Objective: 1) To investigate the prevalence of dystonia in Fragile X mental retardation ( FMR1 ) premutation carriers with or without Fragile X-associated tremor/ataxia syndrome (FXTAS) compared to normal controls. (2) To investigate the association in the FMR1 premutation carriers between dystonia and FMR1 CGG repeat length and gender. Background FXTAS is characterized by tremor, ataxia, and parkinsonism in FMR1 premutation carriers. In the literature, isolated case studies have described dystonia in FMR1 premutation carriers, and we hypothesized that dystonia may be more common in these patients than in age-matched controls. Design/Methods: One hundred forty-six FMR1 premutation carriers and 98 age-matched controls underwent a videotaped protocol of neurological testing. A movement disorders specialist blinded to mutation status rated the videotapes using the FXTAS Motor Rating Scale. The control group was composed predominantly of spouses of the carriers and all cases and controls were recruited through fragile X syndrome probands. Results: There were no significant differences between the cases (11%) and controls (7.1%) with respect to dystonia prevalence (p=0.32). Logistic regression analyses were performed to evaluate the odds of dystonia in carriers, adjusted for gender and age (OR 1.62; CI, 0.64 - 4.10). There was no increased likelihood of dystonia with increasing CGG repeat size, adjusting for gender and age (p=0.65).Wilcoxon rank-sum test showed no significant difference in CGG repeat size between subjects with and without dystonia (p=0.52). Conclusions: The prevalence of dystonia in FMR1 premutation carriers is not significantly different compared to age matched controls using age and gender as covariates, and there is no association between CGG repeat length and dystonia. Despite isolated case reports of dystonia in FMR1 premutation carriers, our results do not suggest a higher likelihood of dystonia in these patients. Supported by: K23NS052487 (DAH); RL1AG032115 (RJH). Disclosure: Dr. Vaughan has received personal compensation for activities Merz Pharma. Dr. Ouyang has nothing to disclose. Dr. Goetz has received personal compensation for activities with Asubio Pharmaceuticals Inc., Campbell Alliance, CNS Therapeutics, Curry Rockerfeller Group, Health Advances, Impax Pharmaceuticals, Ingenix, Juvantia Pharma LTD as a consultant and participant on an advisory board. Dr. Goetz has received personal compensation in an editorial capacity for Movement Disorders and Oxford University Press. Dr. Goetz has received research support from Michael J. Fox Foundation, National Institute of Health and Parkinson9s Disease Foundation. Dr. Berry-Kravis has nothing to disclose. Dr. Hagerman has received personal compensation for activities with Novartis and Roche Diagnostics Corporation.Dr. Hagerman has received research support from Roche Diagnostics Corporation, Novartis, Seaside Therapeutics, Forest Laboratories, Inc., Curemark, NFXF and NIH. Dr. Leehey has received personal compensation for activities with Gerson Lehrman Group as a consultant. Dr. Hall has nothing to disclose.