Whole genome bisulfite sequencing

Whole genome bisulfite sequencing (WGBS), is a next-generation sequencing technology used to determine the DNA methylation status of single cytosines by treating the DNA with sodium bisulfite before sequencing. Sodium bisulfite is a chemical compound that converts unmethylated cytosines into uracil. The cytosines that haven't converted in uracil are methylated. After sequencing, the unmethylated cytosines appear as thymines.

This technique measures single-cytosine methylation levels genome-wide and directly estimates the ratio of molecules methylated rather than enrichment levels. However, this method requires essentially resequencing the entire genome multiple times for every experiment.