New insights into Rett syndrome pathogenesis: defining the role of MEPC2 in DNA damage

Rett Syndrome (RTT), a severe neurodevelopmental disorder, is caused by mutations in the X-linked MECP2 gene, which encodes a key chromatin-modifying protein. Originally described as a transcriptional repressor due to its ability to bind methylated DNA, RTT pathology was first to the misregulation of target genes. However, we present a synthesis of recent research that could re-frame the etiology of the disease. This model proposes that MECP2 deficiency triggers a cellular stress response that is one of the direct and primary causes of RTT pathology. The central hypothesis emerging from this body of work is that the loss of MECP2 function directly impairs cellular machinery for DNA repair. This failure in genomic maintenance results in an accumulation of DNA damage, which acts as a primary trigger for a senescence response triggered by the p53 pathway. This senescent state initiates a cascade of downstream physiological deficits, including severe metabolic dysfunction, reduced dendritic branching, and impaired synaptic activity. This model represents a repositioning of RTT from a disorder of simple transcriptional misregulation to a complex pathology rooted in a fundamental failure of genomic integrity and cellular homeostasis. The findings open new, targeted therapeutic avenues and offer not only a potential mechanistic understanding of RTT, and potentially other Intellectual Disability syndromes caused by mutations in genes that act in the same pathways.