the brain sample was much smaller than that using the blood sample (Fig. 5, Supplementary Figs. 23–25), with at least 50% of genes (DNAm sites) in common between the two sets. These results provide strong justification for the use of blood samples to discover genes related to brain phenotypes and diseases. In practice, we recommend using a blood data set with large sample size for discovery, and an additional data set from brain for replication. This paradigm is certainly applicable to other phenotypes and their related tissues.
