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.^[1][2] 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.^[3]

References

1. Frommer, M.; McDonald, L. E.; Millar, D. S.; Collis, C. M.; Watt, F.; Grigg, G. W.; Molloy, P. L.; Paul, C. L. (1992-03-01). "A genomic sequencing protocol that yields a positive display of 5-methylcytosine residues in individual DNA strands". Proceedings of the National Academy of Sciences of the United States of America. 89 (5): 1827–1831. doi:10.1073/pnas.89.5.1827. ISSN 0027-8424. PMC 48546. PMID 1542678.
2. Clark, S J; Harrison, J; Paul, C L; Frommer, M (1994-08-11). "High sensitivity mapping of methylated cytosines.". Nucleic Acids Research. 22 (15): 2990–2997. doi:10.1093/nar/22.15.2990. ISSN 0305-1048. PMC 310266. PMID 8065911.
3. Stevens, Michael; Cheng, Jeffrey B.; Li, Daofeng; Xie, Mingchao; Hong, Chibo; Maire, Cécile L.; Ligon, Keith L.; Hirst, Martin; Marra, Marco A. (2013-09-01). "Estimating absolute methylation levels at single-CpG resolution from methylation enrichment and restriction enzyme sequencing methods". Genome Research. 23 (9): 1541–1553. doi:10.1101/gr.152231.112. ISSN 1088-9051. PMC 3759729. PMID 23804401.