Fig 2. Distribution of signal intensities and methylation β-values in mice and humans.

For the full set of 866,836 probes on the Illumina Infinium MethylationEPIC, the mouse samples have (A) low signal intensity compared to the two human samples, and (B) the β-values have a unimodal distribution that peaks at ~0.4. The two human samples have the expected bimodal distribution for β-values. For the conserved set of 13665 probes, both the (C) signal intensity, and the (D) β-value distribution in the mouse samples are comparable to the two human reference samples. The signal intensity for mouse1 is relatively low for the conserved set of probes and this sample plots as an outlier in the principal component analysis.