Recently, it was shown that the expansion of CGG repeats in the 5′-UTR of the Fmr1 gene, which is closely associated with fragile X-associated tremor/ataxia syndrome (FXTAS), leads to the production of polyglycine or polyalanine by RAN translation (Todd et al., 2013), whose spontaneous aggregation may contribute to the FXTAS pathologies. This evidence concerns the gene RAN and fragile X-associated tremor/ataxia syndrome.