Bisulfite modification for analysis of DNA methylation.

Bisulfite is known to deaminate cytosine in nucleic acids, while 5-methylcytosine resists this bisulfite action. For this reason, bisulfite treatment has been used for detecting 5-methylcytosine in DNA, a minor component of eukaryotic DNA, presently recognized as playing an important role in the control of gene function. This procedure, called bisulfite genomic sequencing, is a principal method for the analysis of DNA methylation in various biological phenomena, including human diseases such as cancer. This unit describes an efficient procedure utilizing a newly developed high-concentration bisulfite solution. Protocols for this methodology are supplemented with discussions focused on chemical aspects of the bisulfite treatment. Copyright 2008 by John Wiley & Sons, Inc.