FMR1 and fragile X syndrome: Lastly, the CYFIP1 (cytoplasmic fragile X mental retardation 1 FMR1 interacting protein 1; OMIM # 606322) gene encodes a protein that interacts with FMRP, the protein produced by the FMR1 (Fragile X Mental Retardation 1; OMIM # 309550) gene and in which triplet-repeat expansion causes fragile X syndrome, the most common cause of inherited cognitive disabilities in families [13].