The significant CpG loci detected in the previous step actually form a methylation signature that differentiates between LCLs and B cells. We can build and visualize this methylation signature using clustering and a heat map.
- Select the LCLs vs. B cells spreadsheet in the spreadsheet pane on the left
- Select Cluster Based on Significant Genes from the Visualization panel of the Illumina BeadArray Methylation workflow
- Select Hierarchical Clustering for Specify Method (Figure 1)
- Select OK
- Verify that LCLs vs B cells is selected in the drop-down menu
- Select Standardize for Expression normalization (Figure 2)
The heat map will be displayed on the Hierarchical Clustering tab (Figure 3).
The experimental groups are rows, while the CpG loci from the LCLs vs B cells spreadsheet are columns. Methylation levels are compared between the LCLs and B cells groups. CpG loci with higher methylation are colored red, CpG loci with lower methylation are colored green. LCLs samples are colored orange and B cells samples are colored red in the dendrogram on the the left-hand side of the heat map.