APP and Alzheimer disease: In spite of some reports suggesting a hypomethylation in the promoter of APP in the temporal cortex of AD (West et al., 1995) and aging (Tohgi et al., 1999), studies using higher sample numbers have not been able to find differences in frontal cortex, parietal cortex, and hippocampus of AD patients (Yoshikai et al., 1990; Wang et al., 2008a; Barrachina and Ferrer, 2009).