Premutations causing FMR1 mRNA overexpression and reduced FMRP synthesis, underly both fragile X-associated tremor/ataxia syndrome (FXTAS, OMIM #300623) and fragile X-associated primary ovarian insufficiency (FXPOI, OMIM #311360). Here, FMR1 is linked to fragile X-associated tremor/ataxia syndrome.