Figure 1.

Drift in the epigenetic landscape that occurs with environmental and biological factors associated with aging leads to transcriptional differences between the HSC compartments in the young population compared with the elderly population. This is proposed to give rise to expansion of particular clones within the heterogeneous HSC pool to produce a myeloid- and platelet-skewed haematopoietic system. These changes may play an important role in driving the increased incidence of myeloproliferative disorders, myeloid malignancies, infection, and acute arterial thrombosis observed in the elderly.