MECP2 and myelodysplastic syndrome: To account for the variability in MECP2 levels in MDS, we selected two human transgenic MDS models developed by the Zoghbi lab36—MECP2Tg1 (Tg1), which expresses MECP2 at approximately two-fold the wild-type level, and MECP2Tg3 (Tg3), which expresses MECP2 at approximately three- to five-fold the wild-type level—to evaluate the efficacy of lead siRNAs.