Objective: To present a case of dystonic head tremor in a female FMR1 premutation carrier.

Background: Fragile X-associated tremor ataxia syndrome (FXTAS) is the main neurological manifestation described in carriers of a premutation expansion of the fragile X mental retardation 1 (FMR1) gene and affects mainly men. Female carriers often develop FMR1-related primary ovarian insufficiency and, less frequently, neurological symptoms. Although movement disorders such as FXTAS in female carriers have been described, other movement disorders have not been well defined in the literature. Some case series report dystonia and bruxism to be more common than in the general population.

Method: Case-report.

Results: A 59-year-old woman, carrier of the premutation expansion of the FMR1 gene was referred to our Movement Disorders Clinic because of progressive head tremor. The neurological examination showed mild saccadic intrusions in slow pursuit movements, head tremor with right shift and right laterocollis and normal gait. Laboratory tests, including ceruloplasmine, cupper and thyroid function, were normal. Brain MRI with tractography showed no abnormalities.

Conclusion: We present a case of dystonic head tremor in a female FMR1 premutation carrier. Although it could be a case of adult-onset primary/idiopathic dystonia, previous reports support the association between FMR1 premutation and dystonia. Tractography did not display abnormalities in cerebellar circuits.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/unusual-expression-of-fragile-x-premutation-in-a-female-patient-clinical-and-tractographic-description/