Specifically, FXTAS is a monogenic late onset neurodegenerative disorder that affects older males and females and caused by an expansion of 55–200 CGG trinucleotide repeats in the 5′ UTR of the Fragile X mental retardation 1 (FMR1) gene that encodes the Fragile X mental retardation protein (FMRP) (Hagerman and Hagerman, 2015, 2016). Here, FMR1 is linked to fragile X-associated tremor/ataxia syndrome.