Fragile X Syndrome (FXS) is the most common monogenic cause of intellectual disability, where a “CGG” triplet expansion at the 5′-UTR of the FMR1 gene is responsible for the loss of the Fragile X mental retardation protein (FMRP), a synaptically expressed RNA-binding protein regulating translation [2]. The gene discussed is FMR1; the disease is Intellectual disability.