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Smogavec M, Cleall A, Hoyer J, Lederer D, Nassogne MC, Palmer EE, Deprez M, Benoit V, Maystadt I, Noakes C, Leal A, Shaw M, Gecz J, Raymond L, Reis A, Shears D, Brockmann K, Zweier C. Eight further individuals with intellectual disability and epilepsy carrying bi-allelic CNTNAP2 aberrations allow delineation of the mutational and phenotypic spectrum. J Med Genet 2016; 53:820-827. [PMID: 27439707 DOI: 10.1136/jmedgenet-2016-103880] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/20/2016] [Accepted: 06/25/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND Heterozygous copy number variants (CNVs) or sequence variants in the contactin-associated protein 2 gene CNTNAP2 have been discussed as risk factors for a wide spectrum of neurodevelopmental and neuropsychiatric disorders. Bi-allelic aberrations in this gene are causative for an autosomal-recessive disorder with epilepsy, severe intellectual disability (ID) and cortical dysplasia (CDFES). As the number of reported individuals is still limited, we aimed at a further characterisation of the full mutational and clinical spectrum. METHODS Targeted sequencing, chromosomal microarray analysis or multigene panel sequencing was performed in individuals with severe ID and epilepsy. RESULTS We identified homozygous mutations, compound heterozygous CNVs or CNVs and mutations in CNTNAP2 in eight individuals from six unrelated families. All aberrations were inherited from healthy, heterozygous parents and are predicted to be deleterious for protein function. Epilepsy occurred in all affected individuals with onset in the first 3.5 years of life. Further common aspects were ID (severe in 6/8), regression of speech development (5/8) and behavioural anomalies (7/8). Interestingly, cognitive impairment in one of two affected brothers was, in comparison, relatively mild with good speech and simple writing abilities. Cortical dysplasia that was previously reported in CDFES was not present in MRIs of six individuals and only suspected in one. CONCLUSIONS By identifying novel homozygous or compound heterozygous, deleterious CNVs and mutations in eight individuals from six unrelated families with moderate-to-severe ID, early onset epilepsy and behavioural anomalies, we considerably broaden the mutational and clinical spectrum associated with bi-allelic aberrations in CNTNAP2.
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Affiliation(s)
- Mateja Smogavec
- Institute of Human Genetics, University Medical Center, Georg August University, Göttingen, Germany
| | - Alison Cleall
- Oxford Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Juliane Hoyer
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Damien Lederer
- Centre de Génétique Humaine, Institut de Pathologie et Génétique, Charleroi, Belgium
| | - Marie-Cécile Nassogne
- Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Woluwe-Saint-Lambert, Belgium
| | - Elizabeth E Palmer
- GOLD (Genetics of Learning and Disability) Service, Hunter Genetics, Waratah, New South Wales, Australia.,University of New South Wales, Sydney, New South Wales, Australia
| | - Marie Deprez
- Centre de Génétique Humaine, Institut de Pathologie et Génétique, Charleroi, Belgium
| | - Valérie Benoit
- Centre de Génétique Humaine, Institut de Pathologie et Génétique, Charleroi, Belgium
| | - Isabelle Maystadt
- Centre de Génétique Humaine, Institut de Pathologie et Génétique, Charleroi, Belgium
| | - Charlotte Noakes
- Oxford Genetics Laboratories, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Alejandro Leal
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.,Section of Genetics and Biotechnology, School of Biology and Neuroscience Research Center, University of Costa Rica, San José, Costa Rica
| | - Marie Shaw
- School of Medicine, and the Robinson Research Institute, the University of Adelaide, Adelaide, South Australia, Australia
| | - Jozef Gecz
- School of Medicine, and the Robinson Research Institute, the University of Adelaide, Adelaide, South Australia, Australia
| | - Lucy Raymond
- Department of Medical Genetics, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK
| | - André Reis
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Deborah Shears
- Department of Clinical Genetics, Churchill Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Knut Brockmann
- Interdisciplinary Pediatric Center for Children with Developmental Disabilities and Severe Chronic Disorders, University Medical Center, Georg August University, Göttingen, Germany
| | - Christiane Zweier
- Institute of Human Genetics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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Characterisation of CASPR2 deficiency disorder--a syndrome involving autism, epilepsy and language impairment. BMC MEDICAL GENETICS 2016; 17:8. [PMID: 26843181 PMCID: PMC4739328 DOI: 10.1186/s12881-016-0272-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 01/29/2016] [Indexed: 11/18/2022]
Abstract
Background Heterozygous mutations in CNTNAP2 have been identified in patients with a range of complex phenotypes including intellectual disability, autism and schizophrenia. However heterozygous CNTNAP2 mutations are also found in the normal population. Conversely, homozygous mutations are rare in patient populations and have not been found in any unaffected individuals. Case presentation We describe a consanguineous family carrying a deletion in CNTNAP2 predicted to abolish function of its protein product, CASPR2. Homozygous family members display epilepsy, facial dysmorphisms, severe intellectual disability and impaired language. We compared these patients with previously reported individuals carrying homozygous mutations in CNTNAP2 and identified a highly recognisable phenotype. Conclusions We propose that CASPR2 loss produces a syndrome involving early-onset refractory epilepsy, intellectual disability, language impairment and autistic features that can be recognized as CASPR2 deficiency disorder. Further screening for homozygous patients meeting these criteria, together with detailed phenotypic and molecular investigations will be crucial for understanding the contribution of CNTNAP2 to normal and disrupted development.
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3
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Marangi G, Zollino M. Pitt-Hopkins Syndrome and Differential Diagnosis: A Molecular and Clinical Challenge. J Pediatr Genet 2015; 4:168-76. [PMID: 27617128 DOI: 10.1055/s-0035-1564570] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 06/16/2015] [Indexed: 12/30/2022]
Abstract
Pitt-Hopkins syndrome is an emerging neurodevelopmental disorder caused by haploinsufficiency of the TCF4 gene on chromosome 18q21. It is characterized by severe intellectual disability, seizures, microcephaly, constipation and a distinctive facial gestalt. Although the overlapping phenotype of microcephaly, epilepsy, absent speech and constipation represents a challenge for the differential diagnosis with Angelman syndrome, Rett syndrome and Mowat-Wilson syndrome, distinctive of Pitt-Hopkins syndrome are breathing abnormalities, that can occur as either hyperventilation episodes or apnea crises, and a typical facial dysmorphism, including bitemporal narrowing, squared forehead, deep-set eyes, peculiar nose conformation, with broad nasal bridge, down-turned nasal tip and flaring nostrils, typical shape of the mouth, with a tented and M shaped upper lip, and widely spaced teeth. The occurrence of these signs in variable association of uncoordinated movements, microcephaly of postnatal onset, eye abnormalities, constipation, epilepsy and subtle brain abnormalities is highly predictive of a TCF4 mutation, making it possible to plan a genetic test of choice among severe encephalopathies. Angelman syndrome represents the nosological condition closest to Pitt-Hopkins syndrome.
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Affiliation(s)
- Giuseppe Marangi
- Department of Laboratory Medicine, Institute of Medical Genetics, Catholic University, Rome, Italy
| | - Marcella Zollino
- Department of Laboratory Medicine, Institute of Medical Genetics, Catholic University, Rome, Italy
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Watson CM, Crinnion LA, Tzika A, Mills A, Coates A, Pendlebury M, Hewitt S, Harrison SM, Daly C, Roberts P, Carr IM, Sheridan EG, Bonthron DT. Diagnostic whole genome sequencing and split-read mapping for nucleotide resolution breakpoint identification in CNTNAP2 deficiency syndrome. Am J Med Genet A 2014; 164A:2649-55. [PMID: 25045150 DOI: 10.1002/ajmg.a.36679] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 06/16/2014] [Indexed: 11/08/2022]
Abstract
Whole genome sequencing (WGS) has the potential to report on all types of genetic abnormality, thus converging diagnostic testing on a single methodology. Although WGS at sufficient depth for robust detection of point mutations is still some way from being affordable for diagnostic purposes, low-coverage WGS is already an excellent method for detecting copy number variants ("CNVseq"). We report on a family in which individuals presented with a presumed autosomal recessive syndrome of severe intellectual disability and epilepsy. Array comparative genomic hybridization (CGH) analysis had revealed a homozygous deletion apparently lying within intron 3 of CNTNAP2. Since this was too small for confirmation by FISH, CNVseq was used, refining the extent of this mutation to approximately 76.8 kb, encompassing CNTNAP2 exon 3 (an out-of-frame deletion). To characterize the precise breakpoints and provide a rapid molecular diagnostic test, we resequenced the CNVseq library at medium coverage and performed split read mapping. This yielded information for a multiplex polymerase chain reaction (PCR) assay, used for cascade screening and/or prenatal diagnosis in this family. This example demonstrates a rapid, low-cost approach to converting molecular cytogenetic findings into robust PCR-based tests.
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Affiliation(s)
- Christopher M Watson
- Yorkshire Regional Genetics Service, St. James's University Hospital, Leeds, United Kingdom; School of Medicine, University of Leeds, St. James's University Hospital, Leeds, United Kingdom
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Rush ET, Stevens JM, Sanger WG, Olney AH. Report of a patient with developmental delay, hearing loss, growth retardation, and cleft lip and palate and a deletion of 7q34-36.1: review of distal 7q deletions. Am J Med Genet A 2013; 161A:1726-32. [PMID: 23696251 DOI: 10.1002/ajmg.a.35951] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 02/09/2013] [Indexed: 11/10/2022]
Abstract
The use of aCGH has improved our ability to find subtle cytogenetic abnormalities as well as to find more precise information in patients with previously known abnormalities. In addition, it has allowed more specific genotype-phenotype correlation. In this report we describe a patient with a chromosomal deletion initially diagnosed with conventional cytogenetic analysis which was redemonstrated and more specifically described upon aCGH analysis. Our patient is a 12-year-old female born to a 26-year-old G1P0 mother. She was noted as a neonate to have a bilateral cleft lip and cleft palate, abnormal external ears, dysmorphic facies, and moderate to severe hearing loss. She has subsequently shown developmental delay, hyperreflexia, seizures, hyperactivity, and absence of speech. Chromosomal analysis showed deletion of 7q34q36.1. FISH studies confirmed the deletion was interstitial. Parental chromosomes were performed and did not show any cytogenetic abnormalities. aCGH was recently performed for the patient to further characterize the breakpoints of the deletion and confirmed the deletion was interstitial and of 13.2 Mb in size. Both proximal and terminal 7q deletion show a different phenotype than that of our patient. A number of patients with similar deletions have been found and while significant variability is observed, a number of findings appear to be common to deletions in this region. Therefore, we feel that distal interstitial deletions of chromosome 7q represent a recognizable phenotype and could be considered a separate deletion syndrome.
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Affiliation(s)
- Eric T Rush
- Munroe-Meyer Institute for Genetics and Rehabilitation, University of Nebraska Medical Center, Omaha, NE, USA.
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Sweatt JD. Pitt-Hopkins Syndrome: intellectual disability due to loss of TCF4-regulated gene transcription. Exp Mol Med 2013; 45:e21. [PMID: 23640545 PMCID: PMC3674405 DOI: 10.1038/emm.2013.32] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 02/03/2013] [Indexed: 01/22/2023] Open
Abstract
TCF4 (transcription factor 4; E2-2, ITF2) is a transcription factor that when haplo-insufficient causes Pitt-Hopkins Syndrome (PTHS), an autism-spectrum disorder that is associated with pervasive developmental delay and severe intellectual disability. The TCF4 gene is also a risk factor with highly significant linkage to schizophrenia, presumably via overexpression of the TCF4 gene product in the central nervous system. This review will present an overview of the clinical manifestations of PTHS and relate those clinical attributes to the underlying molecular genetics of TCF4. In order to provide a molecular biological context for the loss of function of TCF4 in PTHS, the review will also present a brief overview of the basic biochemistry of TCF4-mediated regulation of cellular and neuronal gene expression. In the final section of this review, I will discuss and speculate upon possible roles for the TCF4 transcription factor in neuronal function and comment upon how understanding these roles may give new insights into the molecular neurobiology of human cognition.
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Affiliation(s)
- J David Sweatt
- Department of Neurobiology and Evelyn F. McKnight Brain Institute, Civitan International Research Center, University of Alabama at Birmingham, Birmingham, AL 35294-2182, USA.
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7
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Navarrete K, Pedroso I, De Jong S, Stefansson H, Steinberg S, Stefansson K, Ophoff RA, Schalkwyk LC, Collier DA. TCF4 (e2-2; ITF2): a schizophrenia-associated gene with pleiotropic effects on human disease. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:1-16. [PMID: 23129290 DOI: 10.1002/ajmg.b.32109] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 09/27/2012] [Indexed: 12/22/2022]
Abstract
Common SNPs in the transcription factor 4 (TCF4; ITF2, E2-2, SEF-2) gene, which encodes a basic Helix-Loop-Helix (bHLH) transcription factor, are associated with schizophrenia, conferring a small increase in risk. Other common SNPs in the gene are associated with the common eye disorder Fuch's corneal dystrophy, while rare, mostly de novo inactivating mutations cause Pitt-Hopkins syndrome. In this review, we present a systematic bioinformatics and literature review of the genomics, biological function and interactome of TCF4 in the context of schizophrenia. The TCF4 gene is present in all vertebrates, and although protein length varies, there is high conservation of primary sequence, including the DNA binding domain. Humans have a unique leucine-rich nuclear export signal. There are two main isoforms (A and B), as well as complex splicing generating many possible N-terminal amino acid sequences. TCF4 is highly expressed in the brain, where plays a role in neurodevelopment, interacting with class II bHLH transcription factors Math1, HASH1, and neuroD2. The Ca(2+) sensor protein calmodulin interacts with the DNA binding domain of TCF4, inhibiting transcriptional activation. It is also the target of microRNAs, including mir137, which is implicated in schizophrenia. The schizophrenia-associated SNPs are in linkage disequilibrium with common variants within putative DNA regulatory elements, suggesting that regulation of expression may underlie association with schizophrenia. Combined gene co-expression analyses and curated protein-protein interaction data provide a network involving TCF4 and other putative schizophrenia susceptibility genes. These findings suggest new opportunities for understanding the molecular basis of schizophrenia and other mental disorders.
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Affiliation(s)
- Katherinne Navarrete
- Social, Genetic and Developmental Psychiatry Centre, King's College London, Institute of Psychiatry, London, UK
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Van Balkom IDC, Vuijk PJ, Franssens M, Hoek HW, Hennekam RCM. Development, cognition, and behaviour in Pitt-Hopkins syndrome. Dev Med Child Neurol 2012; 54:925-31. [PMID: 22712893 DOI: 10.1111/j.1469-8749.2012.04339.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
AIM The aim of the study was to collect detailed data on behavioural, adaptive, and psychological functioning in 10 individuals with Pitt-Hopkins syndrome (PTHS), with specific attention to manifestations of autism spectrum disorder (ASD). METHOD The participants (four females, six males), residing in the Netherlands and Belgium, were ascertained through the Dutch national PTHS support group. Median age of participants was 10 years, the age range was between 32 and 289 months. They underwent psychiatric examinations and neuropsychological measurements using a comprehensive assessment battery. Additionally, parental information was gathered through standardized interviews and questionnaires. Findings were compared with those from the literature. RESULTS All participants showed profound intellectual disability, amiable demeanour with minimal maladaptive behaviours, severe impairments of communication and language, and intense, frequent motor stereotypies. Impairments in all participants were beyond what would be expected for cognitive abilities, fitting a classification of ASD. INTERPRETATION Patients with PTHS are characterized not only by specific physical and genetic manifestations but also by specific behavioural and cognitive characteristics. Studying behaviour and cognition may improve diagnosis and prognosis, allows recognition of comorbidities, and contributes to adequate counselling of families.
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Affiliation(s)
- Ingrid D C Van Balkom
- Jonx Department of Youth Mental Health, Lentis Psychiatric Institute, Zuidlaren, the Netherlands.
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Marangi G, Ricciardi S, Orteschi D, Tenconi R, Monica MD, Scarano G, Battaglia D, Lettori D, Vasco G, Zollino M. Proposal of a clinical score for the molecular test for Pitt-Hopkins syndrome. Am J Med Genet A 2012; 158A:1604-11. [PMID: 22678594 DOI: 10.1002/ajmg.a.35419] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 03/15/2012] [Indexed: 11/07/2022]
Abstract
Pitt-Hopkins syndrome (PTHS) is an emerging condition characterized by severe intellectual disability (ID), typical facial gestalt, and additional features, such as breathing abnormalities. Because of the overlapping phenotype of severe ID with absent speech, epilepsy, microcephaly, large mouth, and constipation, differential diagnosis of PTHS with respect to Angelman, Rett, and Mowat-Wilson syndromes represents a relevant clinical issue, and many patients are currently undergoing genetic tests for different conditions that are assumed to fall within the PTHS clinical spectrum. During a search for TCF4 mutations in 78 patients with a suspected PTHS, haploinsufficiency of TCF4 was identified in 18. By evaluating clinical features of patients with a proven TCF4 mutation with those of patients without, we noticed that, in addition to the typical facial gestalt, the PTHS phenotype results from the various combination of the following characteristics: ID with severe speech impairment, normal growth parameters at birth, postnatal microcephaly, breathing abnormalities, motor incoordination, ocular anomalies, constipation, seizures, typical behavior, and subtle brain abnormalities. On the basis of these observations, here we propose a clinically based score system as useful tool for driving a first choice molecular test for PTHS. This scoring system is also proposed for a clinically based diagnosis of PTHS in absence of a proven TCF4 mutation.
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Affiliation(s)
- Giuseppe Marangi
- Istituto di Genetica Medica, Università Cattolica del Sacro Cuore, Roma, Italy
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Genetic differences in the two main groups of the Japanese population based on autosomal SNPs and haplotypes. J Hum Genet 2012; 57:326-34. [PMID: 22456480 DOI: 10.1038/jhg.2012.26] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Although the Japanese population has a rather low genetic diversity, we recently confirmed the presence of two main clusters (the Hondo and Ryukyu clusters) through principal component analysis of genome-wide single-nucleotide polymorphism (SNP) genotypes. Understanding the genetic differences between the two main clusters requires further genome-wide analyses based on a dense SNP set and comparison of haplotype frequencies. In the present study, we determined haplotypes for the Hondo cluster of the Japanese population by detecting SNP homozygotes with 388,591 autosomal SNPs from 18,379 individuals and estimated the haplotype frequencies. Haplotypes for the Ryukyu cluster were inferred by a statistical approach using the genotype data from 504 individuals. We then compared the haplotype frequencies between the Hondo and Ryukyu clusters. In most genomic regions, the haplotype frequencies in the Hondo and Ryukyu clusters were very similar. However, in addition to the human leukocyte antigen region on chromosome 6, other genomic regions (chromosomes 3, 4, 5, 7, 10 and 12) showed dissimilarities in haplotype frequency. These regions were enriched for genes involved in the immune system, cell-cell adhesion and the intracellular signaling cascade. These differentiated genomic regions between the Hondo and Ryukyu clusters are of interest because they (1) should be examined carefully in association studies and (2) likely contain genes responsible for morphological or physiological differences between the two groups.
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Abstract
Pitt-Hopkins syndrome (PTHS, MIM #610954) is characterized by severe intellectual disability, typical facial features and tendency to epilepsy, panting-and-holding breathing anomaly, stereotypic movements, constipation, and high myopia. Growth is normal or only mildly retarded, but half of the patients have postnatal microcephaly. Remarkably, congenital malformations are practically nonexistent. The cause of PTHS is de novo haploinsufficiency of the TCF4 gene (MIM *602272) at 18q21.2. Altogether 78 PTHS patients with abnormalities of the TCF4 gene have been published since 2007 when the etiology of PTHS was revealed. In addition, 27 patients with 18q deletion encompassing the TCF4 gene but without given PTHS diagnosis have been published, and thus, the number of reported patients with a TCF4 abnormality exceeds 100. The mutational spectrum includes large chromosomal deletions encompassing the whole TCF4 gene, partial gene deletions, frameshift (including premature stop codon), nonsense, splice site, and missense mutations. So far, almost all patients have a private mutation and only 2 recurrent mutations are known. There is no evident genotype-phenotype correlation. No familial cases have been reported. Diagnosis of PTHS is based on the molecular confirmation of the characteristic clinical features. Recently, a Pitt-Hopkins-like phenotype has been assigned to autosomal recessive mutations of the CNTNAP2 gene at 7q33q36 and the NRXN1 gene at 2p16.3.
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Affiliation(s)
- M Peippo
- Department of Medical Genetics, The Family Federation of Finland, Helsinki, Finland
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12
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Marangi G, Ricciardi S, Orteschi D, Lattante S, Murdolo M, Dallapiccola B, Biscione C, Lecce R, Chiurazzi P, Romano C, Greco D, Pettinato R, Sorge G, Pantaleoni C, Alfei E, Toldo I, Magnani C, Bonanni P, Martinez F, Serra G, Battaglia D, Lettori D, Vasco G, Baroncini A, Daolio C, Zollino M. The Pitt-Hopkins syndrome: report of 16 new patients and clinical diagnostic criteria. Am J Med Genet A 2011; 155A:1536-45. [PMID: 21671391 DOI: 10.1002/ajmg.a.34070] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Accepted: 03/30/2011] [Indexed: 11/05/2022]
Abstract
Pitt-Hopkins syndrome (PTHS) is characterized by severe intellectual disability, typical facial gestalt and additional features, such as breathing anomalies. Following the discovery of the causative haploinsufficiency of transcription factor 4 (TCF4), about 60 patients have been reported. We looked for TCF4 mutations in 63 patients with a suspected PTHS. Haploinsufficiency of TCF4 was identified in 14 patients, as a consequence of large 18q21.2 chromosome deletions involving TCF4 (2 patients), gene mutations (11 patients) and a t(14q;18q) balanced translocation disrupting TCF4 (one patient). By evaluating the clinical features of these patients, along with literature data, we noticed that, in addition to the typical facial gestalt, the PTHS phenotype results from the various combinations of the following characteristics: intellectual disability with severe speech impairment, normal growth parameters at birth, postnatal microcephaly, breathing anomalies, motor incoordination, ocular anomalies, constipation, seizures, typical behavior and subtle brain abnormalities. Although PTHS is currently considered to be involved in differential diagnosis with Angelman and Rett syndromes, we found that combining the facial characteristics with a detailed analysis of both the physical and the neurological phenotype, made molecular testing for PTHS the first choice. Based on striking clinical criteria, a diagnosis of PTHS was made clinically in two patients who had normal TCF4. This report deals with the first series of PTHS patients of Italian origin.
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Affiliation(s)
- Giuseppe Marangi
- Istituto di Genetica Medica, Università Cattolica del Sacro Cuore, Roma, Italy
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Taddeucci G, Bonuccelli A, Mantellassi I, Orsini A, Tarantino E. Pitt-Hopkins syndrome: report of a case with a TCF4 gene mutation. Ital J Pediatr 2010; 36:12. [PMID: 20205897 PMCID: PMC2827426 DOI: 10.1186/1824-7288-36-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Accepted: 02/02/2010] [Indexed: 11/13/2022] Open
Abstract
Aims We will discuss the clinical and genetic diagnosis of a child with severe psychomotor delay, who at 3 years of age presented with paroxysms of hyperpnea-apnea and seizures unrelated to breathing anomalies. Methods The child underwent genetic (karyotype, FISH telomeres) and neuroradiological (cranial CT and MRI) tests, which proved to be normal. He came under our clinical observation at 3 years and 5 months of age. Due to severe psychomotor delay and facial dysmorphisms we completed the genetic investigations based on his clinical feature and analysis of the available literature. Results The presence of severe mental retardation associated with anomalous breathing pattern may suggest the Joubert and Rett syndrome, however these were excluded on the basis of clinical and genetic examination. Angelman syndrome, suspected for facial dysmorphisms and absent language, was also excluded because of the presence of a normal pattern of methylation at SNRPN locus. Another possible diagnosis was the Pitt-Hopkins Syndrome (PHS), characterized by severe mental retardation, breathing anomalies (paroxisms of hyperpnea-apnea), dysmorphisms and sometimes epilepsy. Haploinsufficiency of TCF4 gene located at 18q21.2 region has been recently identified as causative of this syndrome. In our patient the research of TCF4 mutation by the Institute of Human Genetics, University Hospital Erlangen (Germany), showed a de novo mutation. Conclusions The diagnosis of Pitt-Hopkins syndrome, an underdiagnosed cause of mental retardation, was based on clinical and genetic findings. Searching for TCF4 mutations is highly recommended when others overlapping syndromes was excluded. At our knowledge our patient is the first italian case of PHS diagnosed at molecular level.
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Affiliation(s)
- Grazia Taddeucci
- Department of Procreation Medicine and Developmental Age, Section of Paediatric Neurology, University of Pisa, Italy.
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Zweier C, de Jong EK, Zweier M, Orrico A, Ousager LB, Collins AL, Bijlsma EK, Oortveld MA, Ekici AB, Reis A, Schenck A, Rauch A. CNTNAP2 and NRXN1 are mutated in autosomal-recessive Pitt-Hopkins-like mental retardation and determine the level of a common synaptic protein in Drosophila. Am J Hum Genet 2009; 85:655-66. [PMID: 19896112 DOI: 10.1016/j.ajhg.2009.10.004] [Citation(s) in RCA: 266] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 09/30/2009] [Accepted: 10/06/2009] [Indexed: 10/20/2022] Open
Abstract
Heterozygous copy-number variants and SNPs of CNTNAP2 and NRXN1, two distantly related members of the neurexin superfamily, have been repeatedly associated with a wide spectrum of neuropsychiatric disorders, such as developmental language disorders, autism spectrum disorders, epilepsy, and schizophrenia. We now identified homozygous and compound-heterozygous deletions and mutations via molecular karyotyping and mutational screening in CNTNAP2 and NRXN1 in four patients with severe mental retardation (MR) and variable features, such as autistic behavior, epilepsy, and breathing anomalies, phenotypically overlapping with Pitt-Hopkins syndrome. With a frequency of at least 1% in our cohort of 179 patients, recessive defects in CNTNAP2 appear to significantly contribute to severe MR. Whereas the established synaptic role of NRXN1 suggests that synaptic defects contribute to the associated neuropsychiatric disorders and to severe MR as reported here, evidence for a synaptic role of the CNTNAP2-encoded protein CASPR2 has so far been lacking. Using Drosophila as a model, we now show that, as known for fly Nrx-I, the CASPR2 ortholog Nrx-IV might also localize to synapses. Overexpression of either protein can reorganize synaptic morphology and induce increased density of active zones, the synaptic domains of neurotransmitter release. Moreover, both Nrx-I and Nrx-IV determine the level of the presynaptic active-zone protein bruchpilot, indicating a possible common molecular mechanism in Nrx-I and Nrx-IV mutant conditions. We therefore propose that an analogous shared synaptic mechanism contributes to the similar clinical phenotypes resulting from defects in human NRXN1 and CNTNAP2.
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de Pontual L, Mathieu Y, Golzio C, Rio M, Malan V, Boddaert N, Soufflet C, Picard C, Durandy A, Dobbie A, Heron D, Isidor B, Motte J, Newburry-Ecob R, Pasquier L, Tardieu M, Viot G, Jaubert F, Munnich A, Colleaux L, Vekemans M, Etchevers H, Lyonnet S, Amiel J. Mutational, functional, and expression studies of the TCF4 gene in Pitt-Hopkins syndrome. Hum Mutat 2009; 30:669-76. [PMID: 19235238 DOI: 10.1002/humu.20935] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Pitt-Hopkins syndrome is a severe congenital encephalopathy recently ascribed to de novo heterozygous TCF4 gene mutations. We report a series of 13 novel PHS cases with a TCF4 mutation and show that EEG, brain magnetic resonance imagain (MRI), and immunological investigations provide valuable additional clues to the diagnosis. We confirm a mutational hot spot in the basic domain of the E-protein. Functional studies illustrate that heterodimerisation of mutant TCF4 proteins with a tissue-specific transcription factor is less effective than that homodimerisation in a luciferase reporter assay. We also show that the TCF4 expression pattern in human embryonic development is widespread but not ubiquitous. In summary, we further delineate an underdiagnosed mental retardation syndrome, highlighting TCF4 function during development and facilitating diagnosis within the first year of life.
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Affiliation(s)
- Loïc de Pontual
- Unité INSERM U-781, Université Paris Descartes, Faculté de Médecine, INSERM
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16
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Peippo MM, Simola KOJ, Valanne LK, Larsen AT, Kähkönen M, Auranen MP, Ignatius J. Pitt-Hopkins syndrome in two patients and further definition of the phenotype. Clin Dysmorphol 2009; 15:47-54. [PMID: 16531728 DOI: 10.1097/01.mcd.0000184973.14775.32] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pitt-Hopkins syndrome is a rare dysmorphic mental retardation syndrome marked by daytime spells of overbreathing interrupted by apnoea. The dysmorphism consists of a large beaked nose, cup-shaped ears with broad helices, a wide mouth, Cupid's bow upper lip, wide and shallow palate and broad or clubbed fingertips. The four patients described so far have been sporadic and represented both sexes. In addition, a pair of sibs with atypical features has been reported as possible Pitt-Hopkins syndrome cases. We describe two unrelated Pitt-Hopkins syndrome patients in order to further define the phenotype. In addition to severe developmental retardation, hypotonia, postnatal growth retardation, microcephaly, abnormal breathing and characteristic dysmorphic features, both had epilepsy and intestinal problems with severe constipation in one and Hirschsprung disease in the other. Other abnormalities were hypopigmented skin macules in one and high-grade myopia in the other. Both had unusual frontal slow-and-sharp-wave discharges on electroencephalography. Magnetic resonance imaging in both showed a similar hypoplastic corpus callosum with missing rostrum and posterior part of the splenium and bulbous caudate nuclei bulging towards the frontal horns. Chromosomal analysis and subtelomere fluorescence in-situ hybridization studies were normal. No mutations were found in the MECP2 or ZFHX1B genes. Extensive metabolic and mitochondrial screens were normal. The electroencephalography and brain magnetic resonance imaging findings appear to be further diagnostic signs in Pitt-Hopkins syndrome, which is also one of the syndromes associated with Hirschsprung disease.
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Affiliation(s)
- Maarit M Peippo
- Department of Medical Genetics, The Family Federation of Finland, Helsinki, Finland.
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17
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Temudo T, Ramos E, Dias K, Barbot C, Vieira JP, Moreira A, Calado E, Carrilho I, Oliveira G, Levy A, Fonseca M, Cabral A, Cabral P, Monteiro JP, Borges L, Gomes R, Santos M, Sequeiros J, Maciel P. Movement disorders in Rett syndrome: An analysis of 60 patients with detected MECP2 mutation and correlation with mutation type. Mov Disord 2008; 23:1384-90. [DOI: 10.1002/mds.22115] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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18
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Brockschmidt A, Todt U, Ryu S, Hoischen A, Landwehr C, Birnbaum S, Frenck W, Radlwimmer B, Lichter P, Engels H, Driever W, Kubisch C, Weber RG. Severe mental retardation with breathing abnormalities (Pitt-Hopkins syndrome) is caused by haploinsufficiency of the neuronal bHLH transcription factor TCF4. Hum Mol Genet 2007; 16:1488-94. [PMID: 17478476 DOI: 10.1093/hmg/ddm099] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pitt-Hopkins syndrome (PHS) is a rare syndromic mental disorder, which is mainly characterized by severe motor and mental retardation including absent language development, a characteristic facial gestalt and episodes of hyperventilation. We report on a female patient with PHS showing severe mental retardation with absent speech, pronounced muscular hypotonia, ataxia, distinctive facial features, such as a coarse face, a broad nasal bridge and a wide mouth, and hyperventilation attacks. In this patient, genomic profiling by array-based comparative genomic hybridization and fluorescence in situ hybridization studies detected and confirmed a de novo 0.5 Mb deletion in 18q21.2 containing a single gene, the basic helix-loop-helix transcription factor TCF4. cDNA and genomic analyses in the patient and her parents demonstrated TCF4 haploinsufficiency as the underlying cause of the disease. Analysis of the embryonal expression pattern of the Danio rerio ortholog, tcf4, by whole-mount in situ hybridization showed a highly specific expression domain in the pallium of the telencephalon during late somitogenesis, when the patterning of the zebrafish brain is advanced and neural differentiation commences. Later expression domains were restricted to several regions in the central nervous system, including continued expression in the pallium of the telencephalon, and starting expression in the diencephalon (thalamus, ventral thalamus and posterior tuberculum), the midbrain tegmentum, the hindbrain and the branchial arches. This expression pattern correlates with the clinical phenotype. Our results show that haploinsufficiency of TCF4 causes PHS and suggest that D. rerio is a valuable model to study the molecular pathogenesis of PHS and the role of TCF4 in brain development.
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Affiliation(s)
- Antje Brockschmidt
- 1Institute of Human Genetics, Rheinische Friedrich-Wilhelms-University, 53111 Bonn, Germany
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19
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Zweier C, Peippo MM, Hoyer J, Sousa S, Bottani A, Clayton-Smith J, Reardon W, Saraiva J, Cabral A, Gohring I, Devriendt K, de Ravel T, Bijlsma EK, Hennekam RCM, Orrico A, Cohen M, Dreweke A, Reis A, Nurnberg P, Rauch A. Haploinsufficiency of TCF4 causes syndromal mental retardation with intermittent hyperventilation (Pitt-Hopkins syndrome). Am J Hum Genet 2007; 80:994-1001. [PMID: 17436255 PMCID: PMC1852727 DOI: 10.1086/515583] [Citation(s) in RCA: 228] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 02/16/2007] [Indexed: 01/01/2023] Open
Abstract
Pitt-Hopkins syndrome is a rarely reported syndrome of so-far-unknown etiology characterized by mental retardation, wide mouth, and intermittent hyperventilation. By molecular karyotyping with GeneChip Human Mapping 100K SNP arrays, we detected a 1.2-Mb deletion on 18q21.2 in one patient. Sequencing of the TCF4 transcription factor gene, which is contained in the deletion region, in 30 patients with significant phenotypic overlap revealed heterozygous stop, splice, and missense mutations in five further patients with severe mental retardation and remarkable facial resemblance. Thus, we establish the Pitt-Hopkins syndrome as a distinct but probably heterogeneous entity caused by autosomal dominant de novo mutations in TCF4. Because of its phenotypic overlap, Pitt-Hopkins syndrome evolves as an important differential diagnosis to Angelman and Rett syndromes. Both null and missense mutations impaired the interaction of TCF4 with ASCL1 from the PHOX-RET pathway in transactivating an E box-containing reporter construct; therefore, hyperventilation and Hirschsprung disease in patients with Pitt-Hopkins syndrome might be explained by altered development of noradrenergic derivatives.
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Affiliation(s)
- Christiane Zweier
- Institute of Human Genetics, Institute of Human Genetics, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
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20
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Amiel J, Rio M, de Pontual L, Redon R, Malan V, Boddaert N, Plouin P, Carter NP, Lyonnet S, Munnich A, Colleaux L. Mutations in TCF4, encoding a class I basic helix-loop-helix transcription factor, are responsible for Pitt-Hopkins syndrome, a severe epileptic encephalopathy associated with autonomic dysfunction. Am J Hum Genet 2007; 80:988-93. [PMID: 17436254 PMCID: PMC1852736 DOI: 10.1086/515582] [Citation(s) in RCA: 215] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 02/16/2007] [Indexed: 11/03/2022] Open
Abstract
Pitt-Hopkins syndrome (PHS) is a rare syndromic encephalopathy characterized by daily bouts of hyperventilation and a facial gestalt. We report a 1.8-Mb de novo microdeletion on chromosome 18q21.1, identified by array-comparative genomic hybridization in one patient with PHS. We subsequently identified two de novo heterozygous missense mutations of a conserved amino acid in the basic region of the TCF4 gene in three additional subjects with PHS. These findings demonstrate that TCF4 anomalies are responsible for PHS and provide the first evidence of a human disorder related to class I basic helix-loop-helix transcription-factor defects (also known as "E proteins"). Moreover, our data may shed new light on the normal processes underlying autonomic nervous system development and maintenance of an appropriate ventilatory neuronal circuitry.
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Affiliation(s)
- Jeanne Amiel
- From the Departments of Genetics, Pediatric Radiology and INSERM U-797, Universite Paris-Descartes, Faculte de Medecine, Hopitaux de Paris, Hopital Necker-Enfants Malades, Paris, France.
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