 In this technique, sodium bisulfite deaminates cytosine into uracil, but does not affect 5-methylcytosine, a methylated form of cytosine with a methyl group attached to carbon 5.When the bisulfite-treated DNA is amplified via polymerase chain reaction, the uracil is amplified as thymine and the methylated cytosines are amplified as cytosine.DNA sequencing techniques are then used to read the sequence of the bisulfite-treated DNA.