MECP2 and atypical Rett syndrome: Also, in contrast to the Kerr et al study, recent studies of isoform-specific MECP2 knockouts in mice appear to show that knockout of MECP2_e2 has no detrimental effect on normal neurodevelopment and behavior [9], whereas knockdown of MECP2_e1 fully recapitulates the neurological symptoms seen in Rett syndrome [10].