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Population genetics of wild-type CAG repeats in the Machado-Joseph disease gene in Portugal

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Detalhes bibliográficos
Resumo:To gain insights on the molecular mechanisms of mutation that led to the emergence of expanded alleles in the MJD gene, by studying the behavior of wild-type alleles and testing the association of its distribution with the representation of the disease. Methods: The number of CAG motifs in the MJD gene was determined in a representative sample of 1000 unrelated individuals. Associations between the repeat size and the epidemiological representation of MJD were tested. Results: The allelic profi le of the total sample was in the normal range (13–41 repeats), with mode (CAG) 23 . No intermediate alleles were present. Allelic size distribution showed a negative skew. The correlation between the epidemiological representation of MJD in each district and the frequency of small, medium and large normal alleles was not signifi cant. Further correlations performed grouping the districts also failed to produce signifi cant results. Conclusions: The absence of association between the size of the repeats and the representation of MJD demonstrates that prevalence is not an indirect refl ection of the frequency of large normal alleles. Globally the results obtained are in accordance with a model that postulates the occurrence of a few mutations on the basis of most of the MJD cases worldwide.
Autores principais:Lima, M.
Outros Autores:Costa, Maria do Carmo; Montiel, R.; Ferro, Anabela; Santos, C.; Silva, C.; Bettencourt, C.; Sousa, Alda; Sequeiros, Jorge; Coutinho, P.; Maciel, P.
Assunto:Machado-Joseph disease Expansion disorder SCA3 Mutational bias Triplet repeats Population study Portugal
Ano:2005
País:Portugal
Tipo de documento:artigo
Tipo de acesso:acesso aberto
Instituição associada:Universidade do Minho
Idioma:inglês
Origem:RepositóriUM - Universidade do Minho
Descrição
Resumo:To gain insights on the molecular mechanisms of mutation that led to the emergence of expanded alleles in the MJD gene, by studying the behavior of wild-type alleles and testing the association of its distribution with the representation of the disease. Methods: The number of CAG motifs in the MJD gene was determined in a representative sample of 1000 unrelated individuals. Associations between the repeat size and the epidemiological representation of MJD were tested. Results: The allelic profi le of the total sample was in the normal range (13–41 repeats), with mode (CAG) 23 . No intermediate alleles were present. Allelic size distribution showed a negative skew. The correlation between the epidemiological representation of MJD in each district and the frequency of small, medium and large normal alleles was not signifi cant. Further correlations performed grouping the districts also failed to produce signifi cant results. Conclusions: The absence of association between the size of the repeats and the representation of MJD demonstrates that prevalence is not an indirect refl ection of the frequency of large normal alleles. Globally the results obtained are in accordance with a model that postulates the occurrence of a few mutations on the basis of most of the MJD cases worldwide.