While carriers of FMR1 premutation alleles do not develop FXS, 40% of male and 16–20% of female premutation carriers suffer from fragile X-associated tremor/ataxia syndrome (FXTAS), and 20% of female carriers are reported to develop fragile X-associated primary ovarian insufficiency (FXPOI) [5]. This evidence concerns the gene PSMB5 and fragile X-associated tremor/ataxia syndrome.