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Barbier M, Bahlo M, Pennisi A, Jacoupy M, Tankard RM, Ewenczyk C, Davies KC, Lino-Coulon P, Colace C, Rafehi H, Auger N, Ansell BRE, van der Stelt I, Howell KB, Coutelier M, Amor DJ, Mundwiller E, Guillot-Noël L, Storey E, Gardner RJM, Wallis MJ, Brusco A, Corti O, Rötig A, Leventer RJ, Brice A, Delatycki MB, Stevanin G, Lockhart PJ, Durr A. Heterozygous PNPT1 variants cause spinocerebellar ataxia type 25. Ann Neurol 2022; 92:122-137. [PMID: 35411967 DOI: 10.1002/ana.26366] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 04/04/2022] [Accepted: 04/08/2022] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Dominant spinocerebellar ataxias (SCA) are characterized by genetic heterogeneity. Some mapped and named loci remain without a causal gene identified. Here we applied next generation sequencing (NGS) to uncover the genetic etiology of the SCA25 locus. METHODS Whole-exome and whole-genome sequencing were performed in families linked to SCA25, including the French family in which the SCA25 locus was originally mapped. Whole exome sequence data was interrogated in a cohort of 796 ataxia patients of unknown aetiology. RESULTS The SCA25 phenotype spans a slowly evolving sensory and cerebellar ataxia, in most cases attributed to ganglionopathy. A pathogenic variant causing exon skipping was identified in the gene encoding Polyribonucleotide Nucleotidyltransferase PNPase 1 (PNPT1) located in the SCA25 linkage interval. A second splice variant in PNPT1 was detected in a large Australian family with a dominant ataxia also mapping to SCA25. An additional nonsense variant was detected in an unrelated individual with ataxia. Both nonsense and splice heterozygous variants result in premature stop codons, all located in the S1-domain of PNPase. In addition, an elevated type I interferon response was observed in blood from all affected heterozygous carriers tested. PNPase notably prevents the abnormal accumulation of double-stranded mtRNAs in the mitochondria and leakage into the cytoplasm, associated with triggering a type I interferon response. INTERPRETATION This study identifies PNPT1 as a new SCA gene, responsible for SCA25, and highlights biological links between alterations of mtRNA trafficking, interferonopathies and ataxia. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mathieu Barbier
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Alessandra Pennisi
- Necker Hospital, APHP, Reference Center for Mitochondrial Diseases, Genetics Department, Institut Imagine, University of Paris, Paris, France.,Inserm UMR_S1163, Institut Imagine, Paris, France
| | - Maxime Jacoupy
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Rick M Tankard
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Claire Ewenczyk
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Kayli C Davies
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Patricia Lino-Coulon
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Claire Colace
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Haloom Rafehi
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Nicolas Auger
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France.,Paris Sciences Lettres Research University, EPHE, Paris, France
| | - Brendan R E Ansell
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Ivo van der Stelt
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Victoria, 3010, Australia.,Donders Centre for Neuroscience, Faculty of Science, Radboud University, The Netherlands
| | - Katherine B Howell
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 3010, Australia.,Department of Neurology, Royal Children's Hospital, Melbourne, Victoria, 3052, Australia.,Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Marie Coutelier
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France.,Paris Sciences Lettres Research University, EPHE, Paris, France
| | - David J Amor
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 3010, Australia.,Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Emeline Mundwiller
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Lena Guillot-Noël
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France.,Paris Sciences Lettres Research University, EPHE, Paris, France
| | - Elsdon Storey
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Victoria, 3004, Australia
| | | | - Mathew J Wallis
- Clinical Genetics Service, Austin Health, Melbourne, Australia; Department of Medicine, University of Melbourne, Austin Health, Melbourne, Australia.,School of Medicine and Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
| | - Alfredo Brusco
- Department of Medical Sciences, University of Torino, Torino, Italy
| | - Olga Corti
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Agnès Rötig
- Necker Hospital, APHP, Reference Center for Mitochondrial Diseases, Genetics Department, Institut Imagine, University of Paris, Paris, France.,Inserm UMR_S1163, Institut Imagine, Paris, France
| | - Richard J Leventer
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 3010, Australia.,Department of Neurology, Royal Children's Hospital, Melbourne, Victoria, 3052, Australia.,Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia
| | - Alexis Brice
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Martin B Delatycki
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 3010, Australia.,Victorian Clinical Genetics Service, Melbourne, 3052, Australia
| | - Giovanni Stevanin
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France.,Paris Sciences Lettres Research University, EPHE, Paris, France
| | - Paul J Lockhart
- Bruce Lefroy Centre, Murdoch Children's Research Institute, Melbourne, Victoria, 3052, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Alexandra Durr
- Sorbonne Université, Institut du Cerveau - Paris Brain Institute - ICM, Inserm, CNRS, APHP, Hôpital de la Pitié Salpêtrière, Paris, France
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2
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Gardner RJM, Crozier IG, Binfield AL, Love DR, Lehnert K, Gibson K, Lintott CJ, Snell RG, Jacobsen JC, Jones PP, Waddell-Smith KE, Kennedy MA, Skinner JR. Penetrance and expressivity of the R858H CACNA1C variant in a five-generation pedigree segregating an arrhythmogenic channelopathy. Mol Genet Genomic Med 2018; 7:e00476. [PMID: 30345660 PMCID: PMC6382452 DOI: 10.1002/mgg3.476] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 08/22/2018] [Accepted: 08/23/2018] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Isolated cardiac arrhythmia due to a variant in CACNA1C is of recent knowledge. Most reports have been of singleton cases or of quite small families, and estimates of penetrance and expressivity have been difficult to obtain. We here describe a large pedigree, from which such estimates have been calculated. METHODS We studied a five-generation family, in which a CACNA1C variant c.2573G>A p.Arg858His co-segregates with syncope and cardiac arrest, documenting electrocardiographic data and cardiac symptomatology. The reported patients/families from the literature with CACNA1C gene variants were reviewed, and genotype-phenotype correlations are drawn. RESULTS The range of phenotype in the studied family is wide, from no apparent effect, through an asymptomatic QT interval prolongation on electrocardiography, to episodes of presyncope and syncope, ventricular fibrillation, and sudden death. QT prolongation showed inconsistent correlation with functional cardiology. Based upon analysis of 28 heterozygous family members, estimates of penetrance and expressivity are derived. CONCLUSIONS These estimates of penetrance and expressivity, for this specific variant, may be useful in clinical practice. Review of the literature indicates that individual CACNA1C variants have their own particular genotype-phenotype correlations. We suggest that, at least in respect of the particular variant reported here, "arrhythmogenic channelopathy" may be a more fitting nomenclature than long QT syndrome.
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Affiliation(s)
- R J McKinlay Gardner
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand.,Clinical Genetics Group, Department of Women's and Children's Health, University of Otago, Dunedin, New Zealand
| | - Ian G Crozier
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Christchurch Hospital, Christchurch, New Zealand
| | - Alex L Binfield
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Paediatrics, Christchurch Hospital, Christchurch, New Zealand.,Department of Paediatrics, University of Otago, Christchurch, New Zealand
| | - Donald R Love
- Cardiac Inherited Disease Group, Auckland, New Zealand.,LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Klaus Lehnert
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Kate Gibson
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand
| | - Caroline J Lintott
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Genetic Health Service New Zealand (South Island Hub), Christchurch Hospital, Christchurch, New Zealand
| | - Russell G Snell
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Jessie C Jacobsen
- Cardiac Inherited Disease Group, Auckland, New Zealand.,School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Peter P Jones
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Physiology and HeartOtago, University of Otago, Dunedin, New Zealand
| | - Kathryn E Waddell-Smith
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
| | - Martin A Kennedy
- Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand
| | - Jonathan R Skinner
- Cardiac Inherited Disease Group, Auckland, New Zealand.,Department of Cardiology, Auckland City Hospital, Auckland, New Zealand
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3
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Glendining KA, Markie D, Gardner RJM, Franz EA, Robertson SP, Jasoni CL. A novel role for the DNA repair gene Rad51 in Netrin-1 signalling. Sci Rep 2017; 7:39823. [PMID: 28057929 PMCID: PMC5216413 DOI: 10.1038/srep39823] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 11/28/2016] [Indexed: 11/09/2022] Open
Abstract
Mutations in RAD51 have recently been linked to human Congenital Mirror Movements (CMM), a developmental disorder of the motor system. The only gene previously linked to CMM encodes the Netrin-1 receptor DCC, which is important for formation of corticospinal and callosal axon tracts. Thus, we hypothesised that Rad51 has a novel role in Netrin-1-mediated axon development. In mouse primary motor cortex neurons, Rad51 protein was redistributed distally down the axon in response to Netrin-1, further suggesting a functional link between the two. We next manipulated Rad51 expression, and assessed Netrin-1 responsiveness. Rad51 siRNA knockdown exaggerated Netrin-1-mediated neurite branching and filopodia formation. RAD51 overexpression inhibited these responses, whereas overexpression of the CMM-linked R250Q mutation, a predicted loss-of-function, had no effect. Thus, Rad51 appears to negatively regulate Netrin-1 signalling. Finally, we examined whether Rad51 might operate by modulating the expression of the Unc5 family, known negative regulators of Netrin-1-responsiveness. Unc5b and Unc5c transcripts were downregulated in response to Rad51 knockdown, and upregulated with RAD51 overexpression, but not R250Q. Thus, Rad51 negatively regulates Netrin-1 signalling, at least in part, by modulating the expression of Unc5s. Imbalance of positive and negative influences is likely to lead to aberrant motor system development resulting in CMMs.
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Affiliation(s)
- K A Glendining
- Brain Health Research Centre, Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - D Markie
- Department of Pathology, University of Otago, Dunedin, New Zealand
| | - R J M Gardner
- Clinical Genetics Group, Department of Women's and Children's Health, University of Otago, Dunedin, New Zealand
| | - E A Franz
- Department of Psychology and fMRIOtago, University of Otago, Dunedin, New Zealand
| | - S P Robertson
- Clinical Genetics Group, Department of Women's and Children's Health, University of Otago, Dunedin, New Zealand
| | - C L Jasoni
- Brain Health Research Centre, Department of Anatomy, University of Otago, Dunedin, New Zealand
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4
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McGillivray G, Rosenfeld JA, McKinlay Gardner RJ, Gillam LH. Genetic counselling and ethical issues with chromosome microarray analysis in prenatal testing. Prenat Diagn 2012; 32:389-95. [PMID: 22467169 DOI: 10.1002/pd.3849] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Molecular karyotyping using chromosome microarray analysis (CMA) detects more pathogenic chromosomal anomalies than classical karyotyping, making CMA likely to become a first tier test for prenatal diagnosis. Detecting copy number variants of uncertain clinical significance raises ethical considerations. We consider the risk of harm to a woman or her fetus following the detection of a copy number variant of uncertain significance, whether it is ethically justifiable to withhold any test result information from a woman, what constitutes an 'informed choice' when women are offered CMA in pregnancy and whether clinicians are morally responsible for 'unnecessary' termination of pregnancy. Although we are cognisant of the distress associated with uncertain prenatal results, we argue in favour of the autonomy of women and their right to information from genome-wide CMA in order to make informed choices about their pregnancies. We propose that information material to a woman's decision-making process, including uncertain information, should not be withheld, and that it would be paternalistic for clinicians to try to take responsibility for women's decisions to terminate pregnancies. Non-directive pre-test and post-test genetic counselling is central to the delivery of these ethical objectives.
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Affiliation(s)
- George McGillivray
- Royal Women's Hospital, Melbourne, Victoria, Australia; Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Victoria, Australia.
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5
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Abstract
Spinocerebellar ataxia type 15 (SCA15), first described in 2001, is a slowly progressive, relatively pure dominantly inherited ataxia. Six pedigrees have been reported to date, in Anglo-Celtic and Japanese populations. Other than notably slow progression, its main distinguishing characteristic is tremor, often affecting the head, which is seen in about half of affecteds and which may be the presenting feature. Neuroradiology shows cerebellar atrophy, particularly affecting the anterior and dorsal vermis. SCA15 is due to various deletions of the inositol 1,4,5-triphosphate receptor 1 gene (ITPR1) on the distal short arm of chromosome 3. The potential of point mutations in ITPR1 to cause SCA15 is not yet confirmed. "SCA16" has now been shown to be due to an ITPR1 mutation, and has now been subsumed into SCA15.
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Affiliation(s)
- Elsdon Storey
- Department of Medicine (Neuroscience), Monash University (Alfred Hospital Campus), Melbourne, Australia.
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6
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Abstract
Spinocerebellar ataxia type 20 (SCA20), first reported in 2004, is a slowly progressive dominantly inherited disorder so far reported in a single Anglo-Celtic family from Australia. It is characterized by dentate calcification from an early stage of the illness. Dysarthria without ataxia is the first symptom in the majority - an unusual feature amongst the SCAs. In addition to ataxia, examination often reveals spasmodic dysphonia and palatal tremor, but the syndrome is otherwise fairly pure. The responsible genetic abnormality has been tentatively identified as a 260-kb duplication in the pericentric region of chromosome 11, but confirmation will necessarily await description of further families.
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Affiliation(s)
- Elsdon Storey
- Department of Medicine (Neuroscience), Monash University (Alfred Hospital Campus), Melbourne, Australia.
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7
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Andreucci E, Aftimos S, Alcausin M, Haan E, Hunter W, Kannu P, Kerr B, McGillivray G, McKinlay Gardner RJ, Patricelli MG, Sillence D, Thompson E, Zacharin M, Zankl A, Lamandé SR, Savarirayan R. TRPV4 related skeletal dysplasias: a phenotypic spectrum highlighted byclinical, radiographic, and molecular studies in 21 new families. Orphanet J Rare Dis 2011; 6:37. [PMID: 21658220 PMCID: PMC3135501 DOI: 10.1186/1750-1172-6-37] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 06/09/2011] [Indexed: 08/30/2023] Open
Abstract
Background The TRPV4 gene encodes a calcium-permeable ion-channel that is widely expressed, responds to many different stimuli and participates in an extraordinarily wide range of physiologic processes. Autosomal dominant brachyolmia, spondylometaphyseal dysplasia Kozlowski type (SMDK) and metatropic dysplasia (MD) are currently considered three distinct skeletal dysplasias with some shared clinical features, including short stature, platyspondyly, and progressive scoliosis. Recently, TRPV4 mutations have been found in patients diagnosed with these skeletal phenotypes. Methods and Results We critically analysed the clinical and radiographic data on 26 subjects from 21 families, all of whom had a clinical diagnosis of one of the conditions described above: 15 with MD; 9 with SMDK; and 2 with brachyolmia. We sequenced TRPV4 and identified 9 different mutations in 22 patients, 4 previously described, and 5 novel. There were 4 mutation-negative cases: one with MD and one with SMDK, both displaying atypical clinical and radiographic features for these diagnoses; and two with brachyolmia, who had isolated spine changes and no metaphyseal involvement. Conclusions Our data suggest the TRPV4 skeletal dysplasias represent a continuum of severity with areas of phenotypic overlap, even within the same family. We propose that AD brachyolmia lies at the mildest end of this spectrum and, since all cases described with this diagnosis and TRPV4 mutations display metaphyseal changes, we suggest that it is not a distinct entity but represents the mildest phenotypic expression of SMDK.
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Affiliation(s)
- Elena Andreucci
- Genetic Health Services Victoria and Murdoch Childrens Research Institute, Parkville, Victoria, Australia.
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8
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Heliövaara E, Tuupanen S, Ahlsten M, Hodgson S, de Menis E, Kuismin O, Izatt L, McKinlay Gardner RJ, Gundogdu S, Lucassen A, Arola J, Tuomisto A, Mäkinen M, Karhu A, Aaltonen LA. No evidence of RET germline mutations in familial pituitary adenoma. J Mol Endocrinol 2011; 46:1-8. [PMID: 20956458 DOI: 10.1677/jme-10-0052] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Pituitary adenomas are common in the general population. Although most of them are sporadic, some occur in a familial setting. In familial pituitary adenoma patients it is common that no germline defects are found after screening of aryl hydrocarbon receptor interacting protein (AIP) and other genes known to underlie the condition, suggesting the existence of yet unknown predisposition genes. Recently, the RET proto-oncogene was found to be a novel in vivo interaction partner of AIP in the pituitary gland. Here, we have screened patients from 16 AIP mutation negative (AIPmut-) pituitary adenoma families for RET germline mutations to assess whether RET could play a role in pituitary adenoma predisposition, similar to AIP. We found five novel germline RET changes: one in RET Exon 4 and the rest in noncoding regions of RET. Two changes, c.1560*G > A and -1285 G > A, were segregated in affected family members. We also analyzed the RET region with enhancer element locator (EEL) to identify RET regulatory elements, and to see whether the changes resided in these. None of the variants mapped to the regions predicted by EEL. Expression of RET was examined in ten AIPmut- and seven AIP mutation positive (AIPmut+) somatotropinomas by immunohistochemistry, with a trend showing reduced expression in the latter (P = 0.05). We conclude that the RET variants are presumably not related to pituitary adenoma predisposition, although reduced RET expression may play a role in AIP-related genesis of somatotropinomas.
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Affiliation(s)
- Elina Heliövaara
- Genome-Scale Biology Research Program, Department of Medical Genetics, University of Helsinki, 00014 Helsinki, Finland
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9
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Coman D, Yaplito-Lee J, La P, Nasioulas S, Bruno D, Slater HR, Stock-Myer SE, Lynch EL, Gardner RJM. Three Mendelian disorders (chronic granulomatous disease, retinitis pigmentosa, ornithine transcarbamylase deficiency) in a young woman with an X chromosome deletion, del(X)(p11.4p21.1). Mol Genet Metab 2010; 99:329. [PMID: 20036594 DOI: 10.1016/j.ymgme.2009.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 11/20/2009] [Indexed: 11/20/2022]
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10
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van Kogelenberg M, Ghedia S, McGillivray G, Bruno D, Leventer R, Macdermot K, Nelson J, Nagarajan L, Veltman JA, de Brouwer AP, McKinlay Gardner RJ, van Bokhoven H, Kirk EP, Robertson SP. Periventricular heterotopia in common microdeletion syndromes. Mol Syndromol 2010; 1:35-41. [PMID: 20648244 DOI: 10.1159/000274491] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Accepted: 11/15/2009] [Indexed: 11/19/2022] Open
Abstract
Periventricular heterotopia (PH) is a brain malformation characterised by heterotopic nodules of neurons lining the walls of the cerebral ventricles. Mutations in FLNA account for 20-24% of instances but a majority have no identifiable genetic aetiology. Often the co-occurrence of PH with a chromosomal anomaly is used to infer a new locus for a Mendelian form of PH. This study reports four PH patients with three different microdeletion syndromes, each characterised by high-resolution genomic microarray. In three patients the deletions at 1p36 and 22q11 are conventional in size, whilst a fourth child had a deletion at 7q11.23 that was larger in extent than is typically seen in Williams syndrome. Although some instances of PH associated with chromosomal deletions could be attributed to the unmasking of a recessive allele or be indicative of more prevalent subclinical migrational anomalies, the rarity of PH in these three microdeletion syndromes and the description of other non-recurrent chromosomal defects do suggest that PH may be a manifestation of multiple different forms of chromosomal imbalance. In many, but possibly not all, instances the co-occurrence of PH with a chromosomal deletion is not necessarily indicative of uncharacterised underlying monogenic loci for this particular neuronal migrational anomaly.
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Affiliation(s)
- M van Kogelenberg
- Department of Paediatrics and Child Health, Dunedin School of Medicine, Otago University, Dunedin, New Zealand
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11
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Ganesamoorthy D, Bruno DL, Schoumans J, Storey E, Delatycki MB, Zhu D, Wei MK, Nicholson GA, McKinlay Gardner RJ, Slater HR. Development of a Multiplex Ligation-Dependent Probe Amplification Assay for Diagnosis and Estimation of the Frequency of Spinocerebellar Ataxia Type 15. Clin Chem 2009; 55:1415-8. [DOI: 10.1373/clinchem.2009.124958] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Background: Spinocerebellar ataxia type 15 (SCA15) is a slowly progressive neurodegenerative disorder characterized by cerebellar ataxia. Mutation of the ITPR1 gene (inositol 1,4,5-triphosphate receptor, type 1) has been identified recently as the underlying cause, and in most cases the molecular defect is a multiexon deletion. To date, 5 different SCA15 families have been identified with ITPR1 gene deletion.
Methods: We have designed a synthetic, dual-color multiplex ligation-dependent probe amplification (MLPA) assay that measures copy number with high precision in selected exons across the entire length of ITPR1 and the proximal region of the neighboring gene, SUMF1 (sulfatase modifying factor 1). We screened 189 idiopathic ataxic patients with this MLPA assay.
Results: We identified ITPR1 deletion of exons 1–10 in the previously reported AUS1 family (4 members) and deletion of exons 1–38 in a new family (2 members). In addition to the multiexon deletions, apparent single-exon deletions identified in 2 other patients were subsequently shown to be due to single-nucleotide changes at the ligation sites.
Conclusions: The frequency of ITPR1 deletions is 2.7% in known familial cases. This finding suggests that SCA15 is one of the “less common” SCAs. Although the deletions in the 5 families identified worldwide thus far have been of differing sizes, all share deletion of exons 1–10. This region may be important, both in terms of the underlying pathogenetic mechanism and as a pragmatic target for an accurate, robust, and cost-effective diagnostic analysis.
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Affiliation(s)
- Devika Ganesamoorthy
- Victorian Clinical Genetic Services and Murdoch Children’s Research Institute, University of Melbourne, Department of Paediatrics, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Damien L Bruno
- Victorian Clinical Genetic Services and Murdoch Children’s Research Institute, University of Melbourne, Department of Paediatrics, Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Jacqueline Schoumans
- Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital Solna, Stockholm, Sweden
| | - Elsdon Storey
- Department of Medicine, Alfred Hospital, Monash University, Melbourne, Australia
| | | | - Danqing Zhu
- ANZAC Research Institute, University of Sydney, Department of Medicine, Concord Hospital, Sydney, Australia
| | - Morgan K Wei
- ANZAC Research Institute, University of Sydney, Department of Medicine, Concord Hospital, Sydney, Australia
| | - Garth A Nicholson
- ANZAC Research Institute, University of Sydney, Department of Medicine, Concord Hospital, Sydney, Australia
| | | | - Howard R Slater
- Victorian Clinical Genetic Services and Murdoch Children’s Research Institute, University of Melbourne, Department of Paediatrics, Royal Children’s Hospital, Parkville, Victoria, Australia
- Genetic Health Services Victoria, Melbourne, Australia
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12
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Abstract
BACKGROUND The spinocerebellar ataxias (SCAs) are clinically and genetically heterogeneous. Currently, 27 forms are known, with the causative gene identified in 16. Although the majority of dominant pedigrees worldwide have SCAs 1, 2, 3, 6 or 8, new SCAs continue to be delineated. We describe a new disorder: SCA 30. METHODS An Australian family of Anglo-Celtic ethnicity manifested a relatively pure, slowly evolving ataxia. Six affected and four unaffected members were personally examined in a standardised fashion. MRI and nerve conduction studies were performed in two. An autosomal genome-wide linkage study was undertaken, and an in silico analysis of potential candidate genes in the linkage region was performed. RESULTS The six affected members had a relatively pure, slowly evolving ataxia developing in mid to late life, with only minor pyramidal signs and no evidence of neuropathy. All had hypermetric saccades with normal vestibulo-ocular reflex gain. Only one displayed (slight) gaze-evoked nystagmus. MRI showed cerebellar atrophy with preservation of nodulus/uvula and brainstem. Linkage analysis excluded currently known SCAs and identified a logarithm (base 10) of odds score of 3.0 at chromosome 4q34.3-q35.1, distinct from all previously reported loci. In silico prioritisation identified the gene ODZ3 as the most likely contender. CONCLUSIONS SCA 30 is a previously undescribed cause of (relatively) pure adult-onset autosomal dominant cerebellar ataxia. The responsible gene is yet to be determined, but ODZ3 is a plausible candidate.
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Affiliation(s)
- E Storey
- Department of Neuroscience, Monash University, Alfred Hospital, Melbourne, VIC, Australia.
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13
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Bruno DL, Ganesamoorthy D, Schoumans J, Bankier A, Coman D, Delatycki M, Gardner RJM, Hunter M, James PA, Kannu P, McGillivray G, Pachter N, Peters H, Rieubland C, Savarirayan R, Scheffer IE, Sheffield L, Tan T, White SM, Yeung A, Bowman Z, Ngo C, Choy KW, Cacheux V, Wong L, Amor DJ, Slater HR. Detection of cryptic pathogenic copy number variations and constitutional loss of heterozygosity using high resolution SNP microarray analysis in 117 patients referred for cytogenetic analysis and impact on clinical practice. J Med Genet 2008; 46:123-31. [PMID: 19015223 DOI: 10.1136/jmg.2008.062604] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Microarray genome analysis is realising its promise for improving detection of genetic abnormalities in individuals with mental retardation and congenital abnormality. Copy number variations (CNVs) are now readily detectable using a variety of platforms and a major challenge is the distinction of pathogenic from ubiquitous, benign polymorphic CNVs. The aim of this study was to investigate replacement of time consuming, locus specific testing for specific microdeletion and microduplication syndromes with microarray analysis, which theoretically should detect all known syndromes with CNV aetiologies as well as new ones. METHODS Genome wide copy number analysis was performed on 117 patients using Affymetrix 250K microarrays. RESULTS 434 CNVs (195 losses and 239 gains) were found, including 18 pathogenic CNVs and 9 identified as "potentially pathogenic". Almost all pathogenic CNVs were larger than 500 kb, significantly larger than the median size of all CNVs detected. Segmental regions of loss of heterozygosity larger than 5 Mb were found in 5 patients. CONCLUSIONS Genome microarray analysis has improved diagnostic success in this group of patients. Several examples of recently discovered "new syndromes" were found suggesting they are more common than previously suspected and collectively are likely to be a major cause of mental retardation. The findings have several implications for clinical practice. The study revealed the potential to make genetic diagnoses that were not evident in the clinical presentation, with implications for pretest counselling and the consent process. The importance of contributing novel CNVs to high quality databases for genotype-phenotype analysis and review of guidelines for selection of individuals for microarray analysis is emphasised.
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Affiliation(s)
- D L Bruno
- Cytogenetics Laboratory, Victorian Clinical Genetics Services/Pathology, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria 3052, Australia
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14
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Knight MA, Hernandez D, Diede SJ, Dauwerse HG, Rafferty I, van de Leemput J, Forrest SM, Gardner RJM, Storey E, van Ommen GJB, Tapscott SJ, Fischbeck KH, Singleton AB. A duplication at chromosome 11q12.2-11q12.3 is associated with spinocerebellar ataxia type 20. Hum Mol Genet 2008; 17:3847-53. [PMID: 18801880 PMCID: PMC2588641 DOI: 10.1093/hmg/ddn283] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Spinocerebellar ataxia type 20 (SCA20) has been linked to chromosome 11q12, but the underlying genetic defect has yet to be identified. We applied single-nucleotide polymorphism genotyping to detect structural alterations in the genomic DNA of patients with SCA20. We found a 260 kb duplication within the previously linked SCA20 region, which was confirmed by quantitative polymerase chain reaction and fiber fluorescence in situ hybridization, the latter also showing its direct orientation. The duplication spans 10 known and 2 unknown genes, and is present in all affected individuals in the single reported SCA20 pedigree. While the mechanism whereby this duplication may be pathogenic remains to be established, we speculate that the critical gene within the duplicated segment may be DAGLA, the product of which is normally present at the base of Purkinje cell dendritic spines and contributes to the modulation of parallel fiber-Purkinje cell synapses.
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Affiliation(s)
- Melanie A Knight
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20894-3708, USA.
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15
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16
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Baker NL, Mörgelin M, Pace RA, Peat RA, Adams NE, Gardner RJM, Rowland LP, Miller G, De Jonghe P, Ceulemans B, Hannibal MC, Edwards M, Thompson EM, Jacobson R, Quinlivan RCM, Aftimos S, Kornberg AJ, North KN, Bateman JF, Lamandé SR. Molecular consequences of dominant Bethlem myopathy collagen VI mutations. Ann Neurol 2007; 62:390-405. [PMID: 17886299 DOI: 10.1002/ana.21213] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Dominant mutations in the three collagen VI genes cause Bethlem myopathy, a disorder characterized by proximal muscle weakness and commonly contractures of the fingers, wrists, and ankles. Although more than 20 different dominant mutations have been identified in Bethlem myopathy patients, the biosynthetic consequences of only a subset of these have been studied, and in many cases, the pathogenic mechanisms remain unknown. METHODS We have screened fourteen Bethlem myopathy patients for collagen VI mutations and performed detailed analyses of collagen VI biosynthesis and intracellular and extracellular assembly. RESULTS Collagen VI abnormalities were identified in eight patients. One patient produced around half the normal amount of alpha1(VI) messenger RNA and reduced amounts of collagen VI protein. Two patients had a previously reported mutation causing skipping of COL6A1 exon 14, and three patients had novel mutations leading to in-frame deletions toward the N-terminal end of the triple-helical domain. These mutations have different and complex effects on collagen VI intracellular and extracellular assembly. Two patients had single amino acid substitutions in the A-domains of COL6A2 and COL6A3. Collagen VI intracellular and extracellular assembly was normal in one of these patients. INTERPRETATION The key to dissecting the pathogenic mechanisms of collagen VI mutations lies in detailed analysis of collagen VI biosynthesis and assembly. The majority of mutations result in secretion and deposition of structurally abnormal collagen VI. However, one A-domain mutation had no detectable effect on assembly, suggesting that it acts by compromising collagen VI interactions in the extracellular matrix of muscle.
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Affiliation(s)
- Naomi L Baker
- Murdoch Childrens Research Institute and Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Victoria, Australia
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17
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Abstract
We describe the case of a woman with some features of the MURCS (Müllerian duct aplasia, renal aplasia, and cervicothoracic somite dysplasia) association, along with a radial ray anomaly. She had fusion of two cervical vertebrae, and a unicornuate uterus as MURCS components; and thenar muscle hypoplasia and absent radial pulses reflecting radial ray elements. We review two similar cases from the literature. We discuss whether our case might represent an incomplete and variant form of the MURCS association, or an example of an overlap between the MURCS and VATER (vertebral, anal, tracheo-esophageal, radial) associations.
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19
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Hildebrand MS, Coman D, Yang T, Gardner RJM, Rose E, Smith RJH, Bahlo M, Dahl HHM. A novel splice site mutation inEYA4 causes DFNA10 hearing loss. Am J Med Genet A 2007; 143A:1599-604. [PMID: 17568404 DOI: 10.1002/ajmg.a.31860] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Nonsyndromic autosomal dominant sensorineural hearing loss (SNHL) at the DFNA10 locus was described in two families in 2001. Causative mutations that affect the EyaHR domain of the 'Eyes absent 4' (EYA4) protein were identified. We report on the clinical and genetic analyses of an Australian family with nonsyndromic SNHL. Screening of the EYA4 gene showed the novel polypyrimidine tract variation ca. 1,282-12T > A that introduces a new 3' splice acceptor site. This is the first report of a point mutation in EYA4 that is hypothesized to lead to aberrant pre-mRNA splicing and human disease. The DFNA10 family described is only the fourth to be identified. One individual presented with apparently the same phenotype as other affected members of the family. However, genotyping illustrated that he did not share the DFNA10 disease haplotype. Detailed clinical investigation showed differences in the onset and severity of his hearing loss and thus he is presumed to represent a phenocopy, perhaps resulting from long-term exposure to loud noise.
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Affiliation(s)
- Michael S Hildebrand
- Department of Otolaryngology--Head and Neck Surgery, University of Iowa, Iowa City, Iowa 52242, USA.
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20
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van de Leemput J, Chandran J, Knight MA, Holtzclaw LA, Scholz S, Cookson MR, Houlden H, Gwinn-Hardy K, Fung HC, Lin X, Hernandez D, Simon-Sanchez J, Wood NW, Giunti P, Rafferty I, Hardy J, Storey E, Gardner RJM, Forrest SM, Fisher EMC, Russell JT, Cai H, Singleton AB. Deletion at ITPR1 underlies ataxia in mice and spinocerebellar ataxia 15 in humans. PLoS Genet 2007; 3:e108. [PMID: 17590087 PMCID: PMC1892049 DOI: 10.1371/journal.pgen.0030108] [Citation(s) in RCA: 213] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Accepted: 05/16/2007] [Indexed: 11/29/2022] Open
Abstract
We observed a severe autosomal recessive movement disorder in mice used within our laboratory. We pursued a series of experiments to define the genetic lesion underlying this disorder and to identify a cognate disease in humans with mutation at the same locus. Through linkage and sequence analysis we show here that this disorder is caused by a homozygous in-frame 18-bp deletion in Itpr1 (Itpr1Δ18/Δ18), encoding inositol 1,4,5-triphosphate receptor 1. A previously reported spontaneous Itpr1 mutation in mice causes a phenotype identical to that observed here. In both models in-frame deletion within Itpr1 leads to a decrease in the normally high level of Itpr1 expression in cerebellar Purkinje cells. Spinocerebellar ataxia 15 (SCA15), a human autosomal dominant disorder, maps to the genomic region containing ITPR1; however, to date no causal mutations had been identified. Because ataxia is a prominent feature in Itpr1 mutant mice, we performed a series of experiments to test the hypothesis that mutation at ITPR1 may be the cause of SCA15. We show here that heterozygous deletion of the 5′ part of the ITPR1 gene, encompassing exons 1–10, 1–40, and 1–44 in three studied families, underlies SCA15 in humans. We have identified a spontaneous in-frame deletion mutation in the gene Itpr1 that causes a recessive movement disorder in mice. In an attempt to define whether any similar disease occurs in humans we performed a literature search for diseases linked to the human chromosomal region containing ITPR1. We identified the disease spinocerebellar ataxia 15 as linked to this region. High-density genomic analysis of affected members from three families revealed that disease in these patients was caused by deletion of a large portion of the region containing ITPR1. We show here that this mutation results in a dramatic reduction in ITPR1 in cells from these patients. These data show convincingly that ITPR1 deletion underlies spinocerebellar ataxia 15 in humans.
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Affiliation(s)
- Joyce van de Leemput
- Molecular Genetics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Neurodegenerative Disease, Institute of Neurology, Queen Square, London, United Kingdom
| | - Jayanth Chandran
- Transgenics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Melanie A Knight
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lynne A Holtzclaw
- Section on Cell Biology and Signal Transduction, National Institute on Child Health and Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sonja Scholz
- Molecular Genetics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
- Reta Lila Weston Institute of Neurological Studies, University College London, London, United Kingdom
| | - Mark R Cookson
- Cell Biology and Gene Expression Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Henry Houlden
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London, United Kingdom
| | - Katrina Gwinn-Hardy
- National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Hon-Chung Fung
- Reta Lila Weston Institute of Neurological Studies, University College London, London, United Kingdom
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Neurology, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taipei, Taiwan
| | - Xian Lin
- Transgenics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Dena Hernandez
- Molecular Genetics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Javier Simon-Sanchez
- Molecular Genetics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
- Unitat de Genética Molecular, Departamento de Genómica y Proteómica, Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Nick W Wood
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London, United Kingdom
| | - Paola Giunti
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London, United Kingdom
| | - Ian Rafferty
- Molecular Genetics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - John Hardy
- Reta Lila Weston Institute of Neurological Studies, University College London, London, United Kingdom
- Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Elsdon Storey
- Department of Medicine, Alfred Hospital, Monash University, Melbourne, Australia
- Genetic Health Services Victoria, Melbourne, Australia
| | - R. J. McKinlay Gardner
- Genetic Health Services Victoria, Melbourne, Australia
- Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
| | - Susan M Forrest
- Australian Genome Research Facility, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Elizabeth M. C Fisher
- Department of Neurodegenerative Disease, Institute of Neurology, Queen Square, London, United Kingdom
| | - James T Russell
- Section on Cell Biology and Signal Transduction, National Institute on Child Health and Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Huaibin Cai
- Transgenics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Andrew B Singleton
- Molecular Genetics Unit, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail:
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Abstract
BACKGROUND Nonsyndromic autosomal-dominant, adult-onset sensorineural hearing loss resulting from DFNA17 was described in a single American kindred in 1997, and the causative gene was subsequently identified as MYH9. OBJECTIVE The objective of this study was to report clinical and genetic analyses of an Australian family with nonsyndromic adult-onset sensorineural hearing loss. METHODS The clinical presentation of the family was detailed and identification of the causative gene was conducted by SNP genotyping and direct sequencing. RESULTS Sequence analysis of the MYH9 gene revealed the same missense mutation as in the original DFNA17 family. We are not aware of a link between the two kindreds, making the present one only the second DFNA17 family to be reported. CONCLUSIONS One important point of clinical relevance is the excellent outcome with cochlear implants in the Australian family compared with a "poor" response in the American family. Thus, cochlear implants should be strongly considered for clinical management of patients with DFNA17 deafness.
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Affiliation(s)
- Michael S Hildebrand
- Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Australia.
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22
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McGillivray G, Savarirayan R, Cox TC, Stojkoski C, McNeil R, Bankier A, Bateman JF, Roscioli T, Gardner RJM, Lamandé SR. Familial scaphocephaly syndrome caused by a novel mutation in the FGFR2 tyrosine kinase domain. J Med Genet 2006; 42:656-62. [PMID: 16061565 PMCID: PMC1736114 DOI: 10.1136/jmg.2004.027888] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Vinton A, Fahey MC, O'Brien TJ, Shaw J, Storey E, Gardner RJM, Mitchell PJ, Du Sart D, King JO. Dentatorubral-pallidoluysian atrophy in three generations, with clinical courses from nearly asymptomatic elderly to severe juvenile, in an Australian family of Macedonian descent. Am J Med Genet A 2005; 136:201-4. [PMID: 15948186 DOI: 10.1002/ajmg.a.30355] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We report a three-generation Caucasian family of Macedonian origin with dentatorubral-pallidoluysian atrophy (DRPLA), manifesting as very mild elderly onset, severe young adult onset, and severe childhood onset presentations in the three generations. The grandparental trinucleotide expansion size (52 repeats) is the smallest overtly pathogenic mutation yet reported. This 67-year-old man displayed only subtle neurological and cognitive deficits on formal examination and very slight signs on MRI. His son had developed a choreiform disorder at age 32 years, and by his 40s suffered severe dementia and motor decline. The grandson, the proband, presented as a teenager with progressive myoclonic epilepsy, dysarthria, ataxia, and cognitive decline, having manifesting learning difficulties from the age 5 years. Atrophin-1 expansion sizes of 52, 57, and 66 repeats were demonstrated in the three patients, respectively. Given an absence of any other indicative history in the family, we speculate that the mutation may have expanded from a 'high-end' normal allele to a pathogenic size at the grandfather's conception, or that one of his parents may have had a pathogenic mutation at the lowest end of the expanded range.
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Affiliation(s)
- Anita Vinton
- Department of Neurology, the Royal Melbourne Hospital, The University of Melbourne, Australia
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Steele DL, Chisholm AK, McGhie JDR, Gardner RJM, Scheffer IE, Slater HR, Dawson G. Superior verbal ability and nonverbal learning disability in a child with a novel 17p12p13.1 deletion. Am J Med Genet B Neuropsychiatr Genet 2005; 134B:104-9. [PMID: 15717294 DOI: 10.1002/ajmg.b.30156] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We report the case of a 10-year-old girl with the karyotype 46,XX,del(17)(p12p13.1) who presented a remarkable incongruence in higher cerebral functioning. Certain language skills were very superior, with reading and spelling at a 17-19 year-old level of proficiency. Nonverbal skills, however, were mostly below average, executive functioning and socialization were impaired, and a diagnosis of "nonverbal learning disability" is applied. We speculate that the genes deleted include one or some which code for certain specific categories of neural substrate that subserve aspects of visual processing and higher functioning, but that no "language loci" have been deleted. The particular neuropsychological profile that we describe may assist diagnosis of this chromosomal deletion.
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Affiliation(s)
- D L Steele
- Department of Psychology, Monash University, Melbourne, Australia
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Abstract
Spinocerebellar ataxia type 20 (SCA20) was reported in 2004 in a single Australian Anglo-Celtic pedigree. The phenotype is distinctive, with palatal tremor, and hypermetric saccades, and early dentate (but not pallidal) calcification in the absence of abnormalities of calcium metabolism. Dysarthria, rather than gait ataxia, was the initial symptom in most, and was typically conjoined with dysphonia, clinically resembling adductor spasmodic dysphonia. The onset of these speech abnormalities was abrupt in some cases. MRI scanning showed mild to moderate pancerebellar atrophy with dentate calcification, with olivary pseudohypertrophy in some cases, in the absence of other brainstem or cerebral changes. Nerve conduction studies were normal. Progression appeared to be slow. SCA20 is probably rare, as despite the distinctive phenotype, only this one pedigree has been described. The locus mapped to the pericentromeric region of chromosome 11 with a LOD score of 4.47, and its candidate region overlaps that of SCA5. It seems probable that these two SCAs may be separate genetic entities, on the basis of their divergent clinical features, but formal proof awaits discovery of one or both responsible genes.
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Affiliation(s)
- Elsdon Storey
- Department of Medicine (Neurosciences), Alfred Hospital Campus of Monash University, Melbourne, Australia.
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Abstract
Spinocerebellar ataxia type 15 (SCA15) was first reported in 2001 on the basis of a single large Anglo-Celtic family from Australia, the locus mapping to chromosomal region 3p24.2-3pter. The characteristic clinical feature was of very slow progression, with two affected individuals remaining ambulant without aids after over 50 years of symptoms. Head and/or upper limb action tremor, and gaze-evoked horizontal nystagmus were seen in several persons. MRI brain scans showed predominant vermal atrophy, sparing the brainstem. In 2004, a Japanese pedigree was reported, which displayed very similar clinical features to the original SCA15 family, and which mapped to an overlapping candidate region. These two families might plausibly reflect a locus homogeneity, but for the present this remains an open question.
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Affiliation(s)
- R J McKinlay Gardner
- Genetic Health Services Victoria, Royal Children's Hospital, Parkville, Melbourne, Australia.
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Abstract
OBJECTIVE To describe a fetal syndrome of abnormal brain development with intracranial calcification, identified in three successive pregnancies. METHODS Clinical, imaging, and pathological descriptions, and pedigree assessment. RESULTS All three affected pregnancies were terminated, following imaging diagnosis of brain abnormality. The most complete fetal study, from the third of these pregnancies, showed widespread foci of brain calcification not associated with inflammation, with extensive necrosis and calcification of periventricular white matter, but with sparing of thalamus and basal ganglia. The corticospinal tracts were severely hypoplastic. CONCLUSION This condition appears to be a 'new' genetically determined, probably autosomal recessive disorder of severe early brain dysgenesis with focal calcification, resembling, but distinct from, certain other clinical genetic entities of which brain calcification is a part.
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Affiliation(s)
- R J McKinlay Gardner
- Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia.
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Wong SS, Lozano G, Gaff CL, Gardner RJM, Strong LC, Aittomäki K, Lindeman GJ. Novel p53 germline mutation in a patient with Li-Fraumeni syndrome. Intern Med J 2004; 33:621. [PMID: 14656244 DOI: 10.1111/j.1445-5994.2003.00487.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Knight MA, Gardner RJM, Bahlo M, Matsuura T, Dixon JA, Forrest SM, Storey E. Dominantly inherited ataxia and dysphonia with dentate calcification: spinocerebellar ataxia type 20. ACTA ACUST UNITED AC 2004; 127:1172-81. [PMID: 14998916 DOI: 10.1093/brain/awh139] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We describe a pedigree of Anglo-Celtic origin with a phenotypically unique form of dominantly inherited spinocerebellar ataxia (SCA) in 14 personally examined affected members. A remarkable observation is dentate nucleus calcification, producing a low signal on MRI sequences. Unusually for an SCA, dysarthria is typically the initial manifestation. Mild pyramidal signs and hypermetric saccades are noted in some. Its distinguishing clinical features, each present in a majority of affected persons, are palatal tremor, and a form of dysphonia resembling spasmodic dysphonia. Repeat expansion detection failed to identify either CAG/CTG or ATTCT/AGAAT repeat expansions segregating with the disease in this family. The testable SCA mutations have been excluded. On linkage analysis, the locus maps to chromosome 11, which rules out all the remaining mapped SCAs except for SCA5. While locus homogeneity with SCA5 is not formally excluded, we consider it rather unlikely on phenotypic grounds, and propose that this condition may represent an addition to the group of neurogenetic disorders subsumed under the rubric SCA. The International Nomenclature Committee has made a provisional assignment of 'SCA20', although firm designation will have to await a definite molecular distinction from SCA5.
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Affiliation(s)
- Melanie A Knight
- Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
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30
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Jamshidi N, Macciocca I, Dargaville PA, Thomas P, Kilpatrick N, McKinlay Gardner RJ, Farlie PG. Isolated Robin sequence associated with a balanced t(2;17) chromosomal translocation. J Med Genet 2004; 41:e1. [PMID: 14729841 PMCID: PMC1757243 DOI: 10.1136/jmg.2003.010157] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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31
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Nasioulas S, Jones IT, St John DJ, Scott RJ, Forrest SM, McKinlay Gardner RJ. Profuse familial adenomatous polyposis with an adenomatous polyposis coli exon 3 mutation. Fam Cancer 2003; 1:3-7. [PMID: 14574009 DOI: 10.1023/a:1011570523343] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The attenuated form of familial adenomatous polyposis coli (AAPC) is associated with mutations in the adenomatous polyposis coli (APC) gene which cluster in the 5' region of the gene. It has been proposed that a 'genotype-phenotype boundary' exists at codons 159-163, and mutations that are 5' of this boundary will produce AAPC. Herein we document a three-generation family with an exon 3 mutation well to the 5' side of the proposed boundary, in which two affected individuals have had, in their 40s, a profuse form of familial adenomatous polyposis coli. We conclude that the codon 159-163 'boundary' is indicative rather than definitive. These two patients also had postoperative intra-abdominal adhesions, severely so in one.
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Affiliation(s)
- S Nasioulas
- Victorian Clinical Genetics Services and Murdoch Childrens research Institute, Royal Children's Hospital, Melbourne, Australia
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Knight MA, Kennerson ML, Anney RJ, Matsuura T, Nicholson GA, Salimi-Tari P, Gardner RJM, Storey E, Forrest SM. Spinocerebellar ataxia type 15 (sca15) maps to 3p24.2-3pter: exclusion of the ITPR1 gene, the human orthologue of an ataxic mouse mutant. Neurobiol Dis 2003; 13:147-57. [PMID: 12828938 DOI: 10.1016/s0969-9961(03)00029-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have studied a large Australian kindred with a dominantly inherited pure cerebellar ataxia, SCA15. The disease is characterised by a very slow rate of progression in some family members, and atrophy predominantly of the superior vermis, and to a lesser extent the cerebellar hemispheres. Repeat expansion detection failed to identify either a CAG/CTG or ATTCT/AGAAT repeat expansions segregating with the disease in this family. A genome-wide scan revealed significant evidence for linkage to the short arm of chromosome 3. The highest two-point LOD score was obtained with D3S3706 (Z = 3.4, theta = 0.0). Haplotype analysis identified recombinants that placed the SCA15 locus within an 11.6-cM region flanked by the markers D3S3630 and D3S1304. The mouse syntenic region contains two ataxic mutants, itpr1-/- and opt, affecting the inositol 1,4,5-triphosphate type 1 receptor, ITPR1 gene. ITPR1 is predominantly expressed in the cerebellar Purkinje cells. Mutation analysis from two representative affected family members excluded the coding region of the ITPR1 gene from being involved in the pathogenesis of SCA15. Thus, the itpr1-/- and opt ITPR1 mouse mutants, which each result in ataxia, are not allelic to the human SCA15 locus.
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Affiliation(s)
- Melanie A Knight
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, Melbourne, Australia
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Aksoy H, Dean G, Elian M, Deng HX, Deng G, Juneja T, Storey E, McKinlay Gardner RJ, Jacob RL, Laing NG, Siddique T. A4T mutation in the SOD1 gene causing familial amyotrophic lateral sclerosis. Neuroepidemiology 2003; 22:235-8. [PMID: 12792143 DOI: 10.1159/000070564] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We report the clinical and laboratory findings in the largest kindred so far recorded with familial amyotrophic lateral sclerosis due to an A4T mutation in the SOD1 gene. The age of onset ranged from 32 to 60 years, with a mean of 46 years. Weakness in the legs was the most frequent early symptom and there was a predominance of lower motor neuron signs. The mean time from onset of symptoms to death was 14 months. One man with onset at the age of 37 has shown a slowly developing form and is currently alive 76 months after diagnosis (October 2002), although severely affected. The A4T mutation, with one exception, was of similar severity to the A4V mutation.
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Affiliation(s)
- Hatice Aksoy
- Department of Neurology, Burhan Nalbantoglu Hospital, Lefkosa (Nicosia), Cyprus, UK
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Li L, Moore P, Ngo C, Petrovic V, White SM, Northrop E, Ioannou PA, McKinlay Gardner RJ, Slater HR. Identification of a haplosufficient 3.6-Mb region in human chromosome 11q14.3-->q21. Cytogenet Genome Res 2003; 97:158-62. [PMID: 12438706 DOI: 10.1159/000066612] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Cytogenetic deletions are almost always associated with phenotypic abnormality and are very rarely transmitted. We have located a hitherto undescribed, familial deletion involving the region 11q14.3-->q21 in five individuals in a three-generation kindred. Four of the deletion carriers show no phenotypic abnormality; the other, who is the proband, was investigated for short stature and poor academic progress. In view of the apparent innocuous nature of this genetic imbalance, the deletion was investigated in detail to determine its size (3.6 Mb) and location with reference to molecular markers and genetic content. The deleted region is described by a contig of 37 BACS including the flanking regions, which we have assembled. Several possible contributory factors are considered, which might explain the lack of clinical significance of this large deletion. It is notable that there are few genes in this region and none have known functions. All most likely have copies elsewhere in the genome and a number of other hypothetical genes appear to be members of certain gene families, i.e. none is unique. Part of the region (1 Mb) is also duplicated at the pericentromeric region 11p11. Given the very low proportion of the genome occupied by single copy genes and their uneven distribution, regions such as this, which appear to be functionally haplosufficient, may be more common than hitherto recognised.
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Affiliation(s)
- L Li
- Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville Vic, Australia
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Wilson SC, Susman M, Bain S, Wohlferd M, Van Dyke DL, Daniel A, White B, Gardner RJM. Isochromosome 5p mosaicism at prenatal diagnosis: observations and outcomes in six cases at chorionic villus sampling and one at amniocentesis. Prenat Diagn 2002; 22:681-5. [PMID: 12210576 DOI: 10.1002/pd.379] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified.
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Affiliation(s)
- Susan Clement Wilson
- Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia.
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Abstract
We report a large family with a previously undescribed, dominantly inherited condition comprising arthropathy of the hands and feet and progressive shortening of the middle and distal phalanges. We have designated the condition familial digital arthropathy-brachydactyly (FDAB). Onset of FDAB is in the first decade and the arthropathy is progressive, resulting in deformity and pain in adult life. The remainder of the skeleton is not affected. It is hypothesized from the radiological appearance of patients at different ages that FDAB might result from subchondral pathology primarily affecting the heads of the phalanges, metacarpals, and metatarsals, with the arthropathy and brachydactyly being secondary effects.
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Affiliation(s)
- David J Amor
- Genetic Health Services Victoria, Royal Children's Hospital, Victoria, Australia.
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Abstract
PURPOSE We analyzed databases on chromosomal anomalies and epilepsy to identify chromosomal regions where abnormalities are associated with clinically recognizable epilepsy syndromes. The expectation was that these regions could then be offered as targets in the search for epilepsy genes. METHODS The cytogenetic program of the Oxford Medical Database, and the PubMed database were used to identify chromosomal aberrations associated with seizures and/or EEG abnormalities. The literature on selected small anomalies thus identified was reviewed from a clinical and electroencephalographic viewpoint, to classify the seizures and syndromes according to the current International League Against Epilepsy (ILAE) classification. RESULTS There were 400 different chromosomal imbalances described with seizures or EEG abnormalities. Eight chromosomal disorders had a high association with epilepsy. These comprised: the Wolf-Hirschhorn (4p-) syndrome, Miller-Dieker syndrome (del 17p13.3), Angelman syndrome (del 15q11-q13), the inversion duplication 15 syndrome, terminal deletions of chromosome 1q and 1p, and ring chromosomes 14 and 20. Many other segments had a weaker association with seizures. The poor quality of description of the epileptology in many reports thwarted an attempt to make precise karyotype-phenotype correlations. CONCLUSIONS We identified certain chromosomal regions where aberrations had an evident association with seizures, and these regions may be useful targets for gene hunters. New correlations with specific epilepsy syndromes were not revealed. Clinicians should continue to search for small chromosomal abnormalities associated with specific epilepsy syndromes that could provide important clues for finding epilepsy genes, and the epileptology should be rigorously characterized.
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Affiliation(s)
- Rita Singh
- Department of Medicine (Neurology), The University of Melbourne, Austin and Repatriation Medical Centre, Australia
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Shore EM, Ahn J, Jan de Beur S, Li M, Xu M, Gardner RJM, Zasloff MA, Whyte MP, Levine MA, Kaplan FS. Paternally inherited inactivating mutations of the GNAS1 gene in progressive osseous heteroplasia. N Engl J Med 2002; 346:99-106. [PMID: 11784876 DOI: 10.1056/nejmoa011262] [Citation(s) in RCA: 237] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Progressive osseous heteroplasia (POH), an autosomal dominant disorder, is characterized by extensive dermal ossification during childhood, followed by disabling and widespread heterotopic ossification of skeletal muscle and deep connective tissue. Occasional reports of mild heterotopic ossification in Albright's hereditary osteodystrophy (AHO) and a recent report of two patients with AHO who had atypically extensive heterotopic ossification suggested a common genetic basis for the two disorders. AHO is caused by heterozygous inactivating mutations in the GNAS1 gene that result in decreased expression or function of the alpha subunit of the stimulatory G protein (Gsalpha) of adenylyl cyclase. METHODS We tested the hypothesis that GNAS1 mutations cause POH, using the polymerase chain reaction to amplify GNAS1 exons and exon-intron boundaries in 18 patients with sporadic or familial POH. RESULTS Heterozygous inactivating GNAS1 mutations were identified in 13 of the 18 probands with POH. The defective allele in POH is inherited exclusively from fathers, a result consistent with a model of imprinting for GNAS1. Direct evidence that the same mutation can cause either POH or AHO was observed within a single family, in which the phenotype correlated with the parental origin of the mutant allele. CONCLUSIONS Paternally inherited inactivating GNAS1 mutations cause POH. This finding extends the range of phenotypes derived from haplo insufficiency of GNAS1, provides evidence that imprinting is a regulatory mechanism for GNAS1 expression, and suggests that Gsalpha is a critical negative regulator of osteogenic commitment in nonosseous connective tissues.
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Affiliation(s)
- Eileen M Shore
- Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia 19104-6018, USA.
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Affiliation(s)
- M A Knight
- Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia
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Wilcox SA, Saunders K, Osborn AH, Arnold A, Wunderlich J, Kelly T, Collins V, Wilcox LJ, McKinlay Gardner RJ, Kamarinos M, Cone-Wesson B, Williamson R, Dahl HH. High frequency hearing loss correlated with mutations in the GJB2 gene. Hum Genet 2000; 106:399-405. [PMID: 10830906 DOI: 10.1007/s004390000273] [Citation(s) in RCA: 150] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Genetic hearing impairment affects approximately 1/2000 live births. Mutations in one gene, GJB2, coding for connexin 26 cause 10%-20% of all genetic sensorineural hearing loss. Mutation analysis in the GJB2 gene and audiology were performed on 106 families presenting with at least one child with congenital hearing loss. The families were recruited from a hospital-based multidisciplinary clinic, which functions to investigate the aetiology of sensorineural hearing loss in children and which serves an ethnically diverse population. In 74 families (80 children), the aetiology was consistent with non-syndromic recessive hearing loss. Six different connexin 26 mutations, including one novel mutation, were identified. We show that GJB2 mutations cause a range of phenotypes from mild to profound hearing impairment and that loss of hearing in the high frequency range (4000-8000 Hz) is a characteristic feature in children with molecularly diagnosed connexin 26 hearing impairment. We also demonstrate that this type of audiology and high frequency hearing loss is found in a similar-sized group of deaf children in whom a mutation could only be found in one of the connexin 26 alleles, suggesting connexin 26 involvement in the aetiology of hearing loss in these cases. In our study of the M34T mutation, only compound heterozygotes exhibited hearing loss, suggesting autosomal recessive inheritance.
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Affiliation(s)
- S A Wilcox
- The Murdoch Institute, Royal Children's Hospital, Melbourne, Australia
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Lamandé SR, Bateman JF, Hutchison W, McKinlay Gardner RJ, Bower SP, Byrne E, Dahl HH. Reduced collagen VI causes Bethlem myopathy: a heterozygous COL6A1 nonsense mutation results in mRNA decay and functional haploinsufficiency. Hum Mol Genet 1998; 7:981-9. [PMID: 9580662 DOI: 10.1093/hmg/7.6.981] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We have identified a new pathogenic mechanism for an inherited muscular dystrophy in which functional haploinsufficiency of the extracellular matrix protein collagen VI causes Bethlem myopathy. The heterozygous COL6A1 mutation results in a single base deletion from the mRNA and a premature stop codon. The mutant mRNA is unstable, subject to nonsense-mediated mRNA decay, and is almost completely absent both from patient fibroblasts and skeletal muscle, resulting in haploinsufficiency of the alpha1(VI) subunit and reduced production of structurally normal collagen VI. This is the first example of a muscular dystrophy caused by haploinsufficiency of a structural protein or member of the dystrophin-glycoprotein complex, and identifies collagen VI as a critical contributor to cell-matrix adhesion in skeletal muscle.
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Affiliation(s)
- S R Lamandé
- Orthopaedic Molecular Biology Research Unit, Department of Paediatrics, University of Melbourne and Murdoch Institute, Royal Children's Hospital, Parkville 3052, Australia.
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