Abstract:Machado-Joseph disease (MJD) is a form of autosomal dominant spinocerebellar ataxia first described in North-American patients originating from the Portuguese islands of the Azores. Clinically this disorder is characterized by late onset progressive ataxia with associated features, such as: ophthalmoplegia, pyramidal and extrapyramidal signs and distal muscular atrophies. The causative mutation is an expansion of a CAG repeat in the coding region of the MJD1 gene. We have identified 25 unrelated families segre… Show more
“…The frequency of subtypes of SCA 1, 3 and 6 found in this study is similar to those found in others reports but different for SCA2 and SCA7 34,45,46 . The differences between these results may be due to distinct loci analyzed and probably because the sample of Brazilian patients come from different regions of the country.…”
Section: Discussionsupporting
confidence: 88%
“…Molecular analysis of unrelated Brazilian families with SCA3 showed that normal alleles ranged from 12 to 33 (CAG)n 34 , and in other populations studied the two major alleles had 14 and 23 (CAG)n 13,35 . Comparisons of allelic frequencies must be made using population studies based on the CE methodology.…”
-The diagnosis and incidence of spinocerebelar ataxias (SCA) is sometimes difficult to analyze due the overlap of phenotypes subtypes and are disorders of mutations caused by CAG trinucleotide repeat expansion. To investigate the incidence of the SCA in Southern Brazil, we analyzed the trinucleotide repeats (CAG)n at the SCA1, SCA2, SCA3, SCA6 and SCA7 loci to identify allele size ranges and frequencies. We examined blood sample from 154 asymptomatic blood donors and 115 individuals with progressive ataxias.
“…The frequency of subtypes of SCA 1, 3 and 6 found in this study is similar to those found in others reports but different for SCA2 and SCA7 34,45,46 . The differences between these results may be due to distinct loci analyzed and probably because the sample of Brazilian patients come from different regions of the country.…”
Section: Discussionsupporting
confidence: 88%
“…Molecular analysis of unrelated Brazilian families with SCA3 showed that normal alleles ranged from 12 to 33 (CAG)n 34 , and in other populations studied the two major alleles had 14 and 23 (CAG)n 13,35 . Comparisons of allelic frequencies must be made using population studies based on the CE methodology.…”
-The diagnosis and incidence of spinocerebelar ataxias (SCA) is sometimes difficult to analyze due the overlap of phenotypes subtypes and are disorders of mutations caused by CAG trinucleotide repeat expansion. To investigate the incidence of the SCA in Southern Brazil, we analyzed the trinucleotide repeats (CAG)n at the SCA1, SCA2, SCA3, SCA6 and SCA7 loci to identify allele size ranges and frequencies. We examined blood sample from 154 asymptomatic blood donors and 115 individuals with progressive ataxias.
“…Two subsequent studies, based on molecular findings, gave estimations of the relative frequencies of some SCAs among 54 and 19 Brazilian families from several geographic origins [41,42]. In these studies, MJD1 mutation was responsible for 44 and for 68 %, respectively, of familial cases.…”
The proportion of MJD cases was very high, probably reflecting an Azorean founder effect. The estimated frequency of affected individuals with MJD, in our region, was 1.8 / 100,000, and of SCAs other than MJD, 0.2/100,000.
“…In Brazil it is the most frequent form of hereditary ataxia (Jardim et al 2001, Lopes-Cendes et al 1997. 5 There is no treatment or control for MJD.…”
In this article I explore the meanings acquired by the notion of 'genetic inheritance' for families in Rio de Janeiro affected by a rare hereditary dis-
ResumoNeste artigo analiso os significados que a noção de "herança genética" adquire para famílias cariocas afetadas por uma enfermidade rara e hereditária, a Doença de Machado Joseph. Considero na análise três pontos: 1) como a experiência da doença foi tematizada na família antes de se saber sua origem genética e hereditária; 2) como o conhecimento em genética afetou a percepção da família sobre sua saúde e reprodução a partir da noção de risco
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