Fragile X-associated tremor/ataxia syndrome

Introduction
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By Niranjan N Singh MD and Florian P Thomas MD PhD

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset triplet repeat disorder that leads to dementia, ataxia, tremor, and neuropathy. Its cause is a restricted triplet repeat expansion mutation in the fragile X mental retardation gene (FMR1), whereas a larger expansion results in fragile X syndrome A in children. Fragile X-associated tremor/ataxia syndrome affects less than 20% of female and about 50% of male carriers. In this review, Dr. Thomas of St. Louis University and Dr. Singh of the University of Missouri-Columbia, focus on fragile X-associated tremor/ataxia syndrome and its relation to fragile X syndrome A. Fragile X-associated tremor/ataxia syndrome illustrates the importance of obtaining a comprehensive family history that is not limited to clinical question of the patient in question. Fragile X-associated tremor/ataxia syndrome is in the differential diagnosis in patients with various combinations of the above symptoms with or without a family history of mental retardation. Some estimates suggest that as many as 1 in 3000 men above 50 years of age may develop fragile X-associated tremor/ataxia syndrome; such numbers would signify a great impact on healthcare costs. The pathomechanistic evidence of mitochondrial and RNA dysfunction and of a neurodevelopmental component to fragile X-associated tremor/ataxia syndrome is discussed.

In This Article

Introduction
Historical note and nomenclature
Clinical manifestations
Clinical vignette
Etiology
Pathogenesis and pathophysiology
Epidemiology
Differential diagnosis
Diagnostic workup
Prognosis and complications
Management
Pregnancy
References cited
Contributors