Correlation between fragile x- syndrome and ataxia
Fragile X syndrome (FXS) is one of the most common inherited cause of mental retardation . In the vast majority of cases, this X-linked disorder is caused by expansions of a CGG repeat in the 5′-untranslated (UTR) region of the FMR1 gene that arises due to the meiotic instability of certain alleles of this repeat tract. FXS causing alleles, or full mutations, contain 200 or more copies of the repeat that are hypermethylated and transcriptionally silenced. The unstable alleles that give rise to full mutations are called premutations and are associated with phenotypes distinct from FXS. The mutational mechanism, combined with the location of this gene on the X chromosome, leads to remarkable inheritance patterns in which the relevant alleles are passed from intellectually normal men through their unaffected daughters and then to affected sons. Clinical phenotype. Individuals with FXS may present with such as (large head) (long narrow face) (large ears) (large forehead) (flat feet) (loose joints) (otitis media), (seizures), and (gastrointestinal problems).
The fragile X syndrome, an X-linked dominant disorder with reduced penetrance, is one of the most common forms of inherited mental retardation. The cognitive, behavioral, and physical phenotype varies by sex, with males being more severely affected because of the X-linked inheritance of the mutation Fragile X-associated tremor/ataxia syndrome is a progressive neurodegenerative disease that occurs in premutation carriers of 55-200 CGG repeats in FMR1 and is characterized by kinetic tremor, gait ataxia, parkinsonism, executive dysfunction, and neuropathy.