Cell, Vol 92, 657-664. In female mammals, one of the two X chromosomes becomes inactive in all cells.
Different alleles indicate different probabilities of being chosen.
Female progeny who had inherited the mutated gene paternally died during embryogenesis due to a failure to undergo X inactivation. However, female progeny who inherited the mutation maternally were healthy, with the wild type paternal X chromosome inactive in every cell. This scheme is indicative of nonrandom selection of the X chromosome for inactivation in mice, in that the paternal X chromosome is always the one that is inactivated. The paper I am reviewing further examines this mutation by attempting to determine if the consistent inactivation of the paternal wild type X chromosome in this mice strain occurred by random choice or by primary nonrandom selection. The Xist gene is transcribed into RNA which upon X inactivation forms a heterochromatin coat around the inactive chromosome.