Semin Reprod Med 2001; 19(2): 125-132
DOI: 10.1055/s-2001-15392
Copyright © 2001 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA. Tel.: +1(212) 584-4662

Equality of the Sexes: Mammalian Dosage Compensation

Carolyn J. Brown
  • Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
Further Information

Publication History

Publication Date:
31 December 2001 (online)

ABSTRACT

X chromosome inactivation achieves dosage equivalence for most X-linked genes between the two X chromosomes in females and the single X chromosome in males. In this article the evidence for random inactivation of an X chromosome is reviewed, along with the exceptions that result in nonrandom inactivation. Another exception to X chromosome inactivation is the presence of genes that escape inactivation and are expressed from both the active and inactive X chromosomes. The phenotypic consequences of such expression from the inactive X chromosome are discussed. The major players in the process of inactivation are presented. Initiation of inactivation requires the functional RNA, XIST, and the subsequent stable inactivation of the X chromosome relies upon the recruitment of many other factors, the majority of which are generally associated with heterochromatin.

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