1
|
Sena LS, Dos Santos Pinheiro J, Hasan A, Saraiva-Pereira ML, Jardim LB. Spinocerebellar ataxia type 2 from an evolutionary perspective: Systematic review and meta-analysis. Clin Genet 2021; 100:258-267. [PMID: 33960424 DOI: 10.1111/cge.13978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/19/2021] [Accepted: 05/05/2021] [Indexed: 01/27/2023]
Abstract
Dominant diseases due to expanded CAG repeat tracts, such as spinocerebellar ataxia type 2 (SCA2), are prone to anticipation and worsening of clinical picture in subsequent generations. There is insufficient data about selective forces acting on the maintenance of these diseases in populations. We made a systematic review and meta-analysis on the effect of the CAG length over age at onset, instability of transmissions, anticipation, de novo or sporadic cases, fitness, segregation of alleles, and ancestral haplotypes. The correlation between CAG expanded and age at onset was r2 = 0.577, and transmission of the mutant allele was associated with an increase of 2.42 CAG repeats in the next generation and an anticipation of 14.62 years per generation, on average. One de novo and 18 sporadic cases were detected. Affected SCA2 individuals seem to have more children than controls. The expanded allele was less segregated than the 22-repeat allele in children of SCA2 subjects. Several ancestral SCA2 haplotypes were published. Data suggest that SCA2 lineages may tend to disappear eventually, due to strong anticipation phenomena. Whether or not the novel cases come from common haplotypes associated with a predisposition to further expansions is a question that needs to be addressed by future studies.
Collapse
Affiliation(s)
- Lucas Schenatto Sena
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Jordânia Dos Santos Pinheiro
- Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Ali Hasan
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Maria Luiza Saraiva-Pereira
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil
| | - Laura Bannach Jardim
- Programa de Pós-Graduação em Genética e Biologia Molecular, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Centros de Pesquisa Clínica e Experimental, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Instituto de Genética Médica Populacional, Porto Alegre, Brazil.,Serviço de Genética Médica, Hospital de Clínicas de Porto Alegre, Porto Alegre, Brazil.,Departamento de Medicina Interna, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| |
Collapse
|
2
|
Nance MA. Genetic counseling and testing for Huntington's disease: A historical review. Am J Med Genet B Neuropsychiatr Genet 2017; 174:75-92. [PMID: 27174011 DOI: 10.1002/ajmg.b.32453] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/15/2016] [Indexed: 12/26/2022]
Abstract
This manuscript describes the ways in which genetic counseling has evolved since John Pearson and Sheldon Reed first promoted "a genetic education" in the 1950s as a voluntary, non-directive clinical tool for permitting individual decision making. It reviews how the emergence of Huntington's disease (HD) registries and patient support organizations, genetic testing, and the discovery of a disease-causing CAG repeat expansion changed the contours of genetic counseling for families with HD. It also reviews the guidelines, outcomes, ethical and laboratory challenges, and uptake of predictive, prenatal, and preimplantation testing, and it casts a vision for how clinicians can better make use of genetic counseling to reach a broader pool of families that may be affected by HD and to ensure that genetic counseling is associated with the best levels of care. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Martha A Nance
- Struthers Parkinson's Center, Golden Valley, Minnesota.,Hennepin County Medical Center, Minneapolis, Minnesota
| |
Collapse
|
3
|
Abstract
Huntington disease (HD) is a dominantly inherited neurodegenerative disorder that usually presents in adulthood with characteristic motor and cognitive features and with variable and diverse psychiatric disturbances. Following the discovery of the causative defect in the HTT gene in 1993, great advances in understanding the pathogenesis of HD have been made, yet no effective disease-modifying therapy has been identified. In this new era of HD research, we have seen the emergence of a number of large clinical trials, the systematic search for novel biomarkers and the recent initiation of the first pre-manifest HD clinical studies. In this review, we seek to provide an overview of the clinical and genetic features of HD together with a summary of clinical research at this time.
Collapse
Affiliation(s)
- Aaron Sturrock
- Department of Medical Genetics, University of British Columbia (UBC), Vancouver, British Columbia, Canada.
| | | |
Collapse
|
4
|
Sartorius GA, Handelsman DJ. Testicular Dysfunction in Systemic Diseases. Andrology 2010. [DOI: 10.1007/978-3-540-78355-8_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
5
|
Van Raamsdonk JM, Murphy Z, Selva DM, Hamidizadeh R, Pearson J, Petersén A, Björkqvist M, Muir C, Mackenzie IR, Hammond GL, Vogl AW, Hayden MR, Leavitt BR. Testicular degeneration in Huntington disease. Neurobiol Dis 2007; 26:512-20. [PMID: 17433700 DOI: 10.1016/j.nbd.2007.01.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Revised: 01/10/2007] [Accepted: 01/14/2007] [Indexed: 11/28/2022] Open
Abstract
Huntington disease (HD) is an adult onset, neurodegenerative disorder that results from CAG expansion in the HD gene. Recent work has demonstrated testicular degeneration in mouse models of HD and alterations in the hypothalamic-pituitary-gonadal (HPG) axis in HD patients. Here, we show that HD patients have specific testicular pathology with reduced numbers of germ cells and abnormal seminiferous tubule morphology. In the YAC128 mouse model, testicular degeneration develops prior to 12 months of age, but at 12 months, there is no evidence for decreased testosterone levels or loss of GnRH neurons in the hypothalamus. This suggests that testicular pathology results from a direct toxic effect of mutant huntingtin in the testis and is supported by the fact that huntingtin is highly expressed in the affected cell populations in the testis. Understanding the pathogenesis of HD in the testis may reveal common critical pathways which lead to degeneration in both the brain and testis.
Collapse
Affiliation(s)
- Jeremy M Van Raamsdonk
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, University of British Columbia, 950 West 28th Ave., Vancouver, BC, Canada V5Z 4H4
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Van Raamsdonk JM, Pearson J, Rogers DA, Bissada N, Vogl AW, Hayden MR, Leavitt BR. Loss of wild-type huntingtin influences motor dysfunction and survival in the YAC128 mouse model of Huntington disease. Hum Mol Genet 2005; 14:1379-92. [PMID: 15829505 DOI: 10.1093/hmg/ddi147] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Huntington disease (HD) is an adult-onset neurodegenerative disease caused by a toxic gain of function in the huntingtin (htt) protein. The contribution of wild-type htt function to the pathogenesis of HD is currently uncertain. To assess the role of wild-type htt in HD, we generated YAC128 mice that do not express wild-type htt (YAC128-/-) but express the same amount of mutant htt as normal YAC128 mice (YAC128+/+). YAC128-/- mice perform worse than YAC128+/+ mice in the rotarod test of motor coordination (P = 0.001) and are hypoactive compared with YAC128+/+ mice at 2 months (P = 0.003). Striatal neuropathology was not clearly worse in YAC128-/- mice compared with YAC128+/+ mice. There was no significant effect of decreased wild-type htt on striatal volume, neuronal counts or DARPP-32 expression but a modest worsening of striatal neuronal atrophy was evident (6%, P = 0.03). The testis of YAC128+/+ mice showed atrophy and degeneration, which was markedly worsened in the absence of wild-type htt (P = 0.001). YAC128+/+ mice also showed a male specific deficit in survival compared with WT mice which was exacerbated by the loss of wild-type htt (12-month-male survival, P < 0.001). Overall, we demonstrate that the loss of wild-type htt influences motor dysfunction, hyperkinesia, testicular degeneration and impaired lifespan in YAC128 mice. The mild effect of wild-type htt on striatal phenotypes in YAC128 mice suggests that the characteristic striatal neuropathology in HD is caused primarily by the toxicity of mutant htt and that replacement of wild-type htt will not be an adequate treatment for HD.
Collapse
|
7
|
Abstract
BACKGROUND Reproductive fitness is an important factor in understanding inheritance in genetic disorders. The purpose of this study was to determine whether fitness is reduced in familial schizophrenia (FS) and if fitness in siblings differs from the norm. METHOD The number of offspring in 36 subjects with RDC schizophrenia or schizoaffective disorder (SZ) and their 101 siblings from large FS families was compared with age-adjusted census figures. RESULTS Fitness in the SZ group was significantly reduced: 23% of expected in males and 51% of expected in females. Fitness of unaffected siblings was within census expectations. However, female siblings with schizophrenia spectrum features had increased fitness over census norms. Reduced fitness was correlated with low marital rates, poor functioning and positive symptoms. CONCLUSIONS These results indicate that reduced fitness is an important genetic force in FS and is likely inherent to the illness. Sex differences are important and would need to be considered when examining maternal and paternal transmission of schizophrenia. The results support a proposed high mutation rate for schizophrenia, consistent with a dynamic mutation mechanism.
Collapse
Affiliation(s)
- A S Bassett
- Department of Psychiatry, University of Toronto, Queen Street Mental Health Centre, Ontario, Canada
| | | | | | | |
Collapse
|
8
|
Abstract
The available information on the world distribution of Huntington's disease (HD) from population surveys and death rate analysis is summarised and discussed in the light of genetic studies. It is concluded that most European populations, both Northern and Southern, show a relatively high prevalence (4-8 per 100,000), and that the disorder may also be frequent in India and parts of central Asia. HD is notably rare in Finland and in Japan, but data for Eastern Asia and Africa are inadequate. The disorder may have been underestimated in the American black population. Populations derived from recent European immigration show frequencies and origins of HD comparable to those expected from their own origins and expansion; there is no evidence to suggest that the HD gene has spread disproportionally and its selective effect may be close to neutral. Multiple separate introductions of the gene have been the rule in large populations. Several major foci of HD exist as the result of rapid population expansion. It is likely that a number of separate mutations for HD will be shown to be responsible for the disease, but that the high frequency of HD in European populations will prove to be the result of one or a very small number of mutations, probably of great antiquity.
Collapse
Affiliation(s)
- P S Harper
- Institute of Medical Genetics, University of Wales College of Medicine, Heath Park, Cardiff, UK
| |
Collapse
|