Epigenomics by DNA Methylation Sequencing 331
Different approaches can be used for regional DNA methylation quanti-
cation. These include approaches to segment the genome into bins, sliding
windows of user- dened size (e.g. 100 bp) [48], or predened regions (such
as promoters, CpG islands, gene bodies, introns, etc.). The mean of methyla-
tion levels of individual cytosine sites, or alternatively the overall proportion
of methylated cytosines among all cytosines, within each of such regions can
be used to represent each region.
These calculations, however, do not take into consideration the possible
existence of SNPs that involve the change from C to T. Some algorithms,
such as Bis- SNP [49], remove this potential confounding factor through ...