Medical Definition of X inactivation
1.
The inactivation of one or other of each pair of X chromosomes to form the Barr body in female mammalian somatic cells.
Thus tissues whose original zygote carried heterozygous X borne genes should have individual cells expressing one or other but not both of the X borne gene products. The inactivation is thought to occur early in development and leads to mosaicism of expression of such genes in the body.
See: Lyon hypothesis.
This entry appears with permission from the Dictionary of Cell and Molecular Biology
(11 Mar 2008)
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Lexicographical Neighbors of X Inactivation
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