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Brain Behav. 2019 Jul;9(7):e01337. doi: 10.1002/brb3.1337. Epub 2019 Jun 3.

Prevalence of fragile X-associated tremor/ataxia syndrome: A survey of essential tremor patients with cerebellar signs or extrapyramidal signs.

Park JH1,2, Jang W3, Youn J1,2, Ki CS4, Kim BJ1,2, Kim HT5, Louis ED6,7,8, Cho JW1,2.

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Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea.
Department of Neurology, Gangneung Asan Hospital, University of Ulsan College of Medicine, Gangneung-si, Republic of Korea.
Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Department of Neurology, College of Medicine, Hanyang University, Seoul, Republic of Korea.
Division of Movement Disorders, Department of Neurology, Yale School of Medicine, Yale University, New Haven, Connecticut.
Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, Connecticut.
Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, Connecticut.



In screening studies of Western patients with cerebellar dysfunction, FMR1 premutations have been detected. A screening study of East Asian patients with presumed essential tremor (ET) did not detect these mutations, possibly because the ET patients did not closely mimic the phenotype of fragile X-associated tremor/ataxia syndrome (FXTAS). The aim of this study was to estimate the prevalence of FMR1 premutations in a carefully recruited group of ET patients with additional phenotypic features of FXTAS.


From April 2014 to April 2018, we prospectively recruited patients with ET diagnoses from three tertiary care centers. Demographic and clinical data were collected, as well as data on presence of cerebellar signs and extrapyramidal signs (EPS). Tremor, cerebellar signs, and EPS were evaluated using appropriate clinical rating scales. For ET patients with additional cerebellar signs or EPS, FMR1 mutation analysis and brain magnetic resonance imaging were performed.


Six hundred and three ET patients were recruited. Cerebellar signs or EPS were present in 168 (27.9%) of 603. FMR1 CGG repeat analysis was performed in 74 of 168 patients. Fifty-two of 74 had cerebellar signs only, three had EPS only, and 19 had both neurologic abnormalities. Two patients had a FMR1 premutation and fulfiled both clinical and radiological criteria of FXTAS.


Two (2.7%) of 74 patients with presumed ET and additional neurological features were discovered to have FXTAS. The possibility of FXTAS should be considered in patients with ET who exhibit mild cerebellar signs or EPS.


FMR1 premutation; cerebellar signs; essential tremor; extrapyramidal signs; fragile X-associated tremor/ataxia syndrome

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