Maintenance of XCI

Maintenance of X-chromosome inactivation (XCI) refers to the ongoing process that keeps one of a female’s two X chromosomes turned off in each cell. This ensures a balance of gene expression between males and females. Once the inactivation is established early in development, specific molecules and epigenetic marks (like DNA methylation and histone modifications) maintain this silent state. These modifications act as a biological memory, preventing the active X from reactivating. Maintaining XCI is essential for normal development and preventing diseases linked to abnormal gene dosage from the X chromosome.