There are numerous approaches to decipher a whole genome DNA methylation profile ("methylome"), each varying in cost, throughput and resolution. The gold standard of these methods, whole genome bisulfite-sequencing (BS-seq), involves treatment of DNA with sodium bisulfite combined with subsequent high throughput sequencing. Using BS-seq, we generated a single-base-resolution methylome in human peripheral blood mononuclear cells (in press). This BS-seq map was then used as the reference methylome to compare two alternative sequencing-based methylome assays (performed on the same donor of PBMCs): methylated DNA immunoprecipitation (MeDIP-seq) and methyl-binding protein (MBD-seq). In our analysis, we found that MeDIP-seq and MBD-seq are complementary strategies, with MeDIP-seq more sensitive to highly methylated, high-CpG densities and MDB-seq more sensitive to highly methylated, moderate-CpG densities. Taking into account the size of a mammalian genome and the current expense of sequencing, we feel 3gigabases (Gbp) 45bp paired-end MeDIP-seq or MBD-seq uniquely mapped reads is the minimum requirement and cost-effective strategy for methylome pattern analysis.
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