FMR1 and Adult onset: Fragile X-associated tremor/ataxia syndrome (FXTAS) is an adult-onset neurodegenerative disorder caused by a CGG repeat expansion (55–200 repeats, premutation) within the 5′ UTR of the fragile X gene (fragile X messenger ribonucleoprotein 1 gene, FMR1) [1,2,3].