FMR1 and fragile X syndrome: In particular, because much is known about the molecular and neurobiological basis of FXS, the considerable overlap observed with ASD-O may help to define specific phenotypes associated with known genetic variation, in this case variation in the FMR1. We observed correlations with molecular genetic variables that support this association – pragmatic language on the CASL and theory of mind were both associated with FMR1-related variation in the FXS group.