Epigenome-wide association studies (EWAS) using bisulfite conversion approaches coupled with the Illumina Infinium® HumanMethylation450 BeadChip have demonstrated robust and reproducible differences in total DNA methylation at a number of loci in AD brain [17–22], including ankyrin 1 (ANK1), ABCA7, BIN1, TREM2, and the HOXA and HOXB gene clusters. Here, TREM2 is linked to Alzheimer disease.