For example, in AD patients and animal AD models some genes are hypermethylated (MTHFR, APOEε4, MAPT, SORBS3, Tau), while others are hypomethylated (CREB5, S100A2, PP2A, BACE, PS1) or exhibit no significant difference (APP) [35,129]. Here, CREB5 is linked to Alzheimer disease.