Fragile X-associated tremor/ataxia syndrome (FXTAS) in grey zone carriers

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46 Scopus citations


The grey zone (GZ; 45-54 CGG repeats in the FMR1 gene) is considered a normal allele; however, several studies have found a high frequency of GZ in movement disordered populations. Here, we describe neurological features of fragile X-associated tremor/ataxia syndrome (FXTAS) in two carriers of GZ alleles, although FXTAS has been defined as occurring only in premutation carriers (55-200 CGG repeats). Both patients had family members who had premutation and were diagnosed with FXTAS. The presence of relatively high GZ alleles with elevated fragile X mental retardation 1 mRNA (FMR1-mRNA) combined with a family history of FXTAS that may represent a facilitating genetic background for FXTAS are the factors that led to the presence of FXTAS in these individuals with a GZ allele. Further research into clinical involvement of GZ alleles is recommended and the definition of FXTAS may require revision.

Original languageEnglish (US)
Pages (from-to)74-77
Number of pages4
JournalClinical Genetics
Issue number1
StatePublished - Jul 2013


  • Ataxia
  • FMR1-mRNA
  • Grey zone
  • Premutation
  • Tremor

ASJC Scopus subject areas

  • Genetics(clinical)
  • Genetics


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