Immunoreactivity analyses of entorhinal cortex layer II, known for substantial AD pathology shows epigenetic dysfunction, particularly significant decrements (such as in 5-Methylcytosine and 5-methylcytidine) in neuronal immunoreactivity of all 10 of the epigenetic markers and factors studied by Mastroeni et al. (2010), including PHF1/PS396, DNMT1 (major methyltransferase) and 6 components of MeCP1/MBD2 methylation complex (MTA2, HDAC1, HDAC2, p66α, RbAp48, and MBD2/3). This evidence concerns the gene HDAC1 and Alzheimer disease.