FMR1 premutation is causally linked to fragile X-associated tremor/ataxia syndrome (FXTAS) and is the most prevalent monogenic NDD risk factor (Krueger and Bear, 2011; Chonchaiya et al., 2012; Leehey and Hagerman, 2012). This evidence concerns the gene FMR1 and fragile X-associated tremor/ataxia syndrome.