A case of fragile X-associated tremor/ataxia syndrome with superior cerebellar peduncle lesions.

Fragile X-associated tremor/ataxia syndrome is a neurodegenerative disorder affecting carriers of a premutation in the FMR1 gene involving expansion of CGG repeats. We present the case of a 66-year-old man with fragile X-associated tremor/ataxia syndrome caused by a premutation of the FMR1 gene with approximately 80-110 CGG repeats. He demonstrated progressive cognitive decline, dysarthria, truncal ataxia, and incoordination. Magnetic resonance imaging revealed prominent middle cerebellar peduncle and corpus callosum splenium signs, while skin biopsy showed p62-positive nuclear inclusion bodies. Genetic analysis showed no expansion of the NOTCH2NLC gene. The diagnosis of fragile X-associated tremor/ataxia syndrome was confirmed by the CGG repeats in the FMR1 gene. We discovered new superior cerebellar peduncle and superior cerebellar peduncle decussation lesions in our case, suggesting the possibility of prominent and early magnetic resonance imaging lesions in fragile X-associated tremor/ataxia syndrome.