HDAC3 and Alzheimer disease: For instance, although HDAC1 and HDAC2 are reduced in AD entorhinal cortex (Mastroeni et al., 2010), HDAC2, but not HDAC1 or HDAC3, are increased in hippocampal and entorhinal cortex neurons in AD compared to HDAC2 in control subjects (Graff et al., 2012).