Methyl-CpG-binding protein 2 (MeCP2) is a crucial nuclear protein predominantly found in mature neurons, initially identified as a transcriptional repressor that recognizes DNA methylation marks. It plays a significant role in neurodevelopment, with mutations in the MECP2 gene causing severe neurological disorders such as Rett syndrome (RTT) and MeCP2 duplication syndrome (MDS), which are characterized by progressive neurological dysfunction and developmental regression. MeCP2 exhibits a preference for binding methylated cytosines in both CpG and non-CpG contexts and can also bind unmethylated DNA. It is involved in chromatin organization and can interact with nucleosomes and other effector proteins, such as the NCoR1/2 co-repressor complex, to regulate gene expression. Recent research suggests that MeCP2's functions are more complex than previously thought, with its roles in neurodevelopment and adult brain function linked to its ability to act as a global chromatin regulator.