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Monckton DG. The Contribution of Somatic Expansion of the CAG Repeat to Symptomatic Development in Huntington's Disease: A Historical Perspective. J Huntingtons Dis 2021; 10:7-33. [PMID: 33579863 PMCID: PMC7990401 DOI: 10.3233/jhd-200429] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The discovery in the early 1990s of the expansion of unstable simple sequence repeats as the causative mutation for a number of inherited human disorders, including Huntington's disease (HD), opened up a new era of human genetics and provided explanations for some old problems. In particular, an inverse association between the number of repeats inherited and age at onset, and unprecedented levels of germline instability, biased toward further expansion, provided an explanation for the wide symptomatic variability and anticipation observed in HD and many of these disorders. The repeats were also revealed to be somatically unstable in a process that is expansion-biased, age-dependent and tissue-specific, features that are now increasingly recognised as contributory to the age-dependence, progressive nature and tissue specificity of the symptoms of HD, and at least some related disorders. With much of the data deriving from affected individuals, and model systems, somatic expansions have been revealed to arise in a cell division-independent manner in critical target tissues via a mechanism involving key components of the DNA mismatch repair pathway. These insights have opened new approaches to thinking about how the disease could be treated by suppressing somatic expansion and revealed novel protein targets for intervention. Exciting times lie ahead in turning these insights into novel therapies for HD and related disorders.
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Affiliation(s)
- Darren G. Monckton
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
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2
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Sawada J, Katayama T, Tokashiki T, Kikuchi S, Kano K, Takahashi K, Saito T, Adachi Y, Okamoto Y, Yoshimura A, Takashima H, Hasebe N. The First Case of Spinocerebellar Ataxia Type 8 in Monozygotic Twins. Intern Med 2020; 59:277-283. [PMID: 31554751 PMCID: PMC7008061 DOI: 10.2169/internalmedicine.2905-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Spinocerebellar ataxia type 8 (SCA8) is a rare hereditary cerebellar ataxia showing mainly pure cerebellar ataxia. We herein report cases of SCA8 in Japanese monozygotic twins that presented with nystagmus, dysarthria, and limb and truncal ataxia. Their ATXN8OS CTA/CTG repeats were 25/97. They showed similar manifestations, clinical courses, and cerebellar atrophy on magnetic resonance imaging. Some of their pedigrees had nystagmus but not ataxia. These are the first monozygotic twins with SCA8 to be reported anywhere in the world. Although not all subjects with the ATXN8OS CTG expansion develop cerebellar ataxia, these cases suggest the pathogenesis of ATXN8OS repeat expansions in hereditary cerebellar ataxia.
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Affiliation(s)
- Jun Sawada
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
| | - Takayuki Katayama
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
| | - Takashi Tokashiki
- Department of Neurology, National Hospital Organization Okinawa Hospital, Japan
| | - Shiori Kikuchi
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
| | - Kohei Kano
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
| | - Kae Takahashi
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
| | - Tsukasa Saito
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
| | - Yoshiki Adachi
- Department of Neurology, National Hospital Organization Matsue Medical Center, Japan
| | - Yuji Okamoto
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Akiko Yoshimura
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Hiroshi Takashima
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Japan
| | - Naoyuki Hasebe
- Division of Neurology, Department of Internal Medicine, Asahikawa Medical University, Japan
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Genetic and clinical analyses of spinocerebellar ataxia type 8 in mainland China. J Neurol 2019; 266:2979-2986. [DOI: 10.1007/s00415-019-09519-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/19/2019] [Accepted: 08/19/2019] [Indexed: 02/01/2023]
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Shuvaev AN, Belozor OS, Smolnikova MV, Yakovleva DA, Shuvaev AN, Kazantseva OM, Pozhilenkova EA, Mozhei OI, Kasparov S. Population genetics of spinoсerebellar ataxias caused by polyglutamine expansions. Vavilovskii Zhurnal Genet Selektsii 2019. [DOI: 10.18699/vj19.516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Hereditary disorders of the neuronal system are some of the most important problems of medicine in the XXI century. The most interesting representatives of this group are highly prevalent polyglutamine spinocerebellar ataxias (SCAs). It has a basement for quick progression of expansion among different groups all over the World. These diseases are SCA1, 2, 3, 6, 7 and 17, which phenotypically belong to one group due to similarities in clinics and genetics. The substrate of these genetic conditions is CAG trinucleotide repeat of Ataxin genes which may expand in the course of reproduction. For this reason a characteristic feature of these diseases is not only an increase in patient numbers, but also a qualitative change in the progression of their neurological symptoms. All these aspects are reflected in the structure of the incidence of polyglutamine SCAs, both at the global level and at the level of individual population groups. However, most scientific reports that describe the population genetics of polyglutamine SCAs are limited to quantitative indicators of a specific condition in a certain area, while the history of the occurrence and principles of the distribution of polyglutamine SCAs are poorly understood. This prevents long-term predictions of the dynamics of the disease and development of strategies for controlling the spread of mutations in the populations. In this paper we make a detailed analysis of the polyglutamine SCAs population genetics, both in the whole world and specifically in theRussian Federation. We note that for a better analysis it would be necessary to cover a wider range of populations in Africa, Asia andSouth America, which will be possible with the development of new methods for molecular genetics. Development of new methods of detection of polyglutamine SCAs will allow the scientists to better understand how they lead to the brain disease, the means of their spread in the population and to develop better methods for therapy and prevention of these diseases.
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Affiliation(s)
- A. N. Shuvaev
- Krasnoyarsk State Medical University named after V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry
| | - O. S. Belozor
- Krasnoyarsk State Medical University named after V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry
| | - M. V. Smolnikova
- Krasnoyarsk State Medical University named after V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry;
Federal Research Center “Krasnoyarsk Science Center” of the Siberian Branch of the Russian Academy of Sciences, Scientific Research Institute of Medical Problems of the North
| | | | | | | | - E. A. Pozhilenkova
- Krasnoyarsk State Medical University named after V.F. Voino-Yasenetsky, Research Institute of Molecular Medicine and Pathobiochemistry
| | | | - S. Kasparov
- Immanuel Kant Baltic Federal University;
University of Bristol
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Sequence configuration of spinocerebellar ataxia type 8 repeat expansions in a Japanese cohort of 797 ataxia subjects. J Neurol Sci 2017; 382:87-90. [PMID: 29111027 DOI: 10.1016/j.jns.2017.08.3256] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 08/04/2017] [Accepted: 08/28/2017] [Indexed: 11/23/2022]
Abstract
Spinocerebellar ataxia type 8 (SCA8), an autosomal dominant neurodegenerative disorder showing slowly progressive cerebellar ataxia, is caused by a tri-nucleotide CTG repeat expansion (CTGexp) in the SCA8 gene. As the CTGexp is not fully penetrant, the significance of screening CTGexp in ataxia subjects remains obscure. We tested SCA8 CTGexp in a cohort of 797 ataxia subjects, and if present, its sequence configuration was analyzed. CTGexp was found in 16 alleles from 14 individuals, 2 of which was homozygous for CTGexp. Nucleotide sequencing disclosed 3 types of CTGexp sequence configurations: uninterrupted CTGexp, tri-nucleotide CTA interruption and CCG interruption. The 2 individuals with homozygous expansions were both sporadic cases with clinical features compatible with SCA8, supporting gene dosage effect. Seven out of 14 CTGexp-positive subjects were also carriers of other SCA expansions [Machado-Joseph disease (n=1), SCA6 (n=3) and SCA31 (n=3)], whereas 7 others were not complicated with such major SCAs. Ages of onset in subjects with pure CTGexp tended to be earlier than those with interrupted CTGexp among the 7 subjects not complicated by major SCAs, suggesting that pure CTGexp have stronger pathogenic effect than interrupted CTGexps. The present study underscores importance of disclosing sequence configuration when testing SCA8.
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Vincent JB. Unstable repeat expansion in major psychiatric disorders: two decades on, is dynamic DNA back on the menu? Psychiatr Genet 2017; 26:156-65. [PMID: 27270050 DOI: 10.1097/ypg.0000000000000141] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
For a period in the mid-1990s, soon after the discovery of the involvement of trinucleotide repeat expansions in fragile-X syndrome (both A and E), Huntington's disease, myotonic dystrophy, and a number of hereditary ataxias, there was a clear sense that this new disease mechanism might provide answers for psychiatric disorders. Given the then failures to replicate initial genetic linkage findings for schizophrenia (SCZ) and bipolar disorder (BD), a greater emphasis was placed on the role of complex and non-Mendelian mechanisms, and repeat instability appeared to have the potential to provide adequate explanations for numerous apparently non-Mendelian features such as anticipation, incomplete penetrance, sporadic occurrence, and nonconcordance of monozygotic twins. Initial molecular studies using a ligation-based amplification method (repeat expansion detection) appeared to support the involvement of CAG•CTG repeat expansion in SCZ and BD. However, subsequent studies that dissected the large repeats responsible for much of the positive signal showed that there were three main loci where CAG•CTG repeat expansion was occurring (on 13q21.33, 17q21.33-q22, and 18q21.2). None of the expansions at these loci appeared to segregate with SCZ or BD, and research into repeat expansions in psychiatric illness petered out in the early 2000s. The 13q expansion occurs within a noncoding RNA and appears to be associated with spinocerebellar ataxia 8 (SCA8), but with a still unexplained dichotomy in penetrance - either very high or very low. The 17q expansion occurs within an intron of the carbonic anhydrase-like gene, CA10. The 18q expansion is located within an intron of the TCF4 gene. Mutations in TCF4 are a known cause of Pitt-Hopkins syndrome. Also, pertinently, genome-wide association studies have shown a well-replicated association between TCF4 and SCZ. Two decades on, in 2016, it appears to be an appropriate juncture to reflect on what we have learned, and, with the arrival of newer technologies, whether there is any mileage to be made in revisiting the unstable DNA hypothesis for psychiatric illness.
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Affiliation(s)
- John B Vincent
- aMolecular Neuropsychiatry & Development (MiND) Lab, Centre for Addiction and Mental Health, Campbell Family Mental Health Research Institute bInstitute of Medical Science cDepartment of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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Gaetano Gatta N, Romano R, Fioretti E, Gentile V. Transglutaminase inhibition: possible therapeutic mechanisms to protect cells from death in neurological disorders. AIMS MOLECULAR SCIENCE 2017. [DOI: 10.3934/molsci.2017.4.399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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8
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Gaetano Gatta N, Cammarota G, Gentile V. Possible roles of transglutaminases in molecular mechanisms responsible for human neurodegenerative diseases. AIMS BIOPHYSICS 2016. [DOI: 10.3934/biophy.2016.4.529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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9
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Serretiello E, Iannaccone M, Titta F, G. Gatta N, Gentile V. Possible pathophysiological roles of transglutaminase-catalyzed reactions in the pathogenesis of human neurodegenerative diseases. AIMS BIOPHYSICS 2015. [DOI: 10.3934/biophy.2015.4.441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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10
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Subramony S, Moscovich M, Ashizawa T. Genetics and Clinical Features of Inherited Ataxias. Mov Disord 2015. [DOI: 10.1016/b978-0-12-405195-9.00062-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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11
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Georgakilas AG, Tsantoulis P, Kotsinas A, Michalopoulos I, Townsend P, Gorgoulis VG. Are common fragile sites merely structural domains or highly organized "functional" units susceptible to oncogenic stress? Cell Mol Life Sci 2014; 71:4519-44. [PMID: 25238782 PMCID: PMC4232749 DOI: 10.1007/s00018-014-1717-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 08/28/2014] [Indexed: 01/07/2023]
Abstract
Common fragile sites (CFSs) are regions of the genome with a predisposition to DNA double-strand breaks in response to intrinsic (oncogenic) or extrinsic replication stress. CFS breakage is a common feature in carcinogenesis from its earliest stages. Given that a number of oncogenes and tumor suppressors are located within CFSs, a question that emerges is whether fragility in these regions is only a structural “passive” incident or an event with a profound biological effect. Furthermore, there is sparse evidence that other elements, like non-coding RNAs, are positioned with them. By analyzing data from various libraries, like miRbase and ENCODE, we show a prevalence of various cancer-related genes, miRNAs, and regulatory binding sites, such as CTCF within CFSs. We propose that CFSs are not only susceptible structural domains, but highly organized “functional” entities that when targeted, severe repercussion for cell homeostasis occurs.
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Affiliation(s)
- Alexandros G Georgakilas
- Physics Department, School of Applied Mathematical and Physical Sciences, National Technical University of Athens (NTUA), Zografou, 15780, Athens, Greece
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12
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Musova Z, Sedlacek Z, Mazanec R, Klempir J, Roth J, Plevova P, Vyhnalek M, Kopeckova M, Apltova L, Krepelova A, Zumrova A. Spinocerebellar ataxias type 8, 12, and 17 and dentatorubro-pallidoluysian atrophy in Czech ataxic patients. THE CEREBELLUM 2013; 12:155-61. [PMID: 22872568 DOI: 10.1007/s12311-012-0403-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Spinocerebellar ataxias (SCAs) are a heterogeneous group of neurodegenerative disorders currently associated with 27 genes. The most frequent types are caused by expansions in coding CAG repeats. The frequency of SCA subtypes varies among populations. We examined the occurrence of rare SCAs, SCA8, SCA12, SCA17 and dentatorubro-pallidoluysian atrophy (DRPLA), in the Czech population from where the data were missing. We analyzed causal gene expansions in 515 familial and sporadic ataxic patients negatively tested for SCA1-3 and SCA6-7. Pathogenic SCA8 and SCA17 expansions were identified in eight and five patients, respectively. Tay-Sachs disease was later diagnosed in one patient with an SCA8 expansion and the diagnosis of multiple sclerosis (MS) was suspected in two other patients with SCA8 expansions. These findings are probably coincidental, although the participation of SCA8 expansions in the susceptibility to MS and disease progression cannot be fully excluded. None of the patients had pathogenic SCA12 or DRPLA expansions. However, three patients had intermediate SCA12 alleles out of the normal range with 36 and 43 CAGs. Amyotrophic lateral sclerosis (ALS) was probable in the patient with 43 CAGs. This coincidence is remarkable, especially in the context with the recently identified predisposing role of longer SCA2 alleles in ALS. Five families with SCA17 represent a significant portion of ataxic patients and this should be reflected in the diagnostics of SCAs in the Czech population. SCA8 expansions must be considered after careful clinical evaluation.
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Affiliation(s)
- Zuzana Musova
- Department of Biology and Medical Genetics, Charles University 2nd Faculty of Medicine and University Hospital Motol, Prague, Czech Republic.
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Gershon ES, Badner JA. Incorporation of molecular data and redefinition of phenotype: new approaches to genetic epidemiology of bipolar manic depressive illness and schizophrenia. DIALOGUES IN CLINICAL NEUROSCIENCE 2012. [PMID: 22034205 PMCID: PMC3181639 DOI: 10.31887/dcns.2001.3.1/esgershon] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Considerable advances have been made in identifying specific genetic components of bipolar manic depressive illness (BP) and schizophrenia (SZ), despite their complex inheritance. Meta-analysis of all published whole-genome linkage scans reveals overall support for illness genes in several chromosomal regions. In two of these regions, on the lonq arm of chromosome 13 and on the long arm of chromosome 22, the combined studies of BP and SZ are consistent with a common susceptibility locus for the two disorders. This lends some plausibility to the hypothesis of some shared genetic predispositions for BP and SZ. Other linkages are supported by multiple studies of specific chromosomal regions, most notably two regions on chromosome 6 in SZ. The velocardiofacial syndrome is associated with deletions very close to the linkage region on chromosome 22, and with psychiatric manifestations of both BP and SZ. Endophenotypes of SZ, previously demonstrated to be heritable, have been found to have chromosomal linkage in at least one study. These include eye-tracking abnormalities linked to the short arm of chromosome 6, and abnormality of the P50 cortical evoked potential linked to chromosome 15. Variants in specific genes have been associated with susceptibility to illness, and other genes have been associated with susceptibility to side effects of pharmacological treatment. These genetic findings may eventually be part of an integrated genetic, environmental, and interactive-factor epidemiology of the major mental illnesses.
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Affiliation(s)
- E S Gershon
- Department of Psychiatry, University of Chicago, Chicago, III, USA
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Ikeda Y, Ranum LPW, Day JW. Clinical and genetic features of spinocerebellar ataxia type 8. HANDBOOK OF CLINICAL NEUROLOGY 2012; 103:493-505. [PMID: 21827909 DOI: 10.1016/b978-0-444-51892-7.00031-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Yoshio Ikeda
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
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Gentile V. Physiopathological roles of human transglutaminase 2. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:47-95. [PMID: 22220472 DOI: 10.1002/9781118105771.ch2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Vittorio Gentile
- Department of Biochemistry and Biophysics, Medical School, Second University of Naples, Naples, Italy
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Martin A, De Vivo G, Gentile V. Possible role of the transglutaminases in the pathogenesis of Alzheimer's disease and other neurodegenerative diseases. Int J Alzheimers Dis 2011; 2011:865432. [PMID: 21350675 PMCID: PMC3042675 DOI: 10.4061/2011/865432] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 01/05/2011] [Indexed: 12/30/2022] Open
Abstract
Transglutaminases are ubiquitous enzymes which catalyze posttranslational modifications of proteins. Recently, transglutaminase-catalyzed post-translational modification of proteins has been shown to be involved in the molecular mechanisms responsible for human diseases. Transglutaminase activity has been hypothesized to be involved also in the pathogenetic mechanisms responsible for several human neurodegenerative diseases. Alzheimer's disease and other neurodegenerative diseases, such as Parkinson's disease, supranuclear palsy, Huntington's disease, and other polyglutamine diseases, are characterized in part by aberrant cerebral transglutaminase activity and by increased cross-linked proteins in affected brains. This paper focuses on the possible molecular mechanisms by which transglutaminase activity could be involved in the pathogenesis of Alzheimer's disease and other neurodegenerative diseases, and on the possible therapeutic effects of selective transglutaminase inhibitors for the cure of patients with diseases characterized by aberrant transglutaminase activity.
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Affiliation(s)
- Antonio Martin
- Department of Biochemistry and Biophysics, Second University of Naples, Via Costantinopoli 16, 80138 Naples, Italy
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Ricotta M, Iannuzzi M, Vivo GD, Gentile V. Physio-pathological roles of transglutaminase-catalyzed reactions. World J Biol Chem 2010; 1:181-7. [PMID: 21541002 PMCID: PMC3083958 DOI: 10.4331/wjbc.v1.i5.181] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2010] [Revised: 05/04/2010] [Accepted: 05/14/2010] [Indexed: 02/05/2023] Open
Abstract
Transglutaminases (TGs) are a large family of related and ubiquitous enzymes that catalyze post-translational modifications of proteins. The main activity of these enzymes is the cross-linking of a glutaminyl residue of a protein/peptide substrate to a lysyl residue of a protein/peptide co-substrate. In addition to lysyl residues, other second nucleophilic co-substrates may include monoamines or polyamines (to form mono- or bi-substituted /crosslinked adducts) or -OH groups (to form ester linkages). In the absence of co-substrates, the nucleophile may be water, resulting in the net deamidation of the glutaminyl residue. The TG enzymes are also capable of catalyzing other reactions important for cell viability. The distribution and the physiological roles of TG enzymes have been widely studied in numerous cell types and tissues and their roles in several diseases have begun to be identified. “Tissue” TG (TG2), a member of the TG family of enzymes, has definitely been shown to be involved in the molecular mechanisms responsible for a very widespread human pathology: i.e. celiac disease (CD). TG activity has also been hypothesized to be directly involved in the pathogenetic mechanisms responsible for several other human diseases, including neurodegenerative diseases, which are often associated with CD. Neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, supranuclear palsy, Huntington’s disease and other recently identified polyglutamine diseases, are characterized, in part, by aberrant cerebral TG activity and by increased cross-linked proteins in affected brains. In this review, we discuss the physio-pathological role of TG-catalyzed reactions, with particular interest in the molecular mechanisms that could involve these enzymes in the physio-pathological processes responsible for human neurodegenerative diseases.
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Affiliation(s)
- Mariangela Ricotta
- Mariangela Ricotta, Maura Iannuzzi, Giulia De Vivo, Vittorio Gentile, Department of Biochemistry and Biophysics, Medical School, Second University of Naples, via Costantinopoli 16, 80138 Napoli, Italy
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Gupta A, Jankovic J. Spinocerebellar ataxia 8: variable phenotype and unique pathogenesis. Parkinsonism Relat Disord 2009; 15:621-6. [PMID: 19559641 DOI: 10.1016/j.parkreldis.2009.06.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 06/01/2009] [Accepted: 06/02/2009] [Indexed: 12/16/2022]
Abstract
Spinocerebellar ataxia 8 (SCA8), a triplet repeat expansion disorder, is genetically distinct from the other inherited ataxias, but its unusually variable phenotype can make its diagnosis difficult. In this review we describe 3 new cases of genetically verified SCA8 to highlight the broad clinical spectrum of symptoms observed with this disorder and to draw attention to the features of myoclonus and migraine headaches, which in the context of cerebellar ataxia warrants the clinician to consider SCA8 as a potential diagnosis. We also address the controversy surrounding the genetic testing approach for diagnosing SCA8. Finally, we evaluate the evidence that SCA8 may affect calcium channel function and that the presentation of episodic ataxia and migraines suggests a clinical and pathogenic overlap of SCA8 with the channelopathies.
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Affiliation(s)
- Amitabh Gupta
- Department of Neurology, University of Toronto, Toronto, ON, Canada M5T 2S8
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Ikeda Y, Daughters RS, Ranum LPW. Bidirectional expression of the SCA8 expansion mutation: one mutation, two genes. THE CEREBELLUM 2009; 7:150-8. [PMID: 18418692 DOI: 10.1007/s12311-008-0010-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Spinocerebellar ataxia type 8 (SCA8) is a dominantly inherited, slowly progressive neurodegenerative disorder caused by a CTG.CAG repeat expansion located on chromosome 13q21. The expansion mutation was isolated directly from the DNA of a single patient using RAPID cloning and subsequently shown to co-segregate with disease in additional ataxia families including a seven-generation kindred (the MN-A family). The size-dependent penetrance of the repeat found in the large MN-A kindred makes it appear as though some parts of the family have a dominant disorder while other parts of this same family have recessive or sporadic forms of ataxia. While the linkage and size-dependent penetrance of the SCA8 CTG.CAG expansion in the MN-A family argue that the SCA8 expansion causes ataxia, the reduced penetrance in other SCA8 families and the discovery of expansions in the general population have led to a controversy surrounding whether or not the SCA8 expansion is pathogenic. A recently reported mouse model in which SCA8 BAC-expansion but not BAC-control lines develop a progressive neurological phenotype now demonstrates the pathogenicity of the (CTG.CAG)(n) expansion. These mice show a loss of cerebellar GABAergic inhibition and, similar to human patients, have 1C2-positive intranuclear inclusions in Purkinje cells and other neurons. Additional studies demonstrate that the SCA8 expansion is expressed in both directions (CUG and CAG) and that a novel gene expressed in the CAG direction encodes a pure polyglutamine expansion protein (ataxin 8, ATXN8). Moreover, the expression of non-coding (CUG)(n) expansion transcripts (ataxin 8 opposite strand, ATXN8OS) and the discovery of intranuclear polyglutamine inclusions suggest SCA8 pathogenesis may involve toxic gain-of-function mechanisms at both the protein and RNA levels. Our data, combined with the recently reported antisense transcripts spanning the DM1 repeat expansion in the CAG direction and the growing number of reports of antisense transcripts expressed throughout the mammalian genome, raises the possibility that bidirectional expression across pathogenic microsatellite expansions may occur in other expansion disorders, and that potential pathogenic effects of mutations expressed from both strands should be considered.
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Affiliation(s)
- Yoshio Ikeda
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
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Ohnari K, Aoki M, Uozumi T, Tsuji S. Severe symptoms of 16q-ADCA coexisting with SCA8 repeat expansion. J Neurol Sci 2008; 273:15-8. [DOI: 10.1016/j.jns.2008.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2007] [Revised: 06/02/2008] [Accepted: 06/05/2008] [Indexed: 10/21/2022]
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21
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Miller A. Social neuroscience of child and adolescent depression. Brain Cogn 2007; 65:47-68. [PMID: 17624647 PMCID: PMC2099694 DOI: 10.1016/j.bandc.2006.02.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Revised: 02/05/2006] [Accepted: 02/05/2006] [Indexed: 11/30/2022]
Abstract
The social neuroscience of child and adolescent depression is inherently multidisciplinary. Depressive disorders beginning early in life can have serious developmental and functional consequences. Psychopathology research has described depression's defining clinical and contextual features, and intervention research has characterized its response to treatment and prevention programs. Neuroendocrine, electrophysiological, and neuroimaging studies have identified core neurobiological aspects of early-onset mood disorders. These areas are reviewed using a developmental social neuroscience perspective for integrating disparate observations. The paper introduces a dynamic adaptive systems framework, and it discusses hedonic capacity, stress sensitivity, ruminative self-focus, and attentional impairments as fundamental components of mood disorders.
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Affiliation(s)
- Anita Miller
- Department of Psychology, Skidmore College, Saratoga Springs, New York, USA.
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He Y, Zu T, Benzow KA, Orr HT, Clark HB, Koob MD. Targeted deletion of a single Sca8 ataxia locus allele in mice causes abnormal gait, progressive loss of motor coordination, and Purkinje cell dendritic deficits. J Neurosci 2006; 26:9975-82. [PMID: 17005861 PMCID: PMC6674467 DOI: 10.1523/jneurosci.2595-06.2006] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Spinocerebellar ataxia type 8 (SCA8) patients typically have a slowly progressive, adult-onset ataxia. SCA8 is dominantly inherited and is caused by large CTG repeat expansions in the untranslated antisense RNA of the Kelch-like 1 gene (KLHL1), but the molecular mechanism through which this expansion leads to disease is still unknown. To more fully characterize the underlying molecular mechanisms involved in SCA8, we developed a mouse model in which Klhl1 is deleted in either all tissues or is deleted specifically in Purkinje cells only. We found that mice that are either homozygous or heterozygous for the Klhl1 deletion have significant gait abnormalities at an early age and develop a significant loss of motor coordination by 24 weeks of age. This loss progresses more rapidly in homozygous knock-outs. Mice with Klhl1 specifically deleted in only Purkinje cells had a loss of motor coordination that was almost identical to the total-tissue deletion mice. Finally, we found significant Purkinje cell dendritic deficits, as measured by the thickness of the molecular layer, in all mice in which Klhl1 was deleted (both total and Purkinje cell-specific deletions) and an intermediate reduction in molecular layer thickness in mice with reduced levels of Klhl1 expression (heterozygous deletions). The results from this mouse model show that even a partial loss of Klhl1 function leads to degeneration of Purkinje cell function and indicates that loss of KLHL1 activity is likely to play a significant part in the underlying pathophysiology of SCA8.
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Affiliation(s)
- Yungui He
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
| | - Tao Zu
- Institute of Human Genetics
| | - Kellie A. Benzow
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
| | - Harry T. Orr
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
| | - H. Brent Clark
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
- Neurology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Michael D. Koob
- Institute of Human Genetics
- Laboratory of Medicine and Pathology, and
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Moseley ML, Zu T, Ikeda Y, Gao W, Mosemiller AK, Daughters RS, Chen G, Weatherspoon MR, Clark HB, Ebner TJ, Day JW, Ranum LPW. Bidirectional expression of CUG and CAG expansion transcripts and intranuclear polyglutamine inclusions in spinocerebellar ataxia type 8. Nat Genet 2006; 38:758-69. [PMID: 16804541 DOI: 10.1038/ng1827] [Citation(s) in RCA: 316] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Accepted: 05/22/2006] [Indexed: 11/08/2022]
Abstract
We previously reported that a (CTG)n expansion causes spinocerebellar ataxia type 8 (SCA8), a slowly progressive ataxia with reduced penetrance. We now report a transgenic mouse model in which the full-length human SCA8 mutation is transcribed using its endogenous promoter. (CTG)116 expansion, but not (CTG)11 control lines, develop a progressive neurological phenotype with in vivo imaging showing reduced cerebellar-cortical inhibition. 1C2-positive intranuclear inclusions in cerebellar Purkinje and brainstem neurons in SCA8 expansion mice and human SCA8 autopsy tissue result from translation of a polyglutamine protein, encoded on a previously unidentified antiparallel transcript (ataxin 8, ATXN8) spanning the repeat in the CAG direction. The neurological phenotype in SCA8 BAC expansion but not BAC control lines demonstrates the pathogenicity of the (CTG-CAG)n expansion. Moreover, the expression of noncoding (CUG)n expansion transcripts (ataxin 8 opposite strand, ATXN8OS) and the discovery of intranuclear polyglutamine inclusions suggests SCA8 pathogenesis involves toxic gain-of-function mechanisms at both the protein and RNA levels.
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Affiliation(s)
- Melinda L Moseley
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Kraft S, Furtado S, Ranawaya R, Parboosingh J, Bleoo S, McElligott K, Bridge P, Spacey S, Das S, Suchowersky O. Adult onset spinocerebellar ataxia in a Canadian movement disorders clinic. Can J Neurol Sci 2006; 32:450-8. [PMID: 16408574 DOI: 10.1017/s0317167100004431] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND The spinocerebellar ataxias (SCAs) are a genetically and clinically heterogeneous group of neurodegenerative disorders. Relative frequencies vary within different ethnic groups and geographical locations. OBJECTIVES 1) To determine the frequencies of hereditary and sporadic adult onset SCAs in the Movement Disorders population; 2) to assess if the fragile X mental retardation gene 1 (FMR1) premutation is found in this population. METHODS A retrospective chart review of individuals with a diagnosis of adult onset SCA was carried out. Testing for SCA types 1, 2, 3, 6, 7, and 8, Dentatorubral-pallidoluysian atrophy (DRPLA), Friedreich ataxia and the FMR1 expansion was performed. RESULTS A total of 69 patients in 60 families were identified. Twenty-one (35%) of the families displayed autosomal dominant and two (3.3%) showed autosomal recessive (AR) pattern of inheritance. A positive but undefined family history was noted in nine (15%). The disorder appeared sporadic in 26 patients (43.3%). In the AD families, the most common mutation was SCA3 (23.8%) followed by SCA2 (14.3%) and SCA6 (14.3%). The SCA1 and SCA8 were each identified in 4.8%. FA was found in a pseudodominant pedigree, and one autosomal recessive pedigree. One sporadic patient had a positive test (SCA3).Dentatorubral-pallidoluysian atrophy and FMR1 testing was negative. CONCLUSION A positive family history was present in 53.3% of our adult onset SCA patients. A specific genetic diagnosis could be given in 61.9% of dominant pedigrees with SCA3 being the most common mutation, followed by SCA2 and SCA6. The yield in sporadic cases was low. The fragile X premutation was not found to be responsible for SCA.
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Affiliation(s)
- Scott Kraft
- Movement Disorsders program, Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
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25
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Martins S, Seixas AI, Magalhães P, Coutinho P, Sequeiros J, Silveira I. Haplotype diversity and somatic instability in normal and expanded SCA8 alleles. Am J Med Genet B Neuropsychiatr Genet 2005; 139B:109-14. [PMID: 16184604 DOI: 10.1002/ajmg.b.30235] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Spinocerebellar ataxia type 8 (SCA8) is an autosomal dominant late-onset neurodegenerative disorder, belonging to the group of diseases caused by trinucleotide repeat expansions. SCA8 remains one of the most intriguing SCAs, regarding the reduced disease penetrance, and the high instability and poorly understood functional meaning of the (CTA)(n)(CTG)(n) expansion. We performed haplotype and sequencing analysis in a large region, encompassing the repeat, in four SCA8 and 20 control Portuguese families. The results from the haplotype study including the combined repeat and six SNP markers showed two different haplotypes, AG-Exp-GTTG and AG-Exp-CTTG, in the SCA8 families. Among the control population, these were also the most frequent, in a total of five haplotypes found unequally distributed throughout repeat sizes. From cloning fragments of control, unstable normal and expanded chromosomes, eleven different base substitutions were identified in exon A of the SCA8 gene. In some instances, somatic variability in repeat size or base composition was found for a same chromosome, regardless of its normal or expanded nature. In conclusion, our results in Portuguese families with ataxia show that SCA8 expansions arose in common backgrounds; in addition, this region seems to be unstable beyond the repeat.
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26
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Corral J, Genís D, Banchs I, San Nicolás H, Armstrong J, Volpini V. Giant SCA8 alleles in nine children whose mother has two moderately large ones. Ann Neurol 2005; 57:549-53. [PMID: 15786481 DOI: 10.1002/ana.20421] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We report here a family in which each of nine children has inherited giant SCA8 CTG expansions from a homozygous mother who has two moderately large SCA8 CTG alleles. In contrast, three homozygous male individuals and a case of coexistence of two expansions of the FRDA gene and one of SCA8, all of them with moderately large alleles, have transmitted their respective SCA8 expanded alleles with minor changes, as usually occurs in heterozygous male transmissions.
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Affiliation(s)
- Jordi Corral
- Centre de Genètica Mèdica i Molecular-Institut de Recerca Oncològica-IDIBELL, Hospital Duran i Reynals, Barcelona, Spain
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27
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Juvonen V, Hietala M, Kairisto V, Savontaus ML. The occurrence of dominant spinocerebellar ataxias among 251 Finnish ataxia patients and the role of predisposing large normal alleles in a genetically isolated population. Acta Neurol Scand 2005; 111:154-62. [PMID: 15691283 DOI: 10.1111/j.1600-0404.2005.00349.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES Frequency and distribution of dominant ataxias caused by dynamic mutations may vary in different populations, which has been explained on the basis of relative frequency of predisposing normal alleles. The aim of the study was to evaluate the occurrence of spinocerebellar ataxias (SCAs) and dentatorubral-pallidoluysian atrophy (DRPLA) in Finland, and to investigate the role of predisposing normal alleles in a genetically homogenous population. MATERIAL AND METHODS Mutation analyses for SCA1, 2, 3, 6, 7, 8, 10, 12, 17, and DRPLA and frataxin genes were performed for 251 unrelated Finnish patients who presented with progressive ataxia disorder. RESULTS Expansions of SCA1, SCA2, SCA6, SCA7, SCA8, and SCA17 genes were detected in 2, 1, 1, 7, 22, and 1 patients, respectively. Altogether, 39 and 7% of dominant and sporadic SCA patients, respectively, harboured expansions at some of the investigated loci. Normal variation, collected from 477 to 502 chromosomes at each disease loci, revealed that Finns were different from the Japanese but largely similar to other Caucasians. CONCLUSIONS Lack of SCA3 and excess of SCA8 are characteristic to the Finnish population. Homozygosity for the SCA8 expansion increases penetrance. Frequencies of large normal alleles at the SCA loci predict poorly prevalence of the respective diseases in Finland. Prioritization in DNA testing, based on ethnic origin and geographical location, is recommendable in Finland, and analogous approach may be applied to other countries as well.
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Affiliation(s)
- V Juvonen
- Department of Medical Genetics, University of Turku, Turku, Finland.
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28
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Ikeda Y, Dalton JC, Moseley ML, Gardner KL, Bird TD, Ashizawa T, Seltzer WK, Pandolfo M, Milunsky A, Potter NT, Shoji M, Vincent JB, Day JW, Ranum LPW. Spinocerebellar ataxia type 8: molecular genetic comparisons and haplotype analysis of 37 families with ataxia. Am J Hum Genet 2004; 75:3-16. [PMID: 15152344 PMCID: PMC1182005 DOI: 10.1086/422014] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Accepted: 04/05/2004] [Indexed: 11/03/2022] Open
Abstract
We reported elsewhere that an untranslated CTG expansion causes the dominantly inherited neurodegenerative disorder spinocerebellar ataxia type 8 (SCA8). SCA8 shows a complex inheritance pattern with extremes of incomplete penetrance, in which often only one or two affected individuals are found in a given family. SCA8 expansions have also been found in control chromosomes, indicating that separate genetic or environmental factors increase disease penetrance among SCA8-expansion-carrying patients with ataxia. We describe the molecular genetic features and disease penetrance of 37 different families with SCA8 ataxia from the United States, Canada, Japan, and Mexico. Haplotype analysis using 17 STR markers spanning an approximately 1-Mb region was performed on the families with ataxia, on a group of expansion carriers in the general population, and on psychiatric patients, to clarify the genetic basis of the reduced penetrance and to investigate whether CTG expansions among different populations share a common ancestral background. Two major ancestrally related haplotypes (A and A') were found among white families with ataxia, normal controls, and patients with major psychosis, indicating a common ancestral origin of both pathogenic and nonpathogenic SCA8 expansions among whites. Two additional and distinct haplotypes were found among a group of Japanese families with ataxia (haplotype B) and a Mexican family with ataxia (haplotype C). Our finding that SCA8 expansions on three independently arising haplotypes are found among patients with ataxia and cosegregate with ataxia when multiple family members are affected further supports the direct role of the CTG expansion in disease pathogenesis.
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Affiliation(s)
- Yoshio Ikeda
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Joline C. Dalton
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Melinda L. Moseley
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Kathy L. Gardner
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Thomas D. Bird
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Tetsuo Ashizawa
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - William K. Seltzer
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Massimo Pandolfo
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Aubrey Milunsky
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Nicholas T. Potter
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Mikio Shoji
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - John B. Vincent
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - John W. Day
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
| | - Laura P. W. Ranum
- Institute of Human Genetics and Departments of Genetics, Cell Biology, and Development and Neurology, University of Minnesota, Minneapolis; Veterans Administration Hospital Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh; Department of Neurology, University of Washington School of Medicine, Seattle; Department of Neurology, University of Texas Medical Branch, Galveston, TX; Department of Neurology, Baylor College of Medicine and Veterans Affairs Medical Center, Houston; Athena Diagnostics, Worcester, MA; Department of Neurology, Erasme Hospital, Brussels Free University, Brussels; Center for Human Genetics, Boston University School of Medicine, Boston; Department of Medical Genetics, University of Tennessee Medical Center, Knoxville, TN; Department of Neurology, Division of Neuroscience, Biophysical Science, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan; and Neurogenetics Section, The Centre for Addiction and Mental Health, Toronto
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Zeman A, Stone J, Porteous M, Burns E, Barron L, Warner J. Spinocerebellar ataxia type 8 in Scotland: genetic and clinical features in seven unrelated cases and a review of published reports. J Neurol Neurosurg Psychiatry 2004; 75:459-65. [PMID: 14966165 PMCID: PMC1738991 DOI: 10.1136/jnnp.2003.018895] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVES To establish whether the DNA expansion linked to spinocerebellar ataxia type 8 (SCA 8) is associated with ataxia in Scotland; to clarify the range of associated clinical phenotypes; and to compare the findings with previous reports. METHODS DNA was screened from 1190 anonymised controls, 137 subjects who had tested negative for Huntington's disease, 176 with schizophrenia, and 173 with undiagnosed ataxia. Five unrelated ataxic patients with the SCA 8 expansion and a sixth identified subsequently had clinical and psychometric assessment; the clinical features were available in a seventh. A systematic search for other reports of SCA 8 was undertaken. RESULTS Over 98% of SCA 8 CTA/CTG repeat lengths fell between 14 and 40. Repeat lengths over 91 were observed in three healthy controls (0.12%), two patients with suspected Huntington's disease (0.73%), and six ataxic subjects (1.74%; p<0.0005 v healthy controls). Repeat lengths over 100 occurred in five ataxic subjects but in only one control. All seven symptomatic subjects with the SCA 8 expansion had a cerebellar syndrome; four had upper motor neurone signs; and 5/6 assessed had cognitive complaints. There was personality change in two and mood disturbance in three. In published reports, SCA 8 repeat lengths over 91 occurred in approximately 0.5% of the healthy population but were over-represented among ataxic patients (3.4%; p<0.0001). The predominant clinical phenotype was cerebellar, with pyramidal signs in 50%, and neuropsychiatric features in some cases. CONCLUSIONS SCA 8 expansion is a risk factor for a cerebellar syndrome, often associated with upper motor neurone and neuropsychiatric features. The expansion occurs unexpectedly often in the general population.
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Affiliation(s)
- A Zeman
- Department of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, UK.
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30
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Tsutsumi T, Holmes SE, McInnis MG, Sawa A, Callahan C, DePaulo JR, Ross CA, DeLisi LE, Margolis RL. Novel CAG/CTG repeat expansion mutations do not contribute to the genetic risk for most cases of bipolar disorder or schizophrenia. Am J Med Genet B Neuropsychiatr Genet 2004; 124B:15-9. [PMID: 14681907 DOI: 10.1002/ajmg.b.20058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The possible presence of anticipation in bipolar affective disorder and schizophrenia has led to the hypothesis that repeat expansion mutations could contribute to the genetic etiology of these diseases. Using the repeat expansion detection (RED) assay, we have systematically examined genomic DNA from 100 unrelated probands with schizophrenia and 68 unrelated probands with bipolar affective disorder for the presence of CAG/CTG repeat expansions. Our results show that 28% of the probands with schizophrenia and 30% of probands with bipolar disorder have a CAG/CTG repeat in the expanded range, but that each expansion could be explained by one of three nonpathogenic repeat expansions known to exist in the general population. We conclude that novel CAG/CTG repeat expansions are not a common genetic risk factor for bipolar disorder or schizophrenia.
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Affiliation(s)
- T Tsutsumi
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University of School of Medicine, Baltimore, Maryland, USA
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Nguyen GH, Bouchard J, Boselli MG, Tolstoi LG, Keith L, Baldwin C, Nguyen NC, Schultz M, Herrera VLM, Smith CL. DNA stability and schizophrenia in twins. Am J Med Genet B Neuropsychiatr Genet 2003; 120B:1-10. [PMID: 12815731 DOI: 10.1002/ajmg.b.20010] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The goal of these experiments was to understand DNA changes relevant to schizophrenia. This work compared DNA of monozygotic (MZ) twins surrounding (CAG)(n) repeating sequences, and characterized the relationship between fragile sites and schizophrenia. Twelve twin-pairs, previously classified as MZ and 18 unrelated sib-pairs, from seven families were studied. Eight twin-pairs were affected by schizophrenia, four concordantly and four discordantly. DNA comparisons were made using profiles of electrophoretic size fractionations of PCR amplified (CAG)(n) containing genomic fragments. These profiles were generated by a new method, developed by us, called targeted genomic differential display (TGDD). Surprisingly, the number of peak profile differences in MZ twin-pairs discordant for schizophrenia was greater than the concordantly ill twins and the well twins and, in some cases, overlapped the range of sib-pairs. These results might mean that some twins were not MZ but it was not possible to definitively test these samples for zygosity. Alternatively, the results might be explained as an increased mutation rate (or genomic instability) around (CAG)(n) sites in individuals afflicted with schizophrenia. Also, we uncovered an association of schizophrenia (i.e., a linkage of chromosomal abnormalities and gene localizations) with fragile sites spread throughout the genome (chi(2), P = 0.001). Furthermore, it appears that an increasing number of genes linked to schizophrenia are associated with (CAG)(n) sequences. Fragile sites and (CAG)(n) repeat sequences are known to be unstable. We speculate the association of genomic instability with schizophrenia accounts for seemingly disparate biological and environmental factors that influence disease occurrence.
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Affiliation(s)
- Giang H Nguyen
- Center for Advanced Biotechnology, Molecular Biotechnology Research Laboratory and Departments of Biomedical Engineering, Biology, and Pharmacology, Boston University, 36 Cummington Street, Boston, Massachusetts 02215, USA
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Schöls L, Bauer I, Zühlke C, Schulte T, Kölmel C, Bürk K, Topka H, Bauer P, Przuntek H, Riess O. Do CTG expansions at the SCA8 locus cause ataxia? Ann Neurol 2003; 54:110-5. [PMID: 12838526 DOI: 10.1002/ana.10608] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
To evaluate the significance of expanded CTG repeats at the SCA8 locus, we analyzed the allele distribution in 1,262 German ataxia patients. We found intermediate and expanded CTG repeats with similar frequencies in ataxia patients with and without established genetic diseases. One family linked to the SCA8 locus showed incomplete penetrance and an association of smaller CTG repeats with more severe disease. Our data question the disease-causing character of CTG expansions for SCA8 and advise great caution in genetic testing.
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Affiliation(s)
- Ludger Schöls
- Department of Neurology, St. Josef Hospital, Ruhr-University, Bochum, Germany.
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33
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Fortune MT, Kennedy JL, Vincent JB. Anticipation and CAG*CTG repeat expansion in schizophrenia and bipolar affective disorder. Curr Psychiatry Rep 2003; 5:145-54. [PMID: 12685994 DOI: 10.1007/s11920-003-0031-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The genetic contribution to the etiologies of schizophrenia and bipolar affective disorder (BPAD) has been considered for many decades, with twin, family, and adoption studies indicating consistently that the familial clustering of affected individuals is accounted for mainly by genetic factors. Despite the strong evidence for a genetic component, very little is understood about the underlying genetic and molecular mechanisms for schizophrenia and BPAD. In the early 1990s, after the discovery of "dynamic mutation" or "unstable DNA" as a molecular basis for the genetic anticipation observed in Huntington's disease, myotonic dystrophy, and many others, and the recently rediscovered, albeit still controversial, evidence for genetic anticipation in major psychoses, the genetic epidemiology of schizophrenia and BPAD was re-evaluated to demonstrate strong endorsement for the unstable DNA model. Many of the non-Mendelian genetic features of schizophrenia and BPAD could be explained by the behaviour of unstable DNA, and several molecular genetic approaches became available for testing the unstable DNA hypothesis. However, despite promising findings in the mid-1990s, no trinucleotide repeat expansion has yet been identified as a cause of idiopathic schizophrenia or BPAD.
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MESH Headings
- Bipolar Disorder/genetics
- Carrier Proteins/genetics
- Chromosome Mapping/methods
- Chromosomes, Human, Pair 13/genetics
- Chromosomes, Human, Pair 19/genetics
- Chromosomes, Human, Pair 5/genetics
- DNA-Binding Proteins/genetics
- Exons
- Homeodomain Proteins/genetics
- Humans
- Huntington Disease/genetics
- Microfilament Proteins/genetics
- Nerve Tissue Proteins/genetics
- Polymorphism, Genetic/genetics
- RNA, Long Noncoding
- RNA, Messenger/genetics
- RNA, Untranslated
- Schizophrenia/genetics
- Schizophrenia/metabolism
- TCF Transcription Factors
- Transcription Factor 7-Like 2 Protein
- Transcription Factors/genetics
- Trinucleotide Repeat Expansion/genetics
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Affiliation(s)
- M Teresa Fortune
- Neurogenetics Section, Centre for Addiction and Mental Health, Clarke Division, 250 College Street, Toronto, ON M5T 1R8, Canada
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34
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Abstract
Although bipolar disorder in adults has been extensively studied, early-onset forms of the disorder have received less attention. We review several lines of evidence indicating that pediatric- and early adolescent-onset bipolar disorder cases may prove the most useful for identifying susceptibility genes. Family studies have consistently found a higher rate of bipolar disorder among the relatives of early-onset bipolar disorder patients than in relatives of later-onset cases, which supports the notion of a larger genetic contribution to the early-onset cases. Comorbid pediatric bipolar disorder and attention-deficit/hyperactivity disorder (ADHD) may also define a familial subtype of ADHD or bipolar disorder that is strongly influenced by genetic factors and may, therefore, be useful in molecular genetic studies. There are no twin and adoption studies of pediatric bipolar disorder, but the heritability of this subtype is expected to be high given the results from family studies. Thus, pediatric- and early adolescent-onset bipolar disorder may represent a genetically loaded and homogeneous subtype of bipolar disorder, which, if used in genetic linkage and association studies, should increase power to detect risk loci and alleles.
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Affiliation(s)
- Stephen V Faraone
- Department of Psychiatry, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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Vincent JB, Paterson AD, Strong E, Petronis A, Kennedy JL. The unstable trinucleotide repeat story of major psychosis. AMERICAN JOURNAL OF MEDICAL GENETICS 2003; 97:77-97. [PMID: 10813808 DOI: 10.1002/(sici)1096-8628(200021)97:1<77::aid-ajmg11>3.0.co;2-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
New hopes for cloning susceptibility genes for schizophrenia and bipolar affective disorder followed the discovery of a novel type of DNA mutation, namely unstable DNA. One class of unstable DNA, trinucleotide repeat expansion, is the causal mutation in myotonic dystrophy, fragile X mental retardation, Huntington disease and a number of other rare Mendelian neurological disorders. This finding has led researchers in psychiatric genetics to search for unstable DNA sites as susceptibility factors for schizophrenia and bipolar affective disorder. Increased severity and decreased age at onset of disease in successive generations, known as genetic anticipation, was reported for undifferentiated psychiatric diseases and for myotonic dystrophy early in the twentieth century, but was initially dismissed as the consequence of ascertainment bias. Because unstable DNA was demonstrated to be a molecular substrate for genetic anticipation in the majority of trinucleotide repeat diseases including myotonic dystrophy, many recent studies looking for genetic anticipation have been performed for schizophrenia and bipolar affective disorder with surprisingly consistent positive results. These studies are reviewed, with particular emphasis placed on relevant sampling and statistical considerations, and concerns are raised regarding the interpretation of such studies. In parallel, molecular genetic investigations looking for evidence of trinucleotide repeat expansion in both schizophrenia and bipolar disorder are reviewed. Initial studies of genome-wide trinucleotide repeats using the repeat expansion detection technique suggested possible association of large CAG/CTG repeat tracts with schizophrenia and bipolar affective disorder. More recently, three loci have been identified that contain large, unstable CAG/CTG repeats that occur frequently in the population and seem to account for the majority of large products identified using the repeat expansion detection method. These repeats localize to an intron in transcription factor gene SEF2-1B at 18q21, a site named ERDA1 on 17q21 with no associated coding region, and the 3' end of a gene on 13q21, SCA8, that is believed to be responsible for a form of spinocerebellar ataxia. At present no strong evidence exists that large repeat alleles at either SEF2-1B or ERDA1 are involved in the etiology of schizophrenia or bipolar disorder. Preliminary evidence suggests that large repeat alleles at SCA8 that are non-penetrant for ataxia may be a susceptibility factor for major psychosis. A fourth, but much more infrequently unstable CAG/CTG repeat has been identified within the 5' untranslated region of the gene, MAB21L1, on 13q13. A fifth CAG/CTG repeat locus has been identified within the coding region of an ion transporter, KCNN3 (hSKCa3), on 1q21. Although neither large alleles nor instability have been observed at KCNN3, this repeat locus has been extensively analyzed in association and family studies of major psychosis, with conflicting findings. Studies of polyglutamine containing genes in major psychosis have also shown some intriguing results. These findings, reviewed here, suggest that, although a major role for unstable trinucleotides in psychosis is unlikely, involvement at a more modest level in a minority of cases cannot be excluded, and warrants further investigation.
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Affiliation(s)
- J B Vincent
- Department of Genetics at the Hospital for Sick Children, Toronto, Canada
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36
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Abstract
Non-coding ribonucleic acids (RNAs) do not contain a peptide-encoding open reading frame and are therefore not translated into proteins. They are expressed in all phyla, and in eukaryotic cells they are found in the nucleus, cytoplasm, and mitochondria. Non-coding RNAs either can exert structural functions, as do transfer and ribosomal RNAs, or they can regulate gene expression. Non-coding RNAs with regulatory functions differ in size ranging from a few nucleotides to over 100 kb and have diverse cell- or development-specific functions. Some of the non-coding RNAs associate with human diseases. This chapter summarizes the current knowledge about regulatory non-coding RNAs.
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Affiliation(s)
- Uwe Michel
- Department of Neurology, Laboratory of Neurobiology, Göttingen, Germany
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Izumi Y, Maruyama H, Oda M, Morino H, Okada T, Ito H, Sasaki I, Tanaka H, Komure O, Udaka F, Nakamura S, Kawakami H. SCA8 repeat expansion: large CTA/CTG repeat alleles are more common in ataxic patients, including those with SCA6. Am J Hum Genet 2003; 72:704-9. [PMID: 12545428 PMCID: PMC1180244 DOI: 10.1086/367775] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2002] [Accepted: 11/25/2002] [Indexed: 11/03/2022] Open
Abstract
We analyzed the SCA8 CTA/CTG repeat in a large group of Japanese subjects. The frequency of large alleles (85-399 CTA/CTG repeats) was 1.9% in spinocerebellar ataxia (SCA), 0.4% in Parkinson disease, 0.3% in Alzheimer disease, and 0% in a healthy control group; the frequency was significantly higher in the group with SCA than in the control group. Homozygotes for large alleles were observed only in the group with SCA. In five patients with SCA from two families, a large SCA8 CTA/CTG repeat and a large SCA6 CAG repeat coexisted. Age at onset was correlated with SCA8 repeats rather than SCA6 repeats in these five patients. In one of these families, at least one patient showed only a large SCA8 CTA/CTG repeat allele, with no large SCA6 CAG repeat allele. We speculate that the presence of a large SCA8 CTA/CTG repeat allele influences the function of channels such as alpha(1A)-voltage-dependent calcium channel through changing or aberrant splicing, resulting in the development of cerebellar ataxia, especially in homozygous patients.
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Affiliation(s)
- Yuishin Izumi
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Hirofumi Maruyama
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Masaya Oda
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Hiroyuki Morino
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Takayuki Okada
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Hidefumi Ito
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Iwao Sasaki
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Hiroyasu Tanaka
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Osamu Komure
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Fukashi Udaka
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Shigenobu Nakamura
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
| | - Hideshi Kawakami
- Department of Clinical Neuroscience and Therapeutics, Hiroshima University Graduate School of Biomedical Science, Hiroshima; Department of Neurology, Kitano Hospital, Department of Neurology, Kansai Medical University, and Department of Neurology, Sumitomo Hospital, Osaka; Third Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan; Third Department of Internal Medicine, Hirosaki University School of Medicine, Aomori, Japan; Department of Neurology, Utano National Hospital, Kyoto
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Andrés AM, Soldevila M, Saitou N, Volpini V, Calafell F, Bertranpetit J. Understanding the dynamics of Spinocerebellar Ataxia 8 (SCA8) locus through a comparative genetic approach in humans and apes. Neurosci Lett 2003; 336:143-6. [PMID: 12505613 DOI: 10.1016/s0304-3940(02)01249-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Spinocerebellar Ataxia 8 (SCA8) is a neurodegenerative disorder caused by expansion of a trinucleotide repeat. We undertake a comparative genetic analysis among human populations and primate species in the normal variation range, where forces that shaped present diversity can be recognised. We determinate number of repeats of the short tandem repeat through allele length sizing and sequencing methods. Human allele distributions are very similar among populations, ruling out ethnicity as a genetic risk for allele expansion. Primate comparison shows human-specific features, with longer human alleles due to a novel variable trinucleotide repeat, not present in non-human primates, which increased the disease-causing expansion likelihood. SCA8 seems to be a human specific disease.
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Affiliation(s)
- A M Andrés
- Unitat de Biologia Evolutiva, Facultat de Ciències de la Salut i de la Vida, Universitat Pompeu Fabra, Dr Aiguader 80, 08003, Barcelona, Spain
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van Swieten JC, Brusse E, de Graaf BM, Krieger E, van de Graaf R, de Koning I, Maat-Kievit A, Leegwater P, Dooijes D, Oostra BA, Heutink P. A mutation in the fibroblast growth factor 14 gene is associated with autosomal dominant cerebellar ataxia [corrected]. Am J Hum Genet 2003; 72:191-9. [PMID: 12489043 PMCID: PMC378625 DOI: 10.1086/345488] [Citation(s) in RCA: 193] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2002] [Accepted: 10/08/2002] [Indexed: 11/03/2022] Open
Abstract
Hereditary spinocerebellar ataxias (SCAs) are a clinically and genetically heterogeneous group of neurodegenerative disorders for which >/=14 different genetic loci have been identified. In some SCA types, expanded tri- or pentanucleotide repeats have been identified, and the length of these expansions correlates with the age at onset and with the severity of the clinical phenotype. In several other SCA types, no genetic defect has yet been identified. We describe a large, three-generation family with early-onset tremor, dyskinesia, and slowly progressive cerebellar ataxia, not associated with any of the known SCA loci, and a mutation in the fibroblast growth factor 14 (FGF14) gene on chromosome 13q34. Our observations are in accordance with the occurrence of ataxia and paroxysmal dyskinesia in Fgf14-knockout mice. As indicated by protein modeling, the amino acid change from phenylalanine to serine at position 145 is predicted to reduce the stability of the protein. The present FGF14 mutation represents a novel gene defect involved in the neurodegeneration of cerebellum and basal ganglia.
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Affiliation(s)
- John C van Swieten
- Department of Neurology, Erasmus Medical Center, Rotterdam, The Netherlands.
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40
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Andrés AM, Lao O, Soldevila M, Calafell F, Bertranpetit J. Dynamics of CAG repeat loci revealed by the analysis of their variability. Hum Mutat 2003; 21:61-70. [PMID: 12497632 DOI: 10.1002/humu.10151] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In order to understand the dynamics of the expressed single tandem repeat trinucleotides (most of them involved in pathological expansion), the diversity in 10 different loci (SCA1, SCA2, SCA3, SCA6, SCA8, SCA12, DRPLA, HD, KCNN3, and NCOA3) was analyzed in four major human groups (Africans, Europeans, Indians, and East Asians). The present analysis intends to disentangle population-based from genetic-based factors having shaped STR (trinucleotide) variation and to recognize, for each locus, the specific rate and pattern of mutation (bias toward expansion or contraction, constraints on allele size), and the footprints of selection. Population differences account for a very small part of the total variation, but a clear footprint appears of population growth after a bottleneck in all non-African populations, giving support to the out-of-Africa model of modern humans. Most of the diversity is found among loci, and different dynamics are inferred for each of them. SCA2 and SCA3 follow an unrestricted stepwise mutation model, while the rest of loci are found under allele size constrictions and a bias to expansion (SCA1, SCA6, HD, and KCNN3), contraction (SCA12, DRPLA, and NCOA3), or unbiased (SCA8).
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Affiliation(s)
- Aida M Andrés
- Unitat de Biologia Evolutiva, Facultat de Ciències de la Salut i de la Vida, Universitat Pompeu Fabra, Barcelona, Spain
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Topisirovic I, Dragasevic N, Savic D, Ristic A, Keckarevic M, Keckarevic D, Culjkovic B, Petrovic I, Romac S, Kostic VS. Genetic and clinical analysis of spinocerebellar ataxia type 8 repeat expansion in Yugoslavia. Clin Genet 2002; 62:321-4. [PMID: 12372061 DOI: 10.1034/j.1399-0004.2002.620412.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Spinocerebellar ataxia type 8 (SCA8) is a slowly progressive ataxia causally associated with untranslated CTG repeat expansion on chromosome 13q21. However, the role of the CTG repeat in SCA8 pathology is not yet well understood. Therefore, we studied the length of the SCA8 CTA/CTG expansions (combined repeats, CRs) in 115 patients with ataxia, 64 unrelated individuals with non-triplet neuromuscular diseases, 70 unrelated patients with schizophrenia, and 125 healthy controls. Only one patient with apparently sporadic ataxia was identified with an expansion of 100 CRs. He had inherited the expansion from his asymptomatic father (140 CRs) and transmitted the mutation to his son (92 CRs). Paternal transmission in this family produced contractions of 40 and 8 CRs, respectively. None of the subjects from other studied groups had an expansion at the SCA8 locus. In the control group the number of CRs at the SCA8 locus ranged from 14 to 34. Our findings support the notion that allelic variants of the expansion mutation at the SCA8 locus can predispose to ataxia.
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Affiliation(s)
- I Topisirovic
- PCR Center, Faculty for Biology, Institute of Neurology CCS, School of Medicine, University of Belgrade, Serbia
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Andrew SE, Peters AC. DNA instability and human disease. AMERICAN JOURNAL OF PHARMACOGENOMICS : GENOMICS-RELATED RESEARCH IN DRUG DEVELOPMENT AND CLINICAL PRACTICE 2002; 1:21-8. [PMID: 12173310 DOI: 10.2165/00129785-200101010-00003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
It is now well established that non-Mendelian examples of DNA instability are associated with human disease. Most malignancies are associated with various chromosomal instabilities, such as aneuploidy, gene amplification, and chromosomal deletion. Furthermore, widespread microsatellite instability (MSI) is associated with a variety of tumors, and instability at specific dynamic repeat expansions underlies a family of neurologic disorders. Inactivation of DNA mismatch repair genes results in genomic instabilities affecting microsatellite regions. Mutations in genes involved in DNA polymerization or Okazaki fragment processing are also associated with MSI. Such instabilities convey a 'mutator' phenotype which is pathogenic. The mechanisms controlling trinucleotide repeat expansions are less well understood. Why this type of genomic instability is particularly pathogenic to neurons is also not clear. An understanding of what normally maintains stability is the first step towards preventing such loss of control and maintaining health.
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Affiliation(s)
- S E Andrew
- Department of Medical Genetics, University of Alberta, Edmonton, Canada
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43
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Abstract
In the past decade, the genetic etiologies accounting for most cases of adult-onset dominant cerebellar ataxia have been discovered. This group of disorders, generally referred to as the spinocerebellar ataxias (SCAs), can now be classified by a simple genetic nosology, essentially a sequential list in which each new SCA is given a number. However, recent advances in the elucidation of SCA pathogenesis provide the opportunity to subclassify the disorders into three discrete groups based on pathogenesis: 1) the polyglutamine disorders, SCAs 1, 2, 3, 7, and 17, which result from proteins with toxic stretches of polyglutamine; 2) the channelopathies, SCA6 and episodic ataxia types 1 and 2 (EA1 and EA2), which result from disruption of calcium or potassium channel function; and 3) the gene expression disorders, SCAs 8, 10, and 12, which result from repeat expansions outside of coding regions that may quantitatively alter gene expression. SCAs 4, 5, 9, 11, 13-16, 19, 21, and 22 are of unknown etiology, and may or may not fit into one of these three groups. At present, most diagnostic and therapeutic strategies apply equally to all of the SCAs. Therapy specific for individual diseases or types of diseases is a realistic goal in the foreseeable future.
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Affiliation(s)
- Russell L Margolis
- Laboratory of Genetic Neurobiology, Division of Neurobiology, Department of Psychiatry and Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Baltimore, MD 21287, USA.
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44
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Abstract
There is consistent evidence that the principal etiology of schizophrenia involves predisposing genetic factors. Recent years have seen several new insights in the genetics of schizophrenia. Several chromosomal regions show significant evidence that they contain schizophrenia susceptibility genes. A clinically relevant genetic subtype of schizophrenia (22q deletion syndrome) has been identified. There is new evidence that spontaneous mutations may play a role. There are new recommendations for genetic counseling. The progress to date suggests that understanding of a neurodevelopmental pathway from genetic susceptibility to schizophrenia will soon be fundamentally altered by molecular genetic advances in this complex disease.
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Affiliation(s)
- Anne S Bassett
- Clinical Genetics Research Program, Centre for Addiction and Mental Health, 1001 Queen Street West, Toronto, Ontario M6J 1H4, Canada.
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Abstract
Advances in molecular genetics have led to identification of an increasing number of genes responsible for inherited ataxic disorders. Consequently, DNA testing has become a powerful method to unambiguously establish the diagnosis in some of these disorders; however, there are limitations in this approach. Furthermore, the ethical, social, legal and psychological implications of the genetic test results are complex, necessitating appropriate counseling. This article intends to help the practicing neurologist clinically differentiate these disorders, choose appropriate genetic tests, and recognize the importance of counseling.
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Affiliation(s)
- Alberto L Rosa
- Universidad de Córdoba, Laboratory of Neurogenetics, Institute for Medical Research Mercedes y Martín Ferreyra-INIMEC, Carrer Researcher of the National Research Council (CONICET), Córdoba, Argentina
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Maruyama H, Izumi Y, Morino H, Oda M, Toji H, Nakamura S, Kawakami H. Difference in disease-free survival curve and regional distribution according to subtype of spinocerebellar ataxia: a study of 1,286 Japanese patients. AMERICAN JOURNAL OF MEDICAL GENETICS 2002; 114:578-83. [PMID: 12116198 DOI: 10.1002/ajmg.10514] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Expansions of trinucleotide repeats have been discovered in spinocerebellar ataxia (SCA) types 1, 2, 6, 7, 12, and 17, Machado-Joseph disease (MJD/SCA3), and dentatorubropallidoluysian atrophy (DRPLA). However, the frequency of familial SCA in Japan remains unclear. The number of trinucleotide repeats was determined for 1,286 patients. Three hundred and thirty families (523 cases) were autosomal dominant group (A), and 165 families were positive for family history but not autosomal dominant group (B), while the remaining 598 cases were the sporadic group (C). The frequency of SCA subtypes in autosomal dominant group was: 1) 5.5% for SCA1; 2) 2.4% for SCA2; 3) 27.6% for MJD/SCA3; 4) 25.5% for SCA6; 5) 0.3% for SCA17; and 6) 7.3% for DRPLA. Abnormal expansion of SCA12 was not detected. Another 31.5% of the patients in the autosomal dominant group had unknown genetic abnormalities. Within group B, SCA6 was the most prominent and within the sporadic group MJD/SCA3 and SCA6 were the most common subtypes observed. The disease-free survival curve of SCA6 was different from that of other SCAs and the mean age at onset for SCA6 was found to be later than that of the other types. Regional differences were observed in the relative rate of SCA subtypes. MJD/SCA3 appears more common in the Kanto and Kyushu districts of Japan, whereas SCA6 is most common in the Chugoku district. In order to establish an effective social welfare system for SCA patients, clinical course and regional differences in the prevalence of SCA subtypes must be taken into consideration.
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Affiliation(s)
- Hirofumi Maruyama
- Third Department of Internal Medicine, Hiroshima University School of Medicine, Hiroshima, Japan
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47
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Gershon ES, Badner JA. Progress toward discovery of susceptibility genes for bipolar manic-depressive illness and schizophrenia. CNS Spectr 2001; 6:965-8, 977. [PMID: 15311192 DOI: 10.1017/s1092852900001073] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The inconsistency in linkage results that has bedeviled psychiatric genetics has been observed to occur regularly in common diseases with complex inheritance. Nonetheless, in two such instances--noninsulin-dependent diabetes mellitus (NIDDM) and inflammatory bowel disease (IBD)--susceptibility genes have been discovered based on the follow-ups of linkage findings. In bipolar illness disorder (BPD) and schizophrenia (SZ), there are some linkage reports with replication of other studies similar to the situation in NIDDM and IBD before the successful positional cloning efforts. Two of the regions with linkage reports, BPD and SZ, on the long arms of chromosomes 13 and 22, show linkage to the same markers in both diseases. This lends some plausibility to the hypothesis of some shared genetic predispositions for both disorders. Cytogenetic evidence offers another positional approach to susceptibility genes. The velocardiofacial syndrome is associated with deletions very close to the linkage region on chromosome 22, and with psychiatric manifestations of both BPD and SZ. Endophenotypes of SZ, previously demonstrated to the be heritable, have been found to have chromosomal linkage in at least one study. These include eye-tracking abnormalities linked to 6p, and an abnormality of the P50 cortical evoked potential linked to chromosome 15. Variants in specific genes have been associated with susceptibility to the psychiatric illnesses. These genetic findings may contribute to etiologic subcategorization of BPD and SZ, and the development of new treatment approaches. A table of genetic terms is included for review
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Affiliation(s)
- E S Gershon
- Department of Psychiatry, University of Chicago, Chicago, Ill, USA.
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48
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Goossens D, Del-Favero J, Van Broeckhoven C. Trinucleotide repeat expansions: do they contribute to bipolar disorder? Brain Res Bull 2001; 56:243-57. [PMID: 11719258 DOI: 10.1016/s0361-9230(01)00657-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
It has long been known that bipolar disorder has a true but complex genetic background. Reports on genetic anticipation in bipolar disorder opened the way to a new approach for genetic studies. Indeed, anticipation, a decreasing age at onset, and/or increasing disease severity in successive generations, were recently explained by an expansion of trinucleotide repeats in monogenic diseases like Huntington's disease and Fragile X syndrome. The involvement of trinucleotide repeat expansions in bipolar disorder received even more support when studies reported association of large CAG/CTG repeats with bipolar disorder. Even though a large number of studies have been conducted, this association is still unexplained. Here, we review the studies investigating the trinucleotide repeat expansion hypothesis in bipolar disorder. Studies on anticipation, on association of anonymous large CAG/CTG repeats and on specific trinucleotide repeats are critically analysed and discussed, showing a field with precipitate conclusions or inconclusive results. The analysis suggests that there are indications, though disputable, supporting the trinucleotide repeat expansion hypothesis in bipolar disorder, but no conclusive evidence has been hitherto provided.
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Affiliation(s)
- D Goossens
- Department of Molecular Genetics, Flanders Interuniversity Institute for Biotechnology (VIB), University of Antwerp (UIA), Antwerpen, Belgium
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Juvonen V, Hietala M, Päivärinta M, Rantamäki M, Hakamies L, Kaakkola S, Vierimaa O, Penttinen M, Savontaus ML. Clinical and genetic findings in Finnish ataxia patients with the spinocerebellar ataxia 8 repeat expansion. Ann Neurol 2001. [DOI: 10.1002/1531-8249(200009)48:3<354::aid-ana10>3.0.co;2-a] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Ikeda Y, Shizuka-Ikeda M, Watanabe M, Schmitt M, Okamoto K, Shoji M. Asymptomatic CTG expansion at the SCA8 locus is associated with cerebellar atrophy on MRI. J Neurol Sci 2000; 182:76-9. [PMID: 11102643 DOI: 10.1016/s0022-510x(00)00446-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spinocerebellar ataxia type 8 (SCA8) is the first example of dominantly inherited ataxia reported to be caused by a dynamic mutation of the untranslated CTG trinucleotide repeat. We performed genetic and clinical analyses of a family with an isolated case with young onset cerebellar ataxia carrying an expanded 95 CTA/CTG repeats, and revealed that the asymptomatic father was also carrying a much greater expansion of 136 repeats. This paternal transmission developed a large contraction of -41 CTG repeats. The ataxia patient showed almost pure cerebellar symptoms, and a cerebral MRI of the patient demonstrated significant atrophy of the cerebellar vermis and hemispheres with preservation of brainstem and cerebrum. Although the father did not show any neurological abnormalities, his MRI demonstrated mild atrophy of the cerebellar hemispheres. The genetic phenomenon on this family has not been observed in other types of SCAs, and this reduced penetrance may cause reproduction of sporadic SCA8 frequently. Therefore, we must perform careful interviews regarding family history, and suggest the genetic and neuroradiological investigations on family members when we encounter a sporadic patient with the CTG expansion at the SCA8 locus.
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Affiliation(s)
- Y Ikeda
- Department of Neurology, Gunma University School of Medicine, 3-39-22 Showa-machi, 371-8511, Maebashi, Japan.
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