In previous reports, different PSCs were shown to harbor unique CpG methylation profiles due to either residual somatic cell memory or aberrant methylation (Lister et al., 2011). To determine whether the epigenetic differences result from the cell type of origin, we grouped iPSC lines into F- and B-iPSCs and compared them using RRBS. In total we identified 655 differentially methylated CpG sites (DMCs) (0.23% of common CGs). Hypermethylated DMCs predominated in B-iPSCs (566 = 86.4% of DMCs) compared with F-iPSCs (Figure 2A).
