Amplification of the Xq28 FRAXE repeats: extreme phenotype variability?
Am J Med Genet
; 64(2): 441-4, 1996 Aug 09.
Article
em En
| MEDLINE
| ID: mdl-8844100
ABSTRACT
We report on a new case of FRAXE mutation identified through the screening of a population of FRAXA-negative mentally retarded individuals. The index case, a 4-year-old boy with distinct minor anomalies and mental retardation with severe verbal impairment, his older brother, referred to as normal, and the mother have undergone careful clinical and molecular evaluation. The molecular defect, characterized by standard Southern blot analysis, is represented by a hypermethylated "full mutation" in the 2 boys and by a unique, altered, presumably unmethylated, band in the mother, which is interpreted as a "premutation." The cytogenetic analysis failed to detect a folate-sensitive Xq27-28 fragile site in either "fully mutated" individual. The phenotype and intellectual performance of the 15-year-old brother of the propositus appeared completely normal. Our propositus shares some traits with previously described FRAXE-mutated subjects, suggesting an association with the Xq28 molecular defect; nevertheless, we find it difficult to reconcile the molecular identity and phenotypic difference in these mutated members of the same family. This could be a case of extreme phenotypic variability or a result of a more complicated molecular mechanism.
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Base de dados:
MEDLINE
Assunto principal:
Aberrações dos Cromossomos Sexuais
/
Cromossomo X
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Fragilidade Cromossômica
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Deficiência Intelectual
Tipo de estudo:
Prognostic_studies
Limite:
Child, preschool
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Female
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Humans
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Male
Idioma:
En
Ano de publicação:
1996
Tipo de documento:
Article