Page 320 - 20dynamics of cancer

CELL LINEAGE HISTORY 305

Figure 14.6 Epidermal skin aberrations often follow the lines of Blaschko. This
pattern frequently traces mosaic cells that carry heritable aberrations, but the
particular genetic or epigenetic modifications have not been described for all
diseases (Taibjee et al. 2004; Chuong et al. 2006; Siegel and Sybert 2006). Draw-
ing by Davide Brunelli (http://www.med- ars.it), reprinted with permission.

early, invisible stages of carcinogenesis. As genetic technologies im-
prove, we will be able to measure the hidden mosaic evolution of cell
lineages that drives cancer progression.
In this section, I mention some readily apparent cases of mosaicism.
Those examples hint at the hidden processes of progression and at what
we may learn in the near future.

DEVELOPMENTAL MOSAICISM
A single mutational event during development transmits through de-
scendant cell lineages to create a large mosaic population. Each cell