Elan D.Louis, MD, MSc, Móstoles General Hospital, C / Río Júcar S/N, E-28935 Móstoles (Madrid), Spainjbenitol@meditex.es
Julián Benito-León, MD, PhD
Submitted August 28, 2006
We thank Drs. Munhoz and Teive for their comments although do not
agree with their idea that FXTAS should be included as an alternative
possibility. An occasional patient
with FXTAS manifesting as an ET-like picture has been reported by us [5] and others. [6,7] These studies included hundreds of ET
patients in different cohorts consistently showing that patients with ET
do not have a higher than expected rate of FMR1 repeat expansions. [8] It is unlikely that the increased prevalence of dementia we observed in
the ET patients we studied was due to an increased prevalence of FMR1
repeat expansions in these patients.
We expect that the underlying
cause(s) for the dementia in ET will become more apparent with rigorous
postmortem studies of ET brains. [9]
References
5. Garcia Arocena D, Louis ED, Tassone F, et al. Screen for expanded
FMR1 alleles in patients with essential tremor. Mov Disord 2004;19:930-
933.
6. Tan EK, Zhao Y, Puong KY, et al. Fragile X premutation alleles in
SCA, ET, and parkinsonism in an Asian cohort. Neurology 2004;63:362-363.
7. Deng H, Jankovic J. Premutation alleles associated with
Parkinson’s disease and essential tremor. JAMA 2004;292:1685-1688.
8. Hall DA, Hagerman RJ, Hagerman PJ, Jacquemont S, Leehey MA.
Prevalence of FMR1 repeat expansions in movement disorders. A systematic
review. Neuroepidemiology 2006;26:151-155.
9. Louis ED, Vonsattel JPG, Honig LS, Ross GW, Lyons KE, Pahwa R.
Neuropathological findings in essential tremor. Neurology 2006;66:1756-
1759.
We thank Drs. Munhoz and Teive for their comments although do not agree with their idea that FXTAS should be included as an alternative possibility. An occasional patient with FXTAS manifesting as an ET-like picture has been reported by us [5] and others. [6,7] These studies included hundreds of ET patients in different cohorts consistently showing that patients with ET do not have a higher than expected rate of FMR1 repeat expansions. [8] It is unlikely that the increased prevalence of dementia we observed in the ET patients we studied was due to an increased prevalence of FMR1 repeat expansions in these patients.
We expect that the underlying cause(s) for the dementia in ET will become more apparent with rigorous postmortem studies of ET brains. [9]
References
5. Garcia Arocena D, Louis ED, Tassone F, et al. Screen for expanded FMR1 alleles in patients with essential tremor. Mov Disord 2004;19:930- 933.
6. Tan EK, Zhao Y, Puong KY, et al. Fragile X premutation alleles in SCA, ET, and parkinsonism in an Asian cohort. Neurology 2004;63:362-363.
7. Deng H, Jankovic J. Premutation alleles associated with Parkinson’s disease and essential tremor. JAMA 2004;292:1685-1688.
8. Hall DA, Hagerman RJ, Hagerman PJ, Jacquemont S, Leehey MA. Prevalence of FMR1 repeat expansions in movement disorders. A systematic review. Neuroepidemiology 2006;26:151-155.
9. Louis ED, Vonsattel JPG, Honig LS, Ross GW, Lyons KE, Pahwa R. Neuropathological findings in essential tremor. Neurology 2006;66:1756- 1759.
The authors report no conflicts of interest.