Repressive (closed symbols) and activating (open symbols) epigenetic marks cover all genes and affect transcriptional status. If an HSC divides, all genomic and epigenomic information must be properly propagated to daughter cells. If epigenetic marks are lost or gained, genes that should be expressed in HSC (B, C, and G) may become repressed; conversely, genes that should be repressed (A, D, F, and H) may become activated. As a consequence, functional stem cell activity of daughter cell 1 and 2 may be reduced compared with the HSC from which they derive.