This is due, in part, to its known functional association with the FXS-relevant protein FMRP (see sections “Synaptic FMRP: Regulator of mRNA and Local Translation,” “FMRP Targets,” “Synaptic CYFIP1: A Negative Regulator of Protein Synthesis and Cytoskeletal Dynamics,” and “FMRP and FMRP Targets in Psychiatric Disorders”) [31, 74]. This evidence concerns the gene FMR1 and fragile X syndrome.