Recently, several trans-acting X-chromosome inactivation factors (XCIFs) have been identified and the inhibitor of two XCIFs (PDPK1, AURKA) has been demonstrated to exhibit reactive expression of the WT MeCP2 allele on the inactive X chromosome, which can be considered as a potential therapy for RTT (Bhatnagar et al., 2014). The gene discussed is MECP2; the disease is Rett syndrome.