Brain 18F-FDG and 18F-Flumetamol PET Imaging of Fragile X-Associated Tremor Ataxia Syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a rare movement disorder caused by a 55-to-200 CGG-trinucleotide expansion premutation in the FMR1 gene. Core diagnostic criteria are tremor, ataxia, and T2-weighted hyperintensity of the middle cerebellar peduncles on MRI, but FXTAS encompass a broad spectrum of neurological symptoms. FXTAS pathophysiology is largely unknown, and some animal models and neuropathology findings suggest possible overlap with Alzheimer disease. We report the combined PET imaging of a genetically confirmed FXTAS patient, presenting reduced temporal-frontal F-18-FDG uptake, and pathological cortical deposition of amyloid to F-18-flumetamol PET scan. This report may offer clues to FXTAS pathophysiology.