Sample clustering based on DNA methylation data. A. A dendrogram of hierarchical clustering of 18 tissue samples using all 27,578 DNA methylation markers. B. A heatmap of DNA methylation data with 488 CpG markers that have the highest standard deviation across all samples (sd > 0.2). Each row is a sample, and each column is a marker. A dendrogram by hierarchical clustering is given by hierarchical clustering. C. Methylation samples are plotted on the second and third principal components. The black circle points are liver samples, the red squares are kidney, and the green triangles are heart.