Figure 2.

(A) Most human genes show pervasive DNA methylation at exons and introns, whereas hypomethylated genes show lack of DNA methylation in both exons and introns.(B) Example of a constitutively body-hypomethylated gene. DNA methylation is remarkably low along the exons (indicated by boxes) and introns along the COMTD1 gene in all 10 tissues analyzed (colored dots: adrenal in green, B-cell in orange, colon in purple, embryonic stem cell (ESC) in pink, hair follicle in green, liver in yellow, neuron in brown, ovary in gray, placenta in blue and sperm in black).