Abstract
X-chromosome inactivation occurs randomly for one of the two X chromosomes in female cells during development. Inactivation occurs when RNA transcribed from the Xist gene on the X chromosome from which it is expressed spreads to coat the whole X chromosome. In the first issue of Epigenetics and Chromatin, Nesterova and colleagues investigate the role of the RNA interference pathway enzyme Dicer in DNA methylation of the Xist promoter.