Figure 2

Aberrant methylations and genetic alterations of 33 imprinted DMRs in 12 hepatoblastomas. Aberrant hypomethylation and aberrant hypermethylation found in each comparison are indicated by blue and red boxes, respectively. Aberrant methylation was identified by comparing adjacent normal liver tissue with normal control livers: AxC; tumors compared with normal control livers: TxC; and tumors compared with adjacent normal livers: TxA. The classes of these DMRs in previous reports are shown in Pat/Mat and Gametic/Somatic rows. ZDBF2-DMR was tentatively assigned as a somatic DMR based on experiments from mice [35]. MALDI-TOF MS revealed that 13 DMRs, such as TP73-DMR, SPTBN1-DMR, IGF2R-DMR2, IGF2-DMR0, IGF2-DMR2, WT1-AS-DMR, DLK1-DMR, IG-DMR-CG4, IG-DMR-CG6, TCEB3C-DMR, USP29-DMR, NNAT-DMR, and GNASXL-DMR did not show differential methylation in control livers. Most of these methylation statuses were confirmed by pyrosequencing analysis. Mat: maternally methylated DMR; Pat: paternally methylated DMR; gametic: gametic DMR; somatic: somatic DMR. ACN: abnormal copy number; LOH: loss of heterozygosity; UPD: paternal uniparental disomy; DD: difficult to decide.