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

ABSTRACT

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]ß-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).