It has been shown that overexpression of APP-C31 in cortical neurons results in apoptotic cell death (McPhie et al., 2001), and that in a murine model of AD, prevention of APP-C31 generation by mutation of the D664 (of APP695) cleavage site reduced synaptic loss and improved synaptic transmission and spatial memory. The gene discussed is APP; the disease is Alzheimer disease.