We approach this review with a focus primarily on features seen outside of the known diagnoses of FXS, FXTAS, and FXPOI, in order to identify additional conditions that may be directly associated with an FMR1 expansion; however, we compare the relative strength of evidence for each feature among those with and without FXTAS or FXPOI in the tables. Here, FMR1 is linked to fragile X-associated tremor/ataxia syndrome.