MECP2 and Rett syndrome: Several studies have shown that RTT iPSC-derived neurons exhibit maturation and electro-physiological defects reminiscent of those seen in RTT patients and mouse models [49,50,51], and we have shown that astrocyte-specific genes (e.g., GFAP) are aberrantly expressed in neural cells generated from iPSC lines that lack MeCP2 expression, which leads to the de-suppression of astrocyte-specific genes (Figure 1A) [52].