<unk>  Abbreviation:<unk>  Pronunciation: "FAX-tass" Location of the FMR1 geneLocation of the FMR1 gene Specialty: Neurology, Movement Disorders Symptoms: intention<unk> ,<unk> , and parkinsonism Prevalence: In patients over 50 with FMR1 premutation: * 40-45% (males) * 16.5% (females) Onset: Late-onset, diagnosed in patients >50 years Diagnosis: Presentation, family history, genetic testing, and MRI<unk> <unk>  is a late-onset neurodegenerative disorder most frequently seen in male premutation carriers of<unk>  X syndrome (FXS) over the age of 50. The main clinical features of<unk>  include problems of movement with cerebellar gait<unk>  and action<unk> .<unk>  features include parkinsonism, cognitive decline, and dysfunction of the autonomic nervous system.<unk>  is found in<unk>  X "premutation" carriers, which is defined as a trinucleotide repeat expansion of 55-200 CGG repeats in the<unk>  X mental retardation-1 (FMR1) gene. 4-40 CGG repeats in this gene is considered normal, while individual with >200 repeats have full<unk>  X Syndrome. In contrast to FXS full mutation, which is diagnosed early in childhood, symptoms of<unk>  manifest in individuals over the age of 50. Like FXS,<unk>  is most common and most severe in males due to the mutation's X-linked inheritance pattern.<unk>  has an incidence of 40-45% (male) and 16.1% (female) among FXS premutation carriers over the age of 50. FMR1 mRNA is found to be elevated in patients with<unk>  in contrast to FXS, where the FMR1 gene is transcriptionally silenced via DNA methylation. In both diseases the FMR1 gene product,<unk>  X mental retardation protein (FMRP) is diminished, but in<unk>  this is believed to be mediated by RNA toxicity, while in FXS, FMRP is absent due to transcriptional silencing. There is no cure for<unk> , but several of the symptoms can be managed with medication.
Fragile X-associated tremor/ataxia syndrome
X-linked dystonia parkinsonism
Huntington's disease-like syndrome
Fragile X syndrome
Rett syndrome
Dravet syndrome
Trichothiodystrophy
Parkinson-plus syndrome