1
|
Espinosa-Mojica AA, Varo Varo C. Determining the Linguistic Profile of Children With Rare Genetic Disorders. JOURNAL OF SPEECH, LANGUAGE, AND HEARING RESEARCH : JSLHR 2024; 67:170-186. [PMID: 38085694 DOI: 10.1044/2023_jslhr-23-00101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
PURPOSE Language studies on populations with rare genetic disorders are limited. Hence, there is little data on commonly found or expected developmental linguistic traits and cognitive mechanisms that may be impaired. Based on the hypothesis that there is a close connection between language and cognition and the relevance of specific genetic changes in the development of each, our goal was to provide linguistic data on relationships with other executive functioning mechanisms. METHOD This study assessed language skills, communicative behaviors, and executive functions in four children, aged 7-9 years, with rare genetic disorders, using standardized protocols and tests. RESULTS The findings revealed different levels of language impairment and executive functioning problems in each case. The overall executive function index performance for each of the four cases studied was clinically significantly high, indicating executive dysfunction. CONCLUSIONS The cases analyzed illustrate different types of atypical development that affect both language and other cognitive mechanisms and underscore the importance of executive skills and the various ways in which they are involved in diverse levels of language that might be affected to a greater or lesser degree in rare genetic disorders. In conclusion, we found that language dysfunction is a salient feature of the rare genetic disorders included in our study, although this is not necessarily true for all genetic disorders. Along with these conclusive results, we performed a qualitative analysis of the linguistic and cognitive components that enable functional communication in order to allow optimal interpretation of the data we have collected, laying the foundations for a more effective therapeutic approach.
Collapse
|
2
|
Church JA, Grigorenko EL, Fletcher JM. The Role of Neural and Genetic Processes in Learning to Read and Specific Reading Disabilities: Implications for Instruction. READING RESEARCH QUARTERLY 2023; 58:203-219. [PMID: 37456924 PMCID: PMC10348696 DOI: 10.1002/rrq.439] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 06/29/2021] [Indexed: 07/18/2023]
Abstract
To learn to read, the brain must repurpose neural systems for oral language and visual processing to mediate written language. We begin with a description of computational models for how alphabetic written language is processed. Next, we explain the roles of a dorsal sublexical system in the brain that relates print and speech, a ventral lexical system that develops the visual expertise for rapid orthographic processing at the word level, and the role of cognitive control networks that regulate attentional processes as children read. We then use studies of children, adult illiterates learning to read, and studies of poor readers involved in intervention, to demonstrate the plasticity of these neural networks in development and in relation to instruction. We provide a brief overview of the rapid increase in the field's understanding and technology for assessing genetic influence on reading. Family studies of twins have shown that reading skills are heritable, and molecular genetic studies have identified numerous regions of the genome that may harbor candidate genes for the heritability of reading. In selected families, reading impairment has been associated with major genetic effects, despite individual gene contributions across the broader population that appear to be small. Neural and genetic studies do not prescribe how children should be taught to read, but these studies have underscored the critical role of early intervention and ongoing support. These studies also have highlighted how structured instruction that facilitates access to the sublexical components of words is a critical part of training the brain to read.
Collapse
Affiliation(s)
| | - Elena L Grigorenko
- University of Houston, Texas, USA; Baylor College of Medicine, Houston, Texas, USA; and St. Petersburg State University, Russia
| | | |
Collapse
|
3
|
Whole-genome sequencing identifies functional noncoding variation in SEMA3C that cosegregates with dyslexia in a multigenerational family. Hum Genet 2021; 140:1183-1200. [PMID: 34076780 PMCID: PMC8263547 DOI: 10.1007/s00439-021-02289-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 04/27/2021] [Indexed: 12/11/2022]
Abstract
Dyslexia is a common heritable developmental disorder involving impaired reading abilities. Its genetic underpinnings are thought to be complex and heterogeneous, involving common and rare genetic variation. Multigenerational families segregating apparent monogenic forms of language-related disorders can provide useful entrypoints into biological pathways. In the present study, we performed a genome-wide linkage scan in a three-generational family in which dyslexia affects 14 of its 30 members and seems to be transmitted with an autosomal dominant pattern of inheritance. We identified a locus on chromosome 7q21.11 which cosegregated with dyslexia status, with the exception of two cases of phenocopy (LOD = 2.83). Whole-genome sequencing of key individuals enabled the assessment of coding and noncoding variation in the family. Two rare single-nucleotide variants (rs144517871 and rs143835534) within the first intron of the SEMA3C gene cosegregated with the 7q21.11 risk haplotype. In silico characterization of these two variants predicted effects on gene regulation, which we functionally validated for rs144517871 in human cell lines using luciferase reporter assays. SEMA3C encodes a secreted protein that acts as a guidance cue in several processes, including cortical neuronal migration and cellular polarization. We hypothesize that these intronic variants could have a cis-regulatory effect on SEMA3C expression, making a contribution to dyslexia susceptibility in this family.
Collapse
|
4
|
The Polygenic Nature and Complex Genetic Architecture of Specific Learning Disorder. Brain Sci 2021; 11:brainsci11050631. [PMID: 34068951 PMCID: PMC8156942 DOI: 10.3390/brainsci11050631] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 12/16/2022] Open
Abstract
Specific Learning Disorder (SLD) is a multifactorial, neurodevelopmental disorder which may involve persistent difficulties in reading (dyslexia), written expression and/or mathematics. Dyslexia is characterized by difficulties with speed and accuracy of word reading, deficient decoding abilities, and poor spelling. Several studies from different, but complementary, scientific disciplines have investigated possible causal/risk factors for SLD. Biological, neurological, hereditary, cognitive, linguistic-phonological, developmental and environmental factors have been incriminated. Despite worldwide agreement that SLD is highly heritable, its exact biological basis remains elusive. We herein present: (a) an update of studies that have shaped our current knowledge on the disorder’s genetic architecture; (b) a discussion on whether this genetic architecture is ‘unique’ to SLD or, alternatively, whether there is an underlying common genetic background with other neurodevelopmental disorders; and, (c) a brief discussion on whether we are at a position of generating meaningful correlations between genetic findings and anatomical data from neuroimaging studies or specific molecular/cellular pathways. We conclude with open research questions that could drive future research directions.
Collapse
|
5
|
Grimm T, Garshasbi M, Puettmann L, Chen W, Ullmann R, Müller-Myhsok B, Klopocki E, Herbst L, Haug J, Jensen LR, Fischer C, Nöthen M, Ludwig K, Warnke A, Ott J, Schulte-Körne G, Ropers HH, Kuss AW. A Novel Locus and Candidate Gene for Familial Developmental Dyslexia on Chromosome 4q. ZEITSCHRIFT FUR KINDER-UND JUGENDPSYCHIATRIE UND PSYCHOTHERAPIE 2020; 48:478-489. [PMID: 33172359 DOI: 10.1024/1422-4917/a000758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Objective: Developmental dyslexia is a highly heritable specific reading and writing disability. To identify a possible new locus and candidate gene for this disability, we investigated a four-generation pedigree where transmission of dyslexia is consistent with an autosomal dominant inheritance pattern. Methods: We performed genome wide array-based SNP genotyping and parametric linkage analysis and sequencing analysis of protein-coding exons, exon-intron boundaries and conserved extragenic regions within the haplotype cosegregating with dyslexia in DNA from one affected and one unaffected family member. Cosegregation was confirmed by sequencing all available family members. Additionally, we analyzed 96 dyslexic individuals who had previously shown positive LOD scores on chromosome 4q28 as well as an even larger sample (n = 2591). Results: We found a single prominent linkage interval on chromosome 4q, where sequence analysis revealed a nucleotide variant in the 3' UTR of brain expressed SPRY1 in the dyslexic family member that cosegregated with dyslexia. This sequence alteration might affect the binding efficiency of the IGF2BP1 RNA-binding protein and thus influence the expression level of the SPRY1 gene product. An analysis of 96 individuals from a cohort of dyslexic individuals revealed a second heterozygous variant in this gene, which was absent in the unaffected sister of the proband. An investigation of the region in a much larger sample further found a nominal p-value of 0.0016 for verbal short-term memory (digit span) in 2,591 individuals for a neighboring SNV. After correcting for the local number of analyzed SNVs, and after taking into account linkage disequilibrium, we found this corresponds to a p-value of 0.0678 for this phenotype. Conclusions: We describe a new locus for familial dyslexia and discuss the possibility that SPRY1 might play a role in the etiology of a monogenic form of dyslexia.
Collapse
Affiliation(s)
- Tiemo Grimm
- Department of Human Genetics, Biozentrum, University of Würzburg, Germany
| | - Masoud Garshasbi
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Lucia Puettmann
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Wei Chen
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Reinhard Ullmann
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | | | - Eva Klopocki
- Department of Human Genetics, Biozentrum, University of Würzburg, Germany
| | - Lina Herbst
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Janina Haug
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Lars R Jensen
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | | | - Markus Nöthen
- Institute of Human Genetics, University of Bonn, Germany
| | - Kerstin Ludwig
- Institute of Human Genetics, University of Bonn, Germany
| | - Andreas Warnke
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Würzburg, Germany
| | - Jürg Ott
- Laboratory of Statistical Genetics, Rockefeller University, New York, USA
| | - Gerd Schulte-Körne
- Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Munich, Germany
| | - Hans-Hilger Ropers
- Department for Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Andreas W Kuss
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Germany
| |
Collapse
|
6
|
Israfil A, Israfil N. RETRACTED: Temperament gene inheritance. Meta Gene 2020. [DOI: 10.1016/j.mgene.2020.100728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
7
|
Karipidis II, Hong DS. Specific learning disorders in sex chromosome aneuploidies: Neural circuits of literacy and mathematics. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:518-530. [DOI: 10.1002/ajmg.c.31801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 05/02/2020] [Accepted: 05/07/2020] [Indexed: 01/25/2023]
Affiliation(s)
- Iliana I. Karipidis
- Center for Interdisciplinary Brain Sciences Research, Department of Psychiatry and Behavioral SciencesSchool of Medicine, Stanford University Stanford California USA
| | - David S. Hong
- Center for Interdisciplinary Brain Sciences Research, Department of Psychiatry and Behavioral SciencesSchool of Medicine, Stanford University Stanford California USA
| |
Collapse
|
8
|
Müller B, Schaadt G, Boltze J, Emmrich F, Skeide MA, Neef NE, Kraft I, Brauer J, Friederici AD, Kirsten H, Wilcke A. ATP2C2 and DYX1C1 are putative modulators of dyslexia-related MMR. Brain Behav 2017; 7:e00851. [PMID: 29201552 PMCID: PMC5698869 DOI: 10.1002/brb3.851] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 08/23/2017] [Accepted: 09/01/2017] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Dyslexia is a specific learning disorder affecting reading and spelling abilities. Its prevalence is ~5% in German-speaking individuals. Although the etiology of dyslexia largely remains to be determined, comprehensive evidence supports deficient phonological processing as a major contributing factor. An important prerequisite for phonological processing is auditory discrimination and, thus, essential for acquiring reading and spelling skills. The event-related potential Mismatch Response (MMR) is an indicator for auditory discrimination capabilities with dyslexics showing an altered late component of MMR in response to auditory input. METHODS In this study, we comprehensively analyzed associations of dyslexia-specific late MMRs with genetic variants previously reported to be associated with dyslexia-related phenotypes in multiple studies comprising 25 independent single-nucleotide polymorphisms (SNPs) within 10 genes. RESULTS First, we demonstrated validity of these SNPs for dyslexia in our sample by showing that additional inclusion of a polygenic risk score improved prediction of impaired writing compared with a model that used MMR alone. Secondly, a multifactorial regression analysis was conducted to uncover the subset of the 25 SNPs that is associated with the dyslexia-specific late component of MMR. In total, four independent SNPs within DYX1C1 and ATP2C2 were found to be associated with MMR stronger than expected from multiple testing. To explore potential pathomechanisms, we annotated these variants with functional data including tissue-specific expression analysis and eQTLs. CONCLUSION Our findings corroborate the late component of MMR as a potential endophenotype for dyslexia and support tripartite relationships between dyslexia-related SNPs, the late component of MMR and dyslexia.
Collapse
Affiliation(s)
- Bent Müller
- Fraunhofer Institute for Cell Therapy and Immunology Leipzig Germany
| | - Gesa Schaadt
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany.,Department of Psychology Humboldt-Universität zu Berlin Berlin Germany
| | - Johannes Boltze
- Fraunhofer Institute for Cell Therapy and Immunology Leipzig Germany.,Department of Medical Cell Technology Fraunhofer Research Institution for Marine Biotechnology Lübeck Germany.,Institute for Medical and Marine Biotechnology University of Lübeck Lübeck Germany
| | - Frank Emmrich
- Fraunhofer Institute for Cell Therapy and Immunology Leipzig Germany
| | | | - Michael A Skeide
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Nicole E Neef
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Indra Kraft
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Jens Brauer
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Angela D Friederici
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Holger Kirsten
- Fraunhofer Institute for Cell Therapy and Immunology Leipzig Germany.,Institute for Medical Informatics Statistics and Epidemiology University of Leipzig Leipzig Germany.,LIFE-Leipzig Research Center for Civilization Diseases University of Leipzig Leipzig Germany
| | - Arndt Wilcke
- Fraunhofer Institute for Cell Therapy and Immunology Leipzig Germany
| |
Collapse
|
9
|
Parrila RK, Protopapas A. Dyslexia and word reading problems. STUDIES IN WRITTEN LANGUAGE AND LITERACY 2017. [DOI: 10.1075/swll.15.19par] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
10
|
Chen XS, Reader RH, Hoischen A, Veltman JA, Simpson NH, Francks C, Newbury DF, Fisher SE. Next-generation DNA sequencing identifies novel gene variants and pathways involved in specific language impairment. Sci Rep 2017; 7:46105. [PMID: 28440294 PMCID: PMC5404330 DOI: 10.1038/srep46105] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/08/2017] [Indexed: 12/22/2022] Open
Abstract
A significant proportion of children have unexplained problems acquiring proficient linguistic skills despite adequate intelligence and opportunity. Developmental language disorders are highly heritable with substantial societal impact. Molecular studies have begun to identify candidate loci, but much of the underlying genetic architecture remains undetermined. We performed whole-exome sequencing of 43 unrelated probands affected by severe specific language impairment, followed by independent validations with Sanger sequencing, and analyses of segregation patterns in parents and siblings, to shed new light on aetiology. By first focusing on a pre-defined set of known candidates from the literature, we identified potentially pathogenic variants in genes already implicated in diverse language-related syndromes, including ERC1, GRIN2A, and SRPX2. Complementary analyses suggested novel putative candidates carrying validated variants which were predicted to have functional effects, such as OXR1, SCN9A and KMT2D. We also searched for potential “multiple-hit” cases; one proband carried a rare AUTS2 variant in combination with a rare inherited haplotype affecting STARD9, while another carried a novel nonsynonymous variant in SEMA6D together with a rare stop-gain in SYNPR. On broadening scope to all rare and novel variants throughout the exomes, we identified biological themes that were enriched for such variants, including microtubule transport and cytoskeletal regulation.
Collapse
Affiliation(s)
- Xiaowei Sylvia Chen
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
| | - Rose H Reader
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Alexander Hoischen
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joris A Veltman
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Clinical Genetics, University of Maastricht, Maastricht, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Nuala H Simpson
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Clyde Francks
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| | - Dianne F Newbury
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK.,Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Oxford, UK
| | - Simon E Fisher
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands.,Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands
| |
Collapse
|
11
|
Kong R, Shao S, Wang J, Zhang X, Guo S, Zou L, Zhong R, Lou J, Zhou J, Zhang J, Song R. Genetic variant in DIP2A gene is associated with developmental dyslexia in Chinese population. Am J Med Genet B Neuropsychiatr Genet 2016; 171B:203-8. [PMID: 26452339 DOI: 10.1002/ajmg.b.32392] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/02/2015] [Indexed: 11/07/2022]
Abstract
Increasing evidence suggests that there is a substantial heritable component including several risk loci and candidate genes for developmental dyslexia (DD). DIP2A has been identified to be partially deleted on chromosome region 21q22.3, which cosegregates with DD. And it fits into a theoretical molecular network of DD implicated in the development of DD. Compared with some DD candidate genes that have been extensively studied (e.g., DYX1C1, DCDC2, KIAA0319, and ROBO1), very little is known about the association between candidate gene DIP2A and DD susceptibility. And given the linguistic and genetic differences between Chinese and other Western populations, it is worthwhile validating the association of DIP2A in Chinese dyslexic children. Here, we investigated two genetic variants, selected by bioinformatics analysis, in DIP2A in a Chinese population with 409 dyslexic cases and 410 healthy controls. We observed a significantly increased DD risk associated with rs2255526 G allele (OR = 1.297, 95% CI = 1.036-1.623, Padjusted = 0.023) and GG genotypes (OR = 1.833, 95% CI = 1.043-3.223, Padjusted = 0.035), compared with their wild-type counterparts. In addition, it was marginally significantly associated with DD under the recessive model (OR = 1.677, 95% CI = 0.967-2.908, Padjusted = 0.066) and the dominant model (OR = 1.314, 95% CI = 0.992-1.741, Padjusted = 0.057). However, we found no evidence of an association of SNP rs16979358 with DD. In conclusion, this study showed that a genetic variant in the DIP2A gene was associated with increased DD risk in China.
Collapse
Affiliation(s)
- Rui Kong
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shanshan Shao
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jia Wang
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaohui Zhang
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shengnan Guo
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li Zou
- Department of Health Care, Baoan Maternal and Child Health Hospital, Shenzhen, China
| | - Rong Zhong
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiao Lou
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jie Zhou
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, District of Columbia
| | - Jiajia Zhang
- Department of Epidemiology and Biostatistics, Arnold School of Public Health, University of South Carolina, District of Columbia
| | - Ranran Song
- Department of Maternal and Child Health and MOE (Ministry of Education) Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| |
Collapse
|
12
|
Eckert MA, Berninger VW, Hoeft F, Vaden KI. A case of Bilateral Perisylvian Syndrome with reading disability. Cortex 2016; 76:121-4. [PMID: 26861558 PMCID: PMC4776332 DOI: 10.1016/j.cortex.2016.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 12/23/2015] [Accepted: 01/05/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Mark A Eckert
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, United States.
| | - Virginia W Berninger
- Department of Educational Psychology, University of Washington, Seattle, WA, United States
| | - Fumiko Hoeft
- Department of Psychiatry, University of California San Francisco, San Francisco, CA, United States
| | - Kenneth I Vaden
- Department of Otolaryngology - Head and Neck Surgery, Medical University of South Carolina, Charleston, SC, United States
| |
Collapse
|
13
|
Paracchini S, Diaz R, Stein J. Advances in Dyslexia Genetics—New Insights Into the Role of Brain Asymmetries. ADVANCES IN GENETICS 2016; 96:53-97. [DOI: 10.1016/bs.adgen.2016.08.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
14
|
Insights into the genetic foundations of human communication. Neuropsychol Rev 2015; 25:3-26. [PMID: 25597031 DOI: 10.1007/s11065-014-9277-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 12/22/2014] [Indexed: 12/19/2022]
Abstract
The human capacity to acquire sophisticated language is unmatched in the animal kingdom. Despite the discontinuity in communicative abilities between humans and other primates, language is built on ancient genetic foundations, which are being illuminated by comparative genomics. The genetic architecture of the language faculty is also being uncovered by research into neurodevelopmental disorders that disrupt the normally effortless process of language acquisition. In this article, we discuss the strategies that researchers are using to reveal genetic factors contributing to communicative abilities, and review progress in identifying the relevant genes and genetic variants. The first gene directly implicated in a speech and language disorder was FOXP2. Using this gene as a case study, we illustrate how evidence from genetics, molecular cell biology, animal models and human neuroimaging has converged to build a picture of the role of FOXP2 in neurodevelopment, providing a framework for future endeavors to bridge the gaps between genes, brains and behavior.
Collapse
|
15
|
Mueller B, Ahnert P, Burkhardt J, Brauer J, Czepezauer I, Quente E, Boltze J, Wilcke A, Kirsten H. Genetic risk variants for dyslexia on chromosome 18 in a German cohort. GENES BRAIN AND BEHAVIOR 2014; 13:350-6. [PMID: 24373531 DOI: 10.1111/gbb.12118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/18/2013] [Accepted: 12/24/2013] [Indexed: 01/17/2023]
Abstract
Dyslexia is characterized by impaired reading and spelling. The disorder has a prevalence of about 5% in Germany, and a strong hereditary component. Several loci are thought to be involved in the development of dyslexia. Scerri et al. identified eight potential dyslexia-associated single nucleotide polymorphisms (SNPs) in seven genes on chromosome 18 in an English-speaking population. Here, we present an association analysis that explores the relevance of these SNPs in a German population comprising 388 dyslexia cases and 364 control cases. In case-control analysis, three nominal SNP associations were replicated. The major alleles of NEDD4L-rs12606138 and NEDD4L-rs8094327 were risk associated [odds ratio (OR) = 1.35, 95% confidence interval (CI) = 1.0-1.7, P-value = 0.017 and OR = 1.39, 95% CI = 1.1-1.7, P-value = 0.007, respectively], and both SNPs were in strong linkage disequilibrium (r(2) = 0.95). For MYO5B-rs555879, the minor allele was risk associated (OR = 1.31, 95% CI = 1.1-1.6, P-value = 0.011). The combined analysis of SNP sets using set enrichment analysis revealed a study-wide significant association for three SNPs with susceptibility for dyslexia. In summary, our results substantiate genetic markers in NEDD4L and MYO5B as risk factors for dyslexia and provide first evidence that the relevance of these markers is not restricted to the English language.
Collapse
Affiliation(s)
- B Mueller
- Department of Cell Therapy, Fraunhofer Institute for Cell Therapy and Immunology
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Carrion-Castillo A, Franke B, Fisher SE. Molecular genetics of dyslexia: an overview. DYSLEXIA (CHICHESTER, ENGLAND) 2013; 19:214-240. [PMID: 24133036 DOI: 10.1002/dys.1464] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 09/02/2013] [Indexed: 05/28/2023]
Abstract
Dyslexia is a highly heritable learning disorder with a complex underlying genetic architecture. Over the past decade, researchers have pinpointed a number of candidate genes that may contribute to dyslexia susceptibility. Here, we provide an overview of the state of the art, describing how studies have moved from mapping potential risk loci, through identification of associated gene variants, to characterization of gene function in cellular and animal model systems. Work thus far has highlighted some intriguing mechanistic pathways, such as neuronal migration, axon guidance, and ciliary biology, but it is clear that we still have much to learn about the molecular networks that are involved. We end the review by highlighting the past, present, and future contributions of the Dutch Dyslexia Programme to studies of genetic factors. In particular, we emphasize the importance of relating genetic information to intermediate neurobiological measures, as well as the value of incorporating longitudinal and developmental data into molecular designs.
Collapse
Affiliation(s)
- Amaia Carrion-Castillo
- Language and Genetics Department, Max Planck Institute for Psycholinguistics, Nijmegen, Netherlands
| | | | | |
Collapse
|
17
|
Xq27 FRAXA locus is a strong candidate for dyslexia: evidence from a genome-wide scan in French families. Behav Genet 2013; 43:132-40. [PMID: 23307483 DOI: 10.1007/s10519-012-9575-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 12/08/2012] [Indexed: 12/11/2022]
Abstract
Dyslexia is a frequent neurodevelopmental learning disorder. To date, nine susceptibility loci have been identified, one of them being DYX9, located in Xq27. We performed the first French SNP linkage study followed by candidate gene investigation in dyslexia by studying 12 multiplex families (58 subjects) with at least two children affected, according to categorical restrictive criteria for phenotype definition. Significant results emerged on Xq27.3 within DYX9. The maximum multipoint LOD score reached 3,884 between rs12558359 and rs454992. Within this region, seven candidate genes were investigated for mutations in exonic sequences (CXORF1, CXORF51, SLITRK2, FMR1, FMR2, ASFMR1, FMR1NB), all having a role during brain development. We further looked for 5'UTR trinucleotide repeats in FMR1 and FMR2 genes. No mutation or polymorphism co-segregating with dyslexia was found. This finding in French families with Dyslexia showed significant linkage on Xq27.3 enclosing FRAXA, and consequently confirmed the DYX9 region as a robust susceptibility locus. We reduced the previously described interval from 6.8 (DXS1227-DXS8091) to 4 Mb also disclosing a higher LOD score.
Collapse
|
18
|
Raskind WH, Peter B, Richards T, Eckert MM, Berninger VW. The genetics of reading disabilities: from phenotypes to candidate genes. Front Psychol 2013; 3:601. [PMID: 23308072 PMCID: PMC3538356 DOI: 10.3389/fpsyg.2012.00601] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/18/2012] [Indexed: 12/19/2022] Open
Abstract
This article provides an overview of (a) issues in definition and diagnosis of specific reading disabilities at the behavioral level that may occur in different constellations of developmental and phenotypic profiles (patterns); (b) rapidly expanding research on genetic heterogeneity and gene candidates for dyslexia and other reading disabilities; (c) emerging research on gene-brain relationships; and (d) current understanding of epigenetic mechanisms whereby environmental events may alter behavioral expression of genetic variations. A glossary of genetic terms (denoted by bold font) is provided for readers not familiar with the technical terms.
Collapse
Affiliation(s)
- Wendy H Raskind
- Department of Medicine, University of Washington Seattle, WA, USA ; Department of Psychiatry and Behavioral Sciences, University of Washington Seattle, WA, USA
| | | | | | | | | |
Collapse
|
19
|
Kouprina N, Lee NCO, Pavlicek A, Samoshkin A, Kim JH, Lee HS, Varma S, Reinhold WC, Otstot J, Solomon G, Davis S, Meltzer PS, Schleutker J, Larionov V. Exclusion of the 750-kb genetically unstable region at Xq27 as a candidate locus for prostate malignancy in HPCX1-linked families. Genes Chromosomes Cancer 2012; 51:933-48. [PMID: 22733720 DOI: 10.1002/gcc.21977] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 05/08/2012] [Indexed: 12/14/2022] Open
Abstract
Several linkage studies provided evidence for the presence of the hereditary prostate cancer locus, HPCX1, at Xq27-q28. The strongest linkage peak of prostate cancer overlies a variable region of ~750 kb at Xq27 enriched by segmental duplications (SDs), suggesting that the predisposition to prostate cancer may be a genomic disorder caused by recombinational interaction between SDs. The large size of SDs and their sequence similarity make it difficult to examine this region for possible rearrangements using standard methods. To overcome this problem, direct isolation of a set of genomic segments by in vivo recombination in yeast (a TAR cloning technique) was used to perform a mutational analysis of the 750 kb region in X-linked families. We did not detect disease-specific rearrangements within this region. In addition, transcriptome and computational analyses were performed to search for nonannotated genes within the Xq27 region, which may be associated with genetic predisposition to prostate cancer. Two candidate genes were identified, one of which is a novel gene termed SPANXL that represents a highly diverged member of the SPANX gene family, and the previously described CDR1 gene that is expressed at a high level in both normal and malignant prostate cells, and mapped 210 kb of upstream the SPANX gene cluster. No disease-specific alterations were identified in these genes. Our results exclude the 750-kb genetically unstable region at Xq27 as a candidate locus for prostate malignancy. Adjacent regions appear to be the most likely candidates to identify the elusive HPCX1 locus.
Collapse
Affiliation(s)
- Natalay Kouprina
- Laboratory of Molecular Pharmacology, NCI, NIH, Bethesda, MD, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Poelmans G, Buitelaar JK, Pauls DL, Franke B. A theoretical molecular network for dyslexia: integrating available genetic findings. Mol Psychiatry 2011; 16:365-82. [PMID: 20956978 DOI: 10.1038/mp.2010.105] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Developmental dyslexia is a common specific childhood learning disorder with a strong heritable component. Previous studies using different genetic approaches have identified several genetic loci and candidate genes for dyslexia. In this article, we have integrated the current knowledge on 14 dyslexia candidate genes suggested by cytogenetic findings, linkage and association studies. We found that 10 of the 14 dyslexia candidate genes (ROBO1, KIAA0319, KIAA0319L, S100B, DOCK4, FMR1, DIP2A, GTF2I, DYX1C1 and DCDC2) fit into a theoretical molecular network involved in neuronal migration and neurite outgrowth. Based on this, we also propose three novel dyslexia candidate genes (SLIT2, HMGB1 and VAPA) from known linkage regions, and we discuss the possible involvement of genes emerging from the two reported genome-wide association studies for reading impairment-related phenotypes in the identified network.
Collapse
Affiliation(s)
- G Poelmans
- Department of Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | | | | |
Collapse
|
21
|
Kere J. Molecular genetics and molecular biology of dyslexia. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2011; 2:441-448. [PMID: 26302203 DOI: 10.1002/wcs.138] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Developmental dyslexia has been recognized as a distinct entity among learning disabilities as early as the late 1800s and its partially genetic nature has been firmly established by family and twin studies. The application of genetic mapping and molecular cloning methods has revealed specific genes that contribute to the genetic risk, but those known now do not yet suffice for explaining all of it. More importantly, the first genes, some of them found by the study of rare families, have indicated specific neurodevelopmental processes important for the development of dyslexia, including control of neuronal migration for the DYX1C1, DCDC2, and KIAA0319 genes, and a role of axonal and dendritic guidance suggested by the ROBO1 gene. I anticipate that forthcoming research within only a few years will yield molecular networks with fundamental roles in the molecular biology of dyslexia, and may aid in resolving relationships between comorbid disorders. WIREs Cogni Sci 2011 2 441-448 DOI: 10.1002/wcs.138 For further resources related to this article, please visit the WIREs website.
Collapse
Affiliation(s)
- Juha Kere
- Department of Biosciences and Nutrition, and Science for Life Laboratory, Karolinska Institutet, Stockholm, Sweden.,Department of Medical Genetics, University of Helsinki, and Folkhälsan Institute of Genetics, Helsinki, Finland
| |
Collapse
|
22
|
Rubenstein K, Matsushita M, Berninger VW, Raskind WH, Wijsman EM. Genome scan for spelling deficits: effects of verbal IQ on models of transmission and trait gene localization. Behav Genet 2011; 41:31-42. [PMID: 20852926 PMCID: PMC3030654 DOI: 10.1007/s10519-010-9390-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 08/26/2010] [Indexed: 02/03/2023]
Abstract
Dyslexia is a complex learning disability with evidence for a genetic basis. Strategies that may be useful for dissecting its genetic basis include the study of component phenotypes, which may simplify the underlying genetic complexity, and use of an analytic approach that accounts for the multilocus nature of the trait to guide the investigation and increase power to detect individual loci. Here we present results of a genetic analysis of spelling disability as a component phenotype. Spelling disability is informative in analysis of extended pedigrees because it persists into adulthood. We show that a small number of hypothesized loci are sufficient to explain the inheritance of the trait in our sample, and that each of these loci maps to one of four genomic regions. Individual trait models and locations are a function of whether a verbal IQ adjustment is included, suggesting mediation through both IQ-related and unrelated pathways.
Collapse
Affiliation(s)
- Kevin Rubenstein
- Department of Biostatistics, University of Washington, Box 357232, Seattle, WA, USA
| | - Mark Matsushita
- Division of Medical Genetics, Department of Medicine, University of Washington, Box 357720, Seattle, WA 98195-7720, USA
| | - Virginia W. Berninger
- Department of Educational Psychology, University of Washington, Box 353600, Seattle, WA, USA
| | - Wendy H. Raskind
- Division of Medical Genetics, Department of Medicine, University of Washington, Box 357720, Seattle, WA 98195-7720, USA, Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, USA
| | - Ellen M. Wijsman
- Division of Medical Genetics, Department of Medicine, University of Washington, Box 357720, Seattle, WA 98195-7720, USA, 4333 Brooklyn Ave, NE, Box 989460, Seattle, WA 98195-9460, USA. Department of Biostatistics, University of Washington, Seattle, WA, USA
| |
Collapse
|
23
|
Skiba T, Landi N, Wagner R, Grigorenko EL. In search of the perfect phenotype: an analysis of linkage and association studies of reading and reading-related processes. Behav Genet 2011; 41:6-30. [PMID: 21243420 PMCID: PMC3056345 DOI: 10.1007/s10519-011-9444-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 12/22/2010] [Indexed: 01/15/2023]
Abstract
Reading ability and specific reading disability (SRD) are complex traits involving several cognitive processes and are shaped by a complex interplay of genetic and environmental forces. Linkage studies of these traits have identified several susceptibility loci. Association studies have gone further in detecting candidate genes that might underlie these signals. These results have been obtained in samples of mainly European ancestry, which vary in their languages, inclusion criteria, and phenotype assessments. Such phenotypic heterogeneity across samples makes understanding the relationship between reading (dis)ability and reading-related processes and the genetic factors difficult; in addition, it may negatively influence attempts at replication. In moving forward, the identification of preferable phenotypes for future sample collection may improve the replicability of findings. This review of all published linkage and association results from the past 15 years was conducted to determine if certain phenotypes produce more replicable and consistent results than others.
Collapse
Affiliation(s)
| | - Nicole Landi
- Yale University & Haskins Laboratories, New Haven, CT, USA
| | | | - Elena L. Grigorenko
- Yale University, New Heaven, CT, USA
- Moscow State University, Moscow, Russia
- Columbia University, New York, NY, USA
| |
Collapse
|
24
|
Benítez-Burraco A. Neurobiología y neurogenética de la dislexia. Neurologia 2010; 25:563-81. [DOI: 10.1016/j.nrl.2009.12.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 12/22/2009] [Indexed: 01/12/2023] Open
|
25
|
Scerri TS, Paracchini S, Morris A, MacPhie IL, Talcott J, Stein J, Smith SD, Pennington BF, Olson RK, DeFries JC, Monaco AP. Identification of candidate genes for dyslexia susceptibility on chromosome 18. PLoS One 2010; 5:e13712. [PMID: 21060895 PMCID: PMC2965662 DOI: 10.1371/journal.pone.0013712] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 09/28/2010] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Six independent studies have identified linkage to chromosome 18 for developmental dyslexia or general reading ability. Until now, no candidate genes have been identified to explain this linkage. Here, we set out to identify the gene(s) conferring susceptibility by a two stage strategy of linkage and association analysis. METHODOLOGY/PRINCIPAL FINDINGS Linkage analysis: 264 UK families and 155 US families each containing at least one child diagnosed with dyslexia were genotyped with a dense set of microsatellite markers on chromosome 18. Association analysis: Using a discovery sample of 187 UK families, nearly 3000 SNPs were genotyped across the chromosome 18 dyslexia susceptibility candidate region. Following association analysis, the top ranking SNPs were then genotyped in the remaining samples. The linkage analysis revealed a broad signal that spans approximately 40 Mb from 18p11.2 to 18q12.2. Following the association analysis and subsequent replication attempts, we observed consistent association with the same SNPs in three genes; melanocortin 5 receptor (MC5R), dymeclin (DYM) and neural precursor cell expressed, developmentally down-regulated 4-like (NEDD4L). CONCLUSIONS Along with already published biological evidence, MC5R, DYM and NEDD4L make attractive candidates for dyslexia susceptibility genes. However, further replication and functional studies are still required.
Collapse
Affiliation(s)
- Thomas S. Scerri
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Silvia Paracchini
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Andrew Morris
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - I. Laurence MacPhie
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Joel Talcott
- School of Life and Health Sciences, Aston University, Birmingham, United Kingdom
| | - John Stein
- Department of Physiology, University of Oxford, Oxford, United Kingdom
| | - Shelley D. Smith
- Department of Pediatrics and Munroe Meyer Institute, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Bruce F. Pennington
- Department of Psychology, University of Denver, Denver, Colorado, United States of America
| | - Richard K. Olson
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado, United States of America
| | - John C. DeFries
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado, United States of America
| | - Anthony P. Monaco
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
26
|
A Cohort of Balanced Reciprocal Translocations Associated with Dyslexia: Identification of Two Putative Candidate Genes at DYX1. Behav Genet 2010; 41:125-33. [PMID: 20798984 DOI: 10.1007/s10519-010-9389-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 08/11/2010] [Indexed: 01/22/2023]
|
27
|
Couto JM, Livne-Bar I, Huang K, Xu Z, Cate-Carter T, Feng Y, Wigg K, Humphries T, Tannock R, Kerr EN, Lovett MW, Bremner R, Barr CL. Association of reading disabilities with regions marked by acetylated H3 histones in KIAA0319. Am J Med Genet B Neuropsychiatr Genet 2010; 153B:447-462. [PMID: 19588467 PMCID: PMC5381965 DOI: 10.1002/ajmg.b.30999] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Reading disabilities (RDs) have been associated with chromosome 6p with recent studies pointing to two genes, DCDC2 and KIAA0319. In this study, markers across the 6p region were tested for association with RD. Our strongest findings were for association with markers in KIAA0319, although with the opposite alleles compared with a previous study. We also found association with markers in VMP, but not with DCDC2. Current evidence indicates that differential regulation of KIAA0319 and DCDC2 contributes to RD, thus we used chromatin immunoprecipitation coupled with genomic tiling arrays (ChIP-chip) to map acetylated histones, a molecular marker for regulatory elements, across a 500 kb genomic region covering the RD locus on 6p. This approach identified several regions marked by acetylated histones that mapped near associated markers, including intron 7 of DCDC2 and the 5' region of KIAA0319. The latter is located within the 70 kb region previously associated with differential expression of KIAA0319. Interestingly, five markers associated with RD in independent studies were also located within the 2.7 kb acetylated region, and six additional associated markers, including the most significant one in this study, were located within a 22 kb haplotype block that encompassed this region. Our data indicates that this putative regulatory region is a likely site of genetic variation contributing to RD in our sample, further narrowing the candidate region.
Collapse
Affiliation(s)
- Jillian M. Couto
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Izzy Livne-Bar
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Katherine Huang
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Zhaodong Xu
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Tasha Cate-Carter
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Yu Feng
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Karen Wigg
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Tom Humphries
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Rosemary Tannock
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Elizabeth N. Kerr
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Maureen W. Lovett
- Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Rod Bremner
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Cathy L. Barr
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada,Program in Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Ontario, Canada,Correspondence to: Prof. Cathy L. Barr, Toronto Western Research Institute, Toronto Western Hospital, MP14-302, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8.
| |
Collapse
|
28
|
Abstract
Developmental dyslexia is a highly heritable disorder with a prevalence of at least 5% in school-aged children. Linkage studies have identified numerous loci throughout the genome that are likely to harbour candidate dyslexia susceptibility genes. Association studies and the refinement of chromosomal translocation break points in individuals with dyslexia have resulted in the discovery of candidate genes at some of these loci. A key function of many of these genes is their involvement in neuronal migration. This complements anatomical abnormalities discovered in dyslexic brains, such as ectopias, that may be the result of irregular neuronal migration.
Collapse
|
29
|
Benítez-Burraco A. Neurobiology and neurogenetics of dyslexia. NEUROLOGÍA (ENGLISH EDITION) 2010. [DOI: 10.1016/s2173-5808(20)70105-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
|
30
|
Couto JM, Gomez L, Wigg K, Cate-Carter T, Archibald J, Anderson B, Tannock R, Kerr EN, Lovett MW, Humphries T, Barr CL. The KIAA0319-like (KIAA0319L) gene on chromosome 1p34 as a candidate for reading disabilities. J Neurogenet 2009; 22:295-313. [PMID: 19085271 DOI: 10.1080/01677060802354328] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A locus on chromosome 1p34-36 (DYX8) has been linked to developmental dyslexia or reading disabilities (RD) in three independent samples. In the current study, we investigated a candidate gene KIAA0319-Like (KIAA0319L) within DYX8, as it is homologous to KIAA0319, a strong RD candidate gene on chromosome 6p (DYX2). Association was assessed by using five tagging single nucleotide polymorphisms in a sample of 291 nuclear families ascertained through a proband with reading difficulties. Evidence of association was found for a single marker (rs7523017; P=0.042) and a haplotype (P=0.031), with RD defined as a categorical trait in a subset of the sample (n=156 families) with a proband that made our criteria for RD. The same haplotype also showed evidence for association with quantitative measures of word-reading efficiency (i.e., a composite score of word identification and decoding; P=0.032) and rapid naming of objects and colors (P=0.047) when analyzed using the entire sample. Although the results from the current study are modestly significant and would not withstand a correction for multiple testing, KIAA0319L remains an intriguing positional and functional candidate for RD, especially when considered alongside the supporting evidence for its homolog KIAA0319 on chromosome 6p. Additional studies in independent samples are now required to confirm these findings.
Collapse
Affiliation(s)
- Jillian M Couto
- Genetics and Development Division, Toronto Western Research Institute, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
Genetic factors contribute substantially to the development of reading disability (RD). Family linkage studies have implicated many chromosomal regions containing RD susceptibility genes, of which putative loci at 1p34-p36 (DYX8), 2p (DYX3), 6p21.3 (DYX2), and 15q21 (DYX1) have been frequently replicated, whereas those at 3p12-q12 (DYX5), 6q13-q16 (DYX4), 11p15 (DYX7), 18p11 (DYX6), and Xq27 (DYX9) have less evidence. Association studies of positional candidate genes have implicated DCDC2 and KIAA0319 in DYX2, as well as C2ORF3 and MRPL19 (DYX3), whereas DYX1C1/EKN1 (DYX1) and ROBO1 (DYX5) were found to be disrupted by rare translocation breakpoints in reading-disabled individuals. Four of the candidate genes (DYX1C1, KIAA0319, DCDC2, and ROBO1) appear to function in neuronal migration and guidance, suggesting the importance of early neurodevelopmental processes in RD. Future studies to help us understand the function of these and other RD candidate genes promise to yield enormous insight into the neurobiologic mechanisms underlying the pathophysiology of this disorder.
Collapse
|
32
|
Poelmans G, Engelen JJM, Van Lent-Albrechts J, Smeets HJ, Schoenmakers E, Franke B, Buitelaar JK, Wuisman-Frerker M, Erens W, Steyaert J, Schrander-Stumpel C. Identification of novel dyslexia candidate genes through the analysis of a chromosomal deletion. Am J Med Genet B Neuropsychiatr Genet 2009; 150B:140-7. [PMID: 18521840 DOI: 10.1002/ajmg.b.30787] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Dyslexia is the most common childhood learning disorder and it is a significantly heritable trait. At least nine chromosomal loci have been linked to dyslexia, and additional susceptibility loci on other chromosomes have been suggested. Within two of these loci, DYX1C1 (15q21) and ROBO1 (3p12) have recently been proposed as dyslexia candidate genes through the molecular analysis of translocation breakpoints in dyslexic individuals carrying balanced chromosomal translocations. Moreover, genetic association studies have indicated a cluster of five dyslexia candidate genes in another linkage region on chromosome 6p22, although there is currently no consensus about which of these five genes contributes to the genetic susceptibility for dyslexia. In this article, we report the identification of four new dyslexia candidate genes (PCNT, DIP2A, S100B, and PRMT2) on chromosome region 21q22.3 by FISH and SNP microarray analyses of a very small deletion in this region, which cosegregates with dyslexia in a father and his three sons.
Collapse
Affiliation(s)
- G Poelmans
- Department of Clinical Genetics, Academic Hospital Maastricht, The Netherlands.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
de Kovel CGF, Franke B, Hol FA, Lebrec JJP, Maassen B, Brunner H, Padberg GW, Platko J, Pauls D. Confirmation of dyslexia susceptibility loci on chromosomes 1p and 2p, but not 6p in a Dutch sib-pair collection. Am J Med Genet B Neuropsychiatr Genet 2008; 147:294-300. [PMID: 17886254 DOI: 10.1002/ajmg.b.30598] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this study, we attempted to confirm genetic linkage to developmental dyslexia and reading-related quantitative traits of loci that have been shown to be associated with dyslexia in previous studies. In our sample of 108 Dutch nuclear families, the categorical trait showed strongest linkage to 1p36 (NPL-LOD = 2.1). LOD scores for quantitative traits word-reading, non-word reading, and rapid naming peaked near the same location as the categorical trait, as well as on chromosome 2. Non-word repetition showed little phenotypic correlation with dyslexia or with the other quantitative traits, and this trait showed linkage peaks on 11p and 15q. No evidence for linkage to 6p22-23 was found for this set of families. Comparison of our results and literature data shows that loci link to different phenotypes in different samples. The mutual connections of these traits and their relation to developmental dyslexia remain elusive.
Collapse
Affiliation(s)
- Carolien G F de Kovel
- Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Berninger VW, Nielsen KH, Abbott RD, Wijsman E, Raskind W. Gender differences in severity of writing and reading disabilities. J Sch Psychol 2008; 46:151-72. [PMID: 19083355 DOI: 10.1016/j.jsp.2007.02.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 02/05/2007] [Accepted: 02/12/2007] [Indexed: 01/30/2023]
|
35
|
Capellini SA, Padula NADMR, Santos LCAD, Lourenceti MD, Carrenho EH, Ribeiro LA. [Phonological awareness, working memory, reading and writing performances in familial dyslexia]. ACTA ACUST UNITED AC 2008; 19:374-80. [PMID: 18200387 DOI: 10.1590/s0104-56872007000400009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 11/06/2007] [Indexed: 11/21/2022]
Abstract
BACKGROUND familial dyslexia. AIM to characterize and compare the phonological awareness, working memory, reading and writing abilities of individuals whose family members are also affected. METHOD in this study 10 familial nuclei of natural family relationship of individuals with dyslexia were analyzed. Families of natural individuals living in the west region of the state of São Paulo were selected. Inclusion criteria were: to be a native speaker of the Brazilian Portuguese language, to have 8 years of age or more, to present positive familial history for learning disabilities, that is, to present at least one relative with difficulties in learning. Exclusion criteria were: to present any neurological disorder genetically caused or not, in any of the family members, such as dystonia, extra pyramidal diseases, mental disorder, epilepsy, attention deficit and hyperactivity disorder (ADHA); psychiatric symptoms or conditions; or any other pertinent conditions that could cause errors in the diagnosis. As for the diagnosis of developmental dyslexia, information about the familial history of the adolescents and children was gathered with the parents, so that a detailed pedigree could be delineated. Neurological, psychological, speech-language, and school performance evaluations were made with the individuals and their families. RESULTS the results of this study suggest that the dyslexic individuals and their respective relatives, also with dyslexia, presented lower performances than the control group in terms of rapid automatic naming, reading, writing and phonological awareness. CONCLUSION deficits in phonological awareness, working memory, reading and writing seem to have genetic susceptibility that possibly determine, when in interaction with the environment, the manifestation of dyslexia.
Collapse
|
36
|
Caylak E. A review of association and linkage studies for genetical analyses of learning disorders. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:923-43. [PMID: 17510947 DOI: 10.1002/ajmg.b.30537] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Learning disorders (LD) commonly comprise of a heterogeneous group of disorders manifested by unexpected problems in some children's experiences in the academic performance arena. These problems especially comprise of a variety of disorders which may be subclassified to attention-deficit hyperactivity disorder (ADHD), reading disability (RD), specific language impairment (SLI), speech-sound disorder (SSD), and dyspraxia. The aim of this review is to summarize the current molecular studies and some of the most exciting recent developments in molecular genetic research on LD. The findings for the association and linkage of LD with candidate genes will help to set the research agendas for future studies to follow.
Collapse
Affiliation(s)
- Emrah Caylak
- Department of Biochemistry and Clinical Biochemistry, Firat University, School of Medicine, Elazig, Turkey.
| |
Collapse
|
37
|
Brkanac Z, Chapman NH, Matsushita MM, Chun L, Nielsen K, Cochrane E, Berninger VW, Wijsman EM, Raskind WH. Evaluation of candidate genes for DYX1 and DYX2 in families with dyslexia. Am J Med Genet B Neuropsychiatr Genet 2007; 144B:556-60. [PMID: 17450541 DOI: 10.1002/ajmg.b.30471] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Dyslexia is a common heterogeneous disorder with a significant genetic component. Multiple studies have replicated the evidence for linkage between variously defined phenotypes of dyslexia and chromosomal regions on 15q21 (DYX1) and 6p22.2 (DYX2). Based on association studies and the possibility for functional significance of several polymorphisms, candidate genes responsible for the observed linkage signal have been proposed-DYX1C1 for 15q21, and KIAA0319 and DCDC2 for 6p22.2. We investigated the evidence for contribution of these candidate genes to dyslexia in our sample of multigenerational families. Our previous quantitative linkage analyses in this dataset provided supportive evidence for linkage of dyslexia to the locus on chromosome 15, but not to the locus on chromosome 6. In the current study, we used probands from 191 families for a case control analysis, and proband-parent trios for family-based TDT analyses. The observation of weak evidence for transmission disequilibrium for one of the two studied polymorphisms in DYX1C1 suggests involvement of this gene in dyslexia in our dataset. We did not find evidence for the association of KIAA0319 or DCDC2 alleles to dyslexia in our sample. We observed a slight tendency for an intronic deletion in DCDC2 to be associated with worse performance on some quantitative measures of dyslexia in the probands in our sample, but not in their parents.
Collapse
Affiliation(s)
- Zoran Brkanac
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington 98198-7720, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Genetik der Lese- und Rechtschreibstörung. Monatsschr Kinderheilkd 2007. [DOI: 10.1007/s00112-007-1479-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
39
|
Schumacher J, Hoffmann P, Schmäl C, Schulte-Körne G, Nöthen MM. Genetics of dyslexia: the evolving landscape. J Med Genet 2007; 44:289-97. [PMID: 17307837 PMCID: PMC2597981 DOI: 10.1136/jmg.2006.046516] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dyslexia is among the most common neurodevelopmental disorders, with a prevalence of 5-12%. At the phenotypic level, various cognitive components that enable reading and spelling and that are disturbed in affected individuals can be distinguished. Depending on the phenotype dimension investigated, inherited factors are estimated to account for up to 80%. Linkage findings in dyslexia are relatively consistent across studies in comparison to findings for other neuropsychiatric disorders. This is particularly true for chromosome regions 1p34-p36, 6p21-p22, 15q21 and 18q11. Four candidate genes have recently been identified through systematic linkage disequilibrium studies in linkage region 6p21-p22, and through cloning approaches at chromosomal breakpoints. Results indicate that a disturbance in neuronal migration is a pathological correlate of dyslexia at the functional level. This review presents a summary of the latest insights into the genetics of dyslexia and an overview of anticipated future developments.
Collapse
|
40
|
Marino C, Citterio A, Giorda R, Facoetti A, Menozzi G, Vanzin L, Lorusso ML, Nobile M, Molteni M. Association of short-term memory with a variant within DYX1C1 in developmental dyslexia. GENES BRAIN AND BEHAVIOR 2007; 6:640-6. [PMID: 17309662 DOI: 10.1111/j.1601-183x.2006.00291.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A substantial genetic contribution in the etiology of developmental dyslexia (DD) has been well documented with independent groups reporting a susceptibility locus on chromosome 15q. After the identification of the DYX1C1 gene as a potential candidate for DD, several independent association studies reported controversial results. We performed a family-based association study to determine whether the DYX1C1 single nucleotide polymorphisms (SNPs) that have been associated with DD before, that is SNPs '-3GA' and '1249GT', influence a broader phenotypic definition of DD. A significant linkage disequilibrium was observed with 'Single Letter Backward Span' (SLBS) in both single-marker and haplotype analyses. These results provide further support to the association between DD and DYX1C1 and it suggests that the linkage disequilibrium with DYX1C1 is more saliently explained in Italian dyslexics by short-term memory, as measured by 'SLBS', than by the categorical diagnosis of DD or other related phenotypes.
Collapse
Affiliation(s)
- C Marino
- Scientific Institute 'Eugenio Medea', Department of Child Psychiatry, Bosisio Parini, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
Genetic factors are important contributors to language and learning disorders, and discovery of the underlying genes can help delineate the basic neurological pathways that are involved. This information, in turn, can help define disorders and their perceptual and processing deficits. Initial molecular genetic studies of dyslexia, for example, appear to converge on defects in neuronal and axonal migration. Further study of individuals with abnormalities of these genes may lead to the recognition of characteristic cognitive deficits attributable to the neurological dysfunction. Such abnormalities may affect other disorders as well, and studies of co-morbidity of dyslexia with attention deficit disorder and speech sound disorder are helping to define the scope of these genes and show the etiological and cognitive commonalities between these conditions. The genetic contributions to specific language impairment (SLI) are not as well defined at this time, but similar molecular approaches are being applied to identify genes that influence SLI and comorbid disorders. While there is co-morbidity of SLI with dyslexia, it appears that most of the common genetic effects may be with the language characteristics of autism spectrum disorders rather than with dyslexia and related disorders. Identification of these genes and their neurological and cognitive effects should lay out a functional network of interacting genes and pathways that subserve language development. Understanding these processes can form the basis for refined procedures for diagnosis and treatment.
Collapse
Affiliation(s)
- Shelley D Smith
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, Nebraska 68198-5456, USA.
| |
Collapse
|
42
|
Bates TC, Luciano M, Castles A, Coltheart M, Wright MJ, Martin NG. Replication of reported linkages for dyslexia and spelling and suggestive evidence for novel regions on chromosomes 4 and 17. Eur J Hum Genet 2006; 15:194-203. [PMID: 17119535 DOI: 10.1038/sj.ejhg.5201739] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We report the first genome-wide linkage analysis for reading and spelling in a sample of 403 families of twins, aged between 12 and 25 years taken from the normal population and unselected for reading ability. These traits showed heritabilities of 0.52-0.73, and support for linkage exceeded replication levels (lod > 1.44) of seven of the 11 linkages reported in dyslexic samples, namely: 2q22.3, 3p12-q13, 6q11.2, 7q32, 15q21.1, 18p21, and Xq27.3. For five of these (2q22.3, 6q11.2, 7q32, 18p21, and Xq27), this study provides the first independent replication. 1p34-36 and 2p15-16 received some support, with lods of 1.2 and 0.83, respectively, whereas two regions received little support (6p23-21.3 and 11p15.5). This study also identified two novel linkages at 4p15.33-16.1 and 17p13.3, which received suggestive support (max. lod 2.08 and 1.99, respectively).
Collapse
Affiliation(s)
- Timothy C Bates
- Department of Psychology, University of Edinburgh, Edinburgh, UK.
| | | | | | | | | | | |
Collapse
|
43
|
Schulte-Körne G, Warnke A, Remschmidt H. Zur Genetik der Lese-Rechtschreibschwäche. ZEITSCHRIFT FUR KINDER-UND JUGENDPSYCHIATRIE UND PSYCHOTHERAPIE 2006; 34:435-44. [PMID: 17094062 DOI: 10.1024/1422-4917.34.6.435] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Zusammenfassung: Die Lese-Rechtschreibstörung (LRS) ist eine der häufigsten Entwicklungsstörungen. Die Ursachen dieser komplexen Störung sind bisher nur kaum verstanden. Familienuntersuchungen zeigen, dass die LRS familiär gehäuft auftritt und dass das Risiko für ein Geschwisterkind, eine LRS zu entwickeln, ca. 3,5fach erhöht ist. Verschiedene kognitive Fähigkeiten sind mit der LRS korreliert. Hierzu gehören die phonologische Bewusstheit, orthographisches Wissen, phonologisches Dekodieren, auditives Kurzzeitgedächtnis und schnelles Benennen. Eine familiäre Häufung dieser mit der LRS korrelierten Dimensionen und eine hohe Erblichkeit (Heritabilität) wurden wiederholt gefunden. Die Heritabilität für die Lesefähigkeit liegt zwischen 50-60%, für die Rechtschreibstörung zwischen 50 und 70%. Durch genomweite Kopplungsuntersuchungen wurden bisher 9 Kandidatengenregionen (DYX1-9) identifiziert. Vier Kandidatengene, DCDC2, KIAA0319, ROBO1 und DYX1C1 wurden kürzlich beschrieben. Diese beeinflussen die neuronale Migration und sind daher funktionell aussichtsreiche Kandidatengene für die LRS. Allerdings konnte bisher keine funktionell relevante Mutation gefunden werden. Die Komorbidität zwischen LRS und ADHD sowie LRS und Sprachentwicklungsstörungen könnte zum Teil durch gemeinsame genetische Faktoren erklärt werden. In der Zukunft wird es für die Ursachenforschung der LRS entscheidend sein, möglichst alle ursachenrelevanten Dimensionen gemeinsam an ausreichend großen Stichproben zu untersuchen. Neben den relevanten neurobiologischen Faktoren sollten auch Umweltfaktoren und die verschiedenen Interaktionen, wie z.B. Gen-Umwelt und Gen-Gen-Interaktionen untersucht werden. In einem europäischen, kollaborativen Forschungsvorhaben (NeuroDys) wird weltweit die größte Stichprobe von Kindern mit einer LRS gesammelt und untersucht, um durch ein verbessertes Ursachenverständnis unter Einschluss der Identifikation von genetischen Risikofaktoren die Komplexität des Störungsbildes besser zu verstehen und perspektivisch spezifische Therapien zu entwickeln.
Collapse
Affiliation(s)
- Gerd Schulte-Körne
- 1 Klinik für Kinder- und Jugendpsychiatrie, Psychosomatik und Psychotherapie, Klinikum der Universität München, Pettenkoferstrasse 8a, DE-80336 München
| | | | | |
Collapse
|
44
|
Abstract
Reading reflects the complex integration of several cognitive processes and proves more difficult to achieve for a significant proportion of the population. Developmental dyslexia (DD), or specific reading disability, is influenced by genes, a fact that has led several research groups to attempt to identify susceptibility genes through the sequential analysis of genetic linkage and association. Strong evidence has now emerged for the presence of genes influencing DD at several chromosomal loci and for at least one of these, there is evidence implicating specific genes. In this review, we present the evidence for a genetic contribution to DD and its component processes and review the current status of molecular genetic research aimed at identifying susceptibility genes for this common, complex disorder.
Collapse
Affiliation(s)
- Julie Williams
- Department of Psychological Medicine, Cardiff University, Henry Wellcome Building, Heath Park, Cardiff CF14 4XN, UK.
| | | |
Collapse
|
45
|
Abstract
Remarkably few research articles on the treatment of developmental dyslexia were published during the last 25 years. Some treatment research arose from the temporal processing theory, some from the phonological deficit hypothesis and some more from the balance model of learning to read and dyslexia. Within the framework of that model, this article reviews the aetiology of dyslexia sub-types, the neuropsychological rationale for treatment, the treatment techniques and the outcomes of treatment research. The possible mechanisms underlying the effects of treatment are discussed.
Collapse
Affiliation(s)
- Dirk J Bakker
- Department of Clinical Neuropsychology, Free University, Amsterdam, The Netherlands.
| |
Collapse
|
46
|
Bellini G, Bravaccio C, Calamoneri F, Donatella Cocuzza M, Fiorillo P, Gagliano A, Mazzone D, del Giudice EM, Scuccimarra G, Militerni R, Pascotto A. No evidence for association between dyslexia and DYX1C1 functional variants in a group of children and adolescents from Southern Italy. J Mol Neurosci 2006; 27:311-4. [PMID: 16280601 DOI: 10.1385/jmn:27:3:311] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2005] [Accepted: 06/01/2005] [Indexed: 11/11/2022]
Abstract
Recently, DYX1C1, a candidate gene for developmental dyslexia, encoding a nuclear tetratricopeptide repeat domain protein dynamically regulated in brain, has been characterized through a translocation breakpoint in a Finnish family. Two putatively functional variants, -3G/A and 1249G/T, have been reported to be significantly associated with dyslexia in this population. Further studies, conducted on different ethnic groups (English and Canadian), have not confirmed a role for DYX1C1 variants in increasing the risk for dyslexia. We investigated the role of these variants in dyslexic children and adolescents from Southern Italy. No significant evidence for association between dyslexia and these DYX1C1 putative functional variants has been shown. We argue that the different DYX1C1 allele frequencies shown among Italian and Finnish subjects with dyslexia could be attributable to the different linkage disequilibrium structure of these populations.
Collapse
Affiliation(s)
- Giulia Bellini
- Chair of Child Neuropsychiatry, Department of Pediatrics, Second University of Naples, Naples, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Hannula-Jouppi K, Kaminen-Ahola N, Taipale M, Eklund R, Nopola-Hemmi J, Kääriäinen H, Kere J. The axon guidance receptor gene ROBO1 is a candidate gene for developmental dyslexia. PLoS Genet 2005; 1:e50. [PMID: 16254601 PMCID: PMC1270007 DOI: 10.1371/journal.pgen.0010050] [Citation(s) in RCA: 216] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Accepted: 09/21/2005] [Indexed: 11/21/2022] Open
Abstract
Dyslexia, or specific reading disability, is the most common learning disorder with a complex, partially genetic basis, but its biochemical mechanisms remain poorly understood. A locus on Chromosome 3, DYX5, has been linked to dyslexia in one large family and speech-sound disorder in a subset of small families. We found that the axon guidance receptor gene ROBO1, orthologous to the Drosophila roundabout gene, is disrupted by a chromosome translocation in a dyslexic individual. In a large pedigree with 21 dyslexic individuals genetically linked to a specific haplotype of ROBO1 (not found in any other chromosomes in our samples), the expression of ROBO1 from this haplotype was absent or attenuated in affected individuals. Sequencing of ROBO1 in apes revealed multiple coding differences, and the selection pressure was significantly different between the human, chimpanzee, and gorilla branch as compared to orangutan. We also identified novel exons and splice variants of ROBO1 that may explain the apparent phenotypic differences between human and mouse in heterozygous loss of ROBO1. We conclude that dyslexia may be caused by partial haplo-insufficiency for ROBO1 in rare families. Thus, our data suggest that a slight disturbance in neuronal axon crossing across the midline between brain hemispheres, dendrite guidance, or another function of ROBO1 may manifest as a specific reading disability in humans.
Collapse
Affiliation(s)
| | | | - Mikko Taipale
- Department of Medical Genetics, University of Helsinki, Finland
- European Molecular Biology Laboratory, Gene Expression Programme, Heidelberg, Germany
| | - Ranja Eklund
- Department of Medical Genetics, University of Helsinki, Finland
| | - Jaana Nopola-Hemmi
- Department of Medical Genetics, University of Helsinki, Finland
- Department of Pediatrics, Jorvi Hospital, Espoo, Finland
| | - Helena Kääriäinen
- Department of Medical Genetics, The Family Federation of Finland, Helsinki, Finland
- Department of Medical Genetics, University of Turku, Turku, Finland
| | - Juha Kere
- Department of Medical Genetics, University of Helsinki, Finland
- Department of Biosciences at Novum and Clinical Research Centre, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|