Unsupervised hierarchical cluster analysis. The heat map represents the unsupervised hierarchical cluster analysis of the 4 sample groups based on the DNA methylation at the 202 CpG sites. Each row represents a CpG site, and each column a sample. The percentage of CpG methylation is depicted using color scales of red (CpG methylation >50%) and green (CpG methylation <50%). Sample group labels are also indicated at the top of the heat map.