FMR1 and Mental deterioration: FXTAS typically manifests after the age of 50 with the late appearance of a tremorsimilar to essential tremor followed by ataxia, while cognitive decline, parkinsonism,peripheral neuropathy, proximal muscle weakness, and autonomic dysfunction have alsobeen reported.3 The over-expression ofthe FMR1 messenger RNA by the premutated alleles, which may be aconsequence of a decrease in FMRP synthesis, has been considered a possible mechanismleading to FXTAS.2