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Akinyele O, Munir A, Johnson MA, Perez MS, Gao Y, Foley JR, Nwafor A, Wu Y, Murray-Stewart T, Casero RA, Bayir H, Kemaladewi DU. Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a mouse model of Snyder-Robinson syndrome. Dis Model Mech 2024; 17:dmm050639. [PMID: 38463005 DOI: 10.1242/dmm.050639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/28/2024] [Indexed: 03/12/2024] Open
Abstract
Snyder-Robinson syndrome (SRS) is a rare X-linked recessive disorder caused by a mutation in the SMS gene, which encodes spermine synthase, and aberrant polyamine metabolism. SRS is characterized by intellectual disability, thin habitus, seizure, low muscle tone/hypotonia and osteoporosis. Progress towards understanding and treating SRS requires a model that recapitulates human gene variants and disease presentations. Here, we evaluated molecular and neurological presentations in the G56S mouse model, which carries a missense mutation in the Sms gene. The lack of SMS protein in the G56S mice resulted in increased spermidine/spermine ratio, failure to thrive, short stature and reduced bone density. They showed impaired learning capacity, increased anxiety, reduced mobility and heightened fear responses, accompanied by reduced total and regional brain volumes. Furthermore, impaired mitochondrial oxidative phosphorylation was evident in G56S cerebral cortex, G56S fibroblasts and Sms-null hippocampal cells, indicating that SMS may serve as a future therapeutic target. Collectively, our study establishes the suitability of the G56S mice as a preclinical model for SRS and provides a set of molecular and functional outcome measures that can be used to evaluate therapeutic interventions for SRS.
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Affiliation(s)
- Oluwaseun Akinyele
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Anushe Munir
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Marie A Johnson
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Megan S Perez
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Yuan Gao
- Children's Neuroscience Institute, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Jackson R Foley
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD 21224, USA
| | - Ashley Nwafor
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD 21224, USA
| | - Yijen Wu
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Tracy Murray-Stewart
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD 21224, USA
| | - Robert A Casero
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins School of Medicine, Baltimore, MD 21224, USA
| | - Hülya Bayir
- Children's Neuroscience Institute, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Dwi U Kemaladewi
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
- Department of Human Genetics, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Children's Neuroscience Institute, Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
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2
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Sriram S, Shahid N, Mysliwiec D D, Lichter-Konecki U, Yatsenko SA, Garibaldi LR. Late diagnosis of the X-linked MCT8 deficiency (Allan-Herndon-Dudley syndrome) in a teenage girl with primary ovarian insufficiency. J Pediatr Endocrinol Metab 2024; 37:371-374. [PMID: 38345890 DOI: 10.1515/jpem-2023-0070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 11/27/2023] [Indexed: 04/11/2024]
Abstract
OBJECTIVES To report an unusual case of MCT8 deficiency (Allan-Herndon-Dudley syndrome), an X-linked condition caused by pathogenic variants in the SLC16A2 gene. Defective transport of thyroid hormones (THs) in this condition leads to severe neurodevelopmental impairment in males, while heterozygous females are usually asymptomatic or have mild TH abnormalities. CASE PRESENTATION A girl with profound developmental delay, epilepsy, primary amenorrhea, elevated T3, low T4 and free T4 levels was diagnosed with MCT8-deficiency at age 17 years, during evaluation for primary ovarian insufficiency (POI). Cytogenetic analysis demonstrated balanced t(X;16)(q13.2;q12.1) translocation with a breakpoint disrupting SLC16A2. X-chromosome inactivation studies revealed a skewed inactivation of the normal X chromosome. CONCLUSIONS MCT8-deficiency can manifest clinically and phenotypically in women with SLC16A2 aberrations when nonrandom X inactivation occurs, while lack of X chromosome integrity due to translocation can cause POI.
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Affiliation(s)
- Swetha Sriram
- Division of Pediatric Endocrinology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nabiha Shahid
- Division of Pediatric Endocrinology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Diana Mysliwiec D
- Division of Pediatric Endocrinology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Uta Lichter-Konecki
- Division of Genetics and Inborn Errors of Metabolism, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
| | - Svetlana A Yatsenko
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Luigi R Garibaldi
- Division of Pediatric Endocrinology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh, Pittsburgh, PA, USA
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3
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Guillén-Yunta M, Valcárcel-Hernández V, García-Aldea Á, Soria G, García-Verdugo JM, Montero-Pedrazuela A, Guadaño-Ferraz A. Neurovascular unit disruption and blood-brain barrier leakage in MCT8 deficiency. Fluids Barriers CNS 2023; 20:79. [PMID: 37924081 PMCID: PMC10623792 DOI: 10.1186/s12987-023-00481-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 10/20/2023] [Indexed: 11/06/2023] Open
Abstract
BACKGROUND The monocarboxylate transporter 8 (MCT8) plays a vital role in maintaining brain thyroid hormone homeostasis. This transmembrane transporter is expressed at the brain barriers, as the blood-brain barrier (BBB), and in neural cells, being the sole known thyroid hormone-specific transporter to date. Inactivating mutations in the MCT8 gene (SLC16A2) cause the Allan-Herndon-Dudley Syndrome (AHDS) or MCT8 deficiency, a rare X-linked disease characterized by delayed neurodevelopment and severe psychomotor disorders. The underlying pathophysiological mechanisms of AHDS remain unclear, and no effective treatments are available for the neurological symptoms of the disease. METHODS Neurovascular unit ultrastructure was studied by means of transmission electron microscopy. BBB permeability and integrity were evaluated by immunohistochemistry, non-permeable dye infiltration assays and histological staining techniques. Brain blood-vessel density was evaluated by immunofluorescence and magnetic resonance angiography. Finally, angiogenic-related factors expression was evaluated by qRT-PCR. The studies were carried out both in an MCT8 deficient subject and Mct8/Dio2KO mice, an AHDS murine model, and their respective controls. RESULTS Ultrastructural analysis of the BBB of Mct8/Dio2KO mice revealed significant alterations in neurovascular unit integrity and increased transcytotic flux. We also found functional alterations in the BBB permeability, as shown by an increased presence of peripheral IgG, Sodium Fluorescein and Evans Blue, along with increased brain microhemorrhages. We also observed alterations in the angiogenic process, with reduced blood vessel density in adult mice brain and altered expression of angiogenesis-related factors during brain development. Similarly, AHDS human brain samples showed increased BBB permeability to IgG and decreased blood vessel density. CONCLUSIONS These findings identify for the first time neurovascular alterations in the MCT8-deficient brain, including a disruption of the integrity of the BBB and alterations in the neurovascular unit ultrastructure as a new pathophysiological mechanism for AHDS. These results open a new field for potential therapeutic targets for the neurological symptoms of these patients and unveils magnetic resonance angiography as a new non-invasive in vivo technique for evaluating the progression of the disease.
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Affiliation(s)
- Marina Guillén-Yunta
- Laboratory of Thyroid Hormones and CNS, Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas 'Alberto-Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), C/ Arturo Duperier 4, 28029, Madrid, Spain
| | - Víctor Valcárcel-Hernández
- Laboratory of Thyroid Hormones and CNS, Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas 'Alberto-Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), C/ Arturo Duperier 4, 28029, Madrid, Spain
| | - Ángel García-Aldea
- Laboratory of Thyroid Hormones and CNS, Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas 'Alberto-Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), C/ Arturo Duperier 4, 28029, Madrid, Spain
| | - Guadalupe Soria
- Laboratory of Surgical and Experimental Neuroanatomy, Faculty of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, Barcelona, Spain
| | - José Manuel García-Verdugo
- Laboratory of Comparative Neurobiology, Cavanilles Institute of Biodiversity and Evolutionary Biology and Department of Cellular Biology, University of Valencia and CIBERNED-ISCIII, Valencia, Spain
| | - Ana Montero-Pedrazuela
- Laboratory of Thyroid Hormones and CNS, Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas 'Alberto-Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), C/ Arturo Duperier 4, 28029, Madrid, Spain.
| | - Ana Guadaño-Ferraz
- Laboratory of Thyroid Hormones and CNS, Department of Endocrine and Nervous System Pathophysiology, Instituto de Investigaciones Biomédicas 'Alberto-Sols', Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid (UAM), C/ Arturo Duperier 4, 28029, Madrid, Spain.
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4
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Pan L, Yin F, Chen S, Xiong J, He F, Peng J. Börjeson -Forssman -Lehmann syndrome: A case report. Zhong Nan Da Xue Xue Bao Yi Xue Ban 2023; 48:294-301. [PMID: 36999477 PMCID: PMC10930350 DOI: 10.11817/j.issn.1672-7347.2023.220414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Indexed: 04/01/2023]
Abstract
Börjeson-Forssman-Lehmann syndrome (BFLS) is a rare X-linked intellectual disability. The main features of the patients include intellectual disability/global developmental delay, characteristic face, anomalies of fingers and toes, hypogonadism, linear skin hyperpigmentation, and tooth abnormalities in female patients, and obesity in male patients. A case of BFLS caused by a novel mutation of PHF6 gene who was treated in the Department of Pediatrics, Xiangya Hospital, Central South University was reported. The 11 months old girl presented the following symptons: Global developmental delay, characteristic face, sparse hair, ocular hypertelorism, flat nasal bridge, hairy anterior to the tragus, thin upper lip, dental anomalies, ankyloglossia, simian line, tapering fingers, camptodactylia, and linear skin hyperpigmentation. The gene results of the second-generation sequencing technology showed that there was a novel heterozygous mutation site c.346C>T (p.Arg116*) of the PHF6 (NM032458.3), variation rating as pathogenic variation. During the follow-up, the patient developed astigmatism, strabismus, awake bruxism, and stereotyped behavior, and the linear skin hyperpigmentation became gradually more evident. The disease is lack of effective therapy so far.
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Affiliation(s)
- Langui Pan
- Department of Pediatrics, Xiangya Hospital, Central South University; Research Center of Children Intellectual Disability of Hunan Province; Clinical Research Center for Children Neurodevelopmental Disabilities of Hunan Province, Changsha 410008, China.
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University; Research Center of Children Intellectual Disability of Hunan Province; Clinical Research Center for Children Neurodevelopmental Disabilities of Hunan Province, Changsha 410008, China.
| | - Shimeng Chen
- Department of Pediatrics, Xiangya Hospital, Central South University; Research Center of Children Intellectual Disability of Hunan Province; Clinical Research Center for Children Neurodevelopmental Disabilities of Hunan Province, Changsha 410008, China
| | - Juan Xiong
- Department of Pediatrics, Xiangya Hospital, Central South University; Research Center of Children Intellectual Disability of Hunan Province; Clinical Research Center for Children Neurodevelopmental Disabilities of Hunan Province, Changsha 410008, China
| | - Fang He
- Department of Pediatrics, Xiangya Hospital, Central South University; Research Center of Children Intellectual Disability of Hunan Province; Clinical Research Center for Children Neurodevelopmental Disabilities of Hunan Province, Changsha 410008, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University; Research Center of Children Intellectual Disability of Hunan Province; Clinical Research Center for Children Neurodevelopmental Disabilities of Hunan Province, Changsha 410008, China
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5
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Rzońca-Niewczas S, Wierzba J, Kaczorowska E, Poryszewska M, Kosińska J, Stawiński P, Płoski R, Bal J. WDR13: A Novel Gene Implicated in Non-Syndromic Intellectual Disability. Genes (Basel) 2021; 12:genes12121911. [PMID: 34946860 PMCID: PMC8701106 DOI: 10.3390/genes12121911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/25/2021] [Accepted: 11/26/2021] [Indexed: 11/16/2022] Open
Abstract
Investigating novel genetic variants involved in intellectual disability (ID) development is essential. X-linked intellectual disability (XLID) accounts for over 10% of all cases of ID in males. XLID genes are involved in many cellular pathways and processes. Some of them are not specific to the development and functioning of the neural system. The implementation of exome sequencing simplifies the search for novel variants, especially those less expected. Here, we describe a nonsense variant of the XLID gene, WDR13. The mutation c.757C>T (p.Arg253Ter) was uncovered by X-chromosome exome sequencing in males with a familial form of intellectual disability. Quantitative PCR (qPCR) analysis showed that variant c.757C>T caused a significant decrease in WDR13 expression in the patient's fibroblast. Moreover, it dysregulated other genes linked to intellectual disability, such as FMR1, SYN1, CAMK2A, and THOC2. The obtained results indicate the pathogenic nature of the detected variant and suggest that the WDR13 gene interacts with other genes essential for the functioning of the nervous system, especially the synaptic plasticity process.
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Affiliation(s)
- Sylwia Rzońca-Niewczas
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland; (M.P.); (J.B.)
- Correspondence:
| | - Jolanta Wierzba
- Department of Internal and Pediatric Nursing, Faculty of Health Sciences with Institute of Maritime and Tropical Medicine, Medical University of Gdansk, 80-210 Gdansk, Poland;
| | - Ewa Kaczorowska
- Department of Biology and Medical Genetics, Medical University of Gdansk, 80-211 Gdansk, Poland;
| | - Milena Poryszewska
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland; (M.P.); (J.B.)
| | - Joanna Kosińska
- Department of Medical Genetics, Warsaw Medical University, 02-106 Warsaw, Poland; (J.K.); (P.S.); (R.P.)
| | - Piotr Stawiński
- Department of Medical Genetics, Warsaw Medical University, 02-106 Warsaw, Poland; (J.K.); (P.S.); (R.P.)
| | - Rafał Płoski
- Department of Medical Genetics, Warsaw Medical University, 02-106 Warsaw, Poland; (J.K.); (P.S.); (R.P.)
| | - Jerzy Bal
- Department of Medical Genetics, Institute of Mother and Child, 01-211 Warsaw, Poland; (M.P.); (J.B.)
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Bengani H, Grozeva D, Moyon L, Bhatia S, Louros SR, Hope J, Jackson A, Prendergast JG, Owen LJ, Naville M, Rainger J, Grimes G, Halachev M, Murphy LC, Spasic-Boskovic O, van Heyningen V, Kind P, Abbott CM, Osterweil E, Raymond FL, Roest Crollius H, FitzPatrick DR. Identification and functional modelling of plausibly causative cis-regulatory variants in a highly-selected cohort with X-linked intellectual disability. PLoS One 2021; 16:e0256181. [PMID: 34388204 PMCID: PMC8362966 DOI: 10.1371/journal.pone.0256181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/01/2021] [Indexed: 11/18/2022] Open
Abstract
Identifying causative variants in cis-regulatory elements (CRE) in neurodevelopmental disorders has proven challenging. We have used in vivo functional analyses to categorize rigorously filtered CRE variants in a clinical cohort that is plausibly enriched for causative CRE mutations: 48 unrelated males with a family history consistent with X-linked intellectual disability (XLID) in whom no detectable cause could be identified in the coding regions of the X chromosome (chrX). Targeted sequencing of all chrX CRE identified six rare variants in five affected individuals that altered conserved bases in CRE targeting known XLID genes and segregated appropriately in families. Two of these variants, FMR1CRE and TENM1CRE, showed consistent site- and stage-specific differences of enhancer function in the developing zebrafish brain using dual-color fluorescent reporter assay. Mouse models were created for both variants. In male mice Fmr1CRE induced alterations in neurodevelopmental Fmr1 expression, olfactory behavior and neurophysiological indicators of FMRP function. The absence of another likely causative variant on whole genome sequencing further supported FMR1CRE as the likely basis of the XLID in this family. Tenm1CRE mice showed no phenotypic anomalies. Following the release of gnomAD 2.1, reanalysis showed that TENM1CRE exceeded the maximum plausible population frequency of a XLID causative allele. Assigning causative status to any ultra-rare CRE variant remains problematic and requires disease-relevant in vivo functional data from multiple sources. The sequential and bespoke nature of such analyses renders them time-consuming and challenging to scale for routine clinical use.
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Affiliation(s)
- Hemant Bengani
- MRC Human Genetics Unit, IGMM, University of Edinburgh (UoE), Edinburgh, United Kingdom
| | - Detelina Grozeva
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
- Institute of Psychological Medicine & Clinical Neurosciences, Cardiff University, Cardiff, United Kingdom
| | - Lambert Moyon
- Ecole Normale Supérieure, Institut de Biologie de l’ENS, IBENS, Paris, France
| | - Shipra Bhatia
- MRC Human Genetics Unit, IGMM, University of Edinburgh (UoE), Edinburgh, United Kingdom
| | - Susana R. Louros
- Centre for Discovery Brain Sciences, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, United Kingdom
| | - Jilly Hope
- Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Adam Jackson
- Centre for Discovery Brain Sciences, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Liusaidh J. Owen
- MRC Human Genetics Unit, IGMM, University of Edinburgh (UoE), Edinburgh, United Kingdom
| | - Magali Naville
- Ecole Normale Supérieure, Institut de Biologie de l’ENS, IBENS, Paris, France
| | - Jacqueline Rainger
- MRC Human Genetics Unit, IGMM, University of Edinburgh (UoE), Edinburgh, United Kingdom
| | - Graeme Grimes
- Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Mihail Halachev
- Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Laura C. Murphy
- Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Olivera Spasic-Boskovic
- East Midlands and East of England NHS Genomic Laboratory Hub, Molecular Genetics, Adden brooke’s Hospital, Cambridge University Hospitals NHS Foundation Trust Cambridge, Cambridge, United Kingdom
| | | | - Peter Kind
- Centre for Discovery Brain Sciences, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, United Kingdom
| | - Catherine M. Abbott
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, United Kingdom
- Institute of Genomic and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Emily Osterweil
- Centre for Discovery Brain Sciences, Patrick Wild Centre, University of Edinburgh, Edinburgh, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, United Kingdom
| | - F. Lucy Raymond
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | | | - David R. FitzPatrick
- MRC Human Genetics Unit, IGMM, University of Edinburgh (UoE), Edinburgh, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, United Kingdom
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7
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Ghirardini E, Calugi F, Sagona G, Di Vetta F, Palma M, Battini R, Cioni G, Pizzorusso T, Baroncelli L. The Role of Preclinical Models in Creatine Transporter Deficiency: Neurobiological Mechanisms, Biomarkers and Therapeutic Development. Genes (Basel) 2021; 12:genes12081123. [PMID: 34440297 PMCID: PMC8392480 DOI: 10.3390/genes12081123] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/12/2022] Open
Abstract
Creatine (Cr) Transporter Deficiency (CTD) is an X-linked metabolic disorder, mostly caused by missense mutations in the SLC6A8 gene and presenting with intellectual disability, autistic behavior, and epilepsy. There is no effective treatment for CTD and patients need lifelong assistance. Thus, the research of novel intervention strategies is a major scientific challenge. Animal models are an excellent tool to dissect the disease pathogenetic mechanisms and drive the preclinical development of therapeutics. This review illustrates the current knowledge about Cr metabolism and CTD clinical aspects, with a focus on mainstay diagnostic and therapeutic options. Then, we discuss the rodent models of CTD characterized in the last decade, comparing the phenotypes expressed within clinically relevant domains and the timeline of symptom development. This analysis highlights that animals with the ubiquitous deletion/mutation of SLC6A8 genes well recapitulate the early onset and the complex pathological phenotype of the human condition. Thus, they should represent the preferred model for preclinical efficacy studies. On the other hand, brain- and cell-specific conditional mutants are ideal for understanding the basis of CTD at a cellular and molecular level. Finally, we explain how CTD models might provide novel insight about the pathogenesis of other disorders, including cancer.
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MESH Headings
- Animals
- Biomarkers/metabolism
- Brain Diseases, Metabolic, Inborn/metabolism
- Brain Diseases, Metabolic, Inborn/pathology
- Brain Diseases, Metabolic, Inborn/therapy
- Central Nervous System/pathology
- Creatine/deficiency
- Creatine/metabolism
- Disease Models, Animal
- Humans
- Mental Retardation, X-Linked/metabolism
- Mental Retardation, X-Linked/pathology
- Mental Retardation, X-Linked/therapy
- Mice
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/metabolism
- Rats
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Affiliation(s)
- Elsa Ghirardini
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
| | - Francesco Calugi
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Giulia Sagona
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Federica Di Vetta
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Biology, University of Pisa, I-56126 Pisa, Italy
| | - Martina Palma
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Roberta Battini
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Department of Clinical and Experimental Medicine, University of Pisa, I-56126 Pisa, Italy
| | - Giovanni Cioni
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Department of Clinical and Experimental Medicine, University of Pisa, I-56126 Pisa, Italy
| | - Tommaso Pizzorusso
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Department of Neuroscience, Psychology, Drug Research and Child Health NEUROFARBA, University of Florence, I-50135 Florence, Italy
| | - Laura Baroncelli
- Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, I-56128 Pisa, Italy; (E.G.); (G.S.); (R.B.); (G.C.)
- Institute of Neuroscience, National Research Council (CNR), I-56124 Pisa, Italy; (F.C.); (F.D.V.); (M.P.); (T.P.)
- Correspondence:
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8
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Wawro AM, Gajera CR, Baker SA, Nirschl JJ, Vogel H, Montine TJ. Creatine transport and pathological changes in creatine transporter deficient mice. J Inherit Metab Dis 2021; 44:939-948. [PMID: 33389772 DOI: 10.1002/jimd.12358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/29/2020] [Accepted: 12/30/2020] [Indexed: 01/26/2023]
Abstract
The severe impact on brain function and lack of effective therapy for patients with creatine (Cr) transporter deficiency motivated the generation of three ubiquitous Slc6a8 deficient mice (-/y). While each mouse knock-out line has similar behavioral effects at 2 to 3 months of age, other features critical to the efficient use of these mice in drug discovery are unclear or lacking: the concentration of Cr in brain and heart differ widely between mouse lines, there are limited data on histopathologic changes, and no data on Cr uptake. Here, we determined survival, measured endogenous Cr and uptake of its deuterium-labeled analogue Cr-d3 using a liquid chromatography coupled with tandem mass spectrometry assay, and performed comprehensive histopathologic examination on the Slc6a8-/y mouse developed by Skelton et al. Our results show that Slc6a8-/y mice have widely varying organ-specific uptake of Cr-d3, significantly diminished growth with the exception of brain, progressive vacuolar myopathy, and markedly shortened lifespan.
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Affiliation(s)
- Adam M Wawro
- Department of Pathology, Stanford University, Stanford, California, USA
| | | | - Steven A Baker
- Department of Pathology, Stanford University, Stanford, California, USA
| | - Jeffrey J Nirschl
- Department of Pathology, Stanford University, Stanford, California, USA
| | - Hannes Vogel
- Department of Pathology, Stanford University, Stanford, California, USA
| | - Thomas J Montine
- Department of Pathology, Stanford University, Stanford, California, USA
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9
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van de Plassche SR, de Brouwer APM. MED12-Related (Neuro)Developmental Disorders: A Question of Causality. Genes (Basel) 2021; 12:663. [PMID: 33925166 PMCID: PMC8146938 DOI: 10.3390/genes12050663] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 12/24/2022] Open
Abstract
MED12 is a member of the Mediator complex that is involved in the regulation of transcription. Missense variants in MED12 cause FG syndrome, Lujan-Fryns syndrome, and Ohdo syndrome, as well as non-syndromic intellectual disability (ID) in hemizygous males. Recently, female patients with de novo missense variants and de novo protein truncating variants in MED12 were described, resulting in a clinical spectrum centered around ID and Hardikar syndrome without ID. The missense variants are found throughout MED12, whether they are inherited in hemizygous males or de novo in females. They can result in syndromic or nonsyndromic ID. The de novo nonsense variants resulting in Hardikar syndrome that is characterized by facial clefting, pigmentary retinopathy, biliary anomalies, and intestinal malrotation, are found more N-terminally, whereas the more C-terminally positioned variants are de novo protein truncating variants that cause a severe, syndromic phenotype consisting of ID, facial dysmorphism, short stature, skeletal abnormalities, feeding difficulties, and variable other abnormalities. This broad range of distinct phenotypes calls for a method to distinguish between pathogenic and non-pathogenic variants in MED12. We propose an isogenic iNeuron model to establish the unique gene expression patterns that are associated with the specific MED12 variants. The discovery of these patterns would help in future diagnostics and determine the causality of the MED12 variants.
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Affiliation(s)
| | - Arjan P. M. de Brouwer
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, 6500 HB Nijmegen, The Netherlands;
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10
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van Geest FS, Gunhanlar N, Groeneweg S, Visser WE. Monocarboxylate Transporter 8 Deficiency: From Pathophysiological Understanding to Therapy Development. Front Endocrinol (Lausanne) 2021; 12:723750. [PMID: 34539576 PMCID: PMC8440930 DOI: 10.3389/fendo.2021.723750] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 08/13/2021] [Indexed: 01/18/2023] Open
Abstract
Genetic defects in the thyroid hormone transporter monocarboxylate transporter 8 (MCT8) result in MCT8 deficiency. This disorder is characterized by a combination of severe intellectual and motor disability, caused by decreased cerebral thyroid hormone signalling, and a chronic thyrotoxic state in peripheral tissues, caused by exposure to elevated serum T3 concentrations. In particular, MCT8 plays a crucial role in the transport of thyroid hormone across the blood-brain-barrier. The life expectancy of patients with MCT8 deficiency is strongly impaired. Absence of head control and being underweight at a young age, which are considered proxies of the severity of the neurocognitive and peripheral phenotype, respectively, are associated with higher mortality rate. The thyroid hormone analogue triiodothyroacetic acid is able to effectively and safely ameliorate the peripheral thyrotoxicosis; its effect on the neurocognitive phenotype is currently under investigation. Other possible therapies are at a pre-clinical stage. This review provides an overview of the current understanding of the physiological role of MCT8 and the pathophysiology, key clinical characteristics and developing treatment options for MCT8 deficiency.
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11
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Tekendo-Ngongang C, Dahoun S, Nguefack S, Moix I, Gimelli S, Zambo H, Morris MA, Sloan-Béna F, Wonkam A. MECP2 duplication syndrome in a patient from Cameroon. Am J Med Genet A 2020; 182:619-622. [PMID: 32052928 PMCID: PMC7450984 DOI: 10.1002/ajmg.a.61510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 11/27/2019] [Accepted: 01/23/2020] [Indexed: 11/07/2022]
Abstract
MECP2 duplication syndrome (MDS; OMIM 300260) is an X-linked neurodevelopmental disorder caused by nonrecurrent duplications of the Xq28 region involving the gene methyl-CpG-binding protein 2 (MECP2; OMIM 300005). The core phenotype of affected individuals includes infantile hypotonia, severe intellectual disability, very poor-to-absent speech, progressive spasticity, seizures, and recurrent infections. The condition is 100% penetrant in males, with observed variability in phenotypic expression within and between families. Features of MDS in individuals of African descent are not well known. Here, we describe a male patient from Cameroon, with MDS caused by an inherited 610 kb microduplication of Xq28 encompassing the genes MECP2, IRAK1, L1CAM, and SLC6A8. This report supplements the public data on MDS and contributes by highlighting the phenotype of this condition in affected individuals of African descent.
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Affiliation(s)
- Cedrik Tekendo-Ngongang
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Sophie Dahoun
- Service of Genetic Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Séraphin Nguefack
- Department of Obstetrics and Gynecology, Yaoundé Gynaeco-Obstetric and Pediatric Hospital, Yaoundé, Cameroon
- Department of Pediatrics, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
| | - Isabelle Moix
- Service of Genetic Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Stefania Gimelli
- Service of Genetic Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Huguette Zambo
- Department of Obstetrics and Gynecology, Yaoundé Gynaeco-Obstetric and Pediatric Hospital, Yaoundé, Cameroon
| | - Michael A Morris
- Service of Genetic Medicine, Geneva University Hospitals, Geneva, Switzerland
| | | | - Ambroise Wonkam
- Division of Human Genetics, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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12
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Liu X, Dou LX, Han J, Zhang ZC. The Renpenning syndrome-associated protein PQBP1 facilitates the nuclear import of splicing factor TXNL4A through the karyopherin β2 receptor. J Biol Chem 2020; 295:4093-4100. [PMID: 32041777 PMCID: PMC7105315 DOI: 10.1074/jbc.ra119.012214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/05/2020] [Indexed: 11/06/2022] Open
Abstract
Renpenning syndrome belongs to a group of X-linked intellectual disability disorders. The Renpenning syndrome-associated protein PQBP1 (polyglutamine-binding protein 1) is intrinsically disordered, associates with several splicing factors, and is involved in pre-mRNA splicing. PQBP1 uses its C-terminal YxxPxxVL motif for binding to the splicing factor TXNL4A (thioredoxin like 4A), but the biological function of this interaction has yet to be elucidated. In this study, using recombinant protein expression, in vitro binding assays, and immunofluorescence microscopy in HeLa cells, we found that a recently reported X-linked intellectual disability-associated missense mutation, resulting in the PQBP1-P244L variant, disrupts the interaction with TXNL4A. We further show that this interaction is critical for the subcellular location of TXNL4A. In combination with other PQBP1 variants lacking a functional nuclear localization signal required for recognition by the nuclear import receptor karyopherin β2, we demonstrate that PQBP1 facilitates the nuclear import of TXNL4A via a piggyback mechanism. These findings expand our understanding of the molecular basis of the PQBP1-TXNL4A interaction and of the etiology and pathogenesis of Renpenning syndrome and related disorders.
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Affiliation(s)
- Xian Liu
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu 210096, China
| | - Lin-Xia Dou
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu 210096, China
| | - Junhai Han
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China
| | - Zi Chao Zhang
- School of Life Science and Technology, the Key Laboratory of Developmental Genes and Human Disease, Southeast University, Nanjing, Jiangsu 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China.
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13
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Lovejoy CA, Takai K, Huh MS, Picketts DJ, de Lange T. ATRX affects the repair of telomeric DSBs by promoting cohesion and a DAXX-dependent activity. PLoS Biol 2020; 18:e3000594. [PMID: 31895940 PMCID: PMC6959610 DOI: 10.1371/journal.pbio.3000594] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/14/2020] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
Alpha thalassemia/mental retardation syndrome X-linked chromatin remodeler (ATRX), a DAXX (death domain-associated protein) interacting protein, is often lost in cells using the alternative lengthening of telomeres (ALT) pathway, but it is not known how ATRX loss leads to ALT. We report that ATRX deletion from mouse cells altered the repair of telomeric double-strand breaks (DSBs) and induced ALT-like phenotypes, including ALT-associated promyelocytic leukemia (PML) bodies (APBs), telomere sister chromatid exchanges (T-SCEs), and extrachromosomal telomeric signals (ECTSs). Mechanistically, we show that ATRX affects telomeric DSB repair by promoting cohesion of sister telomeres and that loss of ATRX in ALT cells results in diminished telomere cohesion. In addition, we document a role for DAXX in the repair of telomeric DSBs. Removal of telomeric cohesion in combination with DAXX deficiency recapitulates all telomeric DSB repair phenotypes associated with ATRX loss. The data reveal that ATRX has an effect on telomeric DSB repair and that this role involves both telomere cohesion and a DAXX-dependent pathway.
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Affiliation(s)
- Courtney A. Lovejoy
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Kaori Takai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Michael S. Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - David J. Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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14
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Rahman SK, Okazawa H, Chen YW. Frameshift PQBP-1 mutants K192S fs*7 and R153S fs*41 implicated in X-linked intellectual disability form stable dimers. J Struct Biol 2019; 206:305-313. [PMID: 30951824 DOI: 10.1016/j.jsb.2019.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 03/30/2019] [Accepted: 04/01/2019] [Indexed: 11/19/2022]
Abstract
Polyglutamine tract-binding protein-1 (PQBP-1) is a nuclear intrinsically disordered protein playing important roles in transcriptional regulation and RNA splicing during embryonic and postembryonic development. In human, its mutations lead to severe cognitive impairment known as the Renpenning syndrome, a form of X-linked intellectual disability (XLID). Here, we report a combined biophysical study of two PQBP-1 frameshift mutants, K192Sfs*7 and R153Sfs*41. Both mutants are dimeric in solution, in contrast to the monomeric wild-type protein. These mutants contain more folded contents and have increased thermal stabilities. Using small-angle X-ray scattering data, we generated three-dimensional envelopes which revealed their overall flat shapes. We also described each mutant using an ensemble model based on a native-like initial pool with a dimeric structural core. PQBP-1 is known to repress transcription by way of interacting with the C-terminal domain of RNA polymerase II, which consists of 52 repeats of a consensus heptapeptide sequence YSPTSPS. We studied the binding of PQBP-1 variants to the labelled peptide which is phosphorylated at positions 2 and 5 (YpSPTpSPS) and found that this interaction is significantly weakened in the two mutants.
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Affiliation(s)
- Shah Kamranur Rahman
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London SE1 1UL, United Kingdom.
| | - Hitoshi Okazawa
- Department of Neuropathology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.
| | - Yu Wai Chen
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London SE1 1UL, United Kingdom.
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15
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Srivastava S, Niranjan T, May MM, Tarpey P, Allen W, Hackett A, Jouk P, Raymond L, Briault S, Skinner C, Toutain A, Gecz J, Heath W, Stevenson RE, Schwartz CE, Wang T. Dysregulations of sonic hedgehog signaling in MED12-related X-linked intellectual disability disorders. Mol Genet Genomic Med 2019; 7:e00569. [PMID: 30729724 PMCID: PMC6465656 DOI: 10.1002/mgg3.569] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/05/2018] [Accepted: 12/11/2018] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Mutations in mediator of RNA polymerase II transcription subunit 12 homolog (MED12, OMIM 300188) cause X-linked intellectual disability (XLID) disorders including FG, Lujan, and Ohdo syndromes. The Gli3-dependent Sonic Hedgehog (SHH) signaling pathway has been implicated in the original FG syndrome and Lujan syndrome. How are SHH-signaling defects related to the complex clinical phenotype of MED12-associated XLID syndromes are not fully understood. METHODS Quantitative RT-PCR was used to study expression levels of three SHH-signaling genes in lymophoblast cell lines carrying four MED12 mutations from four unrelated XLID families. Genotype and phenotype correlation studies were performed on these mutations. RESULTS Three newly identified and one novel MED12 mutations in six affected males from four unrelated XLID families were studied. Three mutations (c.2692A>G; p.N898D, c.3640C>T; p.R1214C, and c.3884G>A; p.R1295H) are located in the LS domain and one (c.617G>A; p.R206Q) is in the L domain of MED12. These mutations involve highly conserved amino acid residues and segregate with ID and related congenital malformations in respective probands families. Patients with the LS-domain mutations share many features of FG syndrome and some features of Lujan syndrome. The patient with the L-domain mutation presented with ID and predominant neuropsychiatric features but little dysmorphic features of either FG or Lujan syndrome. Transcript levels of three Gli3-dependent SHH-signaling genes, CREB5, BMP4, and NEUROG2, were determined by quantitative RT-PCR and found to be significantly elevated in lymphoblasts from patients with three mutations in the MED12-LS domain. CONCLUSIONS These results support a critical role of MED12 in regulating Gli3-dependent SHH signaling and in developing ID and related congenital malformations in XLID syndromes. Differences in the expression profile of SHH-signaling genes potentially contribute to variability in clinical phenotypes in patients with MED12-related XLID disorders.
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Affiliation(s)
- Siddharth Srivastava
- Institute of Genetic Medicine and Department of PediatricsJohns Hopkins UniversityBaltimoreMaryland
| | - Tejasvi Niranjan
- Institute of Genetic Medicine and Department of PediatricsJohns Hopkins UniversityBaltimoreMaryland
| | | | | | | | - Anna Hackett
- Genetics of Learning Disability ServiceHunter GeneticsWaratahNSWAustralia
| | | | - Lucy Raymond
- Cambridge Institute of Medical ResearchCambridgeUK
| | | | | | - Annick Toutain
- Service de Génétique Clinique, Hôpital BretonneauToursFrance
| | - Jozef Gecz
- Adelaide Medical School and Robinson Research InstituteThe University of AdelaideAdelaideAustralia
| | - William Heath
- J.I. Riddle Developmental CenterMorgantonNorth Carolina
| | | | | | - Tao Wang
- Institute of Genetic Medicine and Department of PediatricsJohns Hopkins UniversityBaltimoreMaryland
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16
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Cheng C, Deng PY, Ikeuchi Y, Yuede C, Li D, Rensing N, Huang J, Baldridge D, Maloney SE, Dougherty JD, Constantino J, Jahani-Asl A, Wong M, Wozniak DF, Wang T, Klyachko VA, Bonni A. Characterization of a Mouse Model of Börjeson-Forssman-Lehmann Syndrome. Cell Rep 2018; 25:1404-1414.e6. [PMID: 30403997 PMCID: PMC6261530 DOI: 10.1016/j.celrep.2018.10.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 09/18/2018] [Accepted: 10/11/2018] [Indexed: 01/10/2023] Open
Abstract
Mutations of the transcriptional regulator PHF6 cause the X-linked intellectual disability disorder Börjeson-Forssman-Lehmann syndrome (BFLS), but the pathogenesis of BFLS remains poorly understood. Here, we report a mouse model of BFLS, generated using a CRISPR-Cas9 approach, in which cysteine 99 within the PHD domain of PHF6 is replaced with phenylalanine (C99F). Mice harboring the patient-specific C99F mutation display deficits in cognitive functions, emotionality, and social behavior, as well as reduced threshold to seizures. Electrophysiological studies reveal that the intrinsic excitability of entorhinal cortical stellate neurons is increased in PHF6 C99F mice. Transcriptomic analysis of the cerebral cortex in C99F knockin mice and PHF6 knockout mice show that PHF6 promotes the expression of neurogenic genes and represses synaptic genes. PHF6-regulated genes are also overrepresented in gene signatures and modules that are deregulated in neurodevelopmental disorders of cognition. Our findings advance our understanding of the mechanisms underlying BFLS pathogenesis.
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Affiliation(s)
- Cheng Cheng
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Pan-Yue Deng
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110, USA
| | - Yoshiho Ikeuchi
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Carla Yuede
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Daofeng Li
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63108, USA; Department of Genetics, Washington University School of Medicine, 4515 McKinley Ave., St. Louis, MO 63108, USA
| | - Nicholas Rensing
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ju Huang
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Dustin Baldridge
- Department of Pediatrics, Division of Newborn Medicine, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Susan E Maloney
- Department of Genetics, Washington University School of Medicine, 4515 McKinley Ave., St. Louis, MO 63108, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Joseph D Dougherty
- Department of Genetics, Washington University School of Medicine, 4515 McKinley Ave., St. Louis, MO 63108, USA; Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - John Constantino
- Department of Psychiatry, Division of Child Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Arezu Jahani-Asl
- Department of Oncology, Faculty of Medicine, McGill University, Montreal, QC H3T 1E2, Canada; Lady Davis Research Institute, Jewish General Hospital, Montreal, QC H3T 1E2, Canada
| | - Michael Wong
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - David F Wozniak
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Ting Wang
- The Edison Family Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, MO 63108, USA; Department of Genetics, Washington University School of Medicine, 4515 McKinley Ave., St. Louis, MO 63108, USA
| | - Vitaly A Klyachko
- Department of Biomedical Engineering, Washington University, St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University, St. Louis, MO 63110, USA
| | - Azad Bonni
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, MO 63110, USA.
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17
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Vancamp P, Darras VM. From zebrafish to human: A comparative approach to elucidate the role of the thyroid hormone transporter MCT8 during brain development. Gen Comp Endocrinol 2018; 265:219-229. [PMID: 29183795 DOI: 10.1016/j.ygcen.2017.11.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/24/2017] [Accepted: 11/24/2017] [Indexed: 02/07/2023]
Abstract
Monocarboxylate transporter 8 (MCT8) facilitates transmembrane transport of thyroid hormones (THs) ensuring their action on gene expression during vertebrate neurodevelopment. A loss of MCT8 in humans results in severe psychomotor deficits associated with the Allan-Herndon-Dudley Syndrome (AHDS). However, where and when exactly a lack of MCT8 causes the neurological manifestations remains unclear because of the varying expression pattern of MCT8 between specific brain regions and cells. Here, we elaborate on the animal models that have been generated to elucidate the mechanisms underlying MCT8-deficient brain development. The absence of a clear neurological phenotype in Mct8 knockout mice made it clear that a single species would not suffice. The evolutionary conservation of TH action on neurodevelopment as well as the components regulating TH signalling however offers the opportunity to answer different aspects of MCT8 function in brain development using different vertebrate species. Moreover, the plethora of tools for genome editing available today facilitates gene silencing in these animals as well. Studies in the recently generated mct8-deficient zebrafish and Mct8/Oatp1c1 double knockout mice have put forward the current paradigm of impaired TH uptake at the level of the blood-brain barrier during peri- and postnatal development as being the main pathophysiological mechanism of AHDS. RNAi vector-based, cell-specific induction of MCT8 knockdown in the chicken embryo points to an additional function of MCT8 at the level of the neural progenitors during early brain development. Future studies including also additional in vivo models like Xenopus or in vitro approaches such as induced pluripotent stem cells will continue to help unravelling the exact role of MCT8 in developmental events. In the end, this multispecies approach will lead to a unifying thesis regarding the cellular and molecular mechanisms responsible for the neurological phenotype in AHDS patients.
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Affiliation(s)
- Pieter Vancamp
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium
| | - Veerle M Darras
- KU Leuven, Laboratory of Comparative Endocrinology, Department of Biology, B-3000 Leuven, Belgium.
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18
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Joncquel-Chevalier Curt M, Bout MA, Fontaine M, Kim I, Huet G, Bekri S, Morin G, Moortgat S, Moerman A, Cuisset JM, Cheillan D, Vamecq J. Functional assessment of creatine transporter in control and X-linked SLC6A8-deficient fibroblasts. Mol Genet Metab 2018; 123:463-471. [PMID: 29478817 DOI: 10.1016/j.ymgme.2018.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 02/15/2018] [Accepted: 02/15/2018] [Indexed: 01/01/2023]
Abstract
Creatine transporter is currently the focus of renewed interest with emerging roles in brain neurotransmission and physiology, and the bioenergetics of cancer metastases. We here report on amendments of a standard creatine uptake assay which might help clinical chemistry laboratories to extend their current range of measurements of creatine and metabolites in body fluids to functional enzyme explorations. In this respect, short incubation times and the use of a stable-isotope-labeled substrate (D3-creatine) preceded by a creatine wash-out step from cultured fibroblast cells by removal of fetal bovine serum (rich in creatine) from the incubation medium are recommended. Together, these measures decreased, by a first order of magnitude, creatine concentrations in the incubation medium at the start of creatine-uptake studies and allowed to functionally discriminate between 4 hemizygous male and 4 heterozygous female patients with X-linked SLC6A8 deficiency, and between this cohort of eight patients and controls. The functional assay corroborated genetic diagnosis of SLC6A8 deficiency. Gene anomalies in our small cohort included splicing site (c.912G > A [p.Ile260_Gln304del], c.778-2A > G and c.1495 + 2 T > G), substitution (c.407C > T) [p.Ala136Val] and deletion (c.635_636delAG [p.Glu212Valfs*84] and c.1324delC [p.Gln442Lysfs*21]) variants with reduced creatine transporter function validating their pathogenicity, including that of a previously unreported c.1324delC variant. The present assay adaptations provide an easy, reliable and discriminative manner for exploring creatine transporter activity and disease variations. It might apply to drug testing or other evaluations in the genetic and metabolic horizons covered by the emerging functions of creatine and its transporter, in a way, however, requiring and completed by additional studies on female patients and blood-brain barrier permeability properties of selected compounds. As a whole, the proposed assay of creatine transporter positively adds to currently existing measurements of this transporter activity, and determining on a large scale the extent of its exact suitability to detect female patients should condition in the future its transfer in clinical practice.
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MESH Headings
- Adolescent
- Brain Diseases, Metabolic, Inborn/genetics
- Brain Diseases, Metabolic, Inborn/metabolism
- Brain Diseases, Metabolic, Inborn/pathology
- Case-Control Studies
- Child
- Child, Preschool
- Cohort Studies
- Creatine/deficiency
- Creatine/genetics
- Creatine/metabolism
- Female
- Fibroblasts/metabolism
- Fibroblasts/pathology
- Follow-Up Studies
- Humans
- Infant
- Male
- Mental Retardation, X-Linked/genetics
- Mental Retardation, X-Linked/metabolism
- Mental Retardation, X-Linked/pathology
- Mutation
- Nerve Tissue Proteins/deficiency
- Nerve Tissue Proteins/genetics
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/genetics
- Plasma Membrane Neurotransmitter Transport Proteins/metabolism
- Prognosis
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Affiliation(s)
- Marie Joncquel-Chevalier Curt
- Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology (HMNO), Center of Biology and Pathology (CBP) Pierre-Marie Degand, CHRU, Lille, France
| | - Marie-Adélaïde Bout
- Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology (HMNO), Center of Biology and Pathology (CBP) Pierre-Marie Degand, CHRU, Lille, France
| | - Monique Fontaine
- Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology (HMNO), Center of Biology and Pathology (CBP) Pierre-Marie Degand, CHRU, Lille, France
| | - Isabelle Kim
- Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology (HMNO), Center of Biology and Pathology (CBP) Pierre-Marie Degand, CHRU, Lille, France
| | - Guillemette Huet
- Cell Culture Department, Center of Biology-Pathology, CHRU Lille, F-59000 Lille, France
| | - Soumeya Bekri
- Inserm U1245, UNIROUEN, Normandie Univ, Normandy Centre for Genomic and Personalized Medicine, France.Department of Metabolic Biochemistry, Rouen University Hospital, Rouen, France
| | - Gilles Morin
- EA 4666, Département de génétique, Université de Picardie-Jules-Verne, CHU d'Amiens, 80054 Amiens, France
| | - Stéphanie Moortgat
- Centre de Génétique Humaine, Institut de Pathologie et de Génétique, Charleroi, Gosselies, Belgium
| | - Alexandre Moerman
- Service de Génétique Clinique Guy Fontaine, Hôpital Jeanne de Flandre, CHRU Lille, 59037 Lille, France
| | - Jean-Marie Cuisset
- Service de Neurologie Infantile, Hôpital Roger Salengro, CHRU Lille, 59037 Lille, France
| | - David Cheillan
- Hospices Civils de Lyon, Service de Biochimie et Biologie Moléculaire Grand Est, Centre de Biologie et de Pathologie Est, 69677 Bron, France and Université de Lyon, INSERM U1060, CarMen; Medical Reference Center for Inherited Metabolic Diseases, Jeanne de Flandre Hospital, CHRU Lille, France
| | - Joseph Vamecq
- Department of Biochemistry and Molecular Biology, Laboratory of Hormonology, Metabolism-Nutrition & Oncology (HMNO), Center of Biology and Pathology (CBP) Pierre-Marie Degand, CHRU, Lille, France; Inserm, Lille, France; Université de Lyon, INSERM U1060 CarMeN, Lyon, France.; Univ. Lille, RADEME - Maladies RAres du Développement et du Métabolisme : du phénotype au génotype et à la Fonction, Lille, EA 7364, France.
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19
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Zada D, Blitz E, Appelbaum L. Zebrafish - An emerging model to explore thyroid hormone transporters and psychomotor retardation. Mol Cell Endocrinol 2017; 459:53-58. [PMID: 28274736 DOI: 10.1016/j.mce.2017.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 02/18/2017] [Accepted: 03/02/2017] [Indexed: 12/17/2022]
Abstract
Thyroid hormones (THs) regulate a variety of fundamental physiological processes, including the development and maintenance of the brain. For decades, it was thought that THs enter the cells by passive diffusion. However, it is now clear that TH transport across the cell membrane requires specific transporter proteins that facilitate the uptake and efflux of THs. Several thyroid hormone transmembrane transporters (THTTs) have been identified, including monocarboxylate transporter 8 (MCT8), MCT10, and organic anion transporting polypeptide 1C1 (OATP1C1). The critical role of THTTs in regulating metabolism and brain function is demonstrated in the Allan-Herndon-Dudley syndrome (AHDS), an X-linked psychomotor retardation associated with mutations in the MCT8/SLC16A2 gene. In addition to traditional research on humans, cell-lines, and rodents, the zebrafish has recently emerged as an attractive model to study THTTs and neuroendocrinological-related disorders. In this review, we describe the unique contribution of zebrafish studies to the understanding of the functional role of THTTs in live animals, and how this transparent vertebrate model can be used for translational studies on TH-related disorders.
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Affiliation(s)
- David Zada
- The Faculty of Life Sciences and the Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Einat Blitz
- The Faculty of Life Sciences and the Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Lior Appelbaum
- The Faculty of Life Sciences and the Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 5290002, Israel.
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20
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Pucheta-Martinez E, D’Amelio N, Lelli M, Martinez-Torrecuadrada JL, Sudol M, Saladino G, Gervasio FL. Changes in the folding landscape of the WW domain provide a molecular mechanism for an inherited genetic syndrome. Sci Rep 2016; 6:30293. [PMID: 27456546 PMCID: PMC4960638 DOI: 10.1038/srep30293] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 07/01/2016] [Indexed: 10/25/2022] Open
Abstract
WW domains are small domains present in many human proteins with a wide array of functions and acting through the recognition of proline-rich sequences. The WW domain belonging to polyglutamine tract-binding protein 1 (PQBP1) is of particular interest due to its direct involvement in several X chromosome-linked intellectual disabilities, including Golabi-Ito-Hall (GIH) syndrome, where a single point mutation (Y65C) correlates with the development of the disease. The mutant cannot bind to its natural ligand WBP11, which regulates mRNA processing. In this work we use high-field high-resolution NMR and enhanced sampling molecular dynamics simulations to gain insight into the molecular causes the disease. We find that the wild type protein is partially unfolded exchanging among multiple beta-strand-like conformations in solution. The Y65C mutation further destabilizes the residual fold and primes the protein for the formation of a disulphide bridge, which could be at the origin of the loss of function.
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Affiliation(s)
| | - Nicola D’Amelio
- Research Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - Moreno Lelli
- University of Florence, Department of Chemistry, Magnetic Resonance Center (CERM), 50019 Sesto Fiorentino (FI), Italy
| | - Jorge L. Martinez-Torrecuadrada
- Crystallography and Protein Engineering Unit, Spanish National Cancer Research Centre (CNIO), C/Melchor Fernandez Almagro 3, 28029, Madrid, Spain
| | - Marius Sudol
- Institute of Molecular and Cell Biology A*STAR, 61 Biopolis, Singapore 138673, Republic of Singapore
- Mechanobiology Institute, 5A Engineering Drive 1, Singapore 117411, Republic of Singapore
- National University of Singapore, Department of Physiology, The Yong Loo Li School of Medicine, 2 Medical Drive, Singapore 117597, Republic of Singapore
| | - Giorgio Saladino
- Department of Chemistry, University College London, London WC1E 6BT, United Kingdom
- Research Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
| | - Francesco Luigi Gervasio
- Department of Chemistry, University College London, London WC1E 6BT, United Kingdom
- Research Institute of Structural and Molecular Biology, University College London, London WC1E 6BT, United Kingdom
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21
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Hanna-El-Daher L, Braissant O. Creatine synthesis and exchanges between brain cells: What can be learned from human creatine deficiencies and various experimental models? Amino Acids 2016; 48:1877-95. [PMID: 26861125 DOI: 10.1007/s00726-016-2189-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 01/27/2016] [Indexed: 12/11/2022]
Abstract
While it has long been thought that most of cerebral creatine is of peripheral origin, the last 20 years has provided evidence that the creatine synthetic pathway (AGAT and GAMT enzymes) is expressed in the brain together with the creatine transporter (SLC6A8). It has also been shown that SLC6A8 is expressed by microcapillary endothelial cells at the blood-brain barrier, but is absent from surrounding astrocytes, raising the concept that the blood-brain barrier has a limited permeability for peripheral creatine. The first creatine deficiency syndrome in humans was also discovered 20 years ago (GAMT deficiency), followed later by AGAT and SLC6A8 deficiencies, all three diseases being characterized by creatine deficiency in the CNS and essentially affecting the brain. By reviewing the numerous and latest experimental studies addressing creatine transport and synthesis in the CNS, as well as the clinical and biochemical characteristics of creatine-deficient patients, our aim was to delineate a clearer view of the roles of the blood-brain and blood-cerebrospinal fluid barriers in the transport of creatine and guanidinoacetate between periphery and CNS, and on the intracerebral synthesis and transport of creatine. This review also addresses the question of guanidinoacetate toxicity for brain cells, as probably found under GAMT deficiency.
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MESH Headings
- Amidinotransferases/deficiency
- Amidinotransferases/genetics
- Amidinotransferases/metabolism
- Amino Acid Metabolism, Inborn Errors/genetics
- Amino Acid Metabolism, Inborn Errors/metabolism
- Amino Acid Metabolism, Inborn Errors/pathology
- Animals
- Blood-Brain Barrier/metabolism
- Blood-Brain Barrier/pathology
- Brain Diseases, Metabolic, Inborn/genetics
- Brain Diseases, Metabolic, Inborn/metabolism
- Brain Diseases, Metabolic, Inborn/pathology
- Capillaries/metabolism
- Capillaries/pathology
- Creatine/biosynthesis
- Creatine/deficiency
- Creatine/genetics
- Creatine/metabolism
- Developmental Disabilities/genetics
- Developmental Disabilities/metabolism
- Developmental Disabilities/pathology
- Disease Models, Animal
- Endothelial Cells/metabolism
- Endothelial Cells/pathology
- Guanidinoacetate N-Methyltransferase/deficiency
- Guanidinoacetate N-Methyltransferase/genetics
- Guanidinoacetate N-Methyltransferase/metabolism
- Humans
- Intellectual Disability/genetics
- Intellectual Disability/metabolism
- Intellectual Disability/pathology
- Language Development Disorders/genetics
- Language Development Disorders/metabolism
- Language Development Disorders/pathology
- Mental Retardation, X-Linked/genetics
- Mental Retardation, X-Linked/metabolism
- Mental Retardation, X-Linked/pathology
- Movement Disorders/congenital
- Movement Disorders/genetics
- Movement Disorders/metabolism
- Movement Disorders/pathology
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/genetics
- Plasma Membrane Neurotransmitter Transport Proteins/metabolism
- Speech Disorders/genetics
- Speech Disorders/metabolism
- Speech Disorders/pathology
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Affiliation(s)
- Layane Hanna-El-Daher
- Service of Biomedicine, Neurometabolic Unit, Lausanne University Hospital, 1011, Lausanne, Switzerland
| | - Olivier Braissant
- Service of Biomedicine, Neurometabolic Unit, Lausanne University Hospital, 1011, Lausanne, Switzerland.
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22
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Armour CM, Kersseboom S, Yoon G, Visser TJ. Further Insights into the Allan-Herndon-Dudley Syndrome: Clinical and Functional Characterization of a Novel MCT8 Mutation. PLoS One 2015; 10:e0139343. [PMID: 26426690 PMCID: PMC4591285 DOI: 10.1371/journal.pone.0139343] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 09/11/2015] [Indexed: 11/23/2022] Open
Abstract
Background Mutations in the thyroid hormone (TH) transporter MCT8 have been identified as the cause for Allan-Herndon-Dudley Syndrome (AHDS), characterized by severe psychomotor retardation and altered TH serum levels. Here we report a novel MCT8 mutation identified in 4 generations of one family, and its functional characterization. Methods Proband and family members were screened for 60 genes involved in X-linked cognitive impairment and the MCT8 mutation was confirmed. Functional consequences of MCT8 mutations were studied by analysis of [125I]TH transport in fibroblasts and transiently transfected JEG3 and COS1 cells, and by subcellular localization of the transporter. Results The proband and a male cousin demonstrated clinical findings characteristic of AHDS. Serum analysis showed high T3, low rT3, and normal T4 and TSH levels in the proband. A MCT8 mutation (c.869C>T; p.S290F) was identified in the proband, his cousin, and several female carriers. Functional analysis of the S290F mutant showed decreased TH transport, metabolism and protein expression in the three cell types, whereas the S290A mutation had no effect. Interestingly, both uptake and efflux of T3 and T4 was impaired in fibroblasts of the proband, compared to his healthy brother. However, no effect of the S290F mutation was observed on TH efflux from COS1 and JEG3 cells. Immunocytochemistry showed plasma membrane localization of wild-type MCT8 and the S290A and S290F mutants in JEG3 cells. Conclusions We describe a novel MCT8 mutation (S290F) in 4 generations of a family with Allan-Herndon-Dudley Syndrome. Functional analysis demonstrates loss-of-function of the MCT8 transporter. Furthermore, our results indicate that the function of the S290F mutant is dependent on cell context. Comparison of the S290F and S290A mutants indicates that it is not the loss of Ser but its substitution with Phe, which leads to S290F dysfunction.
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Affiliation(s)
- Christine M. Armour
- Regional Genetics Program, Children’s Hospital of Eastern Ontario, and Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada
| | - Simone Kersseboom
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Grace Yoon
- Department of Paediatrics, Divisions of Neurology and Clinical and Metabolic Genetics, Hospital for Sick Children, Toronto, Canada
| | - Theo J. Visser
- Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
- * E-mail:
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23
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Kumar R, Corbett MA, van Bon BWM, Woenig JA, Weir L, Douglas E, Friend KL, Gardner A, Shaw M, Jolly LA, Tan C, Hunter MF, Hackett A, Field M, Palmer EE, Leffler M, Rogers C, Boyle J, Bienek M, Jensen C, Van Buggenhout G, Van Esch H, Hoffmann K, Raynaud M, Zhao H, Reed R, Hu H, Haas SA, Haan E, Kalscheuer VM, Gecz J. THOC2 Mutations Implicate mRNA-Export Pathway in X-Linked Intellectual Disability. Am J Hum Genet 2015; 97:302-10. [PMID: 26166480 DOI: 10.1016/j.ajhg.2015.05.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 05/27/2015] [Indexed: 11/30/2022] Open
Abstract
Export of mRNA from the cell nucleus to the cytoplasm is essential for protein synthesis, a process vital to all living eukaryotic cells. mRNA export is highly conserved and ubiquitous. Mutations affecting mRNA and mRNA processing or export factors, which cause aberrant retention of mRNAs in the nucleus, are thus emerging as contributors to an important class of human genetic disorders. Here, we report that variants in THOC2, which encodes a subunit of the highly conserved TREX mRNA-export complex, cause syndromic intellectual disability (ID). Affected individuals presented with variable degrees of ID and commonly observed features included speech delay, elevated BMI, short stature, seizure disorders, gait disturbance, and tremors. X chromosome exome sequencing revealed four missense variants in THOC2 in four families, including family MRX12, first ascertained in 1971. We show that two variants lead to decreased stability of THOC2 and its TREX-complex partners in cells derived from the affected individuals. Protein structural modeling showed that the altered amino acids are located in the RNA-binding domains of two complex THOC2 structures, potentially representing two different intermediate RNA-binding states of THOC2 during RNA transport. Our results show that disturbance of the canonical molecular pathway of mRNA export is compatible with life but results in altered neuronal development with other comorbidities.
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MESH Headings
- Active Transport, Cell Nucleus/genetics
- Amino Acid Sequence
- Base Sequence
- Chromosomes, Human, X/genetics
- Humans
- Mental Retardation, X-Linked/genetics
- Mental Retardation, X-Linked/pathology
- Models, Molecular
- Molecular Sequence Data
- Mutation, Missense/genetics
- Pedigree
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- Sequence Analysis, DNA
- Syndrome
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Affiliation(s)
- Raman Kumar
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Mark A Corbett
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Bregje W M van Bon
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia; Department of Human Genetics, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6500 HB Nijmegen, the Netherlands
| | - Joshua A Woenig
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Lloyd Weir
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Evelyn Douglas
- Genetics and Molecular Pathology, SA Pathology, North Adelaide, SA 5006, Australia
| | - Kathryn L Friend
- Genetics and Molecular Pathology, SA Pathology, North Adelaide, SA 5006, Australia
| | - Alison Gardner
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Marie Shaw
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Lachlan A Jolly
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Chuan Tan
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia
| | - Matthew F Hunter
- Monash Genetics, Monash Medical Centre, Clayton, VIC 3168, Australia; Department of Paediatrics, Monash University, Clayton, VIC 3168, Australia
| | - Anna Hackett
- Genetics of Learning Disability Service, Hunter Genetics, Waratah, NSW 2298, Australia
| | - Michael Field
- Genetics of Learning Disability Service, Hunter Genetics, Waratah, NSW 2298, Australia
| | - Elizabeth E Palmer
- Genetics of Learning Disability Service, Hunter Genetics, Waratah, NSW 2298, Australia
| | - Melanie Leffler
- Genetics of Learning Disability Service, Hunter Genetics, Waratah, NSW 2298, Australia
| | - Carolyn Rogers
- Genetics of Learning Disability Service, Hunter Genetics, Waratah, NSW 2298, Australia
| | - Jackie Boyle
- Genetics of Learning Disability Service, Hunter Genetics, Waratah, NSW 2298, Australia
| | - Melanie Bienek
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Corinna Jensen
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | | | - Hilde Van Esch
- Center for Human Genetics, University Hospitals Leuven, Leuven 3000, Belgium
| | - Katrin Hoffmann
- Institute of Human Genetics, Martin Luther University Halle-Wittenberg, Magdeburger Strasse 2, 06112 Halle (Saale), Germany
| | - Martine Raynaud
- INSERM U930, Imaging and Brain, François-Rabelais University, 37000 Tours, France; INSERM U930, Service de Génétique, Centre Hospitalier Régional Universitaire, 37000 Tours, France
| | - Huiying Zhao
- QIMR Berghofer Medical Research Institute, Brisbane, QLD 4029, Australia
| | - Robin Reed
- Department of Cell Biology, Harvard Medical School, Harvard University, Boston, MA 02115, USA
| | - Hao Hu
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Stefan A Haas
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Eric Haan
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia; South Australian Clinical Genetics Service, SA Pathology, North Adelaide, SA 5006, Australia
| | - Vera M Kalscheuer
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany
| | - Jozef Gecz
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Adelaide, SA 5000, Australia; School of Molecular and Biomedical Sciences, University of Adelaide, Adelaide, SA 5005, Australia.
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24
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Abstract
Two severe, progressive neurological disorders characterized by intellectual disability, autism, and developmental regression, Rett syndrome and MECP2 duplication syndrome, result from loss and gain of function, respectively, of the same critical gene, methyl-CpG-binding protein 2 (MECP2). Neurons acutely require the appropriate dose of MECP2 to function properly but do not die in its absence or overexpression. Instead, neuronal dysfunction can be reversed in a Rett syndrome mouse model if MeCP2 function is restored. Thus, MECP2 disorders provide a unique window into the delicate balance of neuronal health, the power of mouse models, and the importance of chromatin regulation in mature neurons. In this Review, we will discuss the clinical profiles of MECP2 disorders, the knowledge acquired from mouse models of the syndromes, and how that knowledge is informing current and future clinical studies.
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25
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Abstract
PHF8 is a JmjC domain-containing histone demethylase, defects in which are associated with X-linked mental retardation. In this study, we examined the roles of two PHF8 homologs, JMJD-1.1 and JMJD-1.2, in the model organism C. elegans in response to DNA damage. A deletion mutation in either of the genes led to hypersensitivity to interstrand DNA crosslinks (ICLs), while only mutation of jmjd-1.1 resulted in hypersensitivity to double-strand DNA breaks (DSBs). In response to ICLs, JMJD-1.1 did not affect the focus formation of FCD-2, a homolog of FANCD2, a key protein in the Fanconi anemia pathway. However, the dynamic behavior of RPA-1 and RAD-51 was affected by the mutation: the accumulations of both proteins at ICLs appeared normal, but their subsequent disappearance was retarded, suggesting that later steps of homologous recombination were defective. Similar changes in the dynamic behavior of RPA-1 and RAD-51 were seen in response to DSBs, supporting a role of JMJD-1.1 in homologous recombination. Such a role was also supported by our finding that the hypersensitivity of jmjd-1.1 worms to ICLs was rescued by knockdown of lig-4, a homolog of Ligase 4 active in nonhomologous end-joining. The hypersensitivity of jmjd-1.1 worms to ICLs was increased by rad-54 knockdown, suggesting that JMJD-1.1 acts in parallel with RAD-54 in modulating chromatin structure. Indeed, the level of histone H3 Lys9 tri-methylation, a marker of heterochromatin, was higher in jmjd-1.1 cells than in wild-type cells. We conclude that the histone demethylase JMJD-1.1 influences homologous recombination either by relaxing heterochromatin structure or by indirectly regulating the expression of multiple genes affecting DNA repair.
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Affiliation(s)
- Changrim Lee
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Seokbong Hong
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Min Hye Lee
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Hyeon-Sook Koo
- Department of Biochemistry, College of Life Science & Biotechnology, Yonsei University, Seoul, Republic of Korea
- * E-mail:
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26
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Aypar U, Wirrell EC, Hoppman NL. CNKSR2 deletions: a novel cause of X-linked intellectual disability and seizures. Am J Med Genet A 2015; 167:1668-70. [PMID: 25754917 DOI: 10.1002/ajmg.a.36902] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 11/12/2014] [Indexed: 12/30/2022]
Affiliation(s)
- Umut Aypar
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | | | - Nicole L Hoppman
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
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Nozaki F, Kumada T, Shibata M, Fujii T, Wada T, Osaka H. [A family with creatine transporter deficiency diagnosed with urinary creatine/creatinine ratio and the family history: the third Japanese familial case]. No To Hattatsu 2015; 47:49-52. [PMID: 25803912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Creatine transporter deficiency (CRTR-D) is an X-linked disorder characterized by hypotonia, developmental delay, and seizures. We report the third Japanese family with CRTR-D. The proband was an 8-year-old boy who presented with hypotonia, severe intellectual disability and two episodes of seizures associated with/without fever. Among 7 siblings (4 males, 3 females), the eldest brother had severe intellectual disability, epilepsy, and sudden death at 17 years of age, while 18-year-old third elder brother had severe intellectual disability, autism, and drug-resistant epilepsy. The proband's urinary creatine/creatinine ratio was increased. A reduced creatine peak on brain magnetic resonance spectroscopy and a known pathogenic mutation in the SLC6A8 gene (c.1661 C > T;p.Pro554Leu) confirmed the diagnosis of CRTR-D. The same mutation was found in the third elder brother. Their mother was a heterozygote. Symptoms of CRTR-D are non-specific. Urinary creatine/creatinine ratio should be measured in patients with hypotonia, developmental delay, seizure and autism whose family history indicates an X-linked inheritance.
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MESH Headings
- Adolescent
- Brain Diseases, Metabolic, Inborn/complications
- Brain Diseases, Metabolic, Inborn/diagnosis
- Brain Diseases, Metabolic, Inborn/genetics
- Brain Diseases, Metabolic, Inborn/pathology
- Child
- Creatine/deficiency
- Creatine/genetics
- Creatine/urine
- Creatinine/urine
- Epilepsy/etiology
- Female
- Humans
- Magnetic Resonance Spectroscopy
- Male
- Mental Retardation, X-Linked/complications
- Mental Retardation, X-Linked/diagnosis
- Mental Retardation, X-Linked/genetics
- Mental Retardation, X-Linked/pathology
- Mutation/genetics
- Pedigree
- Plasma Membrane Neurotransmitter Transport Proteins/deficiency
- Plasma Membrane Neurotransmitter Transport Proteins/genetics
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Kobayashi S, Onuma A, Inui T, Wakusawa K, Tanaka S, Shimojima K, Yamamoto T, Haginoya K. Clinical course and images of four familial cases of Allan-Herndon-Dudley syndrome with a novel monocarboxylate transporter 8 gene mutation. Pediatr Neurol 2014; 51:414-6. [PMID: 25160547 DOI: 10.1016/j.pediatrneurol.2014.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 05/02/2014] [Accepted: 05/02/2014] [Indexed: 11/18/2022]
Abstract
BACKGROUND Allan-Herndon-Dudley syndrome, an X-linked condition characterized by severe intellectual disability, dysarthria, athetoid movements, muscle hypoplasia, and spastic paraplegia, is associated with defects in the monocarboxylate transporter 8 gene (MCT8). The long-term prognosis of Allan-Herndon-Dudley syndrome remains uncertain. PATIENTS We describe the clinical features and course of four adults in a family with Allan-Herndon-Dudley syndrome with athetoid type cerebral palsy. RESULTS We identified an MCT8 gene mutation in this family. Two of the four affected family members died at 32 and 24 years of age. CONCLUSIONS Individuals with Allan-Herndon-Dudley syndrome are at increased risk for recurrent infection, such as aspiration pneumonia. These individuals require careful management with consideration for this increased risk of recurrent infection.
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Affiliation(s)
- Satoru Kobayashi
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Japan.
| | - Akira Onuma
- Department of Pediatrics, Ekoh-Ryoikuen, Sendai, Japan
| | - Takehiko Inui
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Japan
| | - Keisuke Wakusawa
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Japan
| | - Soichiro Tanaka
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Japan
| | - Keiko Shimojima
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
| | - Toshiyuki Yamamoto
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Tokyo, Japan
| | - Kazuhiro Haginoya
- Department of Pediatric Neurology, Takuto Rehabilitation Center for Children, Sendai, Japan
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Qiao Y, Mondal K, Trapani V, Wen J, Carpenter G, Wildin R, Price EM, Gibbons RJ, Eichmeyer J, Jiang R, DuPont B, Martell S, Lewis SME, Robinson WP, O'Driscoll M, Wolf FI, Zwick ME, Rajcan-Separovic E. Variant ATRX syndrome with dysfunction of ATRX and MAGT1 genes. Hum Mutat 2014; 35:58-62. [PMID: 24130152 DOI: 10.1002/humu.22465] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/24/2013] [Accepted: 10/02/2013] [Indexed: 01/10/2023]
Abstract
A 0.8 kb intronic duplication in MAGT1 and a single base pair deletion in the last exon of ATRX were identified using a chromosome X-specific microarray and exome sequencing in a family with five males demonstrating intellectual disability (ID) and unusual skin findings (e.g., generalized pruritus). MAGT1 is an Mg²⁺ transporter previously associated with primary immunodeficiency and ID, whereas mutations in ATRX cause ATRX-ID syndrome. In patient cells, the function of ATRX was demonstrated to be abnormal based on altered RNA/protein expression, hypomethylation of rDNA, and abnormal cytokinesis. Dysfunction of MAGT1 was reflected in reduced RNA/protein expression and Mg²⁺ influx. The mutation in ATRX most likely explains the ID, whereas MAGT1 disruption could be linked to abnormal skin findings, as normal magnesium homeostasis is necessary for skin health. This work supports observations that multiple mutations collectively contribute to the phenotypic variability of syndromic ID, and emphasizes the importance of correlating clinical phenotype with genomic and cell function analyses.
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Abstract
Mitosis and meiosis are essential processes that occur during development. Throughout these processes, cohesion is required to keep the sister chromatids together until their separation at anaphase. Cohesion is created by multiprotein subunit complexes called cohesins. Although the subunits differ slightly in mitosis and meiosis, the canonical cohesin complex is composed of four subunits that are quite diverse. The cohesin complexes are also important for DNA repair, gene expression, development, and genome integrity. Here we provide an overview of the roles of cohesins during these different events as well as their roles in human health and disease, including the cohesinopathies. Although the exact roles and mechanisms of these proteins are still being elucidated, this review serves as a guide for the current knowledge of cohesins.
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Affiliation(s)
- Amanda S Brooker
- Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, 245 N. 15th Street, MS 497, Philadelphia, PA, 19102, USA
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31
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López-Marín L, Martín-Belinchón M, Gutiérrez-Solana LG, Morte-Molina B, Duat-Rodríguez A, Bernal J. [MCT8-specific thyroid hormone cell transporter deficiency: a case report and review of the literature]. Rev Neurol 2013; 56:615-622. [PMID: 23744248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
INTRODUCTION MCT8 is a specific transporter for the T4 and T3 thyroid hormones that allows their entry in the brain and other organs. Mutations in MCT8 (Allan-Herndon-Dudley syndrome) lead to a severe form of X-linked psychomotor retardation, which is characterised by elevated plasma T3 and low T4. AIM We describe the first case diagnosed in Spain with this syndrome and review the published literature about this topic. We both review the various clinical presentations, genetic advances, differential diagnosis and therapeutic perspectives of this syndrome and propose a diagnostic algorithm for it. CASE REPORT A 5 year-old boy, with a clinical picture compatible with Pelizaeus-Merzbacher disease. PLP1 gene sequencing showed no abnormalities. All the genetic and metabolic studies conducted were normal. Finally, a complete study of thyroid profile revealed abnormalities that were consistent with MCT8 transporter deficiency. The sequencing of the SLC16A2 gene (MCT8) showed a mutation in exon 3 and the study made at a cellular level, has confirmed that this mutation changes the properties of the protein. CONCLUSIONS In the last five years, there have been many publications about this syndrome, with the identification of more than 50 families worldwide. It is important to both know and suspect this syndrome, because the diagnosis is easy, cheap and accessible (thyroid profile) and, although it has no specific treatment, early diagnosis prevents unnecessary testing and allows to offer genetic counseling to the families affected by it.
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MESH Headings
- Amino Acid Substitution
- Anticonvulsants/therapeutic use
- Biological Transport
- Brain/pathology
- Child, Preschool
- Cord Blood Stem Cell Transplantation
- Diagnosis, Differential
- Dystonic Disorders/genetics
- Exons/genetics
- Genetic Diseases, X-Linked/diagnosis
- Genetic Diseases, X-Linked/drug therapy
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/pathology
- Genetic Diseases, X-Linked/surgery
- Genotype
- Humans
- Intellectual Disability/genetics
- Magnetic Resonance Imaging
- Male
- Mental Retardation, X-Linked/diagnosis
- Mental Retardation, X-Linked/drug therapy
- Mental Retardation, X-Linked/genetics
- Mental Retardation, X-Linked/pathology
- Mental Retardation, X-Linked/surgery
- Monocarboxylic Acid Transporters/chemistry
- Monocarboxylic Acid Transporters/deficiency
- Monocarboxylic Acid Transporters/genetics
- Monocarboxylic Acid Transporters/physiology
- Muscle Hypotonia/diagnosis
- Muscle Hypotonia/drug therapy
- Muscle Hypotonia/genetics
- Muscle Hypotonia/pathology
- Muscle Hypotonia/surgery
- Muscular Atrophy/diagnosis
- Muscular Atrophy/drug therapy
- Muscular Atrophy/genetics
- Muscular Atrophy/pathology
- Muscular Atrophy/surgery
- Nystagmus, Pathologic/genetics
- Pelizaeus-Merzbacher Disease/diagnosis
- Point Mutation
- Symporters
- Thyroxine/blood
- Triiodothyronine/blood
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Affiliation(s)
- Laura López-Marín
- Sección de Neuropediatría, Hospital Infantil Universitario Niño Jesús.
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32
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Rehnberg M, Jonasson J, Gunnarsson C. Novel L1CAM splice site mutation in a young male with L1 syndrome. Am J Med Genet A 2010; 155A:439-41. [PMID: 21271669 DOI: 10.1002/ajmg.a.33803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 10/18/2010] [Indexed: 01/21/2023]
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33
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Reardon W, Donoghue V, Murphy AM, King MD, Mayne PD, Horn N, Birk Møller L. Progressive cerebellar degenerative changes in the severe mental retardation syndrome caused by duplication of MECP2 and adjacent loci on Xq28. Eur J Pediatr 2010; 169:941-9. [PMID: 20177701 DOI: 10.1007/s00431-010-1144-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 01/15/2010] [Indexed: 11/26/2022]
Abstract
Localised duplications, involving the MECP2 locus, at Xq28 have been associated with a syndrome comprising X-linked mental retardation, hypotonia and recurrent infections in males. We now present neuroradiological evidence that progressive cerebellar degenerative changes may also be a consistent feature of this syndrome, emerging in the second decade of life. We report seven affected males, from three different families who, in addition to the previously described clinical findings, have a reduction in the volume of the white matter and mild dilatation of the lateral ventricles. Three of the older patients show a consistent cerebellar degenerative phenotype. Furthermore, we describe the first female affected with the disorder. The female was mildly affected and shows X-inactivation in the ratio of 70:30, demonstrating that X-inactivation cannot be exclusively relied upon to spare the female carriers from symptoms. In conclusion, there is a radiological phenotype associated with Xq28 duplication which clearly demonstrates progressive degenerative cerebellar disease as part of the syndrome.
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Morís G, Arias M, López MV, Alvarez V. Hyperintensity in the basis pontis: atypical neuroradiological findings in a woman with FXTAS. Mov Disord 2010; 25:649-50. [PMID: 20201003 DOI: 10.1002/mds.22811] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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35
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Tarpey PS, Raymond FL, Nguyen LS, Rodriguez J, Hackett A, Vandeleur L, Smith R, Shoubridge C, Edkins S, Stevens C, O'Meara S, Tofts C, Barthorpe S, Buck G, Cole J, Halliday K, Hills K, Jones D, Mironenko T, Perry J, Varian J, West S, Widaa S, Teague J, Dicks E, Butler A, Menzies A, Richardson D, Jenkinson A, Shepherd R, Raine K, Moon J, Luo Y, Parnau J, Bhat SS, Gardner A, Corbett M, Brooks D, Thomas P, Parkinson-Lawrence E, Porteous ME, Warner JP, Sanderson T, Pearson P, Simensen RJ, Skinner C, Hoganson G, Superneau D, Wooster R, Bobrow M, Turner G, Stevenson RE, Schwartz CE, Futreal PA, Srivastava AK, Stratton MR, Gécz J. Mutations in UPF3B, a member of the nonsense-mediated mRNA decay complex, cause syndromic and nonsyndromic mental retardation. Nat Genet 2007; 39:1127-33. [PMID: 17704778 PMCID: PMC2872770 DOI: 10.1038/ng2100] [Citation(s) in RCA: 191] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2007] [Accepted: 06/11/2007] [Indexed: 12/11/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is of universal biological significance. It has emerged as an important global RNA, DNA and translation regulatory pathway. By systematically sequencing 737 genes (annotated in the Vertebrate Genome Annotation database) on the human X chromosome in 250 families with X-linked mental retardation, we identified mutations in the UPF3 regulator of nonsense transcripts homolog B (yeast) (UPF3B) leading to protein truncations in three families: two with the Lujan-Fryns phenotype and one with the FG phenotype. We also identified a missense mutation in another family with nonsyndromic mental retardation. Three mutations lead to the introduction of a premature termination codon and subsequent NMD of mutant UPF3B mRNA. Protein blot analysis using lymphoblastoid cell lines from affected individuals showed an absence of the UPF3B protein in two families. The UPF3B protein is an important component of the NMD surveillance machinery. Our results directly implicate abnormalities of NMD in human disease and suggest at least partial redundancy of NMD pathways.
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Affiliation(s)
- Patrick S Tarpey
- Cancer Genome Project, Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
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36
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Menten B, Buysse K, Vermeulen S, Meersschaut V, Vandesompele J, Ng BL, Carter NP, Mortier GR, Speleman F. Report of a female patient with mental retardation and tall stature due to a chromosomal rearrangement disrupting the OPHN1 gene on Xq12. Eur J Med Genet 2007; 50:446-54. [PMID: 17845870 PMCID: PMC2688819 DOI: 10.1016/j.ejmg.2007.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2007] [Accepted: 07/21/2007] [Indexed: 10/23/2022]
Abstract
We report on a patient with mental retardation, seizures and tall stature with advanced bone age in whom a de novo apparently balanced chromosomal rearrangement 46,XX,t(X;9)(q12;p13.3) was identified. Using array CGH on flow-sorted derivative chromosomes (array painting) and subsequent FISH and qPCR analysis, we mapped and sequenced both breakpoints. The Xq12 breakpoint was located within the gene coding for oligophrenin 1 (OPHN1) whereas the 9p13.3 breakpoint was assigned to a non-coding segment within a gene dense region. Disruption of OPHN1 by the Xq12 breakpoint was considered the major cause of the abnormal phenotype observed in the proband.
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Affiliation(s)
- Björn Menten
- Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium.
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37
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Shoubridge C, Cloosterman D, Parkinson-Lawerence E, Brooks D, Gécz J. Molecular pathology of expanded polyalanine tract mutations in the Aristaless-related homeobox gene. Genomics 2007; 90:59-71. [PMID: 17490853 DOI: 10.1016/j.ygeno.2007.03.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 03/14/2007] [Accepted: 03/14/2007] [Indexed: 11/30/2022]
Abstract
The Aristaless-related homeobox gene (ARX) is one of the major genes causing X-linked mental retardation. We have been interested in the pathogenic mechanism of expanded polyalanine tract mutations in ARX. We showed that the c.304ins(GCG)7 mutation causing an increase from 16 to 23 alanines increased the propensity of ARX protein aggregation and a shift from nuclear to cytoplasmic localization. We proposed that mislocalization of ARX via cytoplasmic aggregation and subsequent degradation leads to a partial loss of function, contributing to the pathogenesis. We identified importin 13 (IPO13), a mediator of nuclear import for a variety of proteins, as a novel ARX interacting protein. We predicted that the transport of ARX by IPO13 from the cytoplasm to the nucleus might be disrupted by expanded polyalanine tract mutations, but our data showed that in both yeast and mammalian cells these mutant ARX proteins were still able to interact with IPO13. We established the nuclear localization regions of the ARX homeodomain that were required for the interaction with IPO13 and correct localization of the full-length ARX transcription factor to the nucleus.
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Affiliation(s)
- Cheryl Shoubridge
- Department of Genetic Medicine, Women's and Children's Hospital, Adelaide 5006, Australia.
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38
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Cilliers DD, Parveen R, Clayton P, Cairns SA, Clarke S, Shalet SM, Black GCM, Newman WG, Clayton-Smith J. A new X-linked mental retardation (XLMR) syndrome with late-onset primary testicular failure, short stature and microcephaly maps to Xq25–q26. Eur J Med Genet 2007; 50:216-23. [PMID: 17369115 DOI: 10.1016/j.ejmg.2007.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2006] [Accepted: 01/07/2007] [Indexed: 10/23/2022]
Abstract
X-linked mental retardation (XLMR) is a heterogeneous disorder with both syndromic and non-syndromic forms. Here we describe the clinical and molecular characterisation of a family with a syndromic form of XLMR with hypogonadism and short stature. We investigated a family in which four male members in two generations presented with hypergonadotrophic hypogonadism associated with development of small and abnormal testes. In two of the males, late-onset testicular ascent was noted. In addition, all affected males had short stature (<0.4th centile) and mild learning difficulties and three out of the four had microcephaly. Karyotypes were normal and endocrine investigations confirmed primary testicular failure. The phenotype segregated as an X-linked trait. Haplotype and genetic two-point linkage analysis with 22 microsatellites excluded the whole X chromosome except for a region on Xq25-Xq27 encompassing 13.7Mb with a maximum LOD score of 1.1 for marker DXS8038 at theta=0.05. One family previously described as having XLMR with hypogonadism and short stature maps to the same X chromosome region implicated in our family. However, the more severe mental retardation, muscle wasting and tremor described in this other family would suggest that our family is affected by a novel XLMR syndrome.
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Affiliation(s)
- Deirdre D Cilliers
- Academic Department of Medical Genetics and Regional Genetic Services, St Mary's Hospital, University of Manchester, Manchester, UK.
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39
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Schwartz CE, Tarpey PS, Lubs HA, Verloes A, May MM, Risheg H, Friez MJ, Futreal PA, Edkins S, Teague J, Briault S, Skinner C, Bauer-Carlin A, Simensen RJ, Joseph SM, Jones JR, Gecz J, Stratton MR, Raymond FL, Stevenson RE. The original Lujan syndrome family has a novel missense mutation (p.N1007S) in the MED12 gene. J Med Genet 2007; 44:472-7. [PMID: 17369503 PMCID: PMC2597996 DOI: 10.1136/jmg.2006.048637] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
A novel missense mutation in the mediator of RNA polymerase II transcription subunit 12 (MED12) gene has been found in the original family with Lujan syndrome and in a second family (K9359) that was initially considered to have Opitz-Kaveggia (FG) syndrome. A different missense mutation in the MED12 gene has been reported previously in the original family with FG syndrome and in five other families with compatible clinical findings. Neither sequence alteration has been found in over 1400 control X chromosomes. Lujan (Lujan-Fryns) syndrome is characterised by tall stature with asthenic habitus, macrocephaly, a tall narrow face, maxillary hypoplasia, a high narrow palate with dental crowding, a small or receding chin, long hands with hyperextensible digits, hypernasal speech, hypotonia, mild-to-moderate mental retardation, behavioural aberrations and dysgenesis of the corpus callosum. Although Lujan syndrome has not been previously considered to be in the differential diagnosis of FG syndrome, there are some overlapping clinical manifestations. Specifically, these are dysgenesis of the corpus callosum, macrocephaly/relative macrocephaly, a tall forehead, hypotonia, mental retardation and behavioural disturbances. Thus, it seems that these two X-linked mental retardation syndromes are allelic, with mutations in the MED12 gene.
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40
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Budny B, Chen W, Omran H, Fliegauf M, Tzschach A, Wisniewska M, Jensen LR, Raynaud M, Shoichet SA, Badura M, Lenzner S, Latos-Bielenska A, Ropers HH. A novel X-linked recessive mental retardation syndrome comprising macrocephaly and ciliary dysfunction is allelic to oral–facial–digital type I syndrome. Hum Genet 2006; 120:171-8. [PMID: 16783569 DOI: 10.1007/s00439-006-0210-5] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2006] [Accepted: 05/15/2006] [Indexed: 10/24/2022]
Abstract
We report on a large family in which a novel X-linked recessive mental retardation (XLMR) syndrome comprising macrocephaly and ciliary dysfunction co-segregates with a frameshift mutation in the OFD1 gene. Mutations of OFD1 have been associated with oral-facial-digital type 1 syndrome (OFD1S) that is characterized by X-chromosomal dominant inheritance and lethality in males. In contrast, the carrier females of our family were clinically inconspicuous, and the affected males suffered from severe mental retardation, recurrent respiratory tract infections and macrocephaly. All but one of the affected males died from respiratory problems in infancy; and impaired ciliary motility was confirmed in the index patient by high-speed video microscopy examination of nasal epithelium. This family broadens the phenotypic spectrum of OFD1 mutations in an unexpected way and sheds light on the complexity of the underlying disease mechanisms.
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Affiliation(s)
- Bartlomiej Budny
- Max Planck Institute for Molecular Genetics, Ihnestr. 73, 14195, Berlin, Germany
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41
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Abstract
X-linked alpha thalassemia mental retardation (ATR-X) syndrome is associated with profound developmental delay, facial dysmorphism, genital abnormalities, and alpha thalassemia. Patients with ATR-X syndrome frequently present with gastrointestinal problems, in particular feeding difficulties, regurgitation and vomiting, abdominal pain, distension, and chronic constipation. Parental reports of prolonged food refusal and distress in these children are common and although these episodes are suspected to be gastro-intestinal in origin they are rarely investigated. Death in early childhood from aspiration of vomitus or from pneumonia presumed to be secondary to aspiration has been recorded in a number of ATR-X cases. In this report we review the gastrointestinal phenotype of ATR-X syndrome in 128 cases. We also demonstrate that in two siblings, regurgitation was secondary to gastric pseudo-volvulus, a condition in which the stomach does not have a normal system of peritoneal ligaments and changes position with possible torsion around itself. Furthermore, ultra-short Hirschsprung disease with colonic hypoganglionosis was shown and this may contribute to the severe constipation affecting these children.
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Affiliation(s)
- Giuseppe Martucciello
- Scientific Institute (IRCCS) Policlinico San Matteo, University of Genoa, Pavia, Italy
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42
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Zhang LJ, Zhang FC, Gao XC. [Progress in the study of OPHN1 gene]. Sheng Li Ke Xue Jin Zhan 2006; 37:69-71. [PMID: 16683552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
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43
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Badens C, Martini N, Courrier S, DesPortes V, Touraine R, Levy N, Edery P. ATRX syndrome in a girl with a heterozygous mutation in theATRX Zn finger domain and a totally skewed X-inactivation pattern. Am J Med Genet A 2006; 140:2212-5. [PMID: 16955409 DOI: 10.1002/ajmg.a.31400] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mutations in the X-encoded gene ATRX are known to give rise to syndromic mental retardation in male patients whereas female carriers show preferential inactivation of the mutated X chromosome and appear healthy. Here, we describe a 4-year-old girl with typical features of ATRX syndrome, carrying the recurrent R246C mutation of ATRX. We show that her pattern of X-inactivation is totally skewed and that her active X chromosome which harbors the ATRX mutation, was maternally inherited. To our knowledge, this is the first report of ATRX syndrome in a female patient. Since she was born after in vitro fertilization (IVF), we propose a possible link between assisted reproduction technologies (ART) and the unexpected X chromosome methylation pattern that we observed.
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Affiliation(s)
- Catherine Badens
- Laboratoire de Génétique Moléculaire, Hôpital d'enfants de la Timone, Marseille, France
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Tabolacci E, Zollino M, Lecce R, Sangiorgi E, Gurrieri F, Leuzzi V, Opitz JM, Neri G. Two brothers with 22q13 deletion syndrome and features suggestive of the Clark-Baraitser syndrome. Clin Dysmorphol 2005; 14:127-132. [PMID: 15930901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We report on two brothers with moderate-to-severe mental retardation, severe macrocephaly, obesity, characteristic face, big hands and feet, advanced bone age and brain abnormalities, including frontal cortical atrophy. These two boys resembled the two brothers described by , two maternal cousins subsequently reported by and a Brazilian boy described by . Upon further investigation, we detected a cryptic subtelomeric deletion of chromosome region 22q13, not present in either parent and probably due to a maternal germinal mosaicism. Thus, we describe the first familial case of 22q13 deletion and recommend that patients with a phenotype suggestive of the so-called Clark-Baraitser syndrome be tested for submicroscopic 22qter deletion.
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Affiliation(s)
- Elisabetta Tabolacci
- Institute of Medical Genetics, Catholic University, Rome, Italy Department of Neurological and Psychiatric Sciences, University of Rome 'La Sapienza', Italy Pediatrics, Human Genetics, Obstetrics and Ginecology, University of Utah, Salt Lake City, Utah
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Mendicino A, Sabbadini G, Pergola MS. Clark-Baraitser syndrome: report of a new case and review of the literature. Clin Dysmorphol 2005; 14:133-135. [PMID: 15930902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
We describe the case of a boy with moderate mental retardation associated with tall stature, obesity, macrocephaly and typical facial features, characterized by a large 'square' forehead, prominent supraorbital ridges, broad nasal tip, prominent lower lip and minor dental anomalies. We think that our proband is affected by Clark-Baraitser syndrome, a rare X-linked mental retardation disorder, to date described only in five male subjects. We present a more complete definition of the clinical phenotype of the syndrome with particular attention to the behavioural aspect that, in combination with the body size and the dysmorphic picture, we think is distinctive for the Clark-Baraitser syndrome. We also summarize the mild features described in female relatives of the patients, as it could disclose a possible carrier condition and be of help with genetic counselling in the families with male patients, until a molecular test is available.
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Affiliation(s)
- Angela Mendicino
- U.O. di Genetica, Dipartimento Materno Infantile, ASL RME, Rome, Italy Istituto PRODA, Rome, Italy
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Bérubé NG, Mangelsdorf M, Jagla M, Vanderluit J, Garrick D, Gibbons RJ, Higgs DR, Slack RS, Picketts DJ. The chromatin-remodeling protein ATRX is critical for neuronal survival during corticogenesis. J Clin Invest 2005; 115:258-67. [PMID: 15668733 PMCID: PMC544602 DOI: 10.1172/jci22329] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Accepted: 11/30/2004] [Indexed: 12/18/2022] Open
Abstract
Mutations in genes encoding chromatin-remodeling proteins, such as the ATRX gene, underlie a number of genetic disorders including several X-linked mental retardation syndromes; however, the role of these proteins in normal CNS development is unknown. Here, we used a conditional gene-targeting approach to inactivate Atrx, specifically in the forebrain of mice. Loss of ATRX protein caused widespread hypocellularity in the neocortex and hippocampus and a pronounced reduction in forebrain size. Neuronal "birthdating" confirmed that fewer neurons reached the superficial cortical layers, despite normal progenitor cell proliferation. The loss of cortical mass resulted from a 12-fold increase in neuronal apoptosis during early stages of corticogenesis in the mutant animals. Moreover, cortical progenitors isolated from Atrx-null mice undergo enhanced apoptosis upon differentiation. Taken together, our results indicate that ATRX is a critical mediator of cell survival during early neuronal differentiation. Thus, increased neuronal loss may contribute to the severe mental retardation observed in human patients.
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Affiliation(s)
- Nathalie G Bérubé
- Molecular Medicine Programs, Ottawa Health Research Institute, Ottawa, Ontario, Canada
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Mancini GMS, Catsman-Berrevoets CE, de Coo IFM, Aarsen FK, Kamphoven JHJ, Huijmans JG, Duran M, van der Knaap MS, Jakobs C, Salomons GS. Two novel mutations in SLC6A8 cause creatine transporter defect and distinctive X-linked mental retardation in two unrelated Dutch families. Am J Med Genet A 2005; 132A:288-95. [PMID: 15690373 DOI: 10.1002/ajmg.a.30473] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Four Dutch male patients, two brothers from unrelated families were referred for investigation of psychomotor and severe language/speech delay. All four patients showed growth deficiency over the years. Facial features and poor body habitus were quite similar in the patients and in their mothers. Brain MRI showed nonspecific periventricular white matter lesions. In all the patients neuropsychological tests revealed moderate mental retardation, attention deficit and hyperactivity with impulsivity, a semantic-pragmatic language disorder, and oral dyspraxia. This specific cognitive profile is different from other children with mental retardation syndromes and seems to be unique. Excretion of creatine to creatinine ratio in urine of the four boys was increased compared to controls and their creatine uptake in fibroblasts was deficient. In the two brothers from the first pedigree, DNA sequence analysis revealed a novel mutation in the splice donor site in intron 10 (IVS10 + 5G>C, c.1495 + 5G>C) of the SLC6A8 gene leading to skipping of exon 10. In the other sib pair a novel missense mutation (c. 1361C>T; p.Pro544Leu) was found. These are the first families reported, in which the clinical suspicion of a creatine transporter disorder was raised on clinical grounds, before a brain 1H-MRS suggested the diagnosis. Screening of apparently X-linked mental retarded patients with this somatic and behavioral phenotype by the biochemical assay of creatine to creatinine ratio in the urine or DNA sequence analysis of SLC6A8 is worthwhile even when 1H-MRS is not available.
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Affiliation(s)
- G M S Mancini
- Department of Clinical Genetics, Erasmus University MC/Sophia Children's Hospital, Rotterdam, The Netherlands.
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Renieri A, Pescucci C, Longo I, Ariani F, Mari F, Meloni I. Non-syndromic X-linked mental retardation: From a molecular to a clinical point of view. J Cell Physiol 2005; 204:8-20. [PMID: 15690397 DOI: 10.1002/jcp.20296] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This review focuses on the 19 identified genes involved in X-linked "non-syndromic" mental retardation (MR) and defines the signaling pathways in which they are involved, focusing on emerging common mechanisms. The majority of proteins are involved in three distinct pathways: (1) Rho GTPases pathway modulating neuronal differentiation and synaptic plasticity; (2) Rab GTPases pathway regulating synaptic vesicle cycling; (3) gene expression regulation. The function of four proteins (ACSL4, AT2, SLC6A8, and SAP102) could not be reconciled to a common pathway. From a clinical point of view, the review discusses whether some common dysmorphic features can be identified even in non-syndromic MR patients and whether it is correct to maintain the distinction between "non-syndromic" and "syndromic" MR.
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Affiliation(s)
- A Renieri
- Medical Genetics, Department of Molecular Biology, University of Siena, Siena, Italy.
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Stevenson RE, Bennett CW, Abidi F, Kleefstra T, Porteous M, Simensen RJ, Lubs HA, Hamel BCJ, Schwartz CE. Renpenning syndrome comes into focus. Am J Med Genet A 2005; 134:415-21. [PMID: 15782410 DOI: 10.1002/ajmg.a.30664] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Renpenning syndrome represents a prototypic X-linked mental retardation condition with full expression of the phenotype in males and little or no expression in females. The predominant clinical findings are microcephaly, long narrow face, short stature with lean body build, and small testes. Mental retardation, usually of severe degree, occurs in 95% of cases. Less than 20% of cases have major malformations, the most common being cardiac defects and cleft palate. Subsequent to the description of mutations in the polyglutamine tract binding protein 1 (PQBP1) in Sutherland-Haan syndrome, Hamel cerebropalatocardiac syndrome, MRX55, and two small XLMR families, a single nucleotide insertion has been found in the original family with Renpenning syndrome and an AGAG deletion in a second family with the Renpenning syndrome. Mutations have also been found in Golabi-Ito-Hall syndrome, Porteous syndrome, and an additional small family. It is now demonstrated that five named XLMR syndromes (Sutherland-Haan, Hamel cerebropalatocardiac, Golabi-Ito-Hall, Porteous, and Renpenning), one nonsyndromic family (MRX55), and three small XLMR families have PQBP1 mutations and are thus allelic XLMR entities. In acknowledgement of the historical importance of the original report of Renpenning syndrome [1962], we propose that the entities with PQBP1 mutations be combined under the name of Renpenning syndrome.
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Abstract
Fragile X syndrome represents the most common inherited cause of mental retardation. It is caused by a stretch of CGG repeats within the fragile X gene, which increases in length as it is transmitted from generation to generation. Once the repeat exceeds a threshold length, no protein is produced, resulting in the fragile X phenotype. Both X chromosome inactivation and inactivation of the FMR1 gene are the result of methylation. X inactivation occurs earlier than inactivation of the FMR1 gene. The instability to a full mutation is dependent on the sex of the transmitting parent and occurs only from mother to child. For most X-chromosomal diseases, female carriers do not express the phenotype. A clear exception is fragile X syndrome. It is clear that more than 50% of the neurons have to express the protein to ensure a normal phenotype in females. This means that a normal phenotype in female carriers of a full mutation is accompanied by a distortion of the normal distribution of X inactivation.
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Affiliation(s)
- B A Oostra
- Department of Clinical Genetics, Erasmus MC, Rotterdam, The Netherlands.
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