Bisulfite Modification for Analysis of DNA Methylation

Abstract 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. Curr. Protoc. Nucleic Acid Chem . 33:6.10.1‐6.10.15. © 2008 by John Wiley & Sons, Inc.