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Noojarern S, Tim-Aroon T, Anurat K, Phetthong T, Khongkraparn A, Wattanasirichaigoon D. A novel AP1S2 variant causing leaky splicing in X-linked intellectual disability: Further delineation and intrafamilial variability. Am J Med Genet A 2024; 194:e63639. [PMID: 38682877 DOI: 10.1002/ajmg.a.63639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 04/07/2024] [Accepted: 04/11/2024] [Indexed: 05/01/2024]
Abstract
Pettigrew syndrome (PGS), an X-linked intellectual disability (XLID), is caused by mutations in the AP1S2 gene. Herein, we described a Thai family with six patients who had severe-to-profound intellectual impairment, limited verbal communication, and varying degrees of limb spasticity. One patient had a unilateral cataract. We demonstrated facial evolution over time, namely coarse facies, long faces, and thick lip vermilions. We identified a novel AP1S2 variant, c.1-2A>G. The mRNA analysis revealed that the variant resulted in splicing defects with leaky splicing, yielding two distinct aberrant transcripts, one of which likely resulting in the mutant protein lacking the first 44 amino acids whereas the other possibly leading to no production of the protein. By performing a literature review, we found 51 patients and 11 AP1S2 pathogenic alleles described and that all the variants were loss-of-function alleles. The severity of ID in Pettigrew syndrome is mostly severe-to-profound (54.8%), followed by moderate (26.2%) and mild. Progressive spasticity was noted in multiple patients. In summary, leaky splicing found in the present family was likely related to the intrafamilial clinical variability. Our data also support the previous notion of variable expression and neuroprogressive nature of the disorder.
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Affiliation(s)
- Saisuda Noojarern
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Thipwimol Tim-Aroon
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Kingthong Anurat
- Chakri Naruebodindra Medical Institute, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Samut Prakan, Thailand
| | - Tim Phetthong
- Division of Medical Genetics, Department of Pediatrics, Phramongkutklao Hospital and Phramongkutklao College of Medicine, Bangkok, Thailand
| | - Arthaporn Khongkraparn
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Duangrurdee Wattanasirichaigoon
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
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Kundishora AJ, Singh AK, Allington G, Duy PQ, Ryou J, Alper SL, Jin SC, Kahle KT. Genomics of human congenital hydrocephalus. Childs Nerv Syst 2021; 37:3325-3340. [PMID: 34232380 DOI: 10.1007/s00381-021-05230-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 05/24/2021] [Indexed: 12/12/2022]
Abstract
Congenital hydrocephalus (CH), characterized by enlarged brain ventricles, is considered a disease of pathological cerebrospinal fluid (CSF) accumulation and, therefore, treated largely by neurosurgical CSF diversion. The persistence of ventriculomegaly and poor neurodevelopmental outcomes in some post-surgical patients highlights our limited knowledge of disease mechanisms. Recent whole-exome sequencing (WES) studies have shown that rare, damaging de novo and inherited mutations with large effect contribute to ~ 25% of sporadic CH. Interestingly, multiple CH genes are key regulators of neural stem cell growth and differentiation and converge in human transcriptional networks and cell types pertinent to fetal neurogliogenesis. These data implicate genetic disruption of early brain development as the primary pathomechanism in a substantial minority of patients with sporadic CH, shedding new light on human brain development and the pathogenesis of hydrocephalus. These data further suggest WES as a clinical tool with potential to re-classify CH according to a molecular nomenclature of increased precision and utility for genetic counseling, outcome prognostication, and treatment stratification.
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Affiliation(s)
- Adam J Kundishora
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Amrita K Singh
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Garrett Allington
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Phan Q Duy
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Jian Ryou
- Department of Genetics, Washington University School of Medicine, St Louis, MO, USA
| | - Seth L Alper
- Division of Nephrology and Center for Vascular Biology Research, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Sheng Chih Jin
- Department of Genetics, Washington University School of Medicine, St Louis, MO, USA
| | - Kristopher T Kahle
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA.
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Faergeman SL, Evans H, Attfield KE, Desel C, Kuttikkatte SB, Sommerlund M, Jensen LT, Frokiaer J, Friese MA, Matthews PM, Luchtenborg C, Brügger B, Oturai AB, Dendrou CA, Fugger L. A novel neurodegenerative spectrum disorder in patients with MLKL deficiency. Cell Death Dis 2020; 11:303. [PMID: 32358523 PMCID: PMC7195448 DOI: 10.1038/s41419-020-2494-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 04/06/2020] [Accepted: 04/07/2020] [Indexed: 12/14/2022]
Abstract
Mixed lineage kinase domain-like (MLKL) is the main executor of necroptosis, an inflammatory form of programmed cell death. Necroptosis is implicated in combating infections, but also in contributing to numerous other clinical conditions, including cardiovascular diseases and neurodegenerative disorders. Inhibition of necroptosis is therefore of therapeutic interest. Here we report two siblings both of whom over the course of 35 years developed a similar progressive, neurodegenerative spectrum disorder characterized by paresis, ataxia and dysarthria. Magnetic resonance imaging of their central nervous system (CNS) revealed severe global cerebral volume loss and atrophy of the cerebellum and brainstem. These brothers are homozygous for a rare haplotype identified by whole genome sequencing carrying a frameshift variant in MLKL, as well as an in-frame deletion of one amino acid in the adjacent fatty acid 2-hydroxylase (FA2H) gene. Functional studies of patient-derived primary cells demonstrated that the variant in MLKL leads to a deficiency of MLKL protein resulting in impairment of necroptosis. Conversely, shotgun lipidomic analysis of the variant in FA2H shows no impact on either the abundance or the enzymatic activity of the encoded hydroxylase. To our knowledge, this is the first report of complete necroptosis deficiency in humans. The findings may suggest that impaired necroptosis is a novel mechanism of neurodegeneration, promoting a disorder that shares some clinical features with primary progressive multiple sclerosis (PPMS) and other neurodegenerative diseases. Importantly, the necroptotic deficiency does not cause symptoms outside the nervous system, nor does it confer susceptibility to infections. Given the current interest in pharmacological inhibition of necroptosis by targeting MLKL and its associated pathways, this strategy should be developed with caution, with careful consideration of the possible development of adverse neurological effects.
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Affiliation(s)
- Soren L Faergeman
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Hayley Evans
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Kathrine E Attfield
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Christiane Desel
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Subita Balaram Kuttikkatte
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK
| | - Mette Sommerlund
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Lise Torp Jensen
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Jorgen Frokiaer
- Department of Clinical Medicine, Aarhus University Hospital, Aarhus, DK-8200, Denmark
| | - Manuel A Friese
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, Hamburg, 20246, Germany
| | - Paul M Matthews
- Division of Brain Sciences, Department of Medicine, UK Dementia Research Institute, Imperial College London, London, SW7 2AZ, UK
| | | | - Britta Brügger
- Heidelberg University Biochemistry Center (BZH), Heidelberg, D-69120, Germany
| | - Annette Bang Oturai
- Danish Multiple Sclerosis Center, Department of Neurology, Copenhagen University Hospital, Copenhagen, 2100, Denmark
| | - Calliope A Dendrou
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Lars Fugger
- Oxford Centre for Neuroinflammation, Nuffield Department of Clinical Neurosciences, Division of Clinical Neurology, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK.
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, OX3 9DS, UK.
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Huo L, Teng Z, Wang H, Liu X. A novel splice site mutation in AP1S2 gene for X-linked mental retardation in a Chinese pedigree and literature review. Brain Behav 2019; 9:e01221. [PMID: 30714330 PMCID: PMC6422709 DOI: 10.1002/brb3.1221] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Pettigrew syndrome (PGS) is a rare X-linked mental retardation that caused by AP1S2 mutation. The pathogenesis of AP1S2 deficiency has remained elusive. The purpose of this study is to give a comprehensive overview of the phenotypic and genetic spectrum of AP1S2 mutations. METHODS This study systematically analyzed clinical features and genetic information of a Chinese family with AP1S2 variation, and reviewed previously reported literatures with the same gene variation. RESULTS We identified a new c.1-1 G>C mutation in AP1S2 gene from a four generation family with seven affected individuals and found the elevated neuron-specific enolase (NSE) in a patient. We summarized the clinical manifestation of 59 patients with AP1S2 mutation. We found that pathogenic point mutations affecting AP1S2 are associated with dysmorphic features and neurodevelopmental problems, which included highly variable mental retardation (MR), delayed in walking, abnormal speech, hypotonia, abnormal brain, abnormal behavior including aggressive behavior, ASD, self-abusive, and abnormal gait. Patients with splice site mutation were more likely to lead to seizures. By contrast, patients with nonsense mutations are more susceptible to microcephaly. CONCLUSION Our findings suggest AP1S2 mutations contribute to a broad spectrum of neurodevelopmental disorders and are important in the etiological spectrum of PGS.
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Affiliation(s)
- Liang Huo
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Ziteng Teng
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Hua Wang
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Xueyan Liu
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, China
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Martinelli D, Dionisi-Vici C. AP1S1 defect causing MEDNIK syndrome: a new adaptinopathy associated with defective copper metabolism. Ann N Y Acad Sci 2014; 1314:55-63. [DOI: 10.1111/nyas.12426] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Diego Martinelli
- Unit of Metabolism; Department of Pediatrics; Bambino Gesu Children's Hospital; Rome Italy
- Section on Translational Neuroscience; Molecular Medicine Program; NICHD/NIH; Bethesda Maryland
| | - Carlo Dionisi-Vici
- Unit of Metabolism; Department of Pediatrics; Bambino Gesu Children's Hospital; Rome Italy
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Stevenson RE, Schwartz CE, Rogers RC. Malformations among the X-linked intellectual disability syndromes. Am J Med Genet A 2013; 161A:2741-9. [PMID: 24166814 DOI: 10.1002/ajmg.a.36179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 07/15/2013] [Indexed: 11/08/2022]
Abstract
Malformations are significant contributions to childhood mortality and disability. Their co-occurrence with intellectual disability may compound the health burden, requiring additional evaluation and management measures. Overall, malformations of greater or lesser severity occur in at least some cases of almost half of the 153 XLID syndromes. Genitourinary abnormalities are most common, but tend to contribute little or no health burden and occur in only a minority of cases of a given XLID syndrome. Some malformations (e.g., lissencephaly, hydranencephaly, long bone deficiency, renal agenesis/dysplasia) are not amenable to medical or surgical intervention; others (e.g., hydrocephaly, facial clefting, cardiac malformations, hypospadias) may be substantially corrected.
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Cacciagli P, Desvignes JP, Girard N, Delepine M, Zelenika D, Lathrop M, Lévy N, Ledbetter DH, Dobyns WB, Villard L. AP1S2 is mutated in X-linked Dandy-Walker malformation with intellectual disability, basal ganglia disease and seizures (Pettigrew syndrome). Eur J Hum Genet 2013; 22:363-8. [PMID: 23756445 DOI: 10.1038/ejhg.2013.135] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 05/14/2013] [Accepted: 05/15/2013] [Indexed: 11/09/2022] Open
Abstract
MRXS5 or Pettigrew syndrome was described 20 years ago in a four generation family including nine affected individuals presenting with facial dysmorphism, intellectual disability, Dandy-Walker malformation and inconstant choreoathetosis. Four individuals had iron deposition in the basal ganglia seen on MRI or at autopsy. The mutation causing Pettigrew has remained elusive since the initial description of the condition. We report the identification of a mutation in the X-linked AP1S2 gene in the original Pettigrew syndrome family using X-chromosome exome sequencing. We report additional phenotype details for several of the affected individuals, allowing us to further refine the phenotype corresponding to this X-linked intellectual disability syndrome. The AP1S2 c.426+1 G>T mutation segregates with the disease in the Pettigrew syndrome family and results in loss of 46 amino acids in the clathrin adaptor complex small chain domain that spans most of the AP1S2 protein sequence. The mutation reported here in AP1S2 is the first mutation that is not predicted to cause a premature termination of the coding sequence or absence of the AP1S2 protein. Although most of the families affected by a mutation in AP1S2 were initially described as having different disorders assigned to at least three different OMIM numbers (MIM 300629, 300630 and 304340), our analysis of the phenotype shows that they are all the same syndrome with recognition complicated by highly variable expressivity that is seen within as well as between families and is probably not explained by differences in mutation severity.
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Affiliation(s)
- Pierre Cacciagli
- 1] Inserm, U910, Faculté de Médecine de La Timone, Marseille, France [2] Aix Marseille Université, Faculté de Médecine, Marseille, France [3] Assistance Publique Hôpitaux de Marseille, Département de Génétique Médicale et de Biologie Cellulaire, Hôpital d'Enfants de La Timone, Marseille, France
| | - Jean-Pierre Desvignes
- 1] Inserm, U910, Faculté de Médecine de La Timone, Marseille, France [2] Aix Marseille Université, Faculté de Médecine, Marseille, France
| | - Nadine Girard
- Assistance Publique Hôpitaux de Marseille, Service de Neuroradiologie, Hôpital de La Timone, Marseille, France
| | - Marc Delepine
- Commissariat à l'Energie Atomique, Institut Génomique, Centre National de Génotypage, Evry, France
| | - Diana Zelenika
- Commissariat à l'Energie Atomique, Institut Génomique, Centre National de Génotypage, Evry, France
| | - Mark Lathrop
- 1] Commissariat à l'Energie Atomique, Institut Génomique, Centre National de Génotypage, Evry, France [2] Fondation Jean Dausset - CEPH, Paris, France
| | - Nicolas Lévy
- 1] Inserm, U910, Faculté de Médecine de La Timone, Marseille, France [2] Aix Marseille Université, Faculté de Médecine, Marseille, France [3] Assistance Publique Hôpitaux de Marseille, Département de Génétique Médicale et de Biologie Cellulaire, Hôpital d'Enfants de La Timone, Marseille, France
| | | | - William B Dobyns
- Departments of Pediatrics and Neurology, University of Washington, Center for Integrative Brain Research, Seattle Children's Hospital, Seattle, Washington, USA
| | - Laurent Villard
- 1] Inserm, U910, Faculté de Médecine de La Timone, Marseille, France [2] Aix Marseille Université, Faculté de Médecine, Marseille, France
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Bardoni B, Abekhoukh S, Zongaro S, Melko M. Intellectual disabilities, neuronal posttranscriptional RNA metabolism, and RNA-binding proteins: three actors for a complex scenario. PROGRESS IN BRAIN RESEARCH 2012; 197:29-51. [PMID: 22541287 DOI: 10.1016/b978-0-444-54299-1.00003-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Intellectual disability (ID) is the most frequent cause of serious handicap in children and young adults and interests 2-3% of worldwide population, representing a serious problem from the medical, social, and economic points of view. The causes are very heterogeneous. Genes involved in ID have various functions altering different pathways important in neuronal function. Regulation of mRNA metabolism is particularly important in neurons for synaptic structure and function. Here, we review ID due to alteration of mRNA metabolism. Functional absence of some RNA-binding proteins--namely, FMRP, FMR2P, PQBP1, UFP3B, VCX-A--causes different forms of ID. These proteins are involved in different steps of RNA metabolism and, even if a detailed analysis of their RNA targets has been performed so far only for FMRP, it appears clear that they modulate some aspects (translation, stability, transport, and sublocalization) of a subset of RNAs coding for proteins, whose function must be relevant for neurons. Two other proteins, DYRK1A and CDKL5, involved in Down syndrome and Rett syndrome, respectively, have been shown to have an impact on splicing efficiency of specific mRNAs. Both proteins are kinases and their effect is indirect. Interestingly, both are localized in nuclear speckles, the nuclear domains where splicing factors are assembled, stocked, and recycled and influence their biogenesis and/or their organization.
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Affiliation(s)
- Barbara Bardoni
- Institute of Molecular and Cellular Pharmacology, CNRS-UMR6097, Université de Nice Sophia-Antipolis,Valbonne, France.
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Deletion of the AP1S2 gene in a child with psychomotor delay and hypotonia. Eur J Med Genet 2011; 55:124-7. [PMID: 22210230 DOI: 10.1016/j.ejmg.2011.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 12/09/2011] [Indexed: 01/28/2023]
Abstract
We identified a 495 Kb interstitial deletion of chromosome Xp22.2, centered on the AP1S2 gene, by means of oligonucleotide array comparative genomic hybridisation (array-CGH) in a child with marked hypotonia in the first months of life, psychomotor retardation, severely delayed walking and speech development, and unspecific dysmorphic facial features. The deletion was inherited from the healthy mother. Point mutations of the AP1S2 gene have been identified in patients with X-linked mental retardation (XLMR). The clinical features of our patient are quite similar to those reported in male patients carrying point mutations, thus suggesting that point mutations and deletions of the AP1S2 gene lead to a recognisable XLMR phenotype in males.
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Phadke SR, Sharda S, Urquhart J, Jenkinson E, Chawala S, Trump D. Report of two brothers with short stature, microcephaly, mental retardation, and retinoschisis-A new mental retardation syndrome? Am J Med Genet A 2010; 155A:9-13. [DOI: 10.1002/ajmg.a.33663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 07/18/2010] [Indexed: 11/07/2022]
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du Souich C, Chou A, Yin J, Oh T, Nelson TN, Hurlburt J, Arbour L, Friedlander R, McGillivray BC, Tyshchenko N, Rump A, Poskitt KJ, Demos MK, Van Allen MI, Boerkoel CF. Characterization of a new X-linked mental retardation syndrome with microcephaly, cortical malformation, and thin habitus. Am J Med Genet A 2010; 149A:2469-78. [PMID: 19842190 DOI: 10.1002/ajmg.a.33071] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
X-linked mental retardation (XLMR) affects 1-2/1,000 males and accounts for approximately 10% of all mental retardation (MR). We have ascertained a syndromic form of XLMR segregating within a five-generation family with seven affected males. Prominent characteristics include mild to severe MR, cortical malformation, microcephaly, seizures, thin build with distinct facial features including a long and thin face, epicanthic folds, almond-shaped eyes, upslanting palpebral fissures and micrognathia and behavioral problems. Carrier females have normal physical appearance and intelligence. This combination of features is unreported and distinct from Lujan-Fryns syndrome, Snyder-Robinson syndrome, and zinc finger DHHC domain-containing 9-associated MR. We propose the name of this new syndrome to be CK syndrome.
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12
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Phylogeny of proteolipid proteins: divergence, constraints, and the evolution of novel functions in myelination and neuroprotection. ACTA ACUST UNITED AC 2009; 4:111-27. [PMID: 19497142 DOI: 10.1017/s1740925x0900009x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The protein composition of myelin in the central nervous system (CNS) has changed at the evolutionary transition from fish to tetrapods, when a lipid-associated transmembrane-tetraspan (proteolipid protein, PLP) replaced an adhesion protein of the immunoglobulin superfamily (P0) as the most abundant constituent. Here, we review major steps of proteolipid evolution. Three paralog proteolipids (PLP/DM20/DMalpha, M6B/DMgamma and the neuronal glycoprotein M6A/DMbeta) exist in vertebrates from cartilaginous fish to mammals, and one (M6/CG7540) can be traced in invertebrate bilaterians including the planktonic copepod Calanus finmarchicus that possess a functional myelin equivalent. In fish, DMalpha and DMgamma are coexpressed in oligodendrocytes but are not major myelin components. PLP emerged at the root of tetrapods by the acquisition of an enlarged cytoplasmic loop in the evolutionary older DMalpha/DM20. Transgenic experiments in mice suggest that this loop enhances the incorporation of PLP into myelin. The evolutionary recruitment of PLP as the major myelin protein provided oligodendrocytes with the competence to support long-term axonal integrity. We suggest that the molecular shift from P0 to PLP also correlates with the concentration of adhesive forces at the radial component, and that the new balance between membrane adhesion and dynamics was favorable for CNS myelination.
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Borck G, Mollà-Herman A, Boddaert N, Encha-Razavi F, Philippe A, Robel L, Desguerre I, Brunelle F, Benmerah A, Munnich A, Colleaux L. Clinical, cellular, and neuropathological consequences ofAP1S2mutations: further delineation of a recognizable X-linked mental retardation syndrome. Hum Mutat 2008; 29:966-74. [DOI: 10.1002/humu.20531] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Tarpey PS, Stevens C, Teague J, Edkins S, O'Meara S, Avis T, Barthorpe S, Buck G, Butler A, Cole J, Dicks E, Gray K, Halliday K, Harrison R, Hills K, Hinton J, Jones D, Menzies A, Mironenko T, Perry J, Raine K, Richardson D, Shepherd R, Small A, Tofts C, Varian J, West S, Widaa S, Yates A, Catford R, Butler J, Mallya U, Moon J, Luo Y, Dorkins H, Thompson D, Easton DF, Wooster R, Bobrow M, Carpenter N, Simensen RJ, Schwartz CE, Stevenson RE, Turner G, Partington M, Gecz J, Stratton MR, Futreal PA, Raymond FL. Mutations in the gene encoding the Sigma 2 subunit of the adaptor protein 1 complex, AP1S2, cause X-linked mental retardation. Am J Hum Genet 2006; 79:1119-24. [PMID: 17186471 PMCID: PMC1698718 DOI: 10.1086/510137] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Accepted: 10/06/2006] [Indexed: 02/03/2023] Open
Abstract
In a systematic sequencing screen of the coding exons of the X chromosome in 250 families with X-linked mental retardation (XLMR), we identified two nonsense mutations and one consensus splice-site mutation in the AP1S2 gene on Xp22 in three families. Affected individuals in these families showed mild-to-profound mental retardation. Other features included hypotonia early in life and delay in walking. AP1S2 encodes an adaptin protein that constitutes part of the adaptor protein complex found at the cytoplasmic face of coated vesicles located at the Golgi complex. The complex mediates the recruitment of clathrin to the vesicle membrane. Aberrant endocytic processing through disruption of adaptor protein complexes is likely to result from the AP1S2 mutations identified in the three XLMR-affected families, and such defects may plausibly cause abnormal synaptic development and function. AP1S2 is the first reported XLMR gene that encodes a protein directly involved in the assembly of endocytic vesicles.
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Affiliation(s)
- Patrick S Tarpey
- Cancer Genome Project, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
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