FMR1 and fragile X syndrome: Interestingly, activation of the FMR1 gene in transcriptionally silent FXS cells (replicating FXS individuals without any FMR1 RNA) using the DNA demethylation agent 5-aza-2′-deoxycytidine (5-AzadC) increased FMR1-217 RNA levels but failed to restore FMRP.