Rett syndrome (RTT) is a neurodevelopmental disorder characterized by loss of acquired skills after a period of normal development in infant girls. The responsible gene, encoding methyl-CpG binding protein 2 (MeCP2), was recently discovered. Here we explore the spectrum of phenotypes resulting from MECP2 mutations. Both nonsense (R168X and R255X) and missense (R106W and R306C) mutations have been found, with multiple recurrences. R168X mutations were identified in six unrelated sporadic cases, as well as in two affected sisters and their normal mother. The missense mutations were de novo and affect conserved domains of MeCP2. All of the nucleotide substitutions involve C-->T transitions at CpG hotspots. A single nucleotide deletion, at codon 137, that creates a L138X stop codon within the methyl-binding domain was found in an individual with features of RTT and incontinentia pigmenti. An 806delG deletion causing a V288X stop in the transcription-repression domain was identified in a woman with motor-coordination problems, mild learning disability, and skewed X inactivation; in her sister and daughter, who were affected with classic RTT; and in her hemizygous son, who died from congenital encephalopathy. Thus, some males with RTT-causing MECP2 mutations may survive to birth, and female heterozygotes with favorably skewed X-inactivation patterns may have little or no involvement. Therefore, MECP2 mutations are not limited to RTT and may be implicated in a much broader phenotypic spectrum.

The transcription factors Gata3 and Zbtb7b are required for intrathymic CD4 T cell differentiation, but their precise roles in this process remain unclear. Here we show that, contrary to previous findings, Gata3 disruption blocked CD4 T cell lineage differentiation before CD4 lineage commitment, and in some contexts permitted 'redirection' of MHC class II-restricted thymocytes into the CD8 lineage. We found that Gata3 promotes Zbtb7b expression, and binds within a region of the Zbtb7b locus established as critical for Zbtb7b expression. Finally, Zbtb7b promoted CD4 lineage differentiation in a manner dependent on Gata3, but inhibited CD8 lineage differentiation independently of Gata3. We propose that Gata3 acts as a specification factor for the CD4 lineage, "upstream" of the Zbtb7b-controlled CD4 commitment checkpoint.

High Slug expression is closely correlated with poor prognosis in patients with BLBC. We speculate that this may be attributed to the involvement of Slug in the EMT of BLBC.