The variable phenotype of FXTAS
2005; Lippincott Williams & Wilkins; Volume: 65; Issue: 2 Linguagem: Inglês
10.1212/01.wnl.0000171744.95027.aa
ISSN1526-632X
AutoresChristoph Kamm, Thomas Gasser,
Tópico(s)Autism Spectrum Disorder Research
ResumoFragile X syndrome (FXS) is the most common inherited cause of mental retardation. It is caused by an expansion of a CGG trinucleotide repeat in the 5′ untranslated region of the fragile X mental retardation gene, the FMR1 gene, on the X chromosome to more than 200 repeats (full mutation). Mothers of patients with FXS typically are not mentally retarded but carry an FMR1 repeat expansion between 55 and 200 repeats (premutation). Such premutation alleles (of >59 repeats) can expand to a full mutation in the next generation. Normal individuals carry between 5 and 39 FMR1 CGG repeats, whereas 40 to 54 repeats (gray-zone alleles) may be unstable in transmission within two generations. Previously, premutation alleles had been associated only with premature ovarian failure in a subset of female carriers. However, recently a neurologic syndrome termed fragile X associated tremor ataxia syndrome (FXTAS) has been identified in male premutation carriers, typically grandfathers of boys with FXS who had passed on the premutation to their daughters.1 FXTAS is characterized by a combination of progressive intention tremor and gait ataxia. …
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