Facultative heterochromatin

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Medical Definition of Facultative heterochromatin

Facultative heterochromatin: Chromosome material that can be either heterochromatin or euchromatin.

The inactive X chromosome is made up of facultative heterochromatin. When a woman transmits that X chromosome to a son, the chromosome reverts to the euchromatic state and to genetic activity.


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Reviewed on 6/9/2016

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