Second, repeats generally do not exceed a few hundred (± 200) in fragile X tremor ataxia syndrome (FXTAS; O'Donnell & Warren, 2002) although longer repeats are associated with fragile X syndrome due to FMR1 loss of function (Verkerk et al,1991). This evidence concerns the gene FMR1 and fragile X-associated tremor/ataxia syndrome.