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Russo N, Kaplan-Kahn EA, Wilson J, Criss A, Burack JA. Choices, challenges, and constraints: a pragmatic examination of the limits of mental age matching in empirical research. Dev Psychopathol 2021; 33:727-738. [PMID: 33955342 PMCID: PMC8108685 DOI: 10.1017/s0954579420001480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The work of Ed Zigler spans decades of research all singularly dedicated to using science to improve the lives of children facing different challenges. The focus of this article is on one of Zigler's numerous lines of work: advocating for the practice of mental age (MA) matching in empirical research, wherein groups of individuals are matched on the basis of developmental level, rather than chronological age. While MA matching practices represented a paradigm shift that provided the seeds from which the developmental approach to developmental disability sprouted, it is not without its own limits. Here, we examine and test the underlying assumption of linearity inherent in MA matching using three commonly used IQ measures. Results provide practical constraints of using MA matching, a solution which we hope refines future clinical and empirical practices, furthering Zigler's legacy of continued commitment to compassionate, meaningful, and rigorous science in the service of children.
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Affiliation(s)
- N. Russo
- Syracuse University, Department of Psychology
| | | | - J. Wilson
- Syracuse University, Department of Psychology
| | - A. Criss
- Syracuse University, Department of Psychology
| | - J. A. Burack
- McGill University, Department of Educational and Counselling Psychology
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2
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Piard J, Hu JH, Campeau PM, Rzonca S, Van Esch H, Vincent E, Han M, Rossignol E, Castaneda J, Chelly J, Skinner C, Kalscheuer VM, Wang R, Lemyre E, Kosinska J, Stawinski P, Bal J, Hoffman DA, Schwartz CE, Van Maldergem L, Wang T, Worley PF. FRMPD4 mutations cause X-linked intellectual disability and disrupt dendritic spine morphogenesis. Hum Mol Genet 2019; 27:589-600. [PMID: 29267967 DOI: 10.1093/hmg/ddx426] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 12/12/2017] [Indexed: 11/13/2022] Open
Abstract
FRMPD4 (FERM and PDZ Domain Containing 4) is a neural scaffolding protein that interacts with PSD-95 to positively regulate dendritic spine morphogenesis, and with mGluR1/5 and Homer to regulate mGluR1/5 signaling. We report the genetic and functional characterization of 4 FRMPD4 deleterious mutations that cause a new X-linked intellectual disability (ID) syndrome. These mutations were found to be associated with ID in ten affected male patients from four unrelated families, following an apparent X-linked mode of inheritance. Mutations include deletion of an entire coding exon, a nonsense mutation, a frame-shift mutation resulting in premature termination of translation, and a missense mutation involving a highly conserved amino acid residue neighboring FRMPD4-FERM domain. Clinical features of these patients consisted of moderate to severe ID, language delay and seizures alongside with behavioral and/or psychiatric disturbances. In-depth functional studies showed that a frame-shift mutation, FRMPD4p.Cys618ValfsX8, results in a disruption of FRMPD4 binding with PSD-95 and HOMER1, and a failure to increase spine density in transfected hippocampal neurons. Behavioral studies of frmpd4-KO mice identified hippocampus-dependent spatial learning and memory deficits in Morris Water Maze test. These findings point to an important role of FRMPD4 in normal cognitive development and function in humans and mice, and support the hypothesis that FRMPD4 mutations cause ID by disrupting dendritic spine morphogenesis in glutamatergic neurons.
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Affiliation(s)
- Juliette Piard
- Centre de Génétique Humaine and Integrative and Cognitive Neuroscience Research Unit EA481, Université de Franche-Comté, Besançon, France
| | - Jia-Hua Hu
- Department of Neuroscience, Department of Pediatrics, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Program in Developmental Neuroscience, Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | | | - Hilde Van Esch
- Department of Human Genetics, University Hospitals Leuven, Belgium
| | - Elizabeth Vincent
- Department of Neuroscience, Department of Pediatrics, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mei Han
- Department of Neuroscience, Department of Pediatrics, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Elsa Rossignol
- Department of Neurosciences, University of Montreal, Montreal, QC, Canada
| | | | - Jamel Chelly
- CNRS UMR7104, Institut de Génétique, Biologie Moléculaire et Cellulaire, Illkirch, France
| | | | - Vera M Kalscheuer
- Research Group Development and Disease, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Ruihua Wang
- Department of Neuroscience, Department of Pediatrics, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Emmanuelle Lemyre
- Department of Pediatrics, University of Montreal, Montreal, QC, Canada
| | | | | | - Jerzy Bal
- Institute of Mother and Child, Warsaw, Poland
| | - Dax A Hoffman
- Program in Developmental Neuroscience, Molecular Neurophysiology and Biophysics Section, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | | | - Lionel Van Maldergem
- Centre de Génétique Humaine and Integrative and Cognitive Neuroscience Research Unit EA481, Université de Franche-Comté, Besançon, France.,Centre of Clinical Investigation 1431, National Institute for Health and Medical Research (INSERM), Université de Franche-Comté, Besançon, France
| | - Tao Wang
- Department of Neuroscience, Department of Pediatrics, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Paul F Worley
- Department of Neuroscience, Department of Pediatrics, Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Teixeira WG, Marques FK, Freire MCM. Retrospective karyotype study in mentally retarded patients. Rev Assoc Med Bras (1992) 2016; 62:262-8. [PMID: 27310551 DOI: 10.1590/1806-9282.62.03.262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 11/04/2014] [Indexed: 11/21/2022] Open
Abstract
OBJECTIVE To describe the chromosomal alterations in patients with mental retardation (MR) using G-banding karyotype analysis. METHOD A retrospective study of the results G-banding karyotype analysis of 369 patients investigated for MR was performed. Based on the structural rearrangements found, the authors searched all chromosomal regions related with breakpoints, and these were compared with the literature on MR and databases. RESULTS 338 (91.6%) normal cases, and 31 (8.4%) with some type of chromosomal abnormality were identified. Among the altered cases, 21 patients (67.8%) were identified with structural chromosomal alterations, nine (29%) with numerical alterations, and one (3.2%) with numerical and structural alterations. CONCLUSION Structural chromosomal abnormalities were observed more frequently in this study. G-banding karyotyping contributes to the investigation of the causes of MR, showing that this technique can be useful for initial screening of patients. However, higher resolution techniques such as array based comparative genomic hybridization (aCGH) and multiplex ligation-dependent probe amplification (MPLA) can detect submicroscopic alterations commonly associated with MR.
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Affiliation(s)
- Wellcy Gonçalves Teixeira
- Instituto Hermes Pardini, Laboratory Specialist, Belo Horizonte MG , Brazil, MSc in General and Applied Biology - Laboratory Specialist at Instituto Hermes Pardini, Belo Horizonte, MG, Brazil
| | - Fabiana Kalina Marques
- Instituto Hermes Pardini, Belo Horizonte MG , Brazil, MSc in Genetics - Researcher at Instituto Hermes Pardini, Belo Horizonte, MG, Brazil
| | - Maíra Cristina Menezes Freire
- Instituto Hermes Pardini, Belo Horizonte MG , Brazil, PhD in Genetics - Researcher at Instituto Hermes Pardini, Belo Horizonte, MG, Brazil
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Friez MJ, Brooks SS, Stevenson RE, Field M, Basehore MJ, Adès LC, Sebold C, McGee S, Saxon S, Skinner C, Craig ME, Murray L, Simensen RJ, Yap YY, Shaw MA, Gardner A, Corbett M, Kumar R, Bosshard M, van Loon B, Tarpey PS, Abidi F, Gecz J, Schwartz CE. HUWE1 mutations in Juberg-Marsidi and Brooks syndromes: the results of an X-chromosome exome sequencing study. BMJ Open 2016; 6:e009537. [PMID: 27130160 PMCID: PMC4854010 DOI: 10.1136/bmjopen-2015-009537] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND X linked intellectual disability (XLID) syndromes account for a substantial number of males with ID. Much progress has been made in identifying the genetic cause in many of the syndromes described 20-40 years ago. Next generation sequencing (NGS) has contributed to the rapid discovery of XLID genes and identifying novel mutations in known XLID genes for many of these syndromes. METHODS 2 NGS approaches were employed to identify mutations in X linked genes in families with XLID disorders. 1 involved exome sequencing of genes on the X chromosome using the Agilent SureSelect Human X Chromosome Kit. The second approach was to conduct targeted NGS sequencing of 90 known XLID genes. RESULTS We identified the same mutation, a c.12928 G>C transversion in the HUWE1 gene, which gives rise to a p.G4310R missense mutation in 2 XLID disorders: Juberg-Marsidi syndrome (JMS) and Brooks syndrome. Although the original families with these disorders were considered separate entities, they indeed overlap clinically. A third family was also found to have a novel HUWE1 mutation. CONCLUSIONS As we identified a HUWE1 mutation in an affected male from the original family reported by Juberg and Marsidi, it is evident the syndrome does not result from a mutation in ATRX as reported in the literature. Additionally, our data indicate that JMS and Brooks syndromes are allelic having the same HUWE1 mutation.
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Affiliation(s)
| | - Susan Sklower Brooks
- Department of Pediatrics, Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA
| | | | - Michael Field
- Hunter Genetics, Waratah, New South Wales, Australia
| | | | - Lesley C Adès
- Institute of Endocrinology and Diabetes, The Children's Hospital of Westmead, University of Sydney, Sydney, New South Wales, Australia
| | - Courtney Sebold
- University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Stephen McGee
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Samantha Saxon
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Cindy Skinner
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Maria E Craig
- Institute of Endocrinology and Diabetes, The Children's Hospital of Westmead, University of Sydney, Sydney, New South Wales, Australia
| | - Lucy Murray
- Hunter Genetics, Waratah, New South Wales, Australia
| | | | - Ying Yzu Yap
- Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
| | - Marie A Shaw
- Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
| | - Alison Gardner
- Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
| | - Mark Corbett
- Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
| | - Raman Kumar
- Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
| | - Matthias Bosshard
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Zurich, Switzerland
| | - Barbara van Loon
- Institute of Veterinary Biochemistry and Molecular Biology, University of Zurich, Zurich, Switzerland
| | | | - Fatima Abidi
- Greenwood Genetic Center, Greenwood, South Carolina, USA
| | - Jozef Gecz
- Department of Paediatrics, University of Adelaide, Adelaide, South Australia, Australia
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Takano K, Liu D, Tarpey P, Gallant E, Lam A, Witham S, Alexov E, Chaubey A, Stevenson RE, Schwartz CE, Board PG, Dulhunty AF. An X-linked channelopathy with cardiomegaly due to a CLIC2 mutation enhancing ryanodine receptor channel activity. Hum Mol Genet 2012; 21:4497-507. [PMID: 22814392 DOI: 10.1093/hmg/dds292] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Chloride intracellular channel 2 (CLIC2) protein is a member of the glutathione transferase class of proteins. Its' only known function is the regulation of ryanodine receptor (RyR) intracellular Ca(2+) release channels. These RyR proteins play a major role in the regulation of Ca(2+) signaling in many cells. Utilizing exome capture and deep sequencing of genes on the X-chromosome, we have identified a mutation in CLIC2 (c.303C>G, p.H101Q) which is associated with X-linked intellectual disability (ID), atrial fibrillation, cardiomegaly, congestive heart failure (CHF), some somatic features and seizures. Functional studies of the H101Q variant indicated that it stimulated rather than inhibited the action of RyR channels, with channels remaining open for longer times and potentially amplifying Ca(2+) signals dependent on RyR channel activity. The overly active RyRs in cardiac and skeletal muscle cells and neuronal cells would result in abnormal cardiac function and trigger post-synaptic pathways and neurotransmitter release. The presence of both cardiomegaly and CHF in the two affected males and atrial fibrillation in one are consistent with abnormal RyR2 channel function. Since the dysfunction of RyR2 channels in the brain via 'leaky mutations' can result in mild developmental delay and seizures, our data also suggest a vital role for the CLIC2 protein in maintaining normal cognitive function via its interaction with RyRs in the brain. Therefore, our patients appear to suffer from a new channelopathy comprised of ID, seizures and cardiac problems because of enhanced Ca(2+) release through RyRs in neuronal cells and cardiac muscle cells.
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Affiliation(s)
- Kyoko Takano
- JC Self Research Institute, Greenwood Genetic Center, Greenwood, SC 29646, USA
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Phenotypic variability in a portuguese family with x-linked creatine transport deficiency. Pediatr Neurol 2012; 46:39-41. [PMID: 22196490 DOI: 10.1016/j.pediatrneurol.2011.10.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/13/2011] [Accepted: 10/05/2011] [Indexed: 11/21/2022]
Abstract
Cerebral creatine transporter deficiency, attributable to mutations in the SLC6A8 gene, causes X-linked mental retardation, language delay, epilepsy, and autistic features. In contrast with creatine synthesis defects, the vast majority of patients with SLC6A8 deficiency do not respond to treatment. We describe a Portuguese family with a mutation (c.456C>T; p.Gln486X) in the SL6CA8 gene: two adult monozygotic twin brothers, with psychomotor delay and severe speech impairment. The family also includes their maternal half-sister with psychomotor retardation, predominantly in language, and their mentally retarded mother. This family illustrates the remarkable phenotypic variability in this condition. Investigation of creatine metabolism is mandatory in patients with developmental delay of unknown etiology, to detect this condition.
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Aziz A, Harrop SP, Bishop NE. DIA1R is an X-linked gene related to Deleted In Autism-1. PLoS One 2011; 6:e14534. [PMID: 21264219 PMCID: PMC3022024 DOI: 10.1371/journal.pone.0014534] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 12/21/2010] [Indexed: 01/28/2023] Open
Abstract
Background Autism spectrum disorders (ASDs) are frequently occurring disorders diagnosed by deficits in three core functional areas: social skills, communication, and behaviours and/or interests. Mental retardation frequently accompanies the most severe forms of ASDs, while overall ASDs are more commonly diagnosed in males. Most ASDs have a genetic origin and one gene recently implicated in the etiology of autism is the Deleted-In-Autism-1 (DIA1) gene. Methodology/Principal Findings Using a bioinformatics-based approach, we have identified a human gene closely related to DIA1, we term DIA1R (DIA1-Related). While DIA1 is autosomal (chromosome 3, position 3q24), DIA1R localizes to the X chromosome at position Xp11.3 and is known to escape X-inactivation. The gene products are of similar size, with DIA1 encoding 430, and DIA1R 433, residues. At the amino acid level, DIA1 and DIA1R are 62% similar overall (28% identical), and both encode signal peptides for targeting to the secretory pathway. Both genes are ubiquitously expressed, including in fetal and adult brain tissue. Conclusions/Significance Examination of published literature revealed point mutations in DIA1R are associated with X-linked mental retardation (XLMR) and DIA1R deletion is associated with syndromes with ASD-like traits and/or XLMR. Together, these results support a model where the DIA1 and DIA1R gene products regulate molecular traffic through the cellular secretory pathway or affect the function of secreted factors, and functional deficits cause disorders with ASD-like symptoms and/or mental retardation.
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Affiliation(s)
- Azhari Aziz
- Department of Microbiology, La Trobe University, Bundoora, Victoria, Australia
| | - Sean P. Harrop
- Department of Microbiology, La Trobe University, Bundoora, Victoria, Australia
| | - Naomi E. Bishop
- Department of Microbiology, La Trobe University, Bundoora, Victoria, Australia
- * E-mail:
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Marco EJ, Abidi FE, Bristow J, Dean WB, Cotter P, Jeremy RJ, Schwartz CE, Sherr EH. ARHGEF9 disruption in a female patient is associated with X linked mental retardation and sensory hyperarousal. BMJ Case Rep 2009; 2009:bcr06.2009.1999. [PMID: 21731583 DOI: 10.1136/bcr.06.2009.1999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
We identified a female patient with mental retardation and sensory hyperarousal. She has a de novo paracentric inversion of one X chromosome with completely skewed inactivation of the normal X chromosome. We aimed to identify whether a single gene or gene region caused her cognitive and behavioural impairment and that of others. Fluorescent in situ hybridisation (FISH) showed that the centromeric breakpoint disrupts a single gene: ARHGEF9 (CDC42 guanine nucleotide exchange factor (GEF) 9). We also found that the levels of the ARHGEF9 transcript from the patient are 10-fold less than those found in control samples. ARHGEF9 encodes a RhoGEF family protein: collybistin (hPEM), which is highly expressed in the brain. Collybistin can regulate actin cytoskeletal dynamics and may also modulate GABAergic and glycinergic neurotransmission through binding of a scaffolding protein, gephyrin, at the synapse. This potential dual role may explain both the mental retardation and hyperarousal observed in our patient.
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Affiliation(s)
- E J Marco
- Department of Neurology, University of California, San Francisco, California, USA
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Zhang L, Jie C, Obie C, Abidi F, Schwartz CE, Stevenson RE, Valle D, Wang T. X chromosome cDNA microarray screening identifies a functional PLP2 promoter polymorphism enriched in patients with X-linked mental retardation. Genome Res 2007; 17:641-8. [PMID: 17416750 PMCID: PMC1855181 DOI: 10.1101/gr.5336307] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
X-linked Mental Retardation (XLMR) occurs in 1 in 600 males and is highly genetically heterogeneous. We used a novel human X chromosome cDNA microarray (XCA) to survey the expression profile of X-linked genes in lymphoblasts of XLMR males. Genes with altered expression verified by Northern blot and/or quantitative PCR were considered candidates. To validate this approach, we documented the expected changes of expression in samples from a patient with a known X chromosome microdeletion and from patients with multiple copies of the X chromosome. We used our XCA to survey lymphoblast RNA samples from 43 unrelated XLMR males and found 15 genes with significant (>or=1.5-fold) reduction in expression in at least one proband. Of these, subsequent analysis confirmed altered expression in 12. We followed up one, PLP2, at Xp11.23, which exhibits approximately fourfold decreased expression in two patients. Sequencing analysis in both patients revealed a promoter variant, -113C>A, that alters the core-binding site of the transcription factor ELK1. We showed that PLP2-(-113C>A) is sufficient to cause reduced expression using a luciferase reporter system and is enriched in a cohort of males with probable XLMR (14 of 239, 5.85%) as compared to normal males (9 of 577, 1.56%) (chi2=11.07, P<0.001). PLP2 is expressed abundantly in the pyramidal cells of hippocampus and granular cells of the cerebellum in the brain. We conclude that our XCA screening is an efficient strategy to identify genes that show significant changes in transcript abundance as candidate genes for XLMR.
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Affiliation(s)
- Lilei Zhang
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore 21205, Maryland
| | - Chunfa Jie
- Microarray Core Facility, Johns Hopkins University School of Medicine, Baltimore , Maryland
| | - Cassandra Obie
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore 21205, Maryland
| | - Fatima Abidi
- Greenwood Genetic Center, Greenwood 29646, South Carolina
| | | | | | - David Valle
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore 21205, Maryland
| | - Tao Wang
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore 21205, Maryland
- Corresponding author.E-mail ; fax (443) 955-7397
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Schwartz CE, Tarpey PS, Lubs HA, Verloes A, May MM, Risheg H, Friez MJ, Futreal PA, Edkins S, Teague J, Briault S, Skinner C, Bauer-Carlin A, Simensen RJ, Joseph SM, Jones JR, Gecz J, Stratton MR, Raymond FL, Stevenson RE. The original Lujan syndrome family has a novel missense mutation (p.N1007S) in the MED12 gene. J Med Genet 2007; 44:472-7. [PMID: 17369503 PMCID: PMC2597996 DOI: 10.1136/jmg.2006.048637] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
A novel missense mutation in the mediator of RNA polymerase II transcription subunit 12 (MED12) gene has been found in the original family with Lujan syndrome and in a second family (K9359) that was initially considered to have Opitz-Kaveggia (FG) syndrome. A different missense mutation in the MED12 gene has been reported previously in the original family with FG syndrome and in five other families with compatible clinical findings. Neither sequence alteration has been found in over 1400 control X chromosomes. Lujan (Lujan-Fryns) syndrome is characterised by tall stature with asthenic habitus, macrocephaly, a tall narrow face, maxillary hypoplasia, a high narrow palate with dental crowding, a small or receding chin, long hands with hyperextensible digits, hypernasal speech, hypotonia, mild-to-moderate mental retardation, behavioural aberrations and dysgenesis of the corpus callosum. Although Lujan syndrome has not been previously considered to be in the differential diagnosis of FG syndrome, there are some overlapping clinical manifestations. Specifically, these are dysgenesis of the corpus callosum, macrocephaly/relative macrocephaly, a tall forehead, hypotonia, mental retardation and behavioural disturbances. Thus, it seems that these two X-linked mental retardation syndromes are allelic, with mutations in the MED12 gene.
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Tarpey PS, Raymond FL, O'Meara S, Edkins S, Teague J, Butler A, Dicks E, Stevens C, Tofts C, Avis T, Barthorpe S, Buck G, Cole J, Gray K, Halliday K, Harrison R, Hills K, Jenkinson A, Jones D, Menzies A, Mironenko T, Perry J, Raine K, Richardson D, Shepherd R, Small A, Varian J, West S, Widaa S, Mallya U, Moon J, Luo Y, Holder S, Smithson SF, Hurst JA, Clayton-Smith J, Kerr B, Boyle J, Shaw M, Vandeleur L, Rodriguez J, Slaugh R, Easton DF, Wooster R, Bobrow M, Srivastava AK, Stevenson RE, Schwartz CE, Turner G, Gecz J, Futreal PA, Stratton MR, Partington M. Mutations in CUL4B, which encodes a ubiquitin E3 ligase subunit, cause an X-linked mental retardation syndrome associated with aggressive outbursts, seizures, relative macrocephaly, central obesity, hypogonadism, pes cavus, and tremor. Am J Hum Genet 2007; 80:345-52. [PMID: 17236139 PMCID: PMC1785336 DOI: 10.1086/511134] [Citation(s) in RCA: 177] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 11/20/2006] [Indexed: 12/23/2022] Open
Abstract
We have identified three truncating, two splice-site, and three missense variants at conserved amino acids in the CUL4B gene on Xq24 in 8 of 250 families with X-linked mental retardation (XLMR). During affected subjects' adolescence, a syndrome emerged with delayed puberty, hypogonadism, relative macrocephaly, moderate short stature, central obesity, unprovoked aggressive outbursts, fine intention tremor, pes cavus, and abnormalities of the toes. This syndrome was first described by Cazebas et al., in a family that was included in our study and that carried a CUL4B missense variant. CUL4B is a ubiquitin E3 ligase subunit implicated in the regulation of several biological processes, and CUL4B is the first XLMR gene that encodes an E3 ubiquitin ligase. The relatively high frequency of CUL4B mutations in this series indicates that it is one of the most commonly mutated genes underlying XLMR and suggests that its introduction into clinical diagnostics should be a high priority.
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Affiliation(s)
- Patrick S Tarpey
- Cancer Genome Project, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, UK
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Martínez-Garay I, Tomás M, Oltra S, Ramser J, Moltó MD, Prieto F, Meindl A, Kutsche K, Martínez F. A two base pair deletion in the PQBP1 gene is associated with microphthalmia, microcephaly, and mental retardation. Eur J Hum Genet 2006; 15:29-34. [PMID: 17033686 DOI: 10.1038/sj.ejhg.5201717] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
X-linked mental retardation has been traditionally divided into syndromic (S-XLMR) and non-syndromic forms (NS-XLMR), although the borderlines between these phenotypes begin to vanish and mutations in a single gene, for example PQBP1, can cause S-XLMR as well as NS-XLMR. Here, we report two maternal cousins with an apparently X-linked phenotype of mental retardation (MR), microphthalmia, choroid coloboma, microcephaly, renal hypoplasia, and spastic paraplegia. By multipoint linkage analysis with markers spanning the entire X-chromosome we mapped the disease locus to a 28-Mb interval between Xp11.4 and Xq12, including the BCOR gene. A missense mutation in BCOR was described in a family with Lenz microphthalmia syndrome, a phenotype showing substantial overlapping features with that described in the two cousins. However, no mutation in the BCOR gene was found in both patients. Subsequent mutation analysis of PQBP1, located within the delineated linkage interval in Xp11.23, revealed a 2-bp deletion, c.461_462delAG, that cosegregated with the disease. Notably, the same mutation is associated with the Hamel cerebropalatocardiac syndrome, another form of S-XLMR. Haplotype analysis suggests a germline mosaicism of the 2-bp deletion in the maternal grandmother of both affected individuals. In summary, our findings demonstrate for the first time that mutations in PQBP1 are associated with an S-XLMR phenotype including microphthalmia, thereby further extending the clinical spectrum of phenotypes associated with PQBP1 mutations.
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Affiliation(s)
- Isabel Martínez-Garay
- Unidad de Genética, Hospital Universitario La Fe, Departamento de Genética, Universidad de Valencia, Valencia, Spain
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Bahi-Buisson N, Chelly J, des Portes V. [Update on the genetics of X-linked mental retardation]. Rev Neurol (Paris) 2006; 162:952-63. [PMID: 17028563 DOI: 10.1016/s0035-3787(06)75105-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Mutations in X-linked genes are likely to account for the observation that more males than females are affected with mental retardation. Causative mutations have been identified in both syndromic XLMR and in the genetically heterogeneous non-syndromic forms of XLMR, without a clear clinical phenotype other than cognitive deficit. Progress in genome analysis and the establishment of large collaborations between clinical and molecular research teams, especially the European XLMR consortium, have led to the identification of 20 non-syndromic XLMR genes and 25 syndromic XLMR genes. Given the extensive heterogeneity of non syndromic XLMR, different strategies are used for the identification of new genes: linkage analysis, studies of balanced chromosomal rearrangements (X-autosome translocations, microdeletions) and candidate genes strategies by mutation screening in regions of the X chromosome known to be involved in neuronal development and function. Delineating the monogenic causes of XLMR and their molecular and cellular consequences will provide insight into the mechanisms that are required for normal development of cognitive function in humans. Non syndromic XLMR proteins include 5 distinct classes: transmembrane receptors, small GTPases effectors or regulators, enzymes and translational regulators.
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Affiliation(s)
- N Bahi-Buisson
- Département de Pédiatrie, Service de Neuropédiatrie et Maladies Métaboliques, Hôpital Necker, and Université René Descartes, Paris, France.
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14
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Lenski C, Abidi F, Meindl A, Gibson A, Platzer M, Frank Kooy R, Lubs HA, Stevenson RE, Ramser J, Schwartz CE. Novel truncating mutations in the polyglutamine tract binding protein 1 gene (PQBP1) cause Renpenning syndrome and X-linked mental retardation in another family with microcephaly. Am J Hum Genet 2004; 74:777-80. [PMID: 15024694 PMCID: PMC1181956 DOI: 10.1086/383205] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Claus Lenski
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Fatima Abidi
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Alfons Meindl
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Alice Gibson
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Matthias Platzer
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - R. Frank Kooy
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Herbert A. Lubs
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Roger E. Stevenson
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Juliane Ramser
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Charles E. Schwartz
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
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15
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Wieland I, Muschke P, Wieacker P. Further delineation of Wittwer syndrome and refinement of the mapping region. Am J Med Genet A 2003; 116A:57-60. [PMID: 12476452 DOI: 10.1002/ajmg.a.10874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In 1996, Wittwer et al. described a XLMR-syndrome mapping in Xp22.3. This family was reexamined. The spectrum of clinical symptoms now includes progressive skeletal lesions with osteoplastic and osteoclastic changes. Haplotype analysis using 23 microsatellite markers on Xp22 localized the disease locus between DXS8095 and DXS7108 comprising 3.9-6.1 Mb. This interval overlaps with known contiguous gene-deletion syndromes. However, deletion analysis of identified genes and ESTs in the critical interval for Wittwer syndrome showed no loss of the corresponding marker sequences in the patients.
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Affiliation(s)
- Ilse Wieland
- Institut für Humangenetik, Otto-von-Guericke-Universität, Magdeburg, Germany
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16
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Lower KM, Turner G, Kerr BA, Mathews KD, Shaw MA, Gedeon AK, Schelley S, Hoyme HE, White SM, Delatycki MB, Lampe AK, Clayton-Smith J, Stewart H, van Ravenswaay CMA, de Vries BBA, Cox B, Grompe M, Ross S, Thomas P, Mulley JC, Gécz J. Mutations in PHF6 are associated with Börjeson-Forssman-Lehmann syndrome. Nat Genet 2002; 32:661-5. [PMID: 12415272 DOI: 10.1038/ng1040] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2002] [Accepted: 10/11/2002] [Indexed: 11/09/2022]
Abstract
Börjeson-Forssman-Lehmann syndrome (BFLS; OMIM 301900) is characterized by moderate to severe mental retardation, epilepsy, hypogonadism, hypometabolism, obesity with marked gynecomastia, swelling of subcutaneous tissue of the face, narrow palpebral fissure and large but not deformed ears. Previously, the gene associated with BFLS was localized to 17 Mb in Xq26-q27 (refs 2-4). We have reduced this interval to roughly 9 Mb containing more than 62 genes. Among these, a novel, widely expressed zinc-finger (plant homeodomain (PHD)-like finger) gene (PHF6) had eight different missense and truncation mutations in seven familial and two sporadic cases of BFLS. Transient transfection studies with PHF6 tagged with green fluorescent protein (GFP) showed diffuse nuclear staining with prominent nucleolar accumulation. Such localization, and the presence of two PHD-like zinc fingers, is suggestive of a role for PHF6 in transcription.
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Affiliation(s)
- Karen M Lower
- Department of Cytogenetics and Molecular Genetics, Centre for Medical Genetics, Women's and Children's Hospital, 72 King William Rd., North Adelaide, SA 5006, Australia
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17
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Frints SGM, Froyen G, Marynen P, Fryns JP. X-linked mental retardation: vanishing boundaries between non-specific (MRX) and syndromic (MRXS) forms. Clin Genet 2002; 62:423-32. [PMID: 12485186 DOI: 10.1034/j.1399-0004.2002.620601.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This review covers the history and nosology of X-linked mental retardation (XLMR) in which the following, largely clinically based, subclassification was used: fragile X syndrome (FRAXA), syndromic forms (MRXS) and non-specific forms (MRX). After the discovery of the FMR2 gene at the FRAXE site, 10 MRX genes have been identified in the last 6 years. A short description is given of the strategies used to identify the genes that cause mental retardation (MR). Furthermore, their potential functions and the association with MR will be discussed. It is emphasized that mutations in several of these MR genes can result in non-specific, as well as in syndromic forms of XLMR. Present findings stress the importance of accurate clinical evaluation. Most considerably, genotype-phenotype correlation studies of affected individuals in XLMR families with MRX gene mutations are necessary to define the criteria of MRX vs MRXS subclassification.
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Affiliation(s)
- S G M Frints
- Flanders Interuniversity Institute for Biotechnology, Department of Human Genetics, Leuven, Belgium
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18
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Frints SGM, Borghgraef M, Froyen G, Marynen P, Fryns JP. Clinical study and haplotype analysis in two brothers with Partington syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 112:361-8. [PMID: 12376938 DOI: 10.1002/ajmg.10630] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Partington et al. [1988] described a three-generation family (MRXS1, MIM *309510, PRTS) with a syndromic form of X-linked mental retardation (XLMR). The clinical features in 10 affected males included mild to moderate MR, dystonic movements of the hands, and dysarthria. After refinement, the PRTS locus was mapped to marker DXS989 (with maximum LOD score of 3.1) with flanking markers DXS365 and DXS28. Since then, no other patients with a similar phenotype have been described. We present a detailed description of the neurological symptoms and the disease history of two brothers with the clinical features of PRTS. Psychomotor development was delayed in both, and neurological features included mild to moderate mental retardation, dysarthria, facial muscle weakness, severe dysdiadochokinesis, slow dystonic movements, and mild spasticity of the hands, without ataxia or spasticity of the legs. The symptoms were nonprogressive and extrapyramidal, and without cerebellar involvement. In general, behavior of the two brothers was friendly and quiet, although the elder brother had periods of depressed mood and outbursts of anger. Karyotypes and subsequent investigation of the subtelomeres as well as DNA analysis of the FMR1 gene, the androgen receptor gene, and the DM locus did not reveal a genetic abnormality. Haplotype analysis showed that the affected brothers share the PRTS region at Xp22.1. Mutation screening of the PDH-E1alpha gene did not reveal a pathogenic mutation.
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Affiliation(s)
- Suzanna G M Frints
- Human Genome Laboratory, Flanders Interuniversity Institute for Biotechnology, Leuven, Belgium
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19
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Saito-Ohara F, Fukuda Y, Ito M, Agarwala KL, Hayashi M, Matsuo M, Imoto I, Yamakawa K, Nakamura Y, Inazawa J. The Xq22 inversion breakpoint interrupted a novel Ras-like GTPase gene in a patient with Duchenne muscular dystrophy and profound mental retardation. Am J Hum Genet 2002; 71:637-45. [PMID: 12145744 PMCID: PMC379199 DOI: 10.1086/342208] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2002] [Accepted: 06/05/2002] [Indexed: 11/03/2022] Open
Abstract
A male patient with profound mental retardation, athetosis, nystagmus, and severe congenital hypotonia (Duchenne muscular dystrophy [DMD]) was previously shown to carry a pericentric inversion of the X chromosome, 46,Y,inv(X)(p21.2q22.2). His mother carried this inversion on one X allele. The patient's condition was originally misdiagnosed as cerebral palsy, and only later was it diagnosed as DMD. Because the DMD gene is located at Xp21.2, which is one breakpoint of the inv(X), and because its defects are rarely associated with severe mental retardation, the other clinical features of this patient were deemed likely to be associated with the opposite breakpoint at Xq22. Our precise molecular-cytogenetic characterization of both breakpoints revealed three catastrophic genetic events that had probably influenced neuromuscular and cognitive development: deletion of part of the DMD gene at Xp21.2, duplication of the human proteolipid protein gene (PLP) at Xq22.2, and disruption of a novel gene. The latter sequence, showing a high degree of homology to the Sec4 gene of yeast, encoded a putative small guanine-protein, Ras-like GTPase that we have termed "RLGP." Immunocytochemistry located RLGP at mitochondria. We speculate that disruption of RLGP was responsible for the patient's profound mental retardation.
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Affiliation(s)
- Fumiko Saito-Ohara
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Yoji Fukuda
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Masahiro Ito
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Kishan Lal Agarwala
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Masaharu Hayashi
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Masafumi Matsuo
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Issei Imoto
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Kazuhiro Yamakawa
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Yusuke Nakamura
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
| | - Johji Inazawa
- Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University, Department of Pediatrics, Tokyo Metropolitan Bokutoh Hospital, Department of Clinical Pathology, Tokyo Metropolitan Institute for Neuroscience, and Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo; Laboratory for Neurogenetics, RIKEN Brain Science Institute, Saitama, Japan; and Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Kobe, Japan
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20
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Barnes AP, Milgram SL. Signals from the X: signal transduction and X-linked mental retardation. Int J Dev Neurosci 2002; 20:397-406. [PMID: 12175880 DOI: 10.1016/s0736-5748(02)00016-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The dramatic increase in genomic information is allowing the rapid identification of genes that are altered in mental retardation (MR). It is necessary to place their resulting gene products in their cellular context to understand how they may have contributed to a patient's cognitive deficits. This review will consider signaling molecules that have been implicated in X-linked MR and the known pathways by which these proteins covey information will be delineated. The proteins discussed include four distinct classes: transmembrane receptors, guanine nucleotide related proteins, kinases, and translational regulators.
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Affiliation(s)
- Anthony P Barnes
- Department of Cell and Developmental Biology, UNC-Neurodevelopmental Disorders Research Center, University of North Carolina, Chapel Hill, NC 27599, USA
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21
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Klauck SM, Lindsay S, Beyer KS, Splitt M, Burn J, Poustka A. A mutation hot spot for nonspecific X-linked mental retardation in the MECP2 gene causes the PPM-X syndrome. Am J Hum Genet 2002; 70:1034-7. [PMID: 11885030 PMCID: PMC379098 DOI: 10.1086/339553] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2001] [Accepted: 01/09/2002] [Indexed: 11/03/2022] Open
Abstract
We report here the genetic cause of the X-linked syndrome of psychosis, pyramidal signs, and macro-orchidism (PPM-X) in a three-generation family manifesting the disorder as a mutation in the methyl-CpG binding-protein 2 (MECP2) gene in Xq28. The A140V mutation was found in all affected males and all carrier females in the family. To date, descriptions have been published of two patients with independent familial mental retardation (MR) and two patients with sporadic MR who harbor this specific mutation in the MECP2 gene. This strongly suggests that A140V is a hot spot of mutation resulting in moderate to severe MR in males. A simple and reliable PCR approach has been developed for detection of the hot spot A140V mutation to prescreen any other unexplained cases of MR before further extensive mutation analyses.
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Affiliation(s)
- Sabine M. Klauck
- Department of Molecular Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany; Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; and South East Thames Regional Genetics Service, Guy’s Hospital, London
| | - Susan Lindsay
- Department of Molecular Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany; Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; and South East Thames Regional Genetics Service, Guy’s Hospital, London
| | - Kim S. Beyer
- Department of Molecular Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany; Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; and South East Thames Regional Genetics Service, Guy’s Hospital, London
| | - Miranda Splitt
- Department of Molecular Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany; Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; and South East Thames Regional Genetics Service, Guy’s Hospital, London
| | - John Burn
- Department of Molecular Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany; Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; and South East Thames Regional Genetics Service, Guy’s Hospital, London
| | - Annemarie Poustka
- Department of Molecular Genome Analysis, Deutsches Krebsforschungszentrum, Heidelberg, Germany; Institute of Human Genetics, Newcastle upon Tyne, United Kingdom; and South East Thames Regional Genetics Service, Guy’s Hospital, London
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22
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Lebel RR, May M, Pouls S, Lubs HA, Stevenson RE, Schwartz CE. Non-syndromic X-linked mental retardation associated with a missense mutation (P312L) in the FGD1 gene. Clin Genet 2002; 61:139-45. [PMID: 11940089 DOI: 10.1034/j.1399-0004.2002.610209.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Three brothers with non-syndromal X-linked mental retardation were found to have a novel missense mutation in FGD1, the gene associated with the Aarskog syndrome. Although the brothers have short stature and small feet, they lack distinct craniofacial, skeletal or genital findings suggestive of Aarskog syndrome. Their mother, the only obligate carrier available for testing, has the FGD1 mutation. The mutation, a C934T base change in exon 4, results in the proline at position 312 to be substituted with a leucine. This missense mutation is predicted to eliminate a beta-turn, creating an extra-long stretch of coiled sequence which may affect the orientations of an SH3 (Src homology 3) binding domain and the first structural conserved region. A new molecular defect associated with non-syndromal X-linked mental retardation affords an opportunity to seek specific diagnosis in males with previously unexplained developmental delays and this opens further predictive tests in families at risk.
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Affiliation(s)
- R R Lebel
- Genetics Services, The Helix Building, Glen Ellyn, IL 60137, USA.
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23
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Abstract
X-linked mental retardation (XLMR) is a most exciting field of modern medical genetics. It made spectacular advances over the last twenty years, after the advent of molecular genetics. The discovery of the FMR1 gene unraveled the cause of the most common form of heritable mental retardation and provided the prototype of dynamic mutations. New genes continue to be mapped to the X chromosome and more and more are being cloned and characterized, clarifying the nosology of XLMR and, more importantly, adding to our understanding of the mechanisms of intellectual development, normal and abnormal. Looking back to a more or less recent past may provide clues for future discoveries.
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Affiliation(s)
- G Neri
- Istituto di Genetica Medica, Università Cattolica, Largo F. Vito, 1, 00168 Roma, Italy.
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24
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Abstract
Mutations in X-linked genes are likely to account for the observation that more males than females are affected by mental retardation. Causative mutations have recently been identified in both syndromic X-linked mental retardation (XLMR) and in the genetically heterogeneous 'nonspecific' forms of XLMR, for which cognitive impairment is the only defining clinical feature. Proteins that function in chromatin remodelling are affected in three important syndromic forms of XLMR. In nonspecific forms of the disorder, defects have been found in signal-transduction pathways that are believed to function during neuronal maturation. These findings provide important insights into the molecular and cellular defects that underlie mental retardation.
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Affiliation(s)
- J Chelly
- Institut Cochin de Génétique Moléculaire, CNRS/INSERM, CHU Cochin 75014 Paris, France.
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