Sequencing 5-methylcytosine residues by the bisulphite method.

Measuring patterns of cytosine methylation in genomic DNA is most efficiently accomplished by use of the bisulphite method. This method depends on the large difference in reactivity of cytosines relative to 5-Methyl cytosines in genomic DNA to bisulphite. The chemistry and history of the method and recent developments which greatly increase its sensitivity, simplicity and reliability are described. An updated protocol to guide users is appended.