High expression of the mammalian X chromosome in brain

Brain Res. 2006 Dec 18;1126(1):46-9. doi: 10.1016/j.brainres.2006.08.053. Epub 2006 Sep 15.


Divergence between the sex chromosomes has led to loss and differentiation of Y-linked genes and haplo-insufficiency for X-linked genes in males. A mechanism of dosage compensation, for which we recently found evidence in mammals, evolved to restore a balanced expression of the genome by doubling the transcriptional output from the X chromosome. X inactivation would then serve to avoid hyper-transcription of X-linked genes in females by silencing one X chromosome. We also found that, compared to the rest of the genome, the X chromosome contains an excess of genes highly expressed in brain tissues. The exceptionally important role of the X chromosome in brain function, evident from the prevalence of X-linked forms of mental retardation, is discussed in view of sex chromosome regulation and evolution and sexual reproduction.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Brain / embryology*
  • Brain / growth & development
  • Brain / metabolism
  • Brain Chemistry / genetics*
  • Dosage Compensation, Genetic / genetics
  • Female
  • Gene Expression Regulation, Developmental / genetics*
  • Genetic Diseases, X-Linked / genetics
  • Humans
  • Male
  • Mammals / genetics*
  • Sex Differentiation / genetics
  • X Chromosome / genetics*
  • X Chromosome Inactivation / genetics
  • Y Chromosome / genetics