MECP2 and nervous system disorder: Invalidation of MeCP2 in mice indicates that MeCP1 cannot compensate for the absence of MeCP2 (Chen et al, 2001; Guy et al, 2001), and, conversely, invalidation of MBD2 does not prompt the neurological disorders observed in MeCP2-null mice mutants (Hendrich et al, 2001).