FMR1 and fragile X syndrome: Two groups have shown that reactivation of FMR1 in FXS-iPSCs [70,71] and FXS-iPSC-derived neurons [70] can be achieved by excising out the expanded CGG repeats using CRISPR/Cas9, confirmed by demethylation of the FMR1 promoter, transition to an active chromatin state, and FMRP expression [70,71].