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Zhang L, Kang H, Perez-Aguilar JM, Zhou R. Possible Co-Evolution of Polyglutamine and Polyproline in Huntingtin Protein: Proline-Rich Domain as Transient Folding Chaperone. J Phys Chem Lett 2022; 13:6331-6341. [PMID: 35796410 DOI: 10.1021/acs.jpclett.2c01184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Huntington's disease is an inherited neurodegenerative disorder caused by the overduplication of CAG repeats in the Huntingtin gene. Recent findings revealed that among the orthologs, the expansion of CAG repeats (polyQ) in the Huntingtin gene occurs in tandem with the duplication of CCG repeats (polyP). However, the molecular mechanism of this possible co-evolution remains unknown. We examined the structures of Huntingtin exon 1 (HttEx1) from six species along with five designed mutants. We found that the polyP segments "chaperone" the rest of the HttEx1 by forming ad hoc polyP binding grooves. Such a process elongates the otherwise poorly solvated polyQ domain, while modulating its secondary structure propensity from β-strands to α-helices. This chaperoning effect is achieved mostly through transient hydrogen bond interactions between polyP and the rest of HttEx1, resulting in a striking golden ratio of ∼2:1 between the chain lengths of polyQ and polyP.
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Affiliation(s)
- Leili Zhang
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Hongsuk Kang
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
| | - Jose Manuel Perez-Aguilar
- School of Chemical Sciences, Meritorious Autonomous University of Puebla (BUAP), University City, Puebla 72570, Mexico
| | - Ruhong Zhou
- Computational Biology Center, IBM Thomas J. Watson Research Center, Yorktown Heights, New York 10598, United States
- Institute of Quantitative Biology, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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Apolinário TA, da Silva IDS, Agostinho LDA, Paiva CLA. Investigation of intermediate CAG alleles of the HTT in the general population of Rio de Janeiro, Brazil, in comparison with a sample of Huntington disease-affected families. Mol Genet Genomic Med 2020; 8:e1181. [PMID: 32067426 PMCID: PMC7196456 DOI: 10.1002/mgg3.1181] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 01/14/2020] [Accepted: 01/30/2020] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Huntington disease (HD) (MIM: 143100) is a severe autosomal dominant neurodegenerative disease caused by the expansion of CAG trinucleotides (>35) in the HTT. OBJECTIVE To investigate the frequency of intermediate CAG alleles (IAs) in individuals residing in Rio de Janeiro city with no familial history of HD (general population, GP) in comparison with a sample of individuals from families presenting with HD who were previously investigated by our group (affected sample, AS). RESULTS The frequency of normal CAG alleles was 96.2%, while that of IAs was 3.6%, and that of reduced penetrance alleles was 0.2% in the GP (n = 470 chromosomes); 7.2% (17/235 individuals) of the GP presented an IA in heterozygosis with a normal allele. There was no statistically significant difference between the frequencies of the IAs in the GP and in the AS (p = .9). The most frequent haplotype per normal allele was (CAG)17-(CCG)7 (101/461) and per IA was (CAG)27-(CCG)7 (6/17) in the GP. These haplotypes were also the most frequent in the normal and IA chromosomes of the AS, respectively. CONCLUSION The genetic profiles of the IAs obtained from GP and AS were rather similar. It is important to investigate the frequencies of the IAs because expansions arise from a step-by-step mechanism in which, during intergenerational transmission, large normal alleles can generate IAs, which are then responsible for generating de novo HD mutations. The genetic investigation of IAs in the GP was also important because it was focused on the population of Rio de Janeiro, an understudied group. CCG7 was the most frequent CCG allele in linkage disequilibrium with normal, intermediate, and expanded CAG alleles, similar to the Western Europe population. However, a more robust investigation, in conjunction with haplogroup determination (A, B, or C), will be required to elucidate the ancestral origin of the HTT mutations in Brazilians.
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Affiliation(s)
- Thays A. Apolinário
- Programa de Pós‐Graduação em NeurologiaUniversidade Federal do Estado do Rio de Janeiro (UNIRIO)Rio de JaneiroRJBrazil
| | - Iane dos Santos da Silva
- Programa de Pós‐Graduação em Biologia Molecular e CelularUniversidade Federal do Estado do Rio de Janeiro (UNIRIO)Rio de JaneiroRJBrazil
| | - Luciana de Andrade Agostinho
- Programa de Pós‐Graduação em NeurologiaUniversidade Federal do Estado do Rio de Janeiro (UNIRIO)Rio de JaneiroRJBrazil
- Centro Universitário FAMINAS – UNIFAMINASMuriaéMGBrazil
- Fundação Cristiano Varella‐Hospital do CâncerMuriaéMGBrazil
| | - Carmen L. A. Paiva
- Programa de Pós‐Graduação em NeurologiaUniversidade Federal do Estado do Rio de Janeiro (UNIRIO)Rio de JaneiroRJBrazil
- Programa de Pós‐Graduação em Biologia Molecular e CelularUniversidade Federal do Estado do Rio de Janeiro (UNIRIO)Rio de JaneiroRJBrazil
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Cheng HR, Li XY, Yu HL, Xu M, Zhang YB, Gan SR, Li HL, Wu ZY. Correlation Between CCG Polymorphisms and CAG Repeats During Germline Transmission in Chinese Patients with Huntington's Disease. Neurosci Bull 2020; 36:811-814. [PMID: 32193782 DOI: 10.1007/s12264-020-00485-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 11/06/2019] [Indexed: 12/29/2022] Open
Affiliation(s)
- Hong-Rong Cheng
- Department of Neurology and Research Center of Neurology in the Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Xiao-Yan Li
- Department of Neurology and Research Center of Neurology in the Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Hui-Li Yu
- Department of Neurology and Research Center of Neurology in the Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China
| | - Miao Xu
- Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, 200040, China
| | - Yan-Bin Zhang
- Department of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Shi-Rui Gan
- Department of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, 350005, China
| | - Hong-Lei Li
- Department of Neurology and Research Center of Neurology in the Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China.
| | - Zhi-Ying Wu
- Department of Neurology and Research Center of Neurology in the Second Affiliated Hospital, and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310009, China. .,Joint Institute for Genetics and Genome Medicine between Zhejiang University and the University of Toronto, Zhejiang University, Hangzhou, 310058, China.
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Barboza LA, Ghisi NC. Evaluating the current state of the art of Huntington disease research: a scientometric analysis. ACTA ACUST UNITED AC 2018; 51:e6299. [PMID: 29340519 PMCID: PMC5769753 DOI: 10.1590/1414-431x20176299] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 09/29/2017] [Indexed: 11/22/2022]
Abstract
Huntington disease (HD) is an incurable neurodegenerative disorder caused by a dominant mutation on the 4th chromosome. We aim to present a scientometric analysis of the extant scientific undertakings devoted to better understanding HD. Therefore, a quantitative study was performed to examine the current state-of-the-art approaches that foster researchers’ understandings of the current knowledge, research trends, and research gaps regarding this disorder. We performed literature searches of articles that were published up to September 2016 in the “ISI Web of Science™” (http://apps.webofknowledge.com/). The keyword used was “Huntington disease”. Of the initial 14,036 articles that were obtained, 7732 were eligible for inclusion in the study according to their relevance. Data were classified according to language, country of publication, year, and area of concentration. The country leader regarding the number of studies published on HD is the United States, accounting for nearly 30% of all publications, followed by England and Germany, who have published 10 and 7% of all publications, respectively. Regarding the language in which the articles were written, 98% of publications were in English. The first publication to be found on HD was published in 1974. A surge of publications on HD can be seen from 1996 onward. In relation to the various knowledge areas that emerged, most publications were in the fields of neuroscience and neurology, likely because HD is a neurodegenerative disorder. Publications written in areas such as psychiatry, genetics, and molecular biology also predominated.
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Affiliation(s)
- L A Barboza
- Laboratório de Biologia Molecular, Universidade Tecnológica Federal do Paraná, Dois Vizinhos, PR, Brasil
| | - N C Ghisi
- Laboratório de Biologia Molecular, Universidade Tecnológica Federal do Paraná, Dois Vizinhos, PR, Brasil
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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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Baias M, Smith PES, Shen K, Joachimiak LA, Żerko S, Koźmiński W, Frydman J, Frydman L. Structure and Dynamics of the Huntingtin Exon-1 N-Terminus: A Solution NMR Perspective. J Am Chem Soc 2017; 139:1168-1176. [DOI: 10.1021/jacs.6b10893] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Maria Baias
- Department
of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Pieter E. S. Smith
- Department
of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Koning Shen
- Stanford University, Stanford, California 94305, United States
| | | | - Szymon Żerko
- Faculty
of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Wiktor Koźmiński
- Faculty
of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Judith Frydman
- Stanford University, Stanford, California 94305, United States
| | - Lucio Frydman
- Department
of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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7
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Kay C, Hayden MR, Leavitt BR. Epidemiology of Huntington disease. HANDBOOK OF CLINICAL NEUROLOGY 2017; 144:31-46. [DOI: 10.1016/b978-0-12-801893-4.00003-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Kim HJ, Shin CW, Jeon B, Park H. Survival of Korean Huntington's Disease Patients. J Mov Disord 2016; 9:166-70. [PMID: 27667189 PMCID: PMC5035942 DOI: 10.14802/jmd.16022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 06/13/2016] [Accepted: 08/03/2016] [Indexed: 01/20/2023] Open
Abstract
OBJECTIVE The survival of Huntington's disease (HD) patients is reported to be 15-20 years. However, most studies on the survival of HD have been conducted in patients without genetic confirmation with the possible inclusion of non-HD patients, and all studies have been conducted in Western countries. The survival of patients with HD in East Asia, where its prevalence is 10-50-fold lower compared with Western populations, has not yet been reported. METHODS Forty-seven genetically confirmed Korean HD patients from independent families were included in this retrospective medical record review study. RESULTS The mean age at onset among the 47 patients was 46.1 ± 14.0 years. At the time of data collection, 25 patients had died, and these patients had a mean age at death of 57.8 ± 13.7 years. The Kaplan-Meier estimate of the median survival from onset in the 47 patients was 14.5 years (95% confidence interval: 12.3-16.6). None of the following factors were associated with the survival time in the univariate Cox regression analysis: gender, age at onset, normal CAG repeat size, mutant CAG repeat size, and the absence or presence of non-motor symptoms at onset. CONCLUSION This is the first Asian study on survival in HD patients. Survival in Korean HD patients may be shorter than that reported for Western populations, or at least is in the lower range of expected survival. A larger longitudinal observation study is needed to confirm the results found in this study.
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Affiliation(s)
- Han-Joon Kim
- Department of Neurology, Movement Disorder Center, Parkinson Study Group, and Neuroscience Research Institute, College of Medicine, Seoul National University, Seoul, Korea
| | - Chae-Won Shin
- Department of Neurology, Movement Disorder Center, Parkinson Study Group, and Neuroscience Research Institute, College of Medicine, Seoul National University, Seoul, Korea
| | - Beomseok Jeon
- Department of Neurology, Movement Disorder Center, Parkinson Study Group, and Neuroscience Research Institute, College of Medicine, Seoul National University, Seoul, Korea
| | - Hyeyoung Park
- Department of Neurology, Movement Disorder Center, Parkinson Study Group, and Neuroscience Research Institute, College of Medicine, Seoul National University, Seoul, Korea
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Abstract
Objective: The objective was to review the major differences of Huntington disease (HD) in Asian population from those in the Caucasian population. Data Sources: Data cited in this review were obtained from PubMed database and China National Knowledge Infrastructure (CNKI) from 1994 to 2014. All the papers were written in English or Chinese languages, with the terms of Asia/Asian, HD, genotype, epidemiology, phenotype, and treatment used for the literature search. Study Selection: From the PubMed database, we included the articles and reviews which contained the HD patients’ data from Asian countries. From the CNKI, we excluded the papers which were not original research. Due to the language's restrictions, those data published in other languages were not included. Results: In total, 50 papers were cited in this review, authors of which were from the mainland of China, Japan, India, Thailand, Taiwan (China), Korea, and western countries. Conclusions: The lower epidemiology in Asians can be partly explained by the less cytosine-adenine-guanine repeats, different haplotypes, and CCG polymorphisms. For the physicians, atypical clinical profiles such as the initial symptom of ataxia, movement abnormalities of Parkinsonism, dystonia, or tics need to be paid more attention to and suggest gene testing if necessary. Moreover, some pathogenesis studies may help progress some new advanced treatments. The clinicians in Asian especially in China should promote the usage of genetic testing and put more effects in rehabilitation, palliative care, and offer comfort of patients and their families. The unified HD rating scale also needs to be popularized in Asia to assist in evaluating the progression of HD.
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Affiliation(s)
| | - Zhi-Ying Wu
- Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai 200040; Department of Neurology and Research Center of Neurology, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
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10
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Sun YM, Zhang YB, Wu ZY. Huntington's Disease: Relationship Between Phenotype and Genotype. Mol Neurobiol 2016; 54:342-348. [PMID: 26742514 DOI: 10.1007/s12035-015-9662-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 12/17/2015] [Indexed: 12/19/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disease with the typical manifestations of involuntary movements, psychiatric and behavior disorders, and cognitive impairment. It is caused by the dynamic mutation in CAG triplet repeat number in exon 1 of huntingtin (HTT) gene. The symptoms of HD especially the age at onset are related to the genetic characteristics, both the CAG triplet repeat and the modified factors. Here, we reviewed the recent advancement on the genotype-phenotype relationship of HD, mainly focus on the characteristics of different expanded CAG repeat number, genetic modifiers, and CCG repeat number in the 3' end of CAG triplet repeat and their effects on the phenotype. We also reviewed the special forms of HD (juvenile HD, atypical onset HD, and homozygous HD) and their phenotype-genotype correlations. The review will aid clinicians to predict the onset age and disease course of HD, give the genetic counseling, and accelerate research into the HD mechanism.
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Affiliation(s)
- Yi-Min Sun
- Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yan-Bin Zhang
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China.,Department of Neurology and Institute of Neurology, First Affiliated Hospital, Fujian Medical University, Fuzhou, China
| | - Zhi-Ying Wu
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China.
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11
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Kim HS, Lyoo CH, Lee PH, Kim SJ, Park MY, Ma HI, Lee JH, Song SK, Baik JS, Kim JH, Lee MS. Current Status of Huntington's Disease in Korea: A Nationwide Survey and National Registry Analysis. J Mov Disord 2015; 8:14-20. [PMID: 25614781 PMCID: PMC4298714 DOI: 10.14802/jmd.14038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 12/19/2014] [Accepted: 12/24/2014] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Huntington's disease (HD) is a rare neurological disorder, and its current status in Korea is not well investigated. This study aims to determine the prevalence and incidence of HD and to investigate the clinical features of HD patients in Korea. METHODS We estimated the crude prevalence and annual incidence of HD based on the databases of the Rare Diseases Registry (RDR) and the National Health Insurance (NHI). The clinical data of genetically confirmed HD patients was collected from 10 referral hospitals and analyzed. RESULTS The mean calculated annual incidence was 0.06 cases per 100,000 persons, and the mean calculated prevalence was 0.38 based on the NHI database. The estimated crude prevalence based on the RDR was 0.41. Of the sixty-eight HD patients recruited, the mean age of onset was 44.16 ± 14.08 years and chorea was most frequently reported as the initial symptom and chief complaint. The mean CAG repeat number of the expanded allele was 44.7 ± 4.8 and correlated inversely with the age of onset (p < 0.001). About two-thirds of the patients have a positive family history, and HD patients without positive family history showed a delay in onset of initial symptoms, a prolonged interval between initial symptom onset and genetic diagnosis and a delay in the age of genetic diagnosis. CONCLUSIONS To the best of our knowledge, this is the first study to estimate the prevalence and incidence of HD in Korea and the largest HD series in the Asian population. Our analyses might be useful for further studies and large-scale investigations in HD patients.
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Affiliation(s)
- Hyun Sook Kim
- Department of Neurology, CHA Bundang Medical Center, CHA University, Seongnam, Korea
| | - Chul Hyoung Lyoo
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Phil Hyu Lee
- Department of Neurology and Brain Research Institute, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Sang Jin Kim
- Department of Neurology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea
| | - Mee Young Park
- Department of Neurology, Yeungnam University Medical Center, Daegu, Korea
| | - Hyeo-Il Ma
- Department of Neurology, Hallym University Sacred Heart Hospital, Anyang, Korea
| | - Jae Hyeok Lee
- Department of Neurology, Pusan National University Yangsan Hospital, Yangsan, Korea
| | - Sook Kun Song
- Department of Neurology, Jeju National University Hospital, Jeju, Korea
| | - Jong Sam Baik
- Department of Neurology, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea
| | - Jin Ho Kim
- Department of Neurology, Chosun University School of Medicine, Gwangju, Korea
| | - Myung Sik Lee
- Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Haplotype analysis of the CAG and CCG repeats in 21 Brazilian families with Huntington's disease. J Hum Genet 2012; 57:796-803. [PMID: 23051704 DOI: 10.1038/jhg.2012.120] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We studied the allelic profile of CAG and CCG repeats in 61 Brazilian individuals in 21 independent families affected by Huntington's disease (HD). Thirteen individuals had two normal alleles for HD, two had one mutable normal allele and no HD phenotype, and forty-six patients carried at least one expanded CAG repeat allele. Forty-five of these individuals had one expanded allele and one individual had one mutable normal allele (27 CAG repeats) and one expanded allele (48 CAG repeats). Eleven of these forty-five subjects had a mutant allele with reduced penetrance, and thirty-four patients had a mutant allele with complete penetrance. Inter- and intragenerational investigations of CAG repeats were also performed. We found a negative correlation between the number of CAG repeats and the age of disease onset (r=-0.84; P<0.001) and no correlation between the number of CCG repeats and the age of disease onset (r=0.06). We found 40 different haplotypes and the analysis showed that (CCG)(10) was linked to a CAG normal allele in 19 haplotypes and to expanded alleles in two haplotypes. We found that (CCG)(7) was linked to expanded CAG repeats in 40 haplotypes (95.24%) and (CCG)(10) was linked to expanded CAG repeats in only two haplotypes (4.76%). Therefore, (CCG)(7) was the most common allele in HD chromosomes in this Brazilian sample. It was also observed that there was a significant association of (CCG)(7) with the expanded CAG alleles (χ(2)=6.97, P=0.0084). Worldwide, the most common CCG alleles have 7 or 10 repeats. In Western Europe, (CCG)(7) is the most frequent allele, similarly to our findings.
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Zhang BR, Tian J, Yan YP, Yin XZ, Zhao GH, Wu ZY, Gu WH, Xia K, Tang BS. CCG polymorphisms in the huntingtin gene have no effect on the pathogenesis of patients with Huntington's disease in mainland Chinese families. J Neurol Sci 2011; 312:92-6. [PMID: 21875723 DOI: 10.1016/j.jns.2011.08.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 08/04/2011] [Accepted: 08/08/2011] [Indexed: 10/17/2022]
Abstract
Huntington's disease (HD) is caused by the abnormal expansion of CAG repeats in the huntingtin gene (HTT). The adjacent proline-rich region, which also has a CCG polymorphism among people of different races, may also affect the pathogenesis of HD. To study the effect of this polymorphism on patients with HD in mainland China, 53 HD mutant alleles were examined. The results showed that 54.72% of the HD mutant alleles had 10-repeat alleles, and the remaining 45.28% had 7-repeat alleles. Moreover, comparison of the clinical features between the two groups revealed no significant difference. We also investigated its effect on the aggregates in vitro. No significant difference was detected when the morphology and size of the aggregates with the two polymorphisms was compared in cells. Given these findings, it was quite reasonable to suppose that the CCG polymorphism may not influence the pathogenesis of patients with HD in mainland China.
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Affiliation(s)
- Bao-rong Zhang
- Department of Neurology, Second Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310009, 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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