Spastic paraparesis, cerebellar ataxia, and intention tremor: a severe variant of FXTAS?

Fragile X associated tremor/ataxia syndrome (FXTAS) is a recently identified neurodegenerative disorder affecting older adult males with pre-mutation alleles of the fragile X mental retardation 1 (FMR1) gene. 1- 3 These male carriers, in their fifties and older, develop progressive intention tremor, cerebellar ataxia, progressive cognitive difficulties, and variable features including peripheral neuropathy, lower limb proximal muscle weakness, and autonomic dysfunction. (AR=1 indicates a normal allele active in 100% of the cells, while an AR=0 indicates that the normal allele is always carried on the inactive X chromosome). Because their mother (I-3) is a carrier of normal alleles (30, 30), all sisters inherited the pre-mutation from their father (I-2).