Xist (X-inactive specific transcript) is an RNA gene on the X chromosome of the placental mammals that acts as major effector of the X inactivation process.

X inactivation is an early developmental process in mammalian females that transcriptionally silences one of the pair of X chromosomes, thus providing dosage equivalence between males and females. The process is regulated by several factors, including a region of chromosome X called the X inactivation center (XIC). The XIST gene is expressed exclusively from the XIC of the inactive X chromosome. The transcript is spliced but apparently does not encode a protein. The transcript remains in the nucleus where it coats the inactive X chromosome. Alternatively spliced transcript variants have been identified, but their full length sequences have not been determined. Mutations in the XIST promoter cause familial skewed X inactivation. [provided by RefSeq]. Publication Note: This RefSeq record includes a subset of the publications that are available for this gene. Please see the Gene record to access additional publications.