Clusters 1, 2, 3, 5, and 6 represented genes that were highly expressed in stages of embryonic development, but were expressed at low levels in adult livers (Fig. S1C), including oncofetal genes Afp, Gpc3, Sall4 (cluster 2), H19 (Cluster 3) and Igf2 (Cluster 5), which are re-expressed in liver cancer (ref. [18–22]). The gene discussed is IGF2; the disease is liver cancer.