Bisulfite Conversion is a process in which genomic DNA is denatured (made single-stranded) and treated with sodium bisulfite, leading to deamination of unmethylated cytosines into uracils, while methylated cytosines (both 5-methylcytosine and 5-hydroxymethylcytosine) remain unchanged. The DNA is then amplified by PCR where the uracils are converted to thymines.
Bisulfite converted DNA can be analyzed for gene-or allele-specific methylation patterns with primers that differentiate between methylated and unmethylated sequences, or adapted for genome-wide DNA methylation analysis. Comparing the sequence of the converted DNA to untreated DNA creates a methylation profile of the sample. The results provide single nucleotide resolution information about the methylation status.