-guided treatments can support increased clinical benefit by considering the patient's neurophysiological profile. We describe a case series of 11 children diagnosed with FXS, aged one to 14 years, mean 4.6 years. Case data are based on longitudinal clinically-observed reports by attending physicians for comorbid symptoms including awake and asleep EEG profiles. We tabulate the comorbid EEG symptoms in this case series, and relate them to the literature on EEG endophenotypes and associated treatment options. The two most common endophenotypes in the data were diffuse slow oscillations and epileptiform EEG, which have been associated with attention and epilepsy respectively. This observation agrees with reported prevalence of comorbid behavioral symptoms for FXS. In this sample of FXS children, attention problems were found in 37% (4 of 11), and epileptic seizures in 45% (5 of 11). Attention problems were found to associate with the epilepsy endophenotype. From the synthesis of this case series and literature review, we argue that the evidence-based personalized treatment approach, exemplified by neurofeedback, could benefit FXS children by focusing on observable, specific characteristics of comorbid disease symptoms.
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Affiliation(s)
- Benjamin Cowley
- Brain Work Research Centre, Finnish Institute of Occupational HealthHelsinki, Finland; Cognitive Brain Research Unit, Cognitive Science, Institute of Behavioral Sciences, University of HelsinkiHelsinki, Finland
| | | | - Juhani Partanen
- Department of Clinical Neurophysiology, University Hospital of Helsinki Helsinki, Finland
| | - Maija L Castrén
- Faculty of Medicine, Physiology, University of HelsinkiHelsinki, Finland; Autism Foundation in FinlandHelsinki, Finland
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Shen N, Zhu X, Lin H, Li J, Li L, Niu F, Liu A, Wu X, Wang Y, Liu Y. Role of BDNF Val66Met functional polymorphism in temporal lobe epilepsy. Int J Neurosci 2015; 126:436-41. [DOI: 10.3109/00207454.2015.1026967] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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12
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Arvio M. Fragile-X syndrome - a 20-year follow-up study of male patients. Clin Genet 2015; 89:55-9. [DOI: 10.1111/cge.12639] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 06/16/2015] [Accepted: 07/06/2015] [Indexed: 11/27/2022]
Affiliation(s)
- M. Arvio
- Department of Neurology; Päijät-Häme Joint Municipal Authority; Lahti Finland
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13
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Makkonen I, Riikonen R, Kuikka JT, Kokki H, Bressler JP, Marshall C, Kaufmann WE. Brain derived neurotrophic factor and serotonin transporter binding as markers of clinical response to fluoxetine therapy in children with autism. JOURNAL OF PEDIATRIC NEUROLOGY 2015; 9:1-8. [PMID: 29056860 DOI: 10.3233/jpn-2010-0446] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), has shown favorable effects in some children with autism. There are no previous studies evaluating the connection between clinical outcome and markers of clinical response to fluoxetine treatment. We examined serum brain derived neurotrophic factor (BDNF) concentrations and serotonin transporter (SERT) binding in the medial frontal cortex and midbrain, measured by single photon emission computed tomography (SPECT) scanning, in a group of 13 autistic children and adolescents (12 males, one female; age 5-16 years), who were treated for six months with fluoxetine at a dose range of 10-40 mg/day. Clinical response was evaluated by the Autism Treatment Evaluation Checklist (ATEC). Serum concentrations of BDNF and SERT binding were measured at baseline and two months after termination of fluoxetine treatment. At baseline, before starting fluoxetine treatment, the serum concentration of BDNF had a bimodal distribution in the autism group with either a low concentration (n = 8, mean 1497 pg/mL) or a high concentration (n = 5, mean 14062 pg/mL) with respect to controls (n = 15, mean 9652 pg/mL), and SERT binding was uniformly low in the autistic subjects in medial frontal cortex and midbrain. Fluoxetine treatment led to positive effects in several aspects of communication, socialization and cognitive awareness, with 6 out 13 subjects being particularly good responders. These six also had a significant decrease in BDNF (p = 0.03) and minimal change in SERT binding after therapy. The other 7 subjects showed a trend towards an increase in BDNF and SERT binding. Our results indicate that fluoxetine may improve core autistic symptoms, and that this clinical response is linked to a decrease in serum BDNF.
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Affiliation(s)
- Ismo Makkonen
- Department of Pediatrics, Unit of Child Neurology, Kuopio University Hospital, Kuopio, Finland;
| | - Raili Riikonen
- Department of Pediatrics, Unit of Child Neurology, Kuopio University Hospital, Kuopio, Finland;
| | - Jyrki T Kuikka
- Imaging Center, Kuopio University Hospital, and Niuvanniemi Hospital, Kuopio, Finland;
| | - Hannu Kokki
- Department of Anesthesiology and Intensive Care, Kuopio University Hospital, Kuopio, Finland;
| | - Joseph P Bressler
- Center for Genetic Disorders of Cognition & Behavior, Kennedy Krieger Institute and the Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America;
| | - Cathleen Marshall
- Center for Genetic Disorders of Cognition & Behavior, Kennedy Krieger Institute and the Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America;
| | - Walter E Kaufmann
- Center for Genetic Disorders of Cognition & Behavior, Kennedy Krieger Institute and the Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America;
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Kidd SA, Lachiewicz A, Barbouth D, Blitz RK, Delahunty C, McBrien D, Visootsak J, Berry-Kravis E. Fragile X syndrome: a review of associated medical problems. Pediatrics 2014; 134:995-1005. [PMID: 25287458 DOI: 10.1542/peds.2013-4301] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common known genetic cause of inherited intellectual disability and the most common known single-gene cause of autism spectrum disorder. It has been reported that a spectrum of medical problems are commonly experienced by people with FXS, such as otitis media, seizures, and gastrointestinal problems. Previous studies examining the prevalence of medical problems related to FXS have been challenging to interpret because of their marked differences in population, setting, and sampling. Through this comprehensive review, we update the literature by reviewing studies that have reported on prominent medical problems associated with FXS. We then compare prevalence results from those studies with results from a large cross-sectional database consisting of data collected by fragile X clinics that specialize in the care of children with FXS and are part of the Fragile X Clinical and Research Consortium. It is vital for pediatricians and other clinicians to be familiar with the medical problems related to FXS so that affected patients may receive proper diagnosis and treatment; improved care may lead to better quality of life for these patients and their families.
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Affiliation(s)
- Sharon A Kidd
- National Fragile X Foundation, Walnut Creek, California;
| | - Ave Lachiewicz
- Departments of Pediatrics, Psychiatry, and Behavioral Sciences, Duke University Medical Center, Durham, North Carolina
| | - Deborah Barbouth
- Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida
| | - Robin K Blitz
- Developmental Pediatrics, Barrow Neurologic Institute at Phoenix Children's Hospital, Phoenix, Arizona; Department of Pediatrics, University of Arizona College of Medicine, Phoenix, Arizona
| | - Carol Delahunty
- Department of Developmental and Rehabilitation Pediatrics, Cleveland Clinic, Cleveland, Ohio
| | - Dianne McBrien
- Department of Pediatrics, University of Iowa Medical Center, Iowa City, Iowa
| | - Jeannie Visootsak
- Departments of Human Genetics, and Pediatrics, Emory University, Atlanta, Georgia; and
| | - Elizabeth Berry-Kravis
- Departments of Pediatrics, Neurologic Sciences, and Biochemistry, Rush University Medical Center, Chicago, Illinois
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Gkampeta A, Fidani L, Clarimón J, Kalinderi K, Katopodi T, Zafeiriou D, Pavlou E. Association of brain-derived neurotrophic factor (BDNF) and elongator protein complex 4 (ELP4) polymorphisms with benign epilepsy with centrotemporal spikes in a Greek population. Epilepsy Res 2014; 108:1734-9. [PMID: 25301525 DOI: 10.1016/j.eplepsyres.2014.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/02/2014] [Accepted: 09/02/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE Benign epilepsy with centrotemporal spikes (BECTS) is considered to be the most common childhood epileptic syndrome. Different mutations in genes that control the excitability of neurons have been described. Recent reports on the involvement of the BDNF and ELP4 genes in cell motility, migration, and adhesion raise the possibility that these genes are involved in pathogenesis of BECTS. MATERIALS AND METHODS We conducted a case-control association study on 60 patients with BECTS and 60 control participants to assess the influence of the BDNF and ELP4 polymorphisms on BECTS. The polymorphisms were detected with a PCR-RFLP method. Moreover, we explored the possible association of these polymorphisms with clinical and electroencephalographic parameters of patients with BECTS. RESULTS Our results show no difference in BDNF and ELP4 genotype frequencies between patients and controls. Haplotype analysis also revealed no statistical difference. CONCLUSION The role of BDNF and ELP4 polymorphisms remains controversial.
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Affiliation(s)
- Anastasia Gkampeta
- 2nd Department of Pediatrics, Aristotle University of Thessaloniki, 'AHEPA' General Hospital, Thessaloniki, Greece.
| | - Liana Fidani
- Department of General Biology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Jordi Clarimón
- Memory Unit, Alzheimer's Laboratory, and Centro de Investigación Biomédica en Red (CIBERNED), Neurology Department, Sant Pau Hospital, Barcelona, Spain
| | - Kallirhoe Kalinderi
- Department of General Biology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Teodora Katopodi
- Department of General Biology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Dimitrios Zafeiriou
- 1st Department of Pediatrics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Evangelos Pavlou
- 2nd Department of Pediatrics, Aristotle University of Thessaloniki, 'AHEPA' General Hospital, Thessaloniki, Greece
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Castrén ML, Castrén E. BDNF in fragile X syndrome. Neuropharmacology 2013; 76 Pt C:729-36. [PMID: 23727436 DOI: 10.1016/j.neuropharm.2013.05.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/07/2013] [Accepted: 05/08/2013] [Indexed: 12/12/2022]
Abstract
Fragile X syndrome (FXS) is a monogenic disorder that is caused by the absence of FMR1 protein (FMRP). FXS serves as an excellent model disorder for studies investigating disturbed molecular mechanisms and synapse function underlying cognitive impairment, autism, and behavioral disturbance. Abnormalities in dendritic spines and synaptic transmission in the brain of FXS individuals and mouse models for FXS indicate perturbations in the development, maintenance, and plasticity of neuronal network connectivity. However, numerous alterations are found during the early development in FXS, including abnormal differentiation of neural progenitors and impaired migration of newly born neurons. Several aspects of FMRP function are modulated by brain-derived neurotrophic factor (BDNF) signaling. Here, we review the evidence of the role for BDNF in the developing and adult FXS brain. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Affiliation(s)
- Maija L Castrén
- Institute of Biomedicine/Physiology, University of Helsinki, P.O. Box 63, FIN-00014 Helsinki, Finland; Rinnekoti Foundation, Rinnekodintie 10, FIN-02980 Espoo, Finland.
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17
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Emerging genetic influences in benign epilepsy with centro-temporal spikes - BECTS. Epilepsy Res 2012; 101:197-201. [PMID: 22818593 DOI: 10.1016/j.eplepsyres.2012.06.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 06/06/2012] [Accepted: 06/30/2012] [Indexed: 02/06/2023]
Abstract
BECTS is considered to be the most common childhood epileptic syndrome. Multifactorial inheritance is the most important model accounting for the genetic behavior of the common epilepsies. In recent years, different mutations in genes that control the excitability of neurons have been described. Recent reports on the involvement of the BDNF and ELP4 genes with possible roles in cell motility, migration, and adhesion have provided first insights into the complex molecular bases of childhood focal epilepsies. However, in the most common idiopathic benign childhood epilepsies (BECTS and occipital epilepsies), major breakthroughs are still awaited.
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Multiple approaches to investigate the transport and activity-dependent release of BDNF and their application in neurogenetic disorders. Neural Plast 2012; 2012:203734. [PMID: 22720171 PMCID: PMC3375105 DOI: 10.1155/2012/203734] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 04/14/2012] [Accepted: 04/15/2012] [Indexed: 01/01/2023] Open
Abstract
Studies utilizing genetic and pharmacological manipulations in rodent models and neuronal cultures have revealed myriad roles of brain-derived neurotrophic factor (BDNF). Currently, this knowledge of BDNF function is being translated into improvement strategies for several debilitating neurological disorders in which BDNF abnormalities play a prominent role. Common among the BDNF-related disorders are irregular trafficking and release of mature BDNF (mBDNF) and/or its prodomain predecessor, proBDNF. Thus, investigating the conditions required for proper trafficking and release of BDNF is an essential step toward understanding and potentially improving these neurological disorders. This paper will provide examples of disorders related to BDNF release and serve as a review of the techniques being used to study the trafficking and release of BDNF.
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Uutela M, Lindholm J, Louhivuori V, Wei H, Louhivuori LM, Pertovaara A, Akerman K, Castrén E, Castrén ML. Reduction of BDNF expression in Fmr1 knockout mice worsens cognitive deficits but improves hyperactivity and sensorimotor deficits. GENES BRAIN AND BEHAVIOR 2012; 11:513-23. [PMID: 22435671 DOI: 10.1111/j.1601-183x.2012.00784.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Fragile X syndrome (FXS) is a common cause of inherited intellectual disability and a well-characterized form of autism spectrum disorder. As brain-derived neurotrophic factor (BDNF) is implicated in the pathophysiology of FXS we examined the effects of reduced BDNF expression on the behavioral phenotype of an animal model of FXS, Fmr1 knockout (KO) mice, crossed with mice carrying a deletion of one copy of the Bdnf gene (Bdnf(+/-)). Fmr1 KO mice showed age-dependent alterations in hippocampal BDNF expression that declined after the age of 4 months compared to wild-type controls. Mild deficits in water maze learning in Bdnf(+/-) and Fmr1 KO mice were exaggerated and contextual fear learning significantly impaired in double transgenics. Reduced BDNF expression did not alter basal nociceptive responses or central hypersensitivity in Fmr1 KO mice. Paradoxically, the locomotor hyperactivity and deficits in sensorimotor learning and startle responses characteristic of Fmr1 KO mice were ameliorated by reducing BNDF, suggesting changes in simultaneously and in parallel working hippocampus-dependent and striatum-dependent systems. Furthermore, the obesity normally seen in Bdnf(+/-) mice was eliminated by the absence of fragile X mental retardation protein 1 (FMRP). Reduced BDNF decreased the survival of newborn cells in the ventral part of the hippocampus both in the presence and absence of FMRP. Since a short neurite phenotype characteristic of newborn cells lacking FMRP was not found in cells derived from double mutant mice, changes in neuronal maturation likely contributed to the behavioral phenotype. Our results show that the absence of FMRP modifies the diverse effects of BDNF on the FXS phenotype.
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Affiliation(s)
- M Uutela
- Institute of Biomedicine, Physiology, University of Helsinki, Finland
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Tondo M, Poo P, Naudó M, Ferrando T, Genovés J, Molero M, Martorell L. Predisposition to epilepsy in fragile X syndrome: does the Val66Met polymorphism in the BDNF gene play a role? Epilepsy Behav 2011; 22:581-3. [PMID: 21890420 DOI: 10.1016/j.yebeh.2011.08.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 07/14/2011] [Accepted: 08/01/2011] [Indexed: 12/25/2022]
Abstract
Epilepsy is detected in about 23% of patients with fragile X syndrome (FXS). Absence or reduced levels of the fragile X mental retardation protein (FMRP), a global regulator of translation in neurons and an important factor in synaptic plasticity, produce the observed epileptic patterns. The brain-derived neurotrophic factor (BDNF) gene is a specific regulator of synaptic plasticity, and disturbances in its function cause dendrite abnormalities similar to those observed in FXS. A putative reciprocal regulation of FMRP and BDNF has been hypothesized. The Val66Met polymorphism in the BDNF gene may be involved in the alteration of normal secretion of the mature peptide and may modulate the epileptic phenotype observed in some patients with FXS. We investigated the relationship of this Met66 allele to the prevalence of epilepsy in 77 patients with FXS. No association was observed between this polymorphism and epilepsy in our group of patients. Therefore, it should not be considered a biomarker for developing epilepsy in patients with FXS.
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Affiliation(s)
- Mireia Tondo
- Molecular Genetics Section, Hospital Sant Joan de Déu, Barcelona, Spain
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Abstract
PURPOSE OF REVIEW Although the association between learning disability and epilepsy is well known, until relatively recently specific processes underlying this association were relatively poorly understood. However, scientific advances in molecular biology are starting to guide researchers towards descriptions of genetic and pathophysiological processes that may explain why syndromes of epilepsy and learning disability often co-exist. RECENT FINDINGS This article will focus largely on three areas of advancing knowledge: insights gained from wider use of genome-wide array comparative genomic hybridization (aCGH), specific insights gained from detailed study of Rett syndrome and the role of abnormalities of astrocytic function in predisposing to both epilepsy and learning disability. SUMMARY The enormous complexity of the biological underpinnings of the co-occurrence of epilepsy and learning disability are becoming apparent. In the future it is likely that research into therapeutic approaches will include, amongst other approaches, investigations of gene structure and expression, the role of astrocytes and the stability of dendritic spines.
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Gauthey M, Poloni CB, Ramelli GP, Roulet-Perez E, Korff CM. Status epilepticus in fragile X syndrome. Epilepsia 2010; 51:2470-3. [PMID: 21204809 DOI: 10.1111/j.1528-1167.2010.02761.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Epilepsy is frequent in fragile X syndrome (FXS), the most common cause of inherited mental retardation. Status epilepticus (SE), however, seems exceptional in FXS, particularly as an initial epileptic manifestation. To our knowledge, SE was reported in only four FXS patients. We report the clinical features and electroencephalography (EEG) findings of five children with FXS, who presented with SE as their initial seizure.
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Affiliation(s)
- Magali Gauthey
- Pediatric Emergencies Service, Child and Adolescent Department, University Hospital, Geneva, Switzerland
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Louhivuori V, Vicario A, Uutela M, Rantamäki T, Louhivuori LM, Castrén E, Tongiorgi E, Akerman KE, Castrén ML. BDNF and TrkB in neuronal differentiation of Fmr1-knockout mouse. Neurobiol Dis 2010; 41:469-80. [PMID: 21047554 DOI: 10.1016/j.nbd.2010.10.018] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Revised: 10/14/2010] [Accepted: 10/27/2010] [Indexed: 01/19/2023] Open
Abstract
Fragile X syndrome (FXS) is a common cause of inherited mental retardation and the best characterized form of autistic spectrum disorders. FXS is caused by the loss of functional fragile X mental retardation protein (FMRP), which leads to abnormalities in the differentiation of neural progenitor cells (NPCs) and in the development of dendritic spines and neuronal circuits. Brain-derived neurotrophic factor (BDNF) and its TrkB receptors play a central role in neuronal maturation and plasticity. We studied BDNF/TrkB actions in the absence of FMRP and show that an increase in catalytic TrkB expression in undifferentiated NPCs of Fmr1-knockout (KO) mice, a mouse model for FXS, is associated with changes in the differentiation and migration of neurons expressing TrkB in neurosphere cultures and in the developing cortex. Aberrant intracellular calcium responses to BDNF and ATP in subpopulations of differentiating NPCs combined with changes in the expression of BDNF and TrkB suggest cell subtype-specific alterations during early neuronal maturation in the absence of FMRP. Furthermore, we show that dendritic targeting of Bdnf mRNA was increased under basal conditions and further enhanced in cortical layer V and hippocampal CA1 neurons of Fmr1-KO mice by pilocarpine-induced neuronal activity represented by convulsive seizures, suggesting that BDNF/TrkB-mediated feedback mechanisms for strengthening the synapses were compromised in the absence of FMRP. Pilocarpine-induced seizures caused an accumulation of Bdnf mRNA transcripts in the most proximal segments of dendrites in cortical but not in hippocampal neurons of Fmr1-KO mice. In addition, BDNF protein levels were increased in the hippocampus but reduced in the cortex of Fmr1-KO mice in line with regional differences of synaptic plasticity in the brain of Fmr1-KO mice. Altogether, the present data suggest that alterations in the BDNF/TrkB signaling modulate brain development and impair synaptic plasticity in FXS.
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Affiliation(s)
- Verna Louhivuori
- Department of Biomedicine/Physiology, University of Helsinki, PO Box 63, FIN-00014 Helsinki, Finland
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No major clinical impact of Val66Met BDNF gene polymorphism on temporal lobe epilepsy. Epilepsy Res 2010; 88:108-11. [DOI: 10.1016/j.eplepsyres.2009.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 08/22/2009] [Accepted: 10/04/2009] [Indexed: 11/22/2022]
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