Why is X chromosome inactivation important?

Question

Oliver Antoine · Accepted Answer

X chromosome inactivation prevents females from having twice as many gene products as males, who only have a single copy of the X chromosome.

The inactive X chromosome condenses into a Barr body, which is a compact structure. Females carry two copies of the X chromosome, resulting in a double dose of X linked genes; to correct this imbalance, mammalian females have evolved the unique mechanism of X chromosome inactivation. In contrast to the gene-poor Y chromosome, the X chromosome contains over 1000 genes, that are essential for proper development and cell viability. Parts of somatic tissue inactivate the maternal X chromosome, while other parts inactivate the paternal X chromosome. This is a random process that happens during the embryonic stage. Barr bodies that are transcriptionally silent thereby preserve gene equality between males (XY) and females (XX).

Sebastian Alvarez · Answer

undefined X chromosome inactivation is important because it ensures dosage compensation between males and females. In mammals, females have two X chromosomes while males have one X chromosome and one Y chromosome. Without X chromosome inactivation, females would have twice as many active X-linked genes as males, leading to potentially harmful gene overdosage in females. X chromosome inactivation balances the gene expression between males and females by randomly silencing one of the X chromosomes in each female cell, ensuring that both males and females have similar levels of X-linked gene expression.