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Ylönen S, Sipilä JOT, Hietala M, Majamaa K. HTT haplogroups in Finnish patients with Huntington disease. NEUROLOGY-GENETICS 2019; 5:e334. [PMID: 31086827 PMCID: PMC6481225 DOI: 10.1212/nxg.0000000000000334] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 03/20/2019] [Indexed: 11/17/2022]
Abstract
Objective To study genetic causes of the low frequency of Huntington disease (HD) in the Finnish population, we determined HTT haplogroups in the population and patients with HD and analyzed intergenerational Cytosine-Adenosine-Guanosine (CAG) stability. Methods A national cohort of patients with HD was used to identify families with mutant HTT (mHTT). HTT haplogroups were determined in 225 archival samples from patients and from 292 population samples. CAG repeats were phased with HTT haplotypes using data from parent-offspring pairs and other mHTT carriers in the family. Results The allele frequencies of HTT haplotypes in the Finnish population differed from those in 411 non-Finnish European subjects (p < 0.00001). The frequency of haplogroup A was lower than that in Europeans and haplogroup C was higher. Haplogroup A alleles were significantly more common in patients than in controls. Among patients with HD haplotypes A1 and A2 were more frequent than among the controls (p = 0.003). The mean size of the CAG repeat change was +1.38 units in paternal transmissions being larger than that (−0.17) in maternal transmissions (p = 0.008). CAG repeats on haplogroup A increased by 3.18 CAG units in paternal transmissions, but only by 0.11 units in maternal transmissions (p = 0.008), whereas haplogroup C repeat lengths decreased in both paternal and maternal transmissions. Conclusions The low frequency of HD in Finland is partly explained by the low frequency of the HD-associated haplogroup A in the Finnish population. There were remarkable differences in intergenerational CAG repeat dynamics that depended on HTT haplotype and parent gender.
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Affiliation(s)
- Susanna Ylönen
- Division of Clinical Neuroscience (S.Y., K.M.), Neurology, University of Oulu; Department of Neurology and Medical Research Center (S.Y., K.M.), Oulu University Hospital; Department of Neurology (J.O.T.S.), North Karelia Central Hospital, Siun Sote, Joensuu; Division of Clinical Neurosciences (J.O.T.S.), Turku University Hospital; Neurology (J.O.T.S.), University of Turku; Department of Clinical Genetics (M.H.), Turku University Hospital; and Institute of Biomedicine (M.H.), University of Turku, Finland
| | - Jussi O T Sipilä
- Division of Clinical Neuroscience (S.Y., K.M.), Neurology, University of Oulu; Department of Neurology and Medical Research Center (S.Y., K.M.), Oulu University Hospital; Department of Neurology (J.O.T.S.), North Karelia Central Hospital, Siun Sote, Joensuu; Division of Clinical Neurosciences (J.O.T.S.), Turku University Hospital; Neurology (J.O.T.S.), University of Turku; Department of Clinical Genetics (M.H.), Turku University Hospital; and Institute of Biomedicine (M.H.), University of Turku, Finland
| | - Marja Hietala
- Division of Clinical Neuroscience (S.Y., K.M.), Neurology, University of Oulu; Department of Neurology and Medical Research Center (S.Y., K.M.), Oulu University Hospital; Department of Neurology (J.O.T.S.), North Karelia Central Hospital, Siun Sote, Joensuu; Division of Clinical Neurosciences (J.O.T.S.), Turku University Hospital; Neurology (J.O.T.S.), University of Turku; Department of Clinical Genetics (M.H.), Turku University Hospital; and Institute of Biomedicine (M.H.), University of Turku, Finland
| | - Kari Majamaa
- Division of Clinical Neuroscience (S.Y., K.M.), Neurology, University of Oulu; Department of Neurology and Medical Research Center (S.Y., K.M.), Oulu University Hospital; Department of Neurology (J.O.T.S.), North Karelia Central Hospital, Siun Sote, Joensuu; Division of Clinical Neurosciences (J.O.T.S.), Turku University Hospital; Neurology (J.O.T.S.), University of Turku; Department of Clinical Genetics (M.H.), Turku University Hospital; and Institute of Biomedicine (M.H.), University of Turku, Finland
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2
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Kay C, Collins JA, Wright GEB, Baine F, Miedzybrodzka Z, Aminkeng F, Semaka AJ, McDonald C, Davidson M, Madore SJ, Gordon ES, Gerry NP, Cornejo-Olivas M, Squitieri F, Tishkoff S, Greenberg JL, Krause A, Hayden MR. The molecular epidemiology of Huntington disease is related to intermediate allele frequency and haplotype in the general population. Am J Med Genet B Neuropsychiatr Genet 2018; 177:346-357. [PMID: 29460498 DOI: 10.1002/ajmg.b.32618] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 12/21/2017] [Indexed: 01/31/2023]
Abstract
Huntington disease (HD) is the most common monogenic neurodegenerative disorder in populations of European ancestry, but occurs at lower prevalence in populations of East Asian or black African descent. New mutations for HD result from CAG repeat expansions of intermediate alleles (IAs), usually of paternal origin. The differing prevalence of HD may be related to the rate of new mutations in a population, but no comparative estimates of IA frequency or the HD new mutation rate are available. In this study, we characterize IA frequency and the CAG repeat distribution in fifteen populations of diverse ethnic origin. We estimate the HD new mutation rate in a series of populations using molecular IA expansion rates. The frequency of IAs was highest in Hispanic Americans and Northern Europeans, and lowest in black Africans and East Asians. The prevalence of HD correlated with the frequency of IAs by population and with the proportion of IAs found on the HD-associated A1 haplotype. The HD new mutation rate was estimated to be highest in populations with the highest frequency of IAs. In European ancestry populations, one in 5,372 individuals from the general population and 7.1% of individuals with an expanded CAG repeat in the HD range are estimated to have a molecular new mutation. Our data suggest that the new mutation rate for HD varies substantially between populations, and that IA frequency and haplotype are closely linked to observed epidemiological differences in the prevalence of HD across major ancestry groups in different countries.
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Affiliation(s)
- Chris Kay
- Centre for Molecular Medicine Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Jennifer A Collins
- Centre for Molecular Medicine Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Galen E B Wright
- Centre for Molecular Medicine Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Fiona Baine
- Division of Human Genetics, Department of Pathology, University of Cape Town, South Africa.,Division of Human Genetics, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Zosia Miedzybrodzka
- Medical Genetics Group, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, UK
| | - Folefac Aminkeng
- Centre for Molecular Medicine Therapeutics, University of British Columbia, Vancouver, BC, Canada.,Translational Laboratory in Genetic Medicine, Agency for Science, Technology and Research (A*STAR), Singapore
| | - Alicia J Semaka
- Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
| | - Cassandra McDonald
- Centre for Molecular Medicine Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | - Mark Davidson
- Medical Genetics Group, School of Medicine and Dentistry, University of Aberdeen, Aberdeen, UK
| | - Steven J Madore
- Molecular Biology Group, Coriell Institute for Medical Research, Camden, New Jersey
| | - Erynn S Gordon
- Molecular Biology Group, Coriell Institute for Medical Research, Camden, New Jersey
| | - Norman P Gerry
- Molecular Biology Group, Coriell Institute for Medical Research, Camden, New Jersey
| | - Mario Cornejo-Olivas
- Neurogenetics Research Center, Instituto Nacional de Ciencias Neurologicas, Lima, Peru
| | - Ferdinando Squitieri
- IRCCS Casa Sollievo della Sofferenza Hospital, Huntington and Rare Diseases Unit (CSS-Mendel Rome), San Giovanni Rotondo, Italy
| | - Sarah Tishkoff
- Department of Genetics, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jacquie L Greenberg
- Division of Human Genetics, Department of Pathology, University of Cape Town, South Africa
| | - Amanda Krause
- Division of Human Genetics, National Health Laboratory Service and School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michael R Hayden
- Centre for Molecular Medicine Therapeutics, University of British Columbia, Vancouver, BC, Canada
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3
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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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4
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Yang J, Chen K, Wei Q, Chen Y, Cao B, Burgunder JM, Shang HF. Clinical and genetic characteristics in patients with Huntington’s disease from China. Neurol Res 2016; 38:916-20. [PMID: 27483361 DOI: 10.1080/01616412.2016.1214555] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Jing Yang
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Ke Chen
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Qianqian Wei
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Yongping Chen
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Bei Cao
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
| | - Jean-Marc Burgunder
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
- Department of Neurology, University of Bern, Bern, Switzerland
| | - Hui-Fang Shang
- Department of Neurology, West China Hospital, Sichuan University, Chengdu, China
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5
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Castilhos RM, Augustin MC, Santos JA, Perandones C, Saraiva-Pereira ML, Jardim LB. Genetic aspects of Huntington's disease in Latin America. A systematic review. Clin Genet 2015; 89:295-303. [PMID: 26178794 DOI: 10.1111/cge.12641] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 07/07/2015] [Accepted: 07/07/2015] [Indexed: 01/16/2023]
Abstract
We aimed to present a systematic review on Huntington's disease (HD) in Latin America (LA). PubMed and LILACS were searched up to March 2015, reporting confirmed HD cases in LA. Case series, cross-sectional, case-control, and prospective studies were included. From 534 communications, 47 were eligible. Population-based studies were not found; minimal prevalence of 0.5-4/100,000 was estimated for Venezuela and Mexico. Geographical isolates were well characterized in Venezuela and in Peru. CAG repeats at HTT gene varied between 7-33 and 37-112 in normal and expanded alleles, respectively. Intermediate alleles were found in 4-10% of controls. Ages at onset and the expanded CAG repeats correlated with r from - 0.55 to -0.91. While haplotype patterns of Venezuelan and Brazilian chromosomes were similar to those observed in Europeans, haplotypes from Peruvian HD patients did not match the same pattern. The limited number of papers found suggests that HD is poorly diagnosed in LA. Minimal prevalence seemed to be halfway between those of Caucasians and Asians. Range of CAG repeats was similar to those of Europeans. Haplotype studies indicate that majority of HD patients might be of Caucasian descent; an Asian origin for some Peruvian patients was proposed.
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Affiliation(s)
- R M Castilhos
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Instituto Nacional de Genética Médica Populacional (INAGEMP), Porto Alegre, Brazil
| | - M C Augustin
- Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - J A Santos
- Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - C Perandones
- Parkinson's Disease and Movement Disorders Program, Hospital de Clínicas, University of Buenos Aires, Buenos Aires, Argentina
| | - M L Saraiva-Pereira
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Departmento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil.,Laboratório de Identificação Humana, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - L B Jardim
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Instituto Nacional de Genética Médica Populacional (INAGEMP), Porto Alegre, Brazil.,Faculdade de Medicina, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil.,Laboratório de Identificação Humana, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Centro de Pesquisa Clínica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Departamento de Medicina Interna, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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6
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Ramos EM, Gillis T, Mysore JS, Lee J, Gögele M, D'Elia Y, Pichler I, Sequeiros J, Pramstaller PP, Gusella JF, MacDonald ME, Alonso I. Haplotype analysis of the 4p16.3 region in Portuguese families with Huntington's disease. Am J Med Genet B Neuropsychiatr Genet 2015; 168B:135-43. [PMID: 25656686 PMCID: PMC5006842 DOI: 10.1002/ajmg.b.32289] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 11/25/2014] [Indexed: 12/12/2022]
Abstract
Huntington's disease (HD) is a neurodegenerative disorder characterized by involuntary choreic movements, cognitive impairment, and behavioral changes, caused by the expansion of an unstable CAG repeat in HTT. We characterized the genetic diversity of the HD mutation by performing an extensive haplotype analysis of ∼1Mb region flanking HTT in over 300 HD families of Portuguese origin. We observed that haplotype A, marked by HTT delta2642, was enriched in HD chromosomes and carried the two largest expansions reported in the Portuguese population. However, the most frequent HD haplotype B carried one of the largest (+12 CAGs) expansions, which resulted in an allele class change to full penetrance. Despite having a normal CAG distribution skewed to the higher end of the range, these two core haplotypes had similar expanded CAG repeat sizes compared to the other major core haplotypes (C and D) and there was no statistical difference in transmitted repeat instability across haplotypes. We observed a diversity of HTT region haplotypes in both normal and expanded chromosomes, representative of more than one ancestral chromosome underlying HD in Portugal, where multiple independent events on distinct chromosome 4 haplotypes have given rise to expansion into the pathogenic range.
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Affiliation(s)
- Eliana Marisa Ramos
- Center for Human Genetic ResearchMassachusetts General HospitalBostonMassachusettsUSA,UnIGENeIBMC–Institute for Molecular and Cell BiologyUniversity of PortoPortoPortugal
| | - Tammy Gillis
- Center for Human Genetic ResearchMassachusetts General HospitalBostonMassachusettsUSA
| | - Jayalakshmi S. Mysore
- Center for Human Genetic ResearchMassachusetts General HospitalBostonMassachusettsUSA
| | - Jong‐Min Lee
- Center for Human Genetic ResearchMassachusetts General HospitalBostonMassachusettsUSA
| | - Martin Gögele
- Center for BiomedicineEuropean Academy of Bozen/Bolzano (EURAC)BolzanoItaly
| | - Yuri D'Elia
- Center for BiomedicineEuropean Academy of Bozen/Bolzano (EURAC)BolzanoItaly
| | - Irene Pichler
- Center for BiomedicineEuropean Academy of Bozen/Bolzano (EURAC)BolzanoItaly
| | - Jorge Sequeiros
- UnIGENeIBMC–Institute for Molecular and Cell BiologyUniversity of PortoPortoPortugal,CGPPIBMC–Institute for Molecular and Cell BiologyUniversity of PortoPortoPortugal,ICBAS–Instituto de Ciências Biomédicas Abel SalazarUniversity of PortoPortoPortugal
| | - Peter P. Pramstaller
- Center for BiomedicineEuropean Academy of Bozen/Bolzano (EURAC)BolzanoItaly,Department of NeurologyCentral HospitalBolzanoItaly,Department of NeurologyUniversity of LübeckLübeckGermany
| | - James F. Gusella
- Center for Human Genetic ResearchMassachusetts General HospitalBostonMassachusettsUSA
| | - Marcy E. MacDonald
- Center for Human Genetic ResearchMassachusetts General HospitalBostonMassachusettsUSA
| | - Isabel Alonso
- UnIGENeIBMC–Institute for Molecular and Cell BiologyUniversity of PortoPortoPortugal,CGPPIBMC–Institute for Molecular and Cell BiologyUniversity of PortoPortoPortugal,ICBAS–Instituto de Ciências Biomédicas Abel SalazarUniversity of PortoPortoPortugal
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7
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Semaka A, Kay C, Doty CN, Collins JA, Tam N, Hayden MR. High frequency of intermediate alleles on Huntington disease-associated haplotypes in British Columbia's general population. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:864-71. [PMID: 24038799 DOI: 10.1002/ajmg.b.32193] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 07/11/2013] [Indexed: 11/08/2022]
Abstract
Intermediate alleles (27-35 CAG, IAs) for Huntington disease (HD) usually do not confer the disease phenotype but are prone to CAG repeat instability. Consequently, offspring are at-risk of inheriting an expanded allele in the HD range (≥36 CAG). IAs that expand into a new mutation have been hypothesized to be more susceptible to instability compared to IAs identified on the non-HD side of a family from the general population. Frequency estimates for IAs are limited and have largely been determined using clinical samples of HD or related disorders, which may result in an ascertainment bias. This study aimed to establish the frequency of IAs in a sample of a British Columbia's (B.C.) general population with no known association to HD and examine the haplotype of new mutation and general population IAs. CAG sizing was performed on 1,600 DNA samples from B.C.'s general population. Haplotypes were determined using 22 tagging SNPs across the HTT gene. 5.8% of individuals were found to have an IA, of which 60% were on HD-associated haplotypes. There was no difference in the haplotype distribution of new mutation and general population IAs. These findings suggest that IAs are relatively frequent in the general population and are often found on haplotypes associated with expanded CAG lengths. There is likely no difference in the propensity of new mutation and general population IAs to expand into the disease range given that they are both found on disease-associated haplotypes. These findings have important implications for clinical practice.
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Affiliation(s)
- Alicia Semaka
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
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8
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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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Turner MR, Goldacre R, Goldacre MJ. Reduced cancer incidence in Huntington's disease: record linkage study clue to an evolutionary trade-off? Clin Genet 2012; 83:588-90. [DOI: 10.1111/cge.12010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Revised: 08/15/2012] [Accepted: 08/31/2012] [Indexed: 11/28/2022]
Affiliation(s)
- MR Turner
- Nuffield Department of Clinical Neurosciences; Oxford University, John Radcliffe Hospital; Oxford; UK
| | - R Goldacre
- Unit of Health-Care Epidemiology, Department of Public Health; University of Oxford; Oxford; UK
| | - MJ Goldacre
- Unit of Health-Care Epidemiology, Department of Public Health; University of Oxford; Oxford; UK
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10
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Gatto E, Parisi V, Persi G, Converso DP, Etcheverry JL, Varela V, Alba L, Fretchel G. Clinical and genetic characteristics in patients with Huntington’s Disease from Argentina. Parkinsonism Relat Disord 2012; 18:166-9. [DOI: 10.1016/j.parkreldis.2011.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 09/09/2011] [Accepted: 09/15/2011] [Indexed: 02/01/2023]
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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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HTT haplotypes contribute to differences in Huntington disease prevalence between Europe and East Asia. Eur J Hum Genet 2011; 19:561-6. [PMID: 21248742 DOI: 10.1038/ejhg.2010.229] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Huntington disease (HD) results from CAG expansion in the huntingtin (HTT) gene. Although HD occurs worldwide, there are large geographic differences in its prevalence. The prevalence in populations derived from Europe is 10-100 times greater than in East Asia. The European general population chromosomes can be grouped into three major haplogroups (group of similar haplotypes): A, B and C. The majority of HD chromosomes in Europe are found on haplogroup A. However, in the East-Asian populations of China and Japan, we find the majority of HD chromosomes are associated with haplogroup C. The highest risk HD haplotypes (A1 and A2), are absent from the general and HD populations of China and Japan, and therefore provide an explanation for why HD prevalence is low in East Asia. Interestingly, both East-Asian and European populations share a similar low level of HD on haplogroup C. Our data are consistent with the hypothesis that different HTT haplotypes have different mutation rates, and geographic differences in HTT haplotypes explain the difference in HD prevalence. Further, the bias for expansion on haplogroup C in the East-Asian population cannot be explained by a higher average CAG size, as haplogroup C has a lower average CAG size in the general East-Asian population compared with other haplogroups. This finding suggests that CAG-tract size is not the only factor important for CAG instability. Instead, the expansion bias may be because of genetic cis-elements within the haplotype that influence CAG instability in HTT, possibly through different mutational mechanisms for the different haplogroups.
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13
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Semaka A, Collins JA, Hayden MR. Unstable familial transmissions of Huntington disease alleles with 27-35 CAG repeats (intermediate alleles). Am J Med Genet B Neuropsychiatr Genet 2010; 153B:314-20. [PMID: 19455596 DOI: 10.1002/ajmg.b.30970] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
There are inconsistent reports regarding the likelihood of repeat instability for alleles with 27-35 CAG repeats in the Huntington disease (HD) gene. We have examined the intergenerational stability of such intermediate alleles in 51 families from the University of British Columbia's DNA and Tissue Bank for Huntington Disease Research (UBC-HD Databank). A total of 181 transmissions were identified, with 30% (n = 54/181) of the alleles being unstable upon transmission. The unstable transmissions included both expansions (n = 37) and contractions (n = 17) of CAG size. Of the expanded alleles, 68% (n = 25/37) expanded into the HD range (>36 CAG). Therefore, 14% (n = 25/181) of the 27-35 CAG allele transmissions examined expanded into the disease-associated range resulting in a new mutation for HD. Significantly, of these new mutations, 40% (n = 10/25) originated from an allele with 35 CAG repeats with CAG repeat expansions ranging from +1 CAG to +23 CAG. The proportion of new mutations in the UBC-HD Databank is consistent with the most recent new mutation rate for HD, estimated to be at least 10%. The observed difference in the stability of HD intermediate allele transmissions in this data set and in other studies may be a reflection of a small sample size. Alternately, these inconsistencies may indicate an underlying difference in genetic factors which influence repeat instability between the different populations examined. Additional studies determining the frequency and magnitude of repeat instability in this CAG repeat range and factors that influence instability are urgently needed. Until we understand the clinical implications of HD alleles with 27-35 CAG repeats and establish reliable risks of instability, we should exercise caution when translating these results to the clinic.
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Affiliation(s)
- A Semaka
- Centre for Molecular Medicine and Therapeutics, Vancouver, Canada
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14
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Warby SC, Montpetit A, Hayden AR, Carroll JB, Butland SL, Visscher H, Collins JA, Semaka A, Hudson TJ, Hayden MR. CAG expansion in the Huntington disease gene is associated with a specific and targetable predisposing haplogroup. Am J Hum Genet 2009; 84:351-66. [PMID: 19249009 DOI: 10.1016/j.ajhg.2009.02.003] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 01/13/2009] [Accepted: 02/03/2009] [Indexed: 12/19/2022] Open
Abstract
Huntington disease (HD) is an autosomal-dominant disorder that results from >or=36 CAG repeats in the HD gene (HTT). Approximately 10% of patients inherit a chromosome that underwent CAG expansion from an unaffected parent with <36 CAG repeats. This study is a comprehensive analysis of genetic diversity in HTT and reveals that HD patients of European origin (n = 65) have a significant enrichment (95%) of a specific set of 22 tagging single nucleotide polymorphisms (SNPs) that constitute a single haplogroup. The disease association of many SNPs is much stronger than any previously reported polymorphism and was confirmed in a replication cohort (n = 203). Importantly, the same haplogroup is also significantly enriched (83%) in individuals with 27-35 CAG repeats (intermediate alleles, n = 66), who are unaffected by the disease, but have increased CAG tract sizes relative to the general population (n = 116). These data support a stepwise model for CAG expansion into the affected range (>or=36 CAG) and identifies specific haplogroup variants in the general population associated with this instability. The specific variants at risk for CAG expansion are not present in the general population in China, Japan, and Nigeria where the prevalence of HD is much lower. The current data argue that cis-elements have a major predisposing influence on CAG instability in HTT. The strong association between specific SNP alleles and CAG expansion also provides an opportunity of personalized therapeutics in HD where the clinical development of only a small number of allele-specific targets may be sufficient to treat up to 88% of the HD patient population.
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Abstract
Trinucleotide repeat expansions are an important cause of inherited neurodegenerative disease. The expanded repeats are unstable, changing in size when transmitted from parents to offspring (intergenerational instability, "meiotic instability") and often showing size variation within the tissues of an affected individual (somatic mosaicism, "mitotic instability"). Repeat instability is a clinically important phenomenon, as increasing repeat lengths correlate with an earlier age of onset and a more severe disease phenotype. The tendency of expanded trinucleotide repeats to increase in length during their transmission from parent to offspring in these diseases provides a molecular explanation for anticipation (increasing disease severity in successive affected generations). In this review, I explore the genetic and molecular basis of trinucleotide repeat instability. Studies of patients and families with trinucleotide repeat disorders have revealed a number of factors that determine the rate and magnitude of trinucleotide repeat change. Analysis of trinucleotide repeat instability in bacteria, yeast, and mice has yielded additional insights. Despite these advances, the pathways and mechanisms underlying trinucleotide repeat instability in humans remain largely unknown. There are many reasons to suspect that this uniquely human phenomenon will significantly impact upon our understanding of development, differentiation and neurobiology.
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Affiliation(s)
- A R La Spada
- Department of Laboratory Medicine and Pharmacology, University of Washington Medical Center, Seattle 98195, USA.
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Morovvati S, Nakagawa M, Osame M, Karami A. Analysis of CCG repeats in Huntingtin gene among HD patients and normal populations in Japan. Arch Med Res 2007; 39:131-3. [PMID: 18068007 DOI: 10.1016/j.arcmed.2007.06.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Accepted: 06/11/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Huntington's disease (HD) is a hereditary autosomal dominant neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. The molecular basis of the disease is the expansion of the trinucleotide CAG in the first exon of a gene on chromosome four (4p 16.3). There is another triplet sequence, a CCG repeat, immediately 3' adjacent to the CAG repeat in Huntingtin. This triplet sequence is also polymorphic, alleles of 7 or 10 repeats are predominant in populations, and strong linkage disequilibrium between the CCG (7) allele and HD has been shown in western HD chromosomes, whereas Japanese HD chromosomes strongly associate with an allele of (CCG)10. METHODS Distribution of CAG and the CCG repeats in Huntingtin in 15 patients with HD living in southern Japan were selected to evaluate the regional difference in the CCG repeat number in Japan. RESULTS Among our 15 HD patients, only 4 patients had the (CCG)7 allele, and the (CCG)10 alleles were found in the remaining 11 patients. CONCLUSIONS In this study, a linkage disequilibrium was found between Japanese HD chromosomes and (CCG)10, whereas western HD chromosomes are strongly associated with (CCG)7. These data suggest that (CCG)10 allele is dominant in southern Japan.
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Affiliation(s)
- Saeid Morovvati
- Research Center of Molecular Biology, Baqiyatallah Medical Sciences University, Tehran, Iran.
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Semaka A, Creighton S, Warby S, Hayden MR. Predictive testing for Huntington disease: interpretation and significance of intermediate alleles. Clin Genet 2006; 70:283-94. [PMID: 16965319 DOI: 10.1111/j.1399-0004.2006.00668.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Direct mutation analysis for Huntington disease (HD) became possible in 1993 with the identification of an expanded CAG trinucleotide repeat as the mutation underlying the disease. Expansion of CAG length beyond 35 repeats may be associated with the clinical presentation of HD. HD has never been seen in a person with a CAG size of <36 repeats. Intermediate alleles are defined as being below the affected CAG range but have the potential to expand to >35 CAG repeats within one generation. Thus, children of intermediate allele carriers have a low risk of developing HD. Currently, the intermediate allele range for HD is between 27 and 35 CAG repeats. In this study, we review the current knowledge on intermediate alleles for HD including the CAG repeat range, the intermediate allele frequency, and the clinical implications of an intermediate allele predictive test result. The factors influencing CAG repeat expansion, including the CAG size of the intermediate allele, the sex and age of the transmitting parent, the family history, and the HD gene sequence and haplotype, will also be reviewed.
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Affiliation(s)
- A Semaka
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
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Maat-Kievit A, Helderman-van den Enden P, Losekoot M, de Knijff P, Belfroid R, Vegter-van der Vlis M, Roos R, Breuning M. Using a roster and haplotyping is useful in risk assessment for persons with intermediate and reduced penetrance alleles in Huntington disease. AMERICAN JOURNAL OF MEDICAL GENETICS 2001; 105:737-44. [PMID: 11803522 DOI: 10.1002/ajmg.1610] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The risk of a person having a child with an inherited disorder, caused by an unstable triplet repeat, such as Huntington disease (HD), depends on the expansion of the mutation in that person, which is connected both to the biological nature of the mutation and to the person's relation to the carrier of the full mutation. Once the mutation causing HD was identified, we were able to diagnose sporadic patients. A sporadic patient can sometimes be connected to a known HD pedigree by using a roster. By haplotyping and calculating the posterior identity-by-descent probability, we could establish whether a connection was coincidental or not. Furthermore, we describe the frequency of intermediate and reduced penetrance alleles detected. Using the family history and the roster to search for a connection, we examined whether these alleles were on the HD haplotype of a family. It is important to know the origin of an intermediate or reduced penetrance allele because if it comes from an HD branch of the family or from the non-HD affected side of the pedigree, different risks for relatives and penetrance ensue. In our study, most intermediate alleles came from the non-HD-affected side of the pedigree and had a repeat size in the lower range with a negligible risk for expansion. Intermediate alleles on the HD haplotypes were larger and found in predictive test applicants from known families or relatives from new mutations with a higher risk for expansion. Reduced penetrance alleles in the higher range were mainly found in symptomatic and predictive test applicants from known families, with a considerable risk for penetrance, although at older age. We conclude that a roster, a thorough family history, and haplotyping in persons with intermediate and reduced penetrance alleles are essential in considering the risk of a person having (a child with) HD.
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Affiliation(s)
- A Maat-Kievit
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Chapter 3 The Genetic Basis and Molecular Pathogenesis of Huntington's Disease. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s1566-3124(08)60023-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Jellinger KA. Structural basis of dementia in neurodegenerative disorders. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 1996; 47:1-29. [PMID: 8841954 DOI: 10.1007/978-3-7091-6892-9_1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Progressive dementia syndromes in adults are caused by a number of conditions associated with different structural lesions of the brain. In most clinical and autopsy series, senile dementia of the Alzheimer type is the most common cause of mental decline in the elderly accounting for up to 90%, whereas degenerative non-Alzheimer dementias range from 7 to 30% (mean 8-10%). They include a variety of disorders featured morphologically by neuron and synapse loss and gliosis, often associated with cytopathological changes involving specific cortical and subcortical circuits. These neuronal/glial inclusions and neuritic alterations show characteristic immunoreactions and ultrastructure indicating cytoskeletal mismetabolism. They are important diagnostic sign posts that, in addition to the distribution pattern of degenerative changes, indicate specific vulnerability of neuronal populations, but their pathogenic role and contribution to mental decline are still poorly understood. In some degenerative disorders no such cytopathological hallmarks have been observed; a small number is genetically determined. While in Alzheimer's disease (AD) mental decline is mainly related to synaptic and neuritic pathologies, other degenerative disorders show variable substrates of dementia involving different cortical and/or subcortical circuits which may or may not be superimposed by cortical Alzheimer lesions. In most demented patients with Lewy body disorders (Parkinson's disease, Lewy body dementia), they show similar distribution as in AD, while in Progressive Supranuclear Palsy (PSP), mainly prefrontal areas are involved. Lobar atrophies, increasingly apparent as causes of dementia, show fronto-temporal cortical neuron loss, spongiosis and gliosis with or without neuronal inclusions (Pick bodies) and ballooned cells, while dementing motor neuron disease and multisystem atrophies reveal ubiquitinated neuronal and oligodendroglial inclusions. There are overlaps or suggested relationships between some neurodegenerative disorders, e.g. between corticobasal degeneration, PSP and Pick's atrophy. In many of these disorders with involvement of the basal ganglia, degeneration of striatofrontal and hippocampo-cortical loops are important factors of mental decline which may be associated with isocortical neuronal degeneration and synapse loss or are superimposed by cortical AD pathology.
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Affiliation(s)
- K A Jellinger
- L. Boltzmann Institute of Clinical Neurobiology, Lainz-Hospital, Vienna, Austria
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