Premutation carriers often have elevated FMR1 mRNA with near-normal or modestly reduced FMRP; and RNA-mediated toxicity is implicated in Fragile X-Associated Tremor/Ataxia Syndrome and Fragile X-Associated Primary Ovarian Insufficiency (FXTAS/FXPOI) and in neurodevelopmental/psychiatric features grouped as Fragile X-associated neurodevelopmental disorder (FXAND) in some carriers [11,13-18]. Here, FMR1 is linked to fragile X-associated tremor/ataxia syndrome.