The dynamics of X-chromosome inactivation in mouse development.

Mammals utilize chromosomes to determine sex, but this leads to a problem with gene inequality. In the mouse, gene dosage disparity is evident by the presence of two X chromosomes in the female and a single X and Y chromosome in the male. To balance the X-linked transcriptional dose difference between the sexes, one of the two female X-chromosomes is silenced to equal the dose of XY males-a crucial developmental process known as X-chromosome inactivation. Here we highlight dosage compensation in the mouse, and detail the known mechanisms to set and erase these epigenetic marks during development.