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Huntington's Chorea-a Rare Neurodegenerative Autosomal Dominant Disease: Insight into Molecular Genetics, Prognosis and Diagnosis. Appl Biochem Biotechnol 2021; 193:2634-2648. [PMID: 34235640 DOI: 10.1007/s12010-021-03523-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 01/27/2021] [Indexed: 12/24/2022]
Abstract
Huntington's disease is a neurodegenerative autosomal disease results due to expansion of polymorphic CAG repeats in the huntingtin gene. Phosphorylation of the translation initiation factor 4E-BP results in the alteration of the translation control leading to unwanted protein synthesis and neuronal function. Consequences of mutant huntington (mhtt) gene transcription are not well known. Variability of age of onset is an important factor of Huntington's disease separating adult and juvenile types. The factors which are taken into account are-genetic modifiers, maternal protection i.e excessive paternal transmission, superior ageing genes and environmental threshold. A major focus has been given to the molecular pathogenesis which includes-motor disturbance, cognitive disturbance and neuropsychiatric disturbance. The diagnosis part has also been taken care of. This includes genetic testing and both primary and secondary symptoms. The present review also focuses on the genetics and pathology of Huntington's disease.
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Li X, Li H, Dong Y, Gao B, Cheng H, Ni W, Gan S, Liu Z, Burgunder J, Wu Z. Haplotype analysis encompassing
HTT
gene in Chinese patients with Huntington's disease. Eur J Neurol 2019; 27:273-279. [DOI: 10.1111/ene.14072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 08/21/2019] [Indexed: 12/19/2022]
Affiliation(s)
- X.‐Y. Li
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
| | - H.‐L. Li
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
| | - Y. Dong
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
| | - B. Gao
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
| | - H.‐R. Cheng
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
| | - W. Ni
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
| | - S.‐R. Gan
- Department of Neurology and Institute of Neurology First Affiliated Hospital Fujian Medical University FuzhouChina
| | - Z.‐J. Liu
- Department of Neurology and Institute of Neurology Huashan Hospital Shanghai Medical College Fudan University Shanghai China
| | - J.‐M. Burgunder
- Swiss Huntington’s Disease Centre, Siloah, Gümligen and Department of Neurology, University of Bern Bern Switzerland
| | - Z.‐Y. Wu
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province Zhejiang University School of Medicine HangzhouChina
- Joint Institute for Genetics and Genome Medicine between Zhejiang University and University of Toronto Zhejiang University HangzhouChina
- CAS Center for Excellence in Brain Science and Intelligence Technology Shanghai China
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Jamali Z, Dianatpour M, Miryounesi M, Modarressi MH. A study of CAG repeat instability of HTT gene following spermatogenesis, by single sperm analysis. GENE REPORTS 2018. [DOI: 10.1016/j.genrep.2018.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Risk factors for the onset and progression of Huntington disease. Neurotoxicology 2017; 61:79-99. [PMID: 28111121 DOI: 10.1016/j.neuro.2017.01.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 01/11/2017] [Indexed: 01/10/2023]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by chorea, behavioural and psychiatric manifestations, and dementia, caused by a CAG triplet repeat expansion in the huntingtin gene. Systematic review of the literature was conducted to determine the risk factors for the onset and progression of HD. Multiple databases were searched, using terms specific to Huntington disease and to studies of aetiology, risk, prevention and genetics, limited to studies on human subjects published in English or French between 1950 and 2010. Two reviewers independently screened the abstracts and identified potentially relevant articles for full-text review using predetermined inclusion criteria. Three major categories of risk factors for onset of HD were identified: CAG repeat length in the huntingtin gene, CAG instability, and genetic modifiers. Of these, CAG repeat length in the huntingtin gene is the most important risk factor. For the progression of HD: genetic, demographic, past medical/clinical and environmental risk factors have been studied. Of these factors, genetic factors appear to play the most important role in the progression of HD. Among the potential risk factors, CAG repeat length in the mutant allele was found to be a relatively consistent and significant risk factor for the progression of HD, especially in motor, cognitive, and other neurological symptom deterioration. In addition, there were many consistent results in the literature indicating that a higher number of CAG repeats was associated with shorter survival, faster institutionalization, and earlier percutaneous endoscopic gastrostomy.
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Arning L. The search for modifier genes in Huntington disease – Multifactorial aspects of a monogenic disorder. Mol Cell Probes 2016; 30:404-409. [DOI: 10.1016/j.mcp.2016.06.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/29/2016] [Accepted: 06/29/2016] [Indexed: 11/24/2022]
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Al-Mamun MM, Sarker SK, Qadri SK, Shirin T, Mohammad QD, LaRocque R, Karlsson EK, Saha N, Asaduzzaman M, Qadri F, Mannoor MK. Examination of Huntington's disease with atypical clinical features in a Bangladeshi family tree. Clin Case Rep 2016; 4:1191-1194. [PMID: 27980761 PMCID: PMC5134195 DOI: 10.1002/ccr3.743] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 10/04/2016] [Accepted: 10/09/2016] [Indexed: 11/20/2022] Open
Abstract
Atypical manifestation of Huntington's disease (HD) could inform ongoing research into HD genetic modifiers not present in the primarily European populations studied to date. This work demonstrates that expanding HD genetic testing into under‐resourced healthcare settings can benefit both local communities and ongoing research into HD etiology and new therapies.
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Affiliation(s)
- Md Mahfuz Al-Mamun
- Institute for Developing Science & Health Initiatives (IDESHI) Dhaka Bangladesh
| | | | | | - Tahmina Shirin
- Department of Virology Institute of Epidemiology, Disease Control and Research Dhaka Bangladesh
| | - Quazi Deen Mohammad
- Department of Neurology National Institute of Neurosciences & Hospital Dhaka Bangladesh
| | - Regina LaRocque
- Division of Infectious Diseases Department of Medicine Massachusetts General Hospital Boston Massachusetts USA
| | - Elinor K Karlsson
- Broad Institute University of Massachusetts Medical School Cambridge Massachusetts USA
| | - Narayan Saha
- Pediatric Neurology National Institute of Neurosciences & Hospital Dhaka Bangladesh
| | - Muhammad Asaduzzaman
- Centre for Vaccine Sciences International Centre for Diarrheal Disease Research Dhaka Bangladesh
| | - Firdausi Qadri
- Institute for Developing Science & Health Initiatives (IDESHI) Dhaka Bangladesh; Centre for Vaccine Sciences International Centre for Diarrheal Disease Research Dhaka Bangladesh
| | - Md Kaiissar Mannoor
- Institute for Developing Science & Health Initiatives (IDESHI) Dhaka Bangladesh
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Kay C, Collins JA, Skotte NH, Southwell AL, Warby SC, Caron NS, Doty CN, Nguyen B, Griguoli A, Ross CJ, Squitieri F, Hayden MR. Huntingtin Haplotypes Provide Prioritized Target Panels for Allele-specific Silencing in Huntington Disease Patients of European Ancestry. Mol Ther 2015. [PMID: 26201449 DOI: 10.1038/mt.2015.128] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Huntington disease (HD) is a dominant neurodegenerative disorder caused by a CAG repeat expansion in the Huntingtin gene (HTT). Heterozygous polymorphisms in cis with the mutation allow for allele-specific suppression of the pathogenic HTT transcript as a therapeutic strategy. To prioritize target selection, precise heterozygosity estimates are needed across diverse HD patient populations. Here we present the first comprehensive investigation of all common target alleles across the HTT gene, using 738 reference haplotypes from the 1000 Genomes Project and 2364 haplotypes from HD patients and relatives in Canada, Sweden, France, and Italy. The most common HD haplotypes (A1, A2, and A3a) define mutually exclusive sets of polymorphisms for allele-specific therapy in the greatest number of patients. Across all four populations, a maximum of 80% are treatable using these three target haplotypes. We identify a novel deletion found exclusively on the A1 haplotype, enabling potent and selective silencing of mutant HTT in approximately 40% of the patients. Antisense oligonucleotides complementary to the deletion reduce mutant A1 HTT mRNA by 78% in patient cells while sparing wild-type HTT expression. By suppressing specific haplotypes on which expanded CAG occurs, we demonstrate a rational approach to the development of allele-specific therapy for a monogenic disorder.
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Affiliation(s)
- Chris Kay
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer A Collins
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Niels H Skotte
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Amber L Southwell
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Simon C Warby
- Department of Psychiatry, Université de Montréal, Montréal, Québec, Canada
| | - Nicholas S Caron
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Crystal N Doty
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Betty Nguyen
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Annamaria Griguoli
- Neurogenetics Unit and Rare Disease Centre, IRCCS Neuromed Pozzilli (IS), Pozzilli, Italy
| | - Colin J Ross
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ferdinando Squitieri
- Neurogenetics Unit and Rare Disease Centre, IRCCS Neuromed Pozzilli (IS), Pozzilli, Italy
| | - Michael R Hayden
- Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.
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Jiang H, Sun YM, Hao Y, Yan YP, Chen K, Xin SH, Tang YP, Li XH, Jun T, Chen YY, Liu ZJ, Wang CR, Li H, Pei Z, Shang HF, Zhang BR, Gu WH, Wu ZY, Tang BS, Burgunder JM. Huntingtin gene CAG repeat numbers in Chinese patients with Huntington's disease and controls. Eur J Neurol 2014; 21:637-42. [PMID: 24471773 DOI: 10.1111/ene.12366] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 12/17/2013] [Indexed: 02/05/2023]
Affiliation(s)
- H. Jiang
- Department of Neurology; Xiangya Hospital; Central South University; Changsha China
- Key Laboratory of Hunan Province in Neurodegenerative Disorders; State Key Laboratory of Medical Genetics of China; Central South University; Changsha China
| | - Y. M. Sun
- Department of Neurology; Institute of Neurology; Huashan Hospital; Shanghai Medical College; Fudan University; Shanghai China
| | - Y. Hao
- Department of Neurology; China−Japan Friendship Hospital; Beijing China
| | - Y. P. Yan
- Department of Neurology; Second Affiliated Hospital; College of Medicine; Zhejiang University; Hangzhou China
| | - K. Chen
- Department of Neurology; West China Hospital; Sichuan University; Chengdu China
| | - S. H. Xin
- First Affiliated Hospital of Sun Yat-Sen University; Guangzhou China
| | - Y. P. Tang
- Department of Medical Genetics; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - X. H. Li
- First Affiliated Hospital of Sun Yat-Sen University; Guangzhou China
| | - T. Jun
- Department of Neurology; Second Affiliated Hospital; College of Medicine; Zhejiang University; Hangzhou China
| | - Y. Y. Chen
- Department of Neurology; China−Japan Friendship Hospital; Beijing China
| | - Z. J. Liu
- Department of Neurology; Institute of Neurology; Huashan Hospital; Shanghai Medical College; Fudan University; Shanghai China
| | - C. R. Wang
- Department of Neurology; Xiangya Hospital; Central South University; Changsha China
| | - H. Li
- Department of Medical Genetics; Tongji Medical College; Huazhong University of Science and Technology; Wuhan China
| | - Z. Pei
- First Affiliated Hospital of Sun Yat-Sen University; Guangzhou China
| | - H. F. Shang
- Department of Neurology; West China Hospital; Sichuan University; Chengdu China
| | - B. R. Zhang
- Department of Neurology; Second Affiliated Hospital; College of Medicine; Zhejiang University; Hangzhou China
| | - W. H. Gu
- Department of Neurology; China−Japan Friendship Hospital; Beijing China
| | - Z. Y. Wu
- Department of Neurology; Institute of Neurology; Huashan Hospital; Shanghai Medical College; Fudan University; Shanghai China
| | - B. S. Tang
- Department of Neurology; Xiangya Hospital; Central South University; Changsha China
| | - J.-M. Burgunder
- Department of Neurology; Xiangya Hospital; Central South University; Changsha China
- Department of Neurology; West China Hospital; Sichuan University; Chengdu China
- First Affiliated Hospital of Sun Yat-Sen University; Guangzhou China
- Swiss Huntington's Disease Centre; Department of Neurology; University of Bern; NeuroBu Clinics; Bern Switzerland
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Metzger S, Walter C, Riess O, Roos RAC, Nielsen JE, Craufurd D, Nguyen HP. The V471A polymorphism in autophagy-related gene ATG7 modifies age at onset specifically in Italian Huntington disease patients. PLoS One 2013; 8:e68951. [PMID: 23894380 PMCID: PMC3718802 DOI: 10.1371/journal.pone.0068951] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 06/09/2013] [Indexed: 11/19/2022] Open
Abstract
The cause of Huntington disease (HD) is a polyglutamine repeat expansion of more than 36 units in the huntingtin protein, which is inversely correlated with the age at onset of the disease. However, additional genetic factors are believed to modify the course and the age at onset of HD. Recently, we identified the V471A polymorphism in the autophagy-related gene ATG7, a key component of the autophagy pathway that plays an important role in HD pathogenesis, to be associated with the age at onset in a large group of European Huntington disease patients. To confirm this association in a second independent patient cohort, we analysed the ATG7 V471A polymorphism in additional 1,464 European HD patients of the "REGISTRY" cohort from the European Huntington Disease Network (EHDN). In the entire REGISTRY cohort we could not confirm a modifying effect of the ATG7 V471A polymorphism. However, analysing a modifying effect of ATG7 in these REGISTRY patients and in patients of our previous HD cohort according to their ethnic origin, we identified a significant effect of the ATG7 V471A polymorphism on the HD age at onset only in the Italian population (327 patients). In these Italian patients, the polymorphism is associated with a 6-years earlier disease onset and thus seems to have an aggravating effect. We could specify the role of ATG7 as a genetic modifier for HD particularly in the Italian population. This result affirms the modifying influence of the autophagic pathway on the course of HD, but also suggests population-specific modifying mechanisms in HD pathogenesis.
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Affiliation(s)
- Silke Metzger
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
- Rare Disease Center, University of Tuebingen, Tuebingen, Germany
| | - Carolin Walter
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
- Rare Disease Center, University of Tuebingen, Tuebingen, Germany
| | - Olaf Riess
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
- Rare Disease Center, University of Tuebingen, Tuebingen, Germany
| | - Raymund A. C. Roos
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Jørgen E. Nielsen
- Memory Disorders Research Unit, Neurogenetics Clinic, Section 6702, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
- Institute of Cellular and Molecular Medicine, Section of Neurogenetics, University of Copenhagen, The Panum Institute, Copenhagen, Denmark
| | - David Craufurd
- Genetic Medicine, University of Manchester, Manchester Academic Health Sciences Centre and Central Manchester University Hospitals NHS Foundation Trust, St. Mary’s Hospital, Manchester, United Kingdom
| | | | - Huu Phuc Nguyen
- Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Tuebingen, Germany
- Rare Disease Center, University of Tuebingen, Tuebingen, Germany
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Zheng YM, Li L, Zhou LM, Le F, Cai LY, Yu P, Zhu YR, Liu XZ, Wang LY, Li LJ, Lou YY, Xu XR, Lou HY, Zhu XM, Sheng JZ, Huang HF, Jin F. Alterations in the frequency of trinucleotide repeat dynamic mutations in offspring conceived through assisted reproductive technology. Hum Reprod 2013; 28:2570-80. [PMID: 23861482 DOI: 10.1093/humrep/det294] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
STUDY QUESTION How does the frequency of trinucleotide repeat dynamic mutations in offspring conceived through assisted reproductive technology (ART) compare with the frequency of these mutations in control offspring conceived from spontaneous pregnancies? SUMMARY ANSWER There is a slight increase in dynamic mutation instability in offspring conceived through ART compared with the naturally conceived offspring. WHAT IS KNOWN ALREADY There is evidence to suggest that ART can increase the risk of birth defects and karyotypic abnormalities. However, the accumulating evidence of an association between ART and de novo genetic aberrations is controversial. STUDY DESIGN, SIZE, DURATION A prospective clinical observational study was performed on 246 families recruited from an in vitro fertilisation (IVF) centre at a tertiary-care, university-affiliated teaching hospital from 2008 to 2012. The study included 147 ART families [75 IVF and 72 intracytoplasmic sperm injection (ICSI)] in the study group and 99 natural-conception families in the control group. PARTICIPANTS, SETTING, METHODS Parental, umbilical cord and infant peripheral blood samples were collected, and the trinucleotide repeats of the ATN1, AR, ATXN1, ATXN3, Huntington, DMPK and FMR-1 genes were investigated between the generations; these genes were chosen due to their ability to undergo dynamic mutation. The frequencies and sizes of the mutational repeats, as well as the intergenerational instability, were measured. MAIN RESULTS AND THE ROLE OF CHANCE In 2466 transmissions identified in the ART offspring, 2.11% (n = 52/2466) of the alleles were unstable upon transmission, while in the control group offspring, the frequency of dynamic mutation was 0.77% (n = 10/1300); this difference was statistically significant (P < 0.01). The unstable transmission alleles were detected in 32 (2.48%) of the 1288 alleles from the IVF offspring and in 20 (1.70%) of the 1178 alleles from the ICSI offspring; both of these frequencies were significantly different from that of naturally conceived offspring (0.77%) (P < 0.01 and P < 0.05, respectively). However, there were no significant differences in the sizes of the mutational repeats or in the rates of expansion or contraction among the three groups (P > 0.05). The repeat copy numbers of the examined genes were found to be within the normal ranges in all parents and infants. LIMITATIONS, REASONS FOR CAUTION One strength of our study is the relatively large sample size; we were able to detect mutations in seven common dynamic genes, and this large sample size allowed us to detect unstable alleles. Although we observed a clear alteration in the frequency of dynamic mutation in the ART offspring compared with controls, further studies are urgently needed to confirm this observation and determine the cause of this phenomenon. WIDER IMPLICATIONS OF THE FINDINGS DNA microsatellite analysis provides an important tool to assess genomic instability. In this study, we report an association between ART and the frequency of dynamic mutation. The instability could be a reflection of the core infertility problem, the controlled ovarian hyperstimulation and/or the in vitro culture conditions.
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Affiliation(s)
- Ying-Ming Zheng
- Department of Reproductive Endocrinology, Zhejiang University School of Medicine, Zhejiang, China
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Ma M, Yang Y, Shang H, Su D, Zhang H, Ma Y, Liu Y, Tao D, Zhang S. Evidence for a predisposing background for CAG expansion leading to HTT mutation in a Chinese population. J Neurol Sci 2011; 298:57-60. [PMID: 20864123 DOI: 10.1016/j.jns.2010.08.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 08/17/2010] [Accepted: 08/23/2010] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To investigate the predisposing background for the instability of CAG expansions of the HTT gene in a Chinese population. METHODS Genotyping and haplotyping of CAG and CCG repeats of the HTT gene were carried out in 32 unrelated HD patients and 95 non-HD control individuals of Han origin, using capillary electrophoresis and DNA sequencing. The frequencies of different CCG repeats were compared between mutant and wild-type HTT genes. In controls, the comparison of the mean CAG repeat size was performed among different CCG repeats. RESULTS A total of five alleles of CCG repeats were distinguished, in which four were present in HD chromosomes. In the CCG alleles, (CCG)10 showed a higher frequency in mutant HTT genes relative to wild-type ones, and the highest mean CAG repeat size was observed in the (CCG)10 background. Additionally, a haplotype of (CAG)32-(CCG)10 was found in the control group. CONCLUSION Our findings indicate that HTT mutation is likely of multiple origins in the Chinese population. Among the origins, more new HTT mutations may arise from the (CCG)10 than from other CCG alleles, which suggests that the (CCG)10 allele may represent a predisposing background for CAG expansion in Chinese populations. Therefore, in comparison with Europeans, the significantly lower prevalence of Huntington's disease in Chinese individuals may not be due to the absence of the predisposing background for CAG expansion but instead may partly result from the lower frequency of the predisposing haplotype for CAG instability in the population.
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Affiliation(s)
- Mingyi Ma
- Department of Medical Genetics, West China Hospital and State Key Laboratory of Biotherapy, Sichuan University, Gaopeng street, Keyuan Road 4, Chengdu, Sichuan 610041, China
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12
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Abstract
In the past few years, a new type of genetic mutation, expansion of trinucleotide repeats, has been shown to cause neurologic disease. This new class of mutations was first identified in 1991 as the underlying genetic defect in spinal and bulbar muscular atrophy and the fragile X syndrome, and in recent years, trinucleotide repeat expansions have been found to be the causative mechanism in 10 other neurologic diseases. These mutations are produced by heritable unstable DNA and are termed "dynamic mutations" because of changes in the number of repeat units inherited from generation to generation. In the normal population, these repeat units, although polymorphic, are stably inherited. To date four types of trinucleotide repeat expansions have been identified: (1) long cytosine-guanine-guanine (CGG) repeats in the two fragile X syndromes (FRAXA and FRAXE), (2) long cytosine-thymine-guanine (CTG) repeat expansions in myotonic dystrophy, (3) long guanine-adenine-adenine repeat expansions in Friedreich's ataxia and (4) short cytosine-adenine-guanine repeat expansions (CAG) which are implicated in eight neurodegenerative disorders and are the focus of this review. Diseases that are caused by trinucleotide repeat expansions exhibit a phenomenon called anticipation that can not be explained by conventional Mendelian genetics. Anticipation is defined as increase in the severity of disease with an earlier age of onset of symptoms in successive generations. Anticipation is often influenced by the sex of the transmitting parent, and for most CAG repeat disorders, the disease is more severe when paternally transmitted. The severity and the age of onset of the disease have been correlated with the size of the repeats on mutant alleles, with the age of onset being inversely correlated with the size of the expansion. In all eight disorders caused by CAG repeat expansion, the repeat is located within the coding region of the gene involved and in all cases it is translated into a stretch of polyglutamines in the respective proteins. All the proteins are unrelated outside of the polyglutamine stretch and most are novel with exception of the androgen receptor and the voltage gated alpha 1A calcium channel, which are mutated in spinal and bulbar muscular atrophy and spinocerebellar ataxia type 6. It is intriguing that the proteins are ubiquitously expressed in both peripheral and nervous tissue but in each disorder only a select population of nerve cells are targeted for degeneration as a consequence of the expanded CAG repeat. Current thinking among scientists working on the molecular mechanisms of neurodegeneration in these diseases is that the presence of an expanded polyglutamine confers a gain of function onto the involved protein. To understand the mechanisms underlying the pathogenesis of these diseases, investigators have turned to generating transgenic mice which recapitulate some of the features of the human disease and hence are excellent model systems to study the progression of the disease in vivo.
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Affiliation(s)
- B T Koshy
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA
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Di Maria E, Marasco A, Tartari M, Ciotti P, Abbruzzese G, Novelli G, Bellone E, Cattaneo E, Mandich P. No evidence of association between BDNF gene variants and age-at-onset of Huntington's disease. Neurobiol Dis 2006; 24:274-9. [PMID: 16905325 DOI: 10.1016/j.nbd.2006.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 07/03/2006] [Accepted: 07/07/2006] [Indexed: 11/16/2022] Open
Abstract
Huntington's disease (HD) is a late-onset, autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion. The number of repeats on the HD chromosome explains most of the variability in age of onset, but genetic factors other than the HD gene are responsible for part of the residual variance. Based on the role played by the brain derived neurotrophic factor (BDNF) in neurodysfunction and neurodegeneration in HD, we searched for novel polymorphisms in the neuron restrictive silencer element located in the BDNF promoter. Then, the effect of the Val66Met variant in determining age of onset was tested in a large sample of HD carriers by using a multivariate regression approach. The CAG repeat number accounted for 62% of the variance. After correction for the predominant effect of the CAG expansion, no multiple regression model provided evidence of association between the Val66Met genotype and variation in age-at-onset. Additional studies are warranted to further investigate BDNF as genetic modifier of the HD phenotype.
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Affiliation(s)
- Emilio Di Maria
- Department of Neuroscience, Ophthalmology and Genetics, Section of Medical Genetics, University of Genova, and Medical Genetics Unit, San Martino Hospital, Genova, Italy.
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14
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Squitieri F, Ciarmiello A, Di Donato S, Frati L. The search for cerebral biomarkers of Huntington's disease: a review of genetic models of age at onset prediction. Eur J Neurol 2006; 13:408-15. [PMID: 16643321 DOI: 10.1111/j.1468-1331.2006.01264.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The mutation causing Huntington's disease is an expanded CAG trinucleotide repeat number beyond 35 in the 5' translated region of the gene. The mutation penetrance varies widely and depends on the CAG expansion length, the low pathological triplet range (36-41) showing a very low penetrance, possibly associated with late ages at onset. No research has so far yielded biomarkers for accurately predicting either age at onset or disease progression in at risk individuals. Specific markers able to follow-up mutation carrier subjects from the pre-symptomatic stages of life are crucial for testing experimental neuroprotective preventive therapies. Nevertheless, the factor accounting for the largest percentage of age at onset variation is the expanded repeat number within the gene. Over the years, this factor has helped in setting up models for genetically predicting age at onset. Once available for practical application in clinics, such models allowed phenotype-genotype correlations that were hitherto inconceivable. In this review, we discuss how these genetic models have been applied in clinical practice and comment on their potential value in searching for cerebral biomarkers of disease onset and severity and in designing trials of therapeutic drugs.
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Affiliation(s)
- F Squitieri
- Neurogenetics Unit, IRCCS Neuromed, Pozzilli (IS), Italy.
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15
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Cannella M, Gellera C, Maglione V, Giallonardo P, Cislaghi G, Muglia M, Quattrone A, Pierelli F, Di Donato S, Squitieri F. The gender effect in juvenile Huntington disease patients of Italian origin. Am J Med Genet B Neuropsychiatr Genet 2004; 125B:92-8. [PMID: 14755452 DOI: 10.1002/ajmg.b.20110] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We analyzed a population of juvenile Huntington disease (HD) subjects of Italian origin (n = 57). The main aim of this study was to analyze the gender effect of the affected parent on age at onset and clinical presentation of offspring with juvenile HD. We also analyzed molecular features of the disease, including CAG mutation length and GluR6 gene polymorphism, according to the affected parent's gender. The mutation length was longer in paternally than in maternally transmitted HD juvenile patients (P = 0.025), nevertheless a similar mean early onset in the two groups (P > 0.05). This data was even enforced by that obtained from the whole cohort of patients included in the databank (n = 600) where, in the presence of increased mean parent-child CAG repeat change in paternal vs. maternal meiotic transmissions (+7.3 vs. +0.7 CAG, P = 0.0002), the mean parent-child year-of-onset change was similar in the two groups (-10.4 and -7.0 years, P > 0.05). A lower TAA-triplet in GluR6 was associated with an earlier age at onset in juvenile patients (P = 0.031, R2 = 0.10). When we added the GluR6 effect on age at onset to the CAG expanded number effect (P = 0.0001, R2 = 0.68) by multiple regression approach, the coefficient of determination R2 increased to 0.81. This effect in addition to the expanded CAG repeat number, found in juvenile and not in adult patients, was slightly enforced by paternal compared to maternal transmissions (R2=0.82). Our findings suggest the occurrence of a weaker effect of the paternal mutation on juvenile age at onset in our population, possibly amplified by other genetic factors, such as the TAA-triplet length in the GluR6 gene.
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16
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Squitieri F, Cannella M, Giallonardo P, Maglione V, Mariotti C, Hayden MR. Onset and pre-onset studies to define the Huntington's disease natural history. Brain Res Bull 2001; 56:233-8. [PMID: 11719256 DOI: 10.1016/s0361-9230(01)00648-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Huntington's disease's (HD) clinical history has not been defined yet. However, many aspects of the most confusing clinical stages, i.e., the first and last disease phases, including the symptom progression and the disease duration, have been better approached after discovery of the responsible gene. The existence of accurate genetic tests, available for affected and pre-symptomatic subjects (i.e., mutation carriers) and the possibility to study transgenic in vivo models, are actually helping us to understand some of the aspects of HD clinical presentation. HD may present with motor symptoms other than chorea, the psychiatric manifestations may represent part of the clinical picture and cognitive deterioration may occur very early in the disease and depend on early cortical involvement. Pre-onset studies are of crucial importance in understanding the temporal sequence of the clinical events. This is also very important for future therapeutic strategies in those diseases initiating late in the life, such as HD.
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Affiliation(s)
- F Squitieri
- Neurogenetics Unit, Neurological Institute IRCCS "Neuromed", (IS), Pozzilli, Italy.
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17
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Giovannone B, Sabbadini G, Di Maio L, Calabrese O, Castaldo I, Frontali M, Novelleto A, Squitieri F. Analysis of (CAG)n size heterogeneity in somatic and sperm cell DNA from intermediate and expanded Huntington disease gene carriers. Hum Mutat 2000; 10:458-64. [PMID: 9401009 DOI: 10.1002/(sici)1098-1004(1997)10:6<458::aid-humu7>3.0.co;2-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The length of the CAG repeat responsible for Huntington disease has been analysed by two PCR methods in blood and sperm DNA of 13 expansion carriers, two carriers of intermediate alleles, and four normal subjects. The two methods consistently confirmed size heterogeneity, more pronounced in sperm and confined to the CAG stretch. Based on densitometric scanning of films, four indexes addressed to different features of the PCR pattern were used to quantitate mosaicism. These revealed strong correlations with CAG size and intergenerational instability. However, mosaicism did not show a greater similarity in sibs who shared the same HD chromosome, nor was correlated with instability in the proband's pedigree. Our data do not support the hypothesis that cis-acting factors play a major role in the instability and leave the CAG size per se as the major determinant of sperm cell CAG instability.
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Affiliation(s)
- B Giovannone
- Dipartimento di Biologia, Università Tor Vergata, Rome, Italy
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18
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Monoi H, Futaki S, Kugimiya S, Minakata H, Yoshihara K. Poly-L-glutamine forms cation channels: relevance to the pathogenesis of the polyglutamine diseases. Biophys J 2000; 78:2892-9. [PMID: 10827970 PMCID: PMC1300875 DOI: 10.1016/s0006-3495(00)76830-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report that long-chain poly-L-glutamine forms cation-selective channels when incorporated into artificial planar lipid bilayer membranes. The channel was permeable to alkali cations and H(+) ions and virtually impermeable to anions; the selectivity sequence based on the single-channel conductance was H(+) >> Cs(+) > K(+) > Na(+). The cation channel was characterized by long-lived open states (often lasting for several minutes to tens of minutes) interrupted by brief closings. The appearance of the channel depended critically on the length of polyglutamine chains; ion channels were observed with 40-residue stretches, whereas no significant conductance changes were detected with 29-residue tracts. The channel-forming threshold length of poly-L-glutamine was thus between 29 and 40 residues. A molecular mechanics calculation suggests a mu-helix (. Biophys. J. 69:1130-1141) as a candidate molecular structure of the channel. The channel-forming nature of long-chain poly-L-glutamine may provide a clue to the elucidation of the pathogenetic mechanism of the polyglutamine diseases, a group of inherited neurodegenerative disorders including Huntington's disease.
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Affiliation(s)
- H Monoi
- Research Institute of Neurodegenerative Diseases, Sendai 980-0871, Japan.
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19
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Lima E Silva TC, Serra HG, Bertuzzo CS, Lopes-Cendes I. Molecular diagnosis of Huntington disease in Brazilian patients. ARQUIVOS DE NEURO-PSIQUIATRIA 2000; 58:11-7. [PMID: 10770860 DOI: 10.1590/s0004-282x2000000100002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Huntington disease (HD) is a progressive neurodegenerative disorder with autosomal dominant inheritance, characterized by choreiform movements and cognitive impairment. Onset of symptoms is around 40 years of age and progression to death occurs in approximately 10 to 15 years from the time of disease onset. HD is associated with an unstable CAG repeat expansion at the 5' and of the IT15 gene. We have genotyped the CAG repeat in the IT15 gene in 44 Brazilian individuals (42 patients and 2 unaffected family members) belonging to 34 unrelated families thought to segregate HD. We found one expanded CAG allele in 32 individuals (76%) belonging to 25 unrelated families. In these HD patients, expanded alleles varied from 43 to 73 CAG units and normal alleles varied from 18 to 26 CAGs. A significant negative correlation between age at onset of symptoms and size of the expanded CAG allele was found (r=0.6; p=0.0001); however, the size of the expanded CAG repeat could explain only about 40% of the variability in age at onset (r2=0.4). In addition, we genotyped 25 unrelated control individuals (total of 50 alleles) and found normal CAG repeats varying from 16 to 33 units. The percentage of heterozigocity of the normal allele in the control population was 88%. In conclusion, our results showed that not all patients with the "HD" phenotype carried the expansion at the IT15 gene. Furthermore, molecular diagnosis was possible in all individuals, since no alleles of intermediate size were found. Therefore, molecular confirmation of the clinical diagnosis in HD should be sought in all suspected patients, making it possible for adequate genetic counseling.
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Affiliation(s)
- T C Lima E Silva
- Departamento de Genética Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP)
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20
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Stevanin G, Giunti P, Belal GD, Dürr A, Ruberg M, Wood N, Brice A. De novo expansion of intermediate alleles in spinocerebellar ataxia 7. Hum Mol Genet 1998; 7:1809-13. [PMID: 9736784 DOI: 10.1093/hmg/7.11.1809] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Spinocerebellar ataxia 7 (SCA7) is the eighth neurodegenerative disorder caused by a translated CAG repeat expansion. Normal SCA7 alleles carry from four to 35 CAG repeats, whereas pathological alleles carry from 37 to approximately 200. Intermediate alleles (IAs), with 28-35 repeats in the SCA7 gene are exceedingly rare in the general population and are not associated with the SCA7 phenotype, although they have been found among relatives of four SCA7 families. In two of these families, IAs bearing 35 and 28 CAG repeats gave rise, during paternal transmission, to SCA7 expansions of 57 and 47 repeats, respectively, that were confirmed by haplotype reconstructions in one case and by inference in the other. Furthermore, the four haplotypes segregating with IAs were identical to the expanded alleles in each kindred, but differed among the families, indicating multiple origins of the SCA7 mutation in these families with different geographical origins. Our results provide the first evidence of de novo SCA7 expansions from IAs that are not associated with the phenotype but can expand to the pathological range during some paternal transmissions. IAs that segregate in unaffected branches of the pedigrees might, therefore, constitute a reservoir for future de novo mutations that occur in a recurrent but random manner. This would explain the persistence of the disease in spite of the great anticipation (approximately 20 years/generation) characteristic of SCA7. So far, de novo expansions among the disorders caused by polyglutamine repeats have only been demonstrated in Huntington's disease.
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Affiliation(s)
- G Stevanin
- INSERM U289, Hôpital de la Salpêtrière, 75013 Paris, France
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21
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Affiliation(s)
- M E MacDonald
- Molecular Neurogenetics Unit, Massachusetts General Hospital East, Charlestown 02129, USA
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22
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Iughetti P, Otto PA, Zatz M, Bueno MRP, Marie SK. Different behavior in the paternally vs. maternally inherited mutated allele in Brazilian Machado-Joseph (MJD1) Families. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1096-8628(19980518)77:3<246::aid-ajmg11>3.0.co;2-g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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23
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Mandich P, Jacopini G, Di Maria E, Sabbadini G, Abbruzzese G, Chimirri F, Bellone E, Novelletto A, Ajmar F, Frontali M. Predictive testing for Huntington's disease: ten years' experience in two Italian centres. ITALIAN JOURNAL OF NEUROLOGICAL SCIENCES 1998; 19:68-74. [PMID: 10935839 DOI: 10.1007/bf02427559] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pre-symptomatic testing for Huntington's disease (HD) has been available as a clinical service in the medical centres of Rome and Genoa since December 1987, initially by DNA-linkage and since mid-1993 by direct mutation analysis. A multidisciplinary approach and a protocol which follows the Ethical Issue Policy Statement on Huntington's Disease Molecular Genetics Predictive Test has been used. In the period under study, 332 subjects requested the test, 288 were enrolled in the protocol and nearly half of these completed it. One hundred and forty-eight people withdrew from the testing procedure for various reasons but most frequently due to a more realistic evaluation of all possible consequences of test results, induced by psychological counselling. Therefore, 140 people completed the test. The overall gene-carrier/non-carrier ratio was 0.46:1. None of the identified gene carriers had catastrophic reactions such as suicide, suicide attempts or major psychiatric disorders. All appear to have had a similar pattern of reactions to an adverse result and none expressed regret for undergoing the test. In conclusion, presymptomatic testing for HD can be considered a safe procedure without adverse consequences when framed in an integrated protocol at qualified genetic centres.
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Affiliation(s)
- P Mandich
- Institute of Biology and Genetics, University of Genova, Italy
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24
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Abstract
Huntington's disease is a genetically inherited degenerative neuropsychiatric disorder, characterized by motor alterations, including involuntary movements such as chorea, dementia and psychiatric disturbances. In this article, the authors review the clinical features of the disease. They also analyze some genetic and pathophysiologic aspects, that can help to improve our understanding of this disorder involving the basal ganglia.
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Affiliation(s)
- M S Haddad
- Department of Neurology, Hospital das Clínicas, University of São Paulo Medical School, Brazil
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25
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Wellington CL, Brinkman RR, O'Kusky JR, Hayden MR. Toward understanding the molecular pathology of Huntington's disease. Brain Pathol 1997; 7:979-1002. [PMID: 9217979 PMCID: PMC8098409 DOI: 10.1111/j.1750-3639.1997.tb00897.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Huntington's Disease (HD) is caused by expansion of a CAG trinucleotide beyond 35 repeats within the coding region of a novel gene. Recently, new insights into the relationship between CAG expansion in the HD gene and pathological mechanisms have emerged. Survival analysis of a large cohort of affected and at-risk individuals with CAG sizes between 39 and 50 repeats have yielded probability curves of developing HD symptoms and dying of HD by a certain age. Animals transgenic for the first exon of huntingtin with large CAG repeats lengths have been reported to have a complex neurological phenotype that bears interesting similarities and differences to HD. The repertoire of huntingtin-interacting proteins continues to expand with the identification of HIP1, a protein whose yeast homologues have known functions in regulating events associated with the cytoskeleton. The ability of huntingtin to interact with two of its four known protein partners appears to be influenced by CAG length. Caspase 3 (apopain), a key cysteine protease known to play a seminal role in neural apoptosis, has also been demonstrated to specifically cleave huntingtin in a CAG length-dependent manner. Many of these features are combined in a model suggesting mechanisms by which the pathogenesis of HD may be initiated. The development of appropriate in vitro and animal models for HD will allow the validity of these models to be tested.
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Affiliation(s)
- C L Wellington
- Centre for Molecular Medicine and Therapeutics, Vancouver, BC, Canada
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26
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McNeil SM, Novelletto A, Srinidhi J, Barnes G, Kornbluth I, Altherr MR, Wasmuth JJ, Gusella JF, MacDonald ME, Myers RH. Reduced penetrance of the Huntington's disease mutation. Hum Mol Genet 1997; 6:775-9. [PMID: 9158152 DOI: 10.1093/hmg/6.5.775] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Controversy persists concerning the significance of Huntington disease (HD) alleles in the 36-39 repeat range. Although some clinically affected persons have been documented with repeats in this range, elderly unaffected individuals have also been reported. We examined 10 paternal transmissions of HD alleles of 37-39 repeats in collateral branches of families with de novo HD. All 10 descendants, including many who are elderly, are without symptoms of HD. Forty percent of the transmissions were unstable, although none varied by more than one repeat. The observation that individuals with alleles of 37-39 repeats may survive unaffected beyond common life expectancy supports the presence of reduced penetrance for HD among some persons with repeat sizes which overlap the clinical range. Non-penetrance may be increased in the collateral branches of de novo mutation families when compared to penetrance estimates from patient series. There was no CAA-->CAG mutation for the penultimate glutamine in either a de novo expanded 42 repeat allele or the corresponding non-penetrant 38 repeat allele in a family with fresh mutation to HD.
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Affiliation(s)
- S M McNeil
- Molecular Neurogenetics Unit, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA
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27
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Cancel G, Dürr A, Didierjean O, Imbert G, Bürk K, Lezin A, Belal S, Benomar A, Abada-Bendib M, Vial C, Guimarães J, Chneiweiss H, Stevanin G, Yvert G, Abbas N, Saudou F, Lebre AS, Yahyaoui M, Hentati F, Vernant JC, Klockgether T, Mandel JL, Agid Y, Brice A. Molecular and clinical correlations in spinocerebellar ataxia 2: a study of 32 families. Hum Mol Genet 1997; 6:709-15. [PMID: 9158145 DOI: 10.1093/hmg/6.5.709] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Spinocerebellar ataxia 2 (SCA2) is caused by the expansion of an unstable CAG repeat encoding a polyglutamine tract. One hundred and eighty four index patients with autosomal dominant cerebellar ataxia type I were screened for this mutation. We found expansion in 109 patients from 30 families of different geographical origins (15%) and in two isolated cases with no known family histories (2%). The SCA2 chromosomes contained from 34 to 57 repeats and consisted of a pure stretch of CAG, whereas all tested normal chromosomes (14-31 repeats), except one with 14 repeats, were interrupted by 1-3 repeats of CAA. As in other diseases caused by unstable mutations, a strong negative correlation was observed between the age at onset and the size of the CAG repeat (r = -0.81). The frequency of several clinical signs such as myoclonus, dystonia and myokymia increased with the number of CAG repeats whereas the frequency of others was related to disease duration. The CAG repeat was highly unstable during transmission with variations ranging from -8 to +12, and a mean increase of +2.2, but there was no significant difference according to the parental sex. This instability was confirmed by the high degree of gonadal mosaicism observed in sperm DNA of one patient.
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28
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Gusella JF, Persichetti F, MacDonald ME. The Genetic Defect Causing Huntington’s Disease: Repeated in Other Contexts? Mol Med 1997. [DOI: 10.1007/bf03401677] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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29
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Frontali M, Sabbadini G, Novelletto A, Jodice C, Naso F, Spadaro M, Giunti P, Jacopini AG, Veneziano L, Mantuano E, Malaspina P, Ulizzi L, Brice A, Durr A, Terrenato L. Genetic fitness in Huntington's Disease and Spinocerebellar Ataxia 1: a population genetics model for CAG repeat expansions. Ann Hum Genet 1996; 60:423-35. [PMID: 8912795 DOI: 10.1111/j.1469-1809.1996.tb00440.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
An analysis of genetic fitness was performed in Huntington's Disease (HD) and Spinocerebellar Ataxia 1 (SCA1) families. Two partially overlapping samples were used: clinically defined HD and SCA1 patients from families ascertained in definite geographical areas, and molecularly typed carriers of HD and SCA1 mutations (CAG trinucleotide expansions). In both cases, a control group of normal relatives was used. HD and SCA1 patients born before 1915-20 had more children than normal controls. Carriers of HD and SCA1 mutations, all in the low/medium expansion range (37-49 and 47-54 CAG repeats respectively), had a higher number of children than controls up to more recent times (1935-1950). The reproduction of heterozygotes for large expansions could be analysed only in subjects born after 1950 and provided indirect evidence of a lower than normal number of children. The above results fit a model based on a differential fitness according to the degree of expansion. Such a model predicts that 1) up to relatively recently the frequency of alleles in the low/medium range has been maintained or even increased by the increased fitness of their carriers, as well as by new mutations, and 2) the frequency of large expansions, part of which are lost at each generation, is maintained through further expansions of alleles in the low/medium expansion range. The implications of such a model on linkage disequilibrium and the possible spread of these diseases in future generations are discussed.
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Affiliation(s)
- M Frontali
- Istituto di Medicina Sperimentale del CNR, Rome, Italy.
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30
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Weigell-Weber M, Schmid W, Spiegel R. Psychiatric symptoms and CAG expansion in Huntington's disease. AMERICAN JOURNAL OF MEDICAL GENETICS 1996; 67:53-7. [PMID: 8678115 DOI: 10.1002/(sici)1096-8628(19960216)67:1<53::aid-ajmg9>3.0.co;2-t] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The mutation responsible for Huntington's disease (HD) is an elongated CAG repeat in the coding region of the IT15 gene. A PCR-based test with high sensitivity and accuracy is now available to identify asymptomatic gene carriers and patients. An inverse correlation between CAG copy number and age at disease onset has been found in a large number of affected individuals. The influence of the CAG repeat expansion on other phenotypic manifestations, especially specific psychiatric symptoms has not been studied intensively. In order to elucidate this situation we investigated the relation between CAG copy number and distinct psychiatric phenotypes found in 79 HD-patients. None of the four differentiated categories (personality change, psychosis, depression, and nonspecific alterations) showed significant differences in respect to size of the CAG expansion. In addition, no influence of individual sex on psychiatric presentation could be found. On the other hand in patients with personality changes maternal transmission was significantly more frequent compared with all other groups. Therefore we suggest that clinical severity of psychiatric features in HD is not directly dependent on the size of the dynamic mutation involved. The complex pathogenetic mechanisms leading to psychiatric alterations are still unknown and thus genotyping does not provide information about expected psychiatric symptoms in HD gene carriers.
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Affiliation(s)
- M Weigell-Weber
- Institute of Medical Genetics, University of Zürich, Switzerland
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31
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Abstract
Huntington's disease, with its progressive uncontrolled movements and characteristic selective neuropathology, has represented a baffling enigma to geneticists and neurobiologists alike. Discovery of the HD gene and its defect has demystified the genetic aspects of the disorder, but has not yet explained its pathogenesis. Attempts to explore this issue suggest that the defect acts as a gain of function, conferring a new deleterious property on the huntingtin protein, and that the gene's normal function may be irrelevant to the disease process.
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Affiliation(s)
- J F Gusella
- Molecular Neurogenetics Unit, Massachusetts General Hospital East, Charlestown 02129, USA
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32
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Masuda N, Goto J, Murayama N, Watanabe M, Kondo I, Kanazawa I. Analysis of triplet repeats in the huntingtin gene in Japanese families affected with Huntington's disease. J Med Genet 1995; 32:701-5. [PMID: 8544189 PMCID: PMC1051670 DOI: 10.1136/jmg.32.9.701] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Huntington's disease (HD) is associated with the expansion of a CAG repeat in the huntingtin gene. Molecular analysis of the repeat in Japanese HD patients and normal controls was performed. The size of the CAG repeat ranged from 37 to 95 repeats in affected subjects and from seven to 29 in normal controls. A significant correlation was found between the age of onset and the CAG expansion. The length of the expanded repeat is unstable in meiotic transmission and large increases occur in paternal transmission. At the same time the CCG repeat polymorphism adjacent to the CAG repeat was analysed and haplotypes of HD chromosomes were identified. Strong linkage disequilibrium was found between the CAG repeat expansion and an allele of (CCG)10 in Japanese HD chromosomes. It is distinct from that described previously in western populations. Western HD chromosomes strongly associate with an allele of (CCG)7. Possible mechanisms underlying the disequilibrium in Japan are discussed.
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Affiliation(s)
- N Masuda
- Department of Clinical Neurology and Neuroscience, Faculty of Medicine, University of Tokyo, Japan
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33
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Soong BW, Wang JT. A comparison of the Huntington's disease associated trinucleotide repeat between Chinese and white populations. J Med Genet 1995; 32:404-5. [PMID: 7616553 PMCID: PMC1050445 DOI: 10.1136/jmg.32.5.404] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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34
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Nørremølle A, Sørensen SA, Fenger K, Hasholt L. Correlation between magnitude of CAG repeat length alterations and length of the paternal repeat in paternally inherited Huntington's disease. Clin Genet 1995; 47:113-7. [PMID: 7634532 DOI: 10.1111/j.1399-0004.1995.tb03941.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An increasing number of diseases are being found to be due to elongation of specific trinucleotide repeat sequences. Inverse correlation between the age at onset and the length of the repeat has been found in most of these. The elongated CAG repeat causing Huntington's disease is highly unstable when inherited from an affected father. In this study we found an average parent-to-offspring difference of +0.08 repeat units in maternally inherited repeats, significantly less than the average difference of +2.92 repeat units with paternal transmission. Large repeat expansions, of more than 5 repeat units, were seen only in paternally inherited cases. With paternal transmission the magnitude of repeat length alterations was directly correlated to increasing paternal repeat length. Increasing variation in repeat length among siblings was correlated to increasing average repeat length in the sibship in both maternally and paternally inherited HD. Comparison of the magnitude of repeat length alterations to parental age at the time of birth of the offspring showed no correlation.
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Affiliation(s)
- A Nørremølle
- Institute of Medical Biochemistry and Genetics, University of Copenhagen, Denmark
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35
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Abstract
Early in 1993, an unstable, expanded trinucleotide repeat in a novel gene of unknown function was identified on HD chromosomes. This discovery unleased a flurry of experimentation that has established the expanded CAG repeat the almost universal cause of the characteristic neurologic symptoms and pathology of this neurodegenerative disorder of midlife onset. The biochemical basis for the specific neuronal loss of HD remains uncertain, but the genetic lesion probably acts via its consequent polyglutamine segment in the protein product, huntingtin. This review will describe the basic parameters of the HD repeat's behavior and the knowledge that has accumulated concerning its potential mechanisms of action.
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Affiliation(s)
- J F Gusella
- Molecular Neurogenetics Unit, Massachusetts General Hospital East, Charlestown 02129, USA
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36
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Abstract
Expansion of trinucleotide repeats is now recognized as a major cause of neurological disease. At least seven disorders result from trinucleotide repeat expansion: X-linked spinal and bulbar muscular atrophy (SBMA), two fragile X syndromes of mental retardation (FRAXA and FRAXE), myotonic dystrophy, Huntington's disease, spinocerebellar ataxia type 1 (SCA1), and dentatorubral-pallidoluysian atrophy (DRPLA). The expanded trinucleotide repeats are unstable, and the phenomenon of anticipation, i.e., worsening of disease phenotype over successive generations, correlates with increasing expansion size. In this review, we compare the clinical and molecular features of the trinucleotide repeat diseases, which may be classified into two types. Fragile X and myotonic dystrophy are multisystem disorders usually associated with large expansions of untranslated repeats, while the four neurodegenerative disorders, SBMA, Huntington's disease, SCA1, and DRPLA, are caused by smaller expansions of CAG repeats within the protein coding portion of the gene. CAG repeats encode polyglutamine tracts. Polyglutamine tract expansion thus appears to be a common mechanism of inherited neurodegenerative disease. Although polyglutamine tract lengthening presumably has a toxic gain of function effect in the CAG trinucleotide repeat disorders, the basis of this neuronal toxicity remains unknown.
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Affiliation(s)
- A R La Spada
- Department of Laboratory Medicine, University of Washington Medical Center, Seattle 98195
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