UNIT 9.7 Detection of Nonrandom X Chromosome Inactivation
Published Online: 1 FEB 2003
Copyright © 2003 by John Wiley and Sons, Inc.
Lab Protocol Title
Current Protocols in Human Genetics
How to Cite
Thouin, M. M., Giron, J. M. and Hoffman, E. P. 2003. Detection of Nonrandom X Chromosome Inactivation. Current Protocols in Human Genetics. 35:9.7:9.7.1–9.7.6.
- Published Online: 1 FEB 2003
- Published Print: OCT 2002
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This unit describes a PCR-based assay for distinguishing between the two X chromosomes in female cells and assessing the percentage of cells having each parental X chromosome active. Methylation of CpG residues in gene promoters is a major mechanism of transcriptional silencing. In mammalian female cells, hypermethylation is the way in which one X chromosome is inactivated. The X-inactivation assay described in the Basic Protocol relies on methylation sensitivity. In this unit, the highly polymorphic and therefore typically heterozygous (CAG)n region of the 5 end of the coding region of the human androgen receptor gene (HUMARA), at Xq11.2, is used to distinguish and compare the methylation activity of the X chromosomes.