FMR1 gene expansion and scans without evidence of dopaminergic deficits in parkinsonism patients

Parkinsonism Relat Disord. 2010 Nov;16(9):608-11. doi: 10.1016/j.parkreldis.2010.07.006. Epub 2010 Aug 11.


Purpose: To determine if patients with parkinsonism and fragile X mental retardation 1 (FMR1) gene expansions have a striatal dopamine deficit similar to Parkinson disease (PD) patients.

Scope: The authors studied three patients with parkinsonism carrying small expansions in the FMR1 gene (41-60 CGG) with [(123)I]β-CIT SPECT imaging. The patients responded to dopaminergic medications, but had preserved dopamine transporter density.

Conclusions: These results suggest that parkinsonism associated with smaller FMR1 expansions may be related to mechanisms other than pre-synaptic dopaminergic changes and may represent a potential explanation for at least some parkinsonian cases with scans without evidence of dopaminergic deficits (SWEDD).

Publication types

  • Case Reports
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Cocaine / analogs & derivatives
  • Corpus Striatum / diagnostic imaging
  • Dopamine / deficiency*
  • Female
  • Fragile X Mental Retardation Protein / genetics*
  • Humans
  • Male
  • Middle Aged
  • Parkinsonian Disorders / diagnostic imaging
  • Parkinsonian Disorders / genetics*
  • Parkinsonian Disorders / metabolism*
  • Parkinsonian Disorders / pathology
  • Tomography, Emission-Computed, Single-Photon / methods
  • Trinucleotide Repeat Expansion / genetics*


  • FMR1 protein, human
  • Fragile X Mental Retardation Protein
  • 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane
  • Cocaine
  • Dopamine